Journal of the International Neuropsychological Society : JINS, Vol. 5, No. 4. (May 1999), pp. 357-369.
A major use of neuropsychological assessment is to measure changes in functioning over time; that is, to determine whether a difference in test performance indicates a real change in the individual or just chance variation. Using 7 illustrative test measures and retest data from 384 neurologically stable adults, this paper compares different methods of predicting retest scores, and of determining whether observed changes in performance are unusual. The methods include the Reliable Change Index, with and without correction for practice effect, and models based upon simple and multiple regression. For all test variables, the most powerful predictor of follow-up performance was initial performance. Adding demographic variables and overall neuropsychological competence at baseline significantly but slightly improved prediction of all follow-up scores. The simple Reliable Change Index without correction for practice performed least well, with high error rates and large prediction intervals (confidence intervals). Overall prediction accuracy was similar for the other three methods; however, different models produce large differences in predicted scores for some individuals, especially those with extremes of initial test performance, overall competency, or demographics. All 5 measures from the Halstead-Reitan Battery had residual (observed--predicted score) variability that increased with poorer initial performance. Two variables showed significant nonnormality in the distribution of residuals. For accurate prediction with smallest prediction--confidence intervals, we recommend multiple regression models with attention to differential variability and nonnormality of residuals.
Friday, May 2, 2008
Detecting change: A comparison of three neuropsychological methods, using normal and clinical samples.
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Vol. 16, No. 1. (January 2001), pp. 75-91.
Detecting change in individual patients is an important goal of neuropsychological testing. However, limited information is available about test-retest changes, and well-validated prediction methods are lacking. Using a large nonclinical subject group (N = 384), we recently investigated test-retest reliabilities and practice effects on the Wechsler Adult Intelligence Scale and Halstead-Reitan Battery. Data from this group also were used to develop models for predicting follow-up test scores and establish confidence intervals around them. In this article we review those findings, examine their generalizability to new nonclinical and clinical groups, and explore the sensitivity of the prediction models to real change. Despite similarities across samples in reliability coefficients and practice effects, limits to the generalizability of prediction methods were found. Also, when multiple test measures were considered together, one or more "significant" changes were common in all (including stable) subject groups. By employing normative cut-offs that correct for this, sensitivity of the models to neurological recovery and deterioration was modest to good. More complex regression models were not more accurate than the simpler Reliable Change Index with correction for practice effects when confidence intervals for all methods were adjusted for variations in level of baseline test performance.
Detecting change in individual patients is an important goal of neuropsychological testing. However, limited information is available about test-retest changes, and well-validated prediction methods are lacking. Using a large nonclinical subject group (N = 384), we recently investigated test-retest reliabilities and practice effects on the Wechsler Adult Intelligence Scale and Halstead-Reitan Battery. Data from this group also were used to develop models for predicting follow-up test scores and establish confidence intervals around them. In this article we review those findings, examine their generalizability to new nonclinical and clinical groups, and explore the sensitivity of the prediction models to real change. Despite similarities across samples in reliability coefficients and practice effects, limits to the generalizability of prediction methods were found. Also, when multiple test measures were considered together, one or more "significant" changes were common in all (including stable) subject groups. By employing normative cut-offs that correct for this, sensitivity of the models to neurological recovery and deterioration was modest to good. More complex regression models were not more accurate than the simpler Reliable Change Index with correction for practice effects when confidence intervals for all methods were adjusted for variations in level of baseline test performance.
Neuropsychological testing for assessment of treatment effects: methodologic issues.
CNS spectrums, Vol. 7, No. 4. (April 2002)
Neuropsychological (NP) testing is now recognized as an important method for evaluating treatment effects. However, there are limitations to how these tests are currently used in most drug treatment protocols. Changes in cognition are typically defined in statistical terms, with little knowledge as to whether the observed differences are meaningful in any other sense. Methods for assessing changes in test scores need to account for test-retest reliability, practice effects, regression to the mean, and the impact of initial performance. All of these factors may vary according to the individual characteristics of the subject. This article reviews two methods from the NP literature that have attempted to account for these sources of test-retest bias. The reliable change index provides a confidence interval for predicted change by taking into account the test-retest reliability of the measure. Standardized regression-based measures use a more sophisticated statistical approach that enables them to better account for other potential sources of confound. Use of this methodology has been limited to studies of epilepsy surgery and sports-related concussion. These methods have the potential for enhancing the interpretation of NP test data in drug treatment protocols by providing an empirically based definition of clinically meaningful change.
Neuropsychological (NP) testing is now recognized as an important method for evaluating treatment effects. However, there are limitations to how these tests are currently used in most drug treatment protocols. Changes in cognition are typically defined in statistical terms, with little knowledge as to whether the observed differences are meaningful in any other sense. Methods for assessing changes in test scores need to account for test-retest reliability, practice effects, regression to the mean, and the impact of initial performance. All of these factors may vary according to the individual characteristics of the subject. This article reviews two methods from the NP literature that have attempted to account for these sources of test-retest bias. The reliable change index provides a confidence interval for predicted change by taking into account the test-retest reliability of the measure. Standardized regression-based measures use a more sophisticated statistical approach that enables them to better account for other potential sources of confound. Use of this methodology has been limited to studies of epilepsy surgery and sports-related concussion. These methods have the potential for enhancing the interpretation of NP test data in drug treatment protocols by providing an empirically based definition of clinically meaningful change.
Standard error in the Jacobson and Truax Reliable Change Index: the "classical approach" leads to poor estimates.
Journal of the International Neuropsychological Society : JINS, Vol. 10, No. 6. (October 2004)
Different authors have used different estimates of variability in the denominator of the Reliable Change Index (RCI). Maassen attempts to clarify some of the differences and the assumptions underlying them. In particular he compares the 'classical' approach using an estimate S(Ed) supposedly based on measurement error alone with an estimate S(Diff) based on the variability of observed differences in a population that should have no true change. Maassen concludes that not only is S(Ed) based on classical theory, but it properly estimates variability due to measurement error and practice effect while S(Diff) overestimates variability by accounting twice for the variability due to practice. Simulations show Maassen to be wrong on both accounts. With an error rate nominally set to 10%, RCI estimates using S(Diff) wrongly declare change in 10.4% and 9.4% of simulated cases without true change while estimates using S(Ed) wrongly declare change in 17.5% and 12.3% of the simulated cases (p < .000000001 and p < .008, respectively). In the simulation that separates measurement error and practice effects, SEd estimates the variability of change due to measurement error to be .34, when the true variability due to measurement error was .014. Neuropsychologists should not use SEd in the denominator of the RCI.
Different authors have used different estimates of variability in the denominator of the Reliable Change Index (RCI). Maassen attempts to clarify some of the differences and the assumptions underlying them. In particular he compares the 'classical' approach using an estimate S(Ed) supposedly based on measurement error alone with an estimate S(Diff) based on the variability of observed differences in a population that should have no true change. Maassen concludes that not only is S(Ed) based on classical theory, but it properly estimates variability due to measurement error and practice effect while S(Diff) overestimates variability by accounting twice for the variability due to practice. Simulations show Maassen to be wrong on both accounts. With an error rate nominally set to 10%, RCI estimates using S(Diff) wrongly declare change in 10.4% and 9.4% of simulated cases without true change while estimates using S(Ed) wrongly declare change in 17.5% and 12.3% of the simulated cases (p < .000000001 and p < .008, respectively). In the simulation that separates measurement error and practice effects, SEd estimates the variability of change due to measurement error to be .34, when the true variability due to measurement error was .014. Neuropsychologists should not use SEd in the denominator of the RCI.
A comparison of methods for measuring cognitive change in older adults.
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Vol. 20, No. 3. (May 2005), pp. 321-333.
Well-researched statistical methods are required to guide clinicians in determining the significance of test score changes in serial neuropsychological assessment of older adults. The following six change score methods were examined using five-year test-retest data from the Canadian Study of Health and Aging: the standard deviation method, three reliable change indices (RCIs), and two standardized regression-based methods. Changes in scores on four memory measures were examined in cognitively healthy older adults, and the RCI with a correction for practice/aging effects most accurately classified this normal variability. Diagnostic change (i.e., developing dementia versus remaining cognitive healthy) was also examined in relation to memory test score changes. All change score methods were significantly associated with diagnostic change, though the strength of association varied by measure and method. In contrast to some previous research, RCIs were found to be useful when making diagnostic discriminations in older adults.
Well-researched statistical methods are required to guide clinicians in determining the significance of test score changes in serial neuropsychological assessment of older adults. The following six change score methods were examined using five-year test-retest data from the Canadian Study of Health and Aging: the standard deviation method, three reliable change indices (RCIs), and two standardized regression-based methods. Changes in scores on four memory measures were examined in cognitively healthy older adults, and the RCI with a correction for practice/aging effects most accurately classified this normal variability. Diagnostic change (i.e., developing dementia versus remaining cognitive healthy) was also examined in relation to memory test score changes. All change score methods were significantly associated with diagnostic change, though the strength of association varied by measure and method. In contrast to some previous research, RCIs were found to be useful when making diagnostic discriminations in older adults.
A battery approach for measuring neuropsychological change.
Archives of clinical neuropsychology : the official journal of the National Academy of Neuropsychologists, Vol. 21, No. 1. (January 2006), pp. 83-89.
The accurate interpretation of serial neuropsychological testing is a fundamental activity of neuropsychologists in clinical and research settings. Although prior research supports the construct validity of several individual tests for the reliable measurement of cognitive change, neuropsychologists are often interested in detecting changes in cognitive functioning across a battery of tests. In the present study, we examined the specificity of a modified Reliable Change Index (RCI) methodology applied across a focused battery of commonly used neuropsychological tests. Fifty-seven healthy controls underwent neuropsychological assessment at two time points separated by approximately 1 year. Test-retest reliability coefficients and standard RCI confidence intervals for the individual tests were broadly comparable with prior research in healthy populations. Battery change scores were generated by calculating z-scores of change for each individual test, which were summed across the entire test battery. The RCI methodology was applied to the summed z-score to provide a 90% confidence interval as an indicator of overall cognitive stability. These battery RCI normative standards demonstrated adequate specificity when applied to 29 persons with HIV-1 infection who were classified as medically and neurologically stable. Findings from this study may be useful for both clinicians and researchers seeking normative standards for determining reliable changes in performance across a commonly used battery of neuropsychological tests.
The accurate interpretation of serial neuropsychological testing is a fundamental activity of neuropsychologists in clinical and research settings. Although prior research supports the construct validity of several individual tests for the reliable measurement of cognitive change, neuropsychologists are often interested in detecting changes in cognitive functioning across a battery of tests. In the present study, we examined the specificity of a modified Reliable Change Index (RCI) methodology applied across a focused battery of commonly used neuropsychological tests. Fifty-seven healthy controls underwent neuropsychological assessment at two time points separated by approximately 1 year. Test-retest reliability coefficients and standard RCI confidence intervals for the individual tests were broadly comparable with prior research in healthy populations. Battery change scores were generated by calculating z-scores of change for each individual test, which were summed across the entire test battery. The RCI methodology was applied to the summed z-score to provide a 90% confidence interval as an indicator of overall cognitive stability. These battery RCI normative standards demonstrated adequate specificity when applied to 29 persons with HIV-1 infection who were classified as medically and neurologically stable. Findings from this study may be useful for both clinicians and researchers seeking normative standards for determining reliable changes in performance across a commonly used battery of neuropsychological tests.
Assessment of statistical change criteria used to define significant change in neuropsychological test performance following cardiac surgery.
European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery, Vol. 29, No. 1. (January 2006), pp. 82-88.
OBJECTIVE: This paper compares four techniques used to assess change in neuropsychological test scores before and after coronary artery bypass graft surgery (CABG), and includes a rationale for the classification of a patient as overall impaired. METHODS: A total of 55 patients were tested before and after surgery on the MicroCog neuropsychological test battery. A matched control group underwent the same testing regime to generate test-retest reliabilities and practice effects. Two techniques designed to assess statistical change were used: the Reliable Change Index (RCI), modified for practice, and the Standardised Regression-based (SRB) technique. These were compared against two fixed cutoff techniques (standard deviation and 20% change methods). RESULTS: The incidence of decline across test scores varied markedly depending on which technique was used to describe change. The SRB method identified more patients as declined on most measures. In comparison, the two fixed cutoff techniques displayed relatively reduced sensitivity in the detection of change. CONCLUSIONS: Overall change in an individual can be described provided the investigators choose a rational cutoff based on likely spread of scores due to chance. A cutoff value of > or =20% of test scores used provided acceptable probability based on the number of tests commonly encountered. Investigators must also choose a test battery that minimises shared variance among test scores.
OBJECTIVE: This paper compares four techniques used to assess change in neuropsychological test scores before and after coronary artery bypass graft surgery (CABG), and includes a rationale for the classification of a patient as overall impaired. METHODS: A total of 55 patients were tested before and after surgery on the MicroCog neuropsychological test battery. A matched control group underwent the same testing regime to generate test-retest reliabilities and practice effects. Two techniques designed to assess statistical change were used: the Reliable Change Index (RCI), modified for practice, and the Standardised Regression-based (SRB) technique. These were compared against two fixed cutoff techniques (standard deviation and 20% change methods). RESULTS: The incidence of decline across test scores varied markedly depending on which technique was used to describe change. The SRB method identified more patients as declined on most measures. In comparison, the two fixed cutoff techniques displayed relatively reduced sensitivity in the detection of change. CONCLUSIONS: Overall change in an individual can be described provided the investigators choose a rational cutoff based on likely spread of scores due to chance. A cutoff value of > or =20% of test scores used provided acceptable probability based on the number of tests commonly encountered. Investigators must also choose a test battery that minimises shared variance among test scores.
Measuring cognitive change in older adults. Do reliable change indices of the SIDAM predict dementia?
Journal of neurology, Vol. 254, No. 10. (October 2007), pp. 1359-1365.
BACKGROUND : In persons free of dementia, accelerated cognitive decline might be an indicator of pathological impairment and a potential predictor of future dementia. However, the reliable detection of cognitive decline is a challenging task in some cases. Changes in psychometric test scores do not necessarily result from 'true' clinical change and may result from factors like measurement error and regression to the mean. Reliable Change Indices (RCI) facilitate the interpretation of changes in psychometric test scores. However, it is unknown whether RCI predict future dementia in persons who are presently free of dementia. AIM : To examine for a widely used screening instrument for cognitive impairment and dementia (SIDAM) whether RCI methods contribute to the prediction of dementia diagnosis in older adults who are presently free of dementia. METHODS : A sample of 554 elderly individuals aged 75 and over who participated in the Leipzig Longitudinal Study of the Aged (LEILA 75+) and had no diagnosis of dementia at the first two visits. Participants have been tested with the test part of the SIDAM at maximal six visits with 1.5 year intervals. In all participants, RCI for change in SIDAM score (Time 1 to Time 2) have been computed. The main outcome measure was the diagnosis of dementia. RESULTS : ROC analyses showed that RCI were significant predictors of future dementia. Participants who deteriorated in SIDAM score -4 points or more had a three-fold increased risk of developing dementia (odds ratio 2.71, CI 1.6 to 4.6). However, RCI were not independent predictors of dementia in multivariate analysis. CONCLUSION : RCI may support the early diagnosis of dementia.
BACKGROUND : In persons free of dementia, accelerated cognitive decline might be an indicator of pathological impairment and a potential predictor of future dementia. However, the reliable detection of cognitive decline is a challenging task in some cases. Changes in psychometric test scores do not necessarily result from 'true' clinical change and may result from factors like measurement error and regression to the mean. Reliable Change Indices (RCI) facilitate the interpretation of changes in psychometric test scores. However, it is unknown whether RCI predict future dementia in persons who are presently free of dementia. AIM : To examine for a widely used screening instrument for cognitive impairment and dementia (SIDAM) whether RCI methods contribute to the prediction of dementia diagnosis in older adults who are presently free of dementia. METHODS : A sample of 554 elderly individuals aged 75 and over who participated in the Leipzig Longitudinal Study of the Aged (LEILA 75+) and had no diagnosis of dementia at the first two visits. Participants have been tested with the test part of the SIDAM at maximal six visits with 1.5 year intervals. In all participants, RCI for change in SIDAM score (Time 1 to Time 2) have been computed. The main outcome measure was the diagnosis of dementia. RESULTS : ROC analyses showed that RCI were significant predictors of future dementia. Participants who deteriorated in SIDAM score -4 points or more had a three-fold increased risk of developing dementia (odds ratio 2.71, CI 1.6 to 4.6). However, RCI were not independent predictors of dementia in multivariate analysis. CONCLUSION : RCI may support the early diagnosis of dementia.
Measuring cognitive change in older adults: reliable change indices for the SIDAM.
Journal of neurology, Vol. 254, No. 1. (January 2007), pp. 91-98.
BACKGROUND: In clinical settings, neuropsychological tests and screening instruments are often used to measure cognitive change over time. However, the interpretation of changes in test scores is often difficult. For most instruments there is no information how much change occurs normally in cognitively healthy individuals. AIM: To examine what is a reliable change for a widely used screening instrument for cognitive impairment and dementia. METHODS: A Sample of 119 cognitively normal elderly individuals aged 75 and over participated in the Leipzig Longitudinal Study of the Aged (LEILA 75+). All participants have been tested six times at 1.5 year intervals with the test part of the SIDAM over a mean period of 7.1 years. Reliable change indices (RCI) were computed for a common confidence interval (90%). It is demonstrated how to compute RCI for individual patients. RESULTS: In repeated assessments with 1.5 year intervals, a change in SIDAM score of at least 4 to 7 points (dependent on which of the six assessments were compared) indicates a reliable change at the 90% confidence level. Smaller changes can be interpreted only with high uncertainty. CONCLUSION: The interpretation of changes in test scores in older adults should account for potential practice effect, normal decline and regression to the mean.
BACKGROUND: In clinical settings, neuropsychological tests and screening instruments are often used to measure cognitive change over time. However, the interpretation of changes in test scores is often difficult. For most instruments there is no information how much change occurs normally in cognitively healthy individuals. AIM: To examine what is a reliable change for a widely used screening instrument for cognitive impairment and dementia. METHODS: A Sample of 119 cognitively normal elderly individuals aged 75 and over participated in the Leipzig Longitudinal Study of the Aged (LEILA 75+). All participants have been tested six times at 1.5 year intervals with the test part of the SIDAM over a mean period of 7.1 years. Reliable change indices (RCI) were computed for a common confidence interval (90%). It is demonstrated how to compute RCI for individual patients. RESULTS: In repeated assessments with 1.5 year intervals, a change in SIDAM score of at least 4 to 7 points (dependent on which of the six assessments were compared) indicates a reliable change at the 90% confidence level. Smaller changes can be interpreted only with high uncertainty. CONCLUSION: The interpretation of changes in test scores in older adults should account for potential practice effect, normal decline and regression to the mean.
The generalizability of neurocognitive test/retest data derived from a nonclinical sample for detecting change among two HIV+ cohorts.
Journal of clinical and experimental neuropsychology : official journal of the International Neuropsychological Society, Vol. 29, No. 6. (August 2007), pp. 669-678.
Objective methods for determining clinically relevant neurocognitive change are useful for clinicians and researchers, but the utility of such methods requires validation studies in order to assess their accuracy among target populations. We examined the generalizability of regression equations and reliable change indexes (RCI) derived from a healthy sample to two HIV-infected samples, one similar in demographic makeup to the normative group and the other dissimilar. Measures administered at baseline and follow-up included the Trail Making Test, Controlled Oral Word Association Test (COWAT), Grooved Pegboard, and Digit Span. Frequencies of decline, improvement, or stability were determined for each measure. Among the demographically similar clinical cohort, elevated rates of decline among more immunologically impaired participants were indicated by simple regression method on measures of psychomotor speed and attention, while RCI addressing practice effects (RCI-PE) indicated improvement on most measures regardless of immunostatus. Conversely, among the demographically dissimilar cohort, simple regression indicated high rates of decline across all measures, while RCI-PE indicated elevated rates of decline on psychomotor and attention measures. Thus, the accuracy of the two methods examined for determining clinically significant change among HIV+ cohorts differs depending upon their similarity with the normative sample.
Objective methods for determining clinically relevant neurocognitive change are useful for clinicians and researchers, but the utility of such methods requires validation studies in order to assess their accuracy among target populations. We examined the generalizability of regression equations and reliable change indexes (RCI) derived from a healthy sample to two HIV-infected samples, one similar in demographic makeup to the normative group and the other dissimilar. Measures administered at baseline and follow-up included the Trail Making Test, Controlled Oral Word Association Test (COWAT), Grooved Pegboard, and Digit Span. Frequencies of decline, improvement, or stability were determined for each measure. Among the demographically similar clinical cohort, elevated rates of decline among more immunologically impaired participants were indicated by simple regression method on measures of psychomotor speed and attention, while RCI addressing practice effects (RCI-PE) indicated improvement on most measures regardless of immunostatus. Conversely, among the demographically dissimilar cohort, simple regression indicated high rates of decline across all measures, while RCI-PE indicated elevated rates of decline on psychomotor and attention measures. Thus, the accuracy of the two methods examined for determining clinically significant change among HIV+ cohorts differs depending upon their similarity with the normative sample.
Vinpocetine increases cerebral blood flow and oxygenation in stroke patients: a near infrared spectroscopy and transcranial Doppler study
European Journal of Ultrasound, Vol. 15, No. 1-2. (June 2002), pp. 85-91.
Objective: To investigate the effect of vinpocetine on cerebral blood flow (CBF) in the compromised circulation of a stroke affected hemisphere using transcranial Doppler (TCD) and near infrared spectroscopy (NIRS) methods. Methods: 43 patients with ischemic stroke were randomized into vinpocetine (VP) and placebo group in a double blind, placebo-controlled study of the effect of a single-dose i.v. infusion of vinpocetine on cerebral blood perfusion and oxygenation. In the VP group 20 mg VP in 500 ml saline, in the placebo group 500 ml saline alone were administered. The concentrations of oxy-, reduced- and total hemoglobin were measured by NIRS frontolaterally on the side of lesion while the mean cerebral blood flow velocity (CBFV), the pulsatility index (PI) and Doppler spectral intensity (DSI) were monitored by TCD in the middle cerebral artery on the same side. Values were averaged for the first 5 min prior to the infusion and for the last 5 min of infusion and they were compared between groups. Results: The concentration of all three chromophores increased during infusion in the VP group (mean dHbT=1.03, CI95=0.84, P=0.058; mean dHbO=0.92, CI95=0.91, P=0.071; mean dHb=0.10, CI95=0.21, P=0.297). The HbT and HbO showed a substantially smaller increase in the placebo group (mean dHbT=0.31, CI95=0.74, P=0.22; mean dHbO=0.57, CI95=0.80, P=0.094) while the Hb decreased (mean dHb=-0.26, CI95=0.29, P=0.05). Comparing to the placebo group Hb increased significantly in the VP group (P=0.027) while the increase of HbO and HbT did not reach the level of significance (P=0.29 and 0.11). DSI showed a significantly larger increase in the VP than in placebo group (dDSI=25.8 CI95=8.8 [VP]; dDSI=3.3, CI95=3.7 [Placebo], P<0.005). The CBFV and PI did not differ significantly between groups. (dVm=5.0+/-2.98 cm/s [VP], dVm=4.1+/-2.57 cm/s [Placebo], P=0.28; dPI=0.08 [VP], dPI=0.09 [Placebo]; P=0.47). Conclusion: VP increases cerebral perfusion and parenchymal oxygen extraction as well. The increased perfusion was indicated by NIRS and by TCD measurement of DSI while conventional velocity and pulsatility measurements failed to detect theses effects. NIRS is a sensitive, feasible method of measuring changes in regional blood flow and tissue oxygenation in the superficial cortex.
Objective: To investigate the effect of vinpocetine on cerebral blood flow (CBF) in the compromised circulation of a stroke affected hemisphere using transcranial Doppler (TCD) and near infrared spectroscopy (NIRS) methods. Methods: 43 patients with ischemic stroke were randomized into vinpocetine (VP) and placebo group in a double blind, placebo-controlled study of the effect of a single-dose i.v. infusion of vinpocetine on cerebral blood perfusion and oxygenation. In the VP group 20 mg VP in 500 ml saline, in the placebo group 500 ml saline alone were administered. The concentrations of oxy-, reduced- and total hemoglobin were measured by NIRS frontolaterally on the side of lesion while the mean cerebral blood flow velocity (CBFV), the pulsatility index (PI) and Doppler spectral intensity (DSI) were monitored by TCD in the middle cerebral artery on the same side. Values were averaged for the first 5 min prior to the infusion and for the last 5 min of infusion and they were compared between groups. Results: The concentration of all three chromophores increased during infusion in the VP group (mean dHbT=1.03, CI95=0.84, P=0.058; mean dHbO=0.92, CI95=0.91, P=0.071; mean dHb=0.10, CI95=0.21, P=0.297). The HbT and HbO showed a substantially smaller increase in the placebo group (mean dHbT=0.31, CI95=0.74, P=0.22; mean dHbO=0.57, CI95=0.80, P=0.094) while the Hb decreased (mean dHb=-0.26, CI95=0.29, P=0.05). Comparing to the placebo group Hb increased significantly in the VP group (P=0.027) while the increase of HbO and HbT did not reach the level of significance (P=0.29 and 0.11). DSI showed a significantly larger increase in the VP than in placebo group (dDSI=25.8 CI95=8.8 [VP]; dDSI=3.3, CI95=3.7 [Placebo], P<0.005). The CBFV and PI did not differ significantly between groups. (dVm=5.0+/-2.98 cm/s [VP], dVm=4.1+/-2.57 cm/s [Placebo], P=0.28; dPI=0.08 [VP], dPI=0.09 [Placebo]; P=0.47). Conclusion: VP increases cerebral perfusion and parenchymal oxygen extraction as well. The increased perfusion was indicated by NIRS and by TCD measurement of DSI while conventional velocity and pulsatility measurements failed to detect theses effects. NIRS is a sensitive, feasible method of measuring changes in regional blood flow and tissue oxygenation in the superficial cortex.
Fully automatic 3D feature-based registration of multi-modality medical images
Image and Vision Computing, Vol. 19, No. 1-2. (January 2001), pp. 75-85.
In this paper, we present an automated multi-modality registration algorithm based on hierarchical feature extraction. The approach, which has not been used previously, can be divided into two distinct stages: feature extraction (edge detection, surface extraction), and geometric matching. Two kinds of corresponding features -- edge and surface -- are extracted hierarchically from various image modalities. The registration then is performed using least-squares matching of the automatically extracted features. Both the robustness and accuracy of feature extraction and geometric matching steps are evaluated using simulated and patient images. The preliminary results show the error is on the average of one voxel. We have shown the proposed 3D registration algorithm provides a simple and fast method for automatic registering of MR-to-CT and MR-to-PET image modalities. Our results are comparable to other techniques and require no user interaction.
In this paper, we present an automated multi-modality registration algorithm based on hierarchical feature extraction. The approach, which has not been used previously, can be divided into two distinct stages: feature extraction (edge detection, surface extraction), and geometric matching. Two kinds of corresponding features -- edge and surface -- are extracted hierarchically from various image modalities. The registration then is performed using least-squares matching of the automatically extracted features. Both the robustness and accuracy of feature extraction and geometric matching steps are evaluated using simulated and patient images. The preliminary results show the error is on the average of one voxel. We have shown the proposed 3D registration algorithm provides a simple and fast method for automatic registering of MR-to-CT and MR-to-PET image modalities. Our results are comparable to other techniques and require no user interaction.
Lake County Police Log
Following are some of the incidents recently reported to area police agencies and the Lake County Sheriff's Office. This information was compiled from public records maintained by those agencies. The Police Log is published Thursdays in the Lake section.
Lake County community notes
Faith Lutheran School Parent-Teacher League will have its fifth annual golf tournament April 19 at the Country Club of Mount Dora, 1900 Country Club Blvd.
County seeking to learn some of Disney's secrets
When it comes to great customer service, you might think of a five-star hotel or a swanky new restaurant long before your local government.
Photographers add a twist to their subjects in Mount Dora exhibit
Photographers add artistic twists to their subjects in a show.
When people see the new photography exhibit at the Mount Dora Center for the Arts, some are bound to ask, "How did they do that?"
When people see the new photography exhibit at the Mount Dora Center for the Arts, some are bound to ask, "How did they do that?"
Eustis chooses director of development services
Dianne Kramer has been hired as this city's development services director, replacing Alton Roane, who retired in January, Eustis officials announced Wednesday.
Technicians will install car seats
Lake-Sumter Emergency Medical Services recently received a grant for $63,900 from the state Department of Transportation to establish a child passenger-safety program in Lake and Sumter counties.
School-volunteer finalists
Three finalists were named Wednesday for the Lake County school district's Outstanding School Volunteer of the Year.
Lake Gertrude residents would block public from its lake
Shore residents irate over proposal to open public waters
After Lake County Commissioner Linda Stewart said last month that scenic Lake Gertrude should be open to outside canoes and kayaks, she drew a severe backlash from lakeside homeowners, who say opening the lake to public boats will bring crowds, trash and injuries.
After Lake County Commissioner Linda Stewart said last month that scenic Lake Gertrude should be open to outside canoes and kayaks, she drew a severe backlash from lakeside homeowners, who say opening the lake to public boats will bring crowds, trash and injuries.
The Not-So-Simple Task of Re-Thinking Certain Breast Cancer Treatments
Breast Cancer Action's March newsletter (#100, congratulations!) covers why it's so difficult to alter reliance on certain breast cancer treatments -- even when there's evidence to indicate the drug is not working.
Two factors cited by BCA Executive Director Barbara Brenner are longstanding attitudes about the best way to treat cancer (read: aggressively) and the pharmaceutical industry's investment in particular drugs.
"Given this training, doctors probably fear giving up on a treatment that they think might help some patients," writes Brenner. "Making a mistake could have big consequences if it turns out that the indications for nontreatment are wrong, or if a patient has a recurrence that might not have happened with treatment and sues for malpractice."
"The other is that there is a huge investment in these drugs, and a lot of money being made in producing and administering them," adds Brenner. "Financial interests stand in the way of many changes. They create a large ship that is very hard to turn in a new direction."
The examples cited are Taxol and anthracyclines, the most common of which is Adriamycin (generic name doxorubicin). Here's what's happening with anthracyclines:
For several years, Dennis Slamon, the person credited with the development of Herceptin, has been reporting on research that shows that women whose breast tumors overexpress the Her2/neu protein (HER2-positive) benefit from anthracyclines, but those whose breast tumors are HER2-negative do not. As Ralph Moss reported in his Cancer Decisions Newsletter in July 2007, a number of studies now support this conclusion and lead inevitably to the observation that women who do not overexpress Her2/neu (and an additional gene known as Topoll-2–topoisomerase II alpha) should not receive anthracyline treatment, because they won't derive any benefit from the drug.Yet doctors, including many who attended the San Antonio Breast Cancer Symposium in December, are not ready to drop this very aggressive treatment from cases where it clearly doesn't seem to work (See my SABCS Reflections).
So what can be done?
Brenner concludes: "[P]atients who are well informed can demand that treatments change as new information becomes available about who benefits and who doesn't. It shouldn't be up to us, but it is."
(Via Feminist Peace Network.)
Stolen Laptop Contains Patients' Data
Rachel last week wrote a great post explaining what you need to know about medical trials -- from costs to informed consent -- and where to go to get other questions answered.
One question being asked now in Washington in the wake of a laptop theft is why protocols concerning patients' privacy were not followed. From the Washington Post, which ran this story Monday on page 1:
A government laptop computer containing sensitive medical information on 2,500 patients enrolled in a National Institutes of Health study was stolen in February, potentially exposing seven years' worth of clinical trial data, including names, medical diagnoses and details of the patients' heart scans. The information was not encrypted, in violation of the government's data-security policy.NIH officials made no public comment about the theft and did not send letters notifying the affected patients of the breach until last Thursday -- almost a month later. They said they hesitated because of concerns that they would provoke undue alarm.
You think?
Leslie Harris, executive director of the Center for Democracy & Technology, explains why it hurts: "The shocking part here is we now have personally identifiable information -- name and age -- linked to clinical data ... If somebody does not want to share the fact that they're in a clinical trial or the fact they've got a heart disease, this is very, very serious. The risk of identity theft and of revealing highly personal information about your health are closely linked here."
Be BOLD for a Good Cause
BOLD is a very cool media arts/birth advocacy group that's trying to win a $10,000 grant from Ideablob.com.
The organization's play, "Birth," is performed each year on, you guessed it, Labor Day. Here's more about BOLD, from founder Karen Brody:
BOLD's mission is to be a global movement to make maternity care mother-friendly through education, truth and action. While it was sparked by performances of my play, Birth, to inspire change BOLD is now much more than my play. [...] At all our BOLD events we're using the arts to educate, tell the truth and take action around maternity care so that birthing options are mother-friendly. Through each event communities take a serious look at how to improve the birthing climate for pregnant mothers. What do mothers want? What do they deserve? What mother-friendly solutions are out there? These are some of the questions BOLD is asking.
If you want to help out, click here to register and vote. The organization with the most votes gets the big bucks.
Our Daily Meds
Melody Petersen, who covered the drug industry for the New York Times for four years, has written a book on the topic, "Our Daily Meds: How the Pharmaceutical Companies Transformed Themselves Into Slick Marketing Machines and Hooked the Nation on Prescription Drugs," Reviewed recently in the Times. The book examines the consequences of Americans' dependency on prescription drugs, and looks at how pharmaceutical companies expand their sales by promoting direct-to-consumer advertising, providing freebies for physicians, ghostwriting research articles, and engaging in other unseemly tactics.
We've written before about advertising and marketing issues, and OBOS offers special sections on the need to remain healthily skeptical of industry-funded research and direct to consumer advertising. Drug advertisements have been the focus of much attention recently, as Pfizer canceled ads for a cholesterol-lowering drug that featured Dr. Robert Jarvik, who is not actually a physician and used a stunt-double for the rowing scene that is supposed to reinforce your belief in the health benefits of the drug. I haven't yet read Peterson's book, and I wouldn't personally go as far as to suggest that nobody would benefit from the advertised drugs (as the review seems to imply), but I'm willing to bet that the percentage of people who would benefit is much, much smaller than those who are being targeted by the commercials (and likely smaller than the percentage actually receiving the drug).
On a related note, Prescription for Change (a campaign of the Consumers Union) is collecting petition signatures to ask the FDA to require these drug ads to include a way for consumers to report side effects, in order to increase understanding of side effects. It's important to realize that the clinical trials that are used to support drug approval do not always catch all of the side effects or adverse outcomes that may occur, simply because the drug is tested in far fewer patients than will eventually have it prescribed. Relatedly, consumers can report serious reactions directly to the FDA via the MedWatch program.
Barbara Seaman's New York Times Legacy
When women's health writer and activist Barbara Seaman died Feb. 27 of lung cancer, her death sent shockwaves through feminist and women's health communities.
Also shocking was The New York Times story on Seaman's death, which many OBOS readers said they found insulting and mean-spirited.
The first half or so provides a fair, if limited, overview of Seaman's work and the impact she had on the women's health movement, which included co-founding the National Women's Health Network in 1975. But it s surprising that there are no comments from any of Seaman's colleagues or those familiar with her work.
And once Seaman's books and the surviving family members are listed, the story takes a turn for the worse. The only quote included is a book reviewer's critique, in which Seaman is called "a conspiracy theorist by temperament and training." Attention is then turned to this 20-year-old episode:
In the 1990s, Ms. Seaman also began to speak out publicly against domestic violence, from which she said she had suffered during her marriage to Mr. Forman. Though she did not identify Mr. Forman by name in the news media, court records show that in 1988 he was arrested and charged with assault after Ms. Seaman accused him of punching her in the face. The criminal case against Mr. Forman was later thrown out, Dudley Gaffin, his lawyer at the time, said in a telephone interview on Thursday.Reached by telephone on Thursday, Mr. Forman denied having assaulted Ms. Seaman, calling the accusation of assault "a divorce tactic" on her part.
It's amazing that the past is dredged up like this -- and, after doing so, the last word is left to Seaman's ex.
In a letter to The New York Times, Our Bodies Ourselves Executive Director Judy Norsigian wrote:
I was taken aback by the petty and gossipy nature of parts of the obituary for Barbara Seaman and hope that the Times will consider issuing an apology at least to her family. The comments of her ex-husband and his lawyer were particularly inappropriate (as one reporter noted to me, there are all sorts of reasons that a case is dropped – and they often have nothing to do with the culpability of the accused). Readers were left with a pretty clear sense that the NY Times thought that Barbara had made false accusations about Milt Forman's behavior.Mostly, I am getting emails about the poor taste exhibited on the part of the Times. Rather than include some of the more substantive criticisms and disagreements that she may have had with colleagues, the piece relied on a few rather general and unopposed character assaults.
As someone who has been close to other luminaries whose obituaries in the Times could easily have included far more damning commentary than was noted in this obituary (and with far better evidence for the character assault), I was left wondering if there was some mean-spirited motivation at play here. In any case, I was sorry to see what I consider a major journalistic lapse.
Naomi at A Little Red Hen offers a similar critique. Her post is also a personal remembrance of Seaman -- both women were students at Oberlin in the 1950s and their paths had crossed several times since then.
After referencing "a respectful obit" in the Washington Post, Naomi writes:
How unregarded significant women like her continue to be is apparent in Saturday's New York Times obituary. First, I'd have expected that it would have been written by someone who knew her work, not someone from the obit staff. Most of the week after Barbara's death had been taken up in the Times with paens to the conservative writer, William Buckley who charmed many in the media. Barbara did not charm. Was this the reason the Times focused on details of her personal life rather than her continuing role as a muckraker, still writing about the dangers of estrogen all these years later.
For comparison, read the more thoughtful obit in the Washington Post -- or this one from the L.A. Times. Both are representative of obituaries that a woman of Barbara Seaman's insight and intellect deserves.
Plus: For an even more intimate view, read OBOS co-founder Norma Swenson's passionate remembrance of Seaman that focuses on their involvement in the early women's health movement.
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