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Normative data and validation of a regression based summary score for assessing meaningful neuropsychological change.

ABSTRACT: Reliable detection and quantification of longitudinal cognitive change are of considerable importance in many neurological disorders, particularly to monitor central nervous system effects of disease progression and treatment. In the current study, we developed normative data for repeated neuropsychological (NP) assessments (6 testings) using a modified standard regression-based (SRB) approach in a sample that includes both HIV-uninfected (HIV-, N = 172) and neuromedically stable HIV-infected (HIV+, N = 124) individuals. Prior analyses indicated no differences in NP change between the infected and uninfected participants. The norms for change included correction for factors found to significantly affect follow-up performance, using hierarchical regression. The most robust and consistent predictors of follow-up performance were the prior performance on the same test (which contributed in all models) and a measure of prior overall NP competence (predictor in 97% of all models). Demographic variables were predictors in 10-46% of all models and in small amounts; while test-retest interval contributed in only 6% of all models. Based on the regression equations, standardized change scores (z scores) were computed for each test measure at each interval; these z scores were then averaged to create a total battery change score. An independent sample of HIV- participants who had completed 8 of the 15 tests was used to validate an abridged summary change score. The normative data are available in an electronic format by e-mail request to the first author. Correction for practice effects based on normative data improved the consistency of NP impairment classification in a clinically stable longitudinal cohort after baseline.

SUBMITTER: Cysique LA

PROVIDER: S-EPMC3151558 | biostudies-literature | 2011 Jun

REPOSITORIES: biostudies-literature

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Normative data and validation of a regression based summary score for assessing meaningful neuropsychological change.

Cysique Lucette A LA Franklin Donald D Abramson Ian I Ellis Ronald J RJ Letendre Scott S Collier Ann A Clifford David D Gelman Benjamin B McArthur Justin J Morgello Susan S Simpson David D McCutchan J Allen JA Grant Igor I Heaton Robert K RK

Journal of clinical and experimental neuropsychology 20110307 5

Reliable detection and quantification of longitudinal cognitive change are of considerable importance in many neurological disorders, particularly to monitor central nervous system effects of disease progression and treatment. In the current study, we developed normative data for repeated neuropsychological (NP) assessments (6 testings) using a modified standard regression-based (SRB) approach in a sample that includes both HIV-uninfected (HIV-, N = 172) and neuromedically stable HIV-infected (H ...[more]

PMID: 21391011

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Project description:IntroductionAssessment of preclinical Alzheimer's disease (AD) requires reliable and validated methods to detect subtle cognitive changes. The battery of standardized cognitive assessments that is used for diagnostic criteria for mild cognitive impairment due to AD in the TOMMORROW study have only been fully validated in English-speaking countries. We conducted a validation and normative study of the German language version of the TOMMORROW neuropsychological test battery, which tests episodic memory, language, visuospatial ability, executive function, and attention.MethodsGerman-speaking cognitively healthy controls (NCs) and subjects with AD were recruited from a memory clinic at a Swiss medical center. Construct validity, test-retest, and alternate form reliability were assessed in NCs. Criterion and discriminant validities of the cognitive measures were tested using logistic regression and discriminant analysis. Cross-cultural equivalency of performance of the German language tests was compared with English language tests.ResultsA total of 198 NCs and 25 subjects with AD (aged 65-88 years) were analyzed. All German language tests discriminated NCs from persons with AD. Episodic memory tests had the highest potential to discriminate with almost twice the predictive power of any other domain. Test-retest reliability of the test battery was adequate, and alternate form reliability for episodic memory tests was supported. For most tests, age was a significant predictor of group effect sizes; therefore, normative data were stratified by age. Validity and reliability results were similar to those in the published US cognitive testing literature.DiscussionThis study establishes the reliability and validity of the German language TOMMORROW test battery, which performed similarly to the English language tests. Some variations in test performance underscore the importance of regional normative values. The German language battery and normative data will improve the precision of measuring cognition and diagnosing incident mild cognitive impairment due to AD in clinical settings in German-speaking countries.

Project description:With the recent publication of new criteria for the diagnosis of preclinical Alzheimer's disease (AD), there is a need for neuropsychological tools that take premorbid functioning into account in order to detect subtle cognitive decline. Using demographic adjustments is one method for increasing the sensitivity of commonly used measures. We sought to provide a useful online z-score calculator that yields estimates of percentile ranges and adjusts individual performance based on sex, age and/or education for each of the neuropsychological tests of the National Alzheimer's Coordinating Center Uniform Data Set (NACC, UDS). In addition, we aimed to provide an easily accessible method of creating norms for other clinical researchers for their own, unique data sets.Data from 3,268 clinically cognitively-normal older UDS subjects from a cohort reported by Weintraub and colleagues (2009) were included. For all neuropsychological tests, z-scores were estimated by subtracting the raw score from the predicted mean and then dividing this difference score by the root mean squared error term (RMSE) for a given linear regression model.For each neuropsychological test, an estimated z-score was calculated for any raw score based on five different models that adjust for the demographic predictors of SEX, AGE and EDUCATION, either concurrently, individually or without covariates. The interactive online calculator allows the entry of a raw score and provides five corresponding estimated z-scores based on predictions from each corresponding linear regression model. The calculator produces percentile ranks and graphical output.An interactive, regression-based, normative score online calculator was created to serve as an additional resource for UDS clinical researchers, especially in guiding interpretation of individual performances that appear to fall in borderline realms and may be of particular utility for operationalizing subtle cognitive impairment present according to the newly proposed criteria for Stage 3 preclinical Alzheimer's disease.

Project description:ObjectivesThe fraction of the population that reaches the age of 100 years is growing. At this age, dementia incidence is high and cognitive functioning is highly variable across individuals. Normative data for neuropsychological tests are lacking in centenarians, which hampers the ability to evaluate their cognitive functioning for both research and clinical practice. Here, we generated norms for neuropsychological tests in a sample of cognitively healthy centenarians while taking sensory impairments into account.DesignCross-sectional cohort study.SettingCentenarians who participate in the prospective 100-plus Study.ParticipantsA total of 235 centenarians (71.5% female), who self-reported to be cognitively healthy, which was confirmed by an informant and a trained researcher.MeasurementsWe generated normative data for 15 cognitive tests, measuring global cognition (Mini-Mental State Examination [MMSE]), premorbid intelligence, attention, language, memory, executive function, and visuospatial function by multiple linear regressions and/or by reporting percentiles.ResultsNormative data for global cognition resulted in a mean MMSE score of 25.6 ± 3.1 (range = 17-30; interquartile range = 24-28). Vision problems and fatigue often complicated the ability to complete tests, and these problems explained 41% and 22% of the missing test scores, respectively. In contrast, hearing problems (4%) and task incomprehension (6%) rarely complicated test performance. While educational level was associated with performance on the majority of the tests, sex and age were only weakly associated with test performance.ConclusionsWe generated normative data for 15 common neuropsychological tests in a large sample of cognitively healthy centenarians, while taking age-related sensory impairments into consideration. These normative data allow the detection of deficits across a wide range of cognitive domains. Our results suggest that, next to education level, vision ability and the level of fatigue should be taken into account when evaluating cognitive functioning in centenarians. J Am Geriatr Soc 67:759-767, 2019.

Project description:ObjectivesThe Nasal Polyposis Symptom Diary (NPSD) is a novel and short patient-reported outcome (PRO) tool specifically developed to assess important and relevant symptoms reported by patients with chronic rhinosinusitis with nasal polyposis (CRSwNP). We evaluated the psychometric properties of 4 predefined NPSD-derived scores intended to support symptom-improvement assessments of investigational therapies for inclusion in product labeling.MethodsFive hundred eighteen patients with severe CRSwNP from a Phase III clinical trial (NCT03401229) completed the NPSD, comprising 11 items: 8 symptom-specific, 2 symptom-impact, and 1 optional medication-compliance. The psychometric characteristics of 3 single-item symptom scores (Nasal Blockage Score [NBS], Nasal Congestion Score [NCS], and Difficulty with Sense of Smell Score [DSS]) and a Total Symptom Score (TSS, summary of the 8 symptom-specific items) were evaluated for reliability, validity, and ability to detect change. Within-patient meaningful change thresholds (MCTs) were established using anchor- and distribution-based methods. Comparative PROs included the 22-item Sino-Nasal Outcome Test (SNOT-22) and Patient Global Impression of Severity (PGI-S).ResultsThe TSS exhibited strong internal consistency (Cronbach α = .88) and test-retest reliability (intraclass correlation coefficient >.80). Correlation between the TSS and SNOT-22 total score indicated good convergent validity (r = .70). All 4 NPSD scores demonstrated known-groups validity (significant differences among subgroups of patients with predetermined disease severity levels based on PGI-S categories) and were sensitive to detect change in patients' clinical status (significant differences among subgroups of patients with reported changes between 2 time-points in PGI-S and Patient Global Impression of Change scores). MCTs for improvement were established at 1.0 point for NBS, NCS, and DSS, and 4.0 points for TSS.ConclusionThese findings support the reliability, validity, and suitability of the 4 NPSD-derived scores for evaluating treatment effect on CRSwNP symptoms and their use in clinical trials with predetermined MCTs for improvement.

Project description:Background: MR-Egger regression has recently been proposed as a method for Mendelian randomization (MR) analyses incorporating summary data estimates of causal effect from multiple individual variants, which is robust to invalid instruments. It can be used to test for directional pleiotropy and provides an estimate of the causal effect adjusted for its presence. MR-Egger regression provides a useful additional sensitivity analysis to the standard inverse variance weighted (IVW) approach that assumes all variants are valid instruments. Both methods use weights that consider the single nucleotide polymorphism (SNP)-exposure associations to be known, rather than estimated. We call this the `NO Measurement Error' (NOME) assumption. Causal effect estimates from the IVW approach exhibit weak instrument bias whenever the genetic variants utilized violate the NOME assumption, which can be reliably measured using the F-statistic. The effect of NOME violation on MR-Egger regression has yet to be studied.MethodsAn adaptation of the I2 statistic from the field of meta-analysis is proposed to quantify the strength of NOME violation for MR-Egger. It lies between 0 and 1, and indicates the expected relative bias (or dilution) of the MR-Egger causal estimate in the two-sample MR context. We call it IGX2 . The method of simulation extrapolation is also explored to counteract the dilution. Their joint utility is evaluated using simulated data and applied to a real MR example.ResultsIn simulated two-sample MR analyses we show that, when a causal effect exists, the MR-Egger estimate of causal effect is biased towards the null when NOME is violated, and the stronger the violation (as indicated by lower values of IGX2 ), the stronger the dilution. When additionally all genetic variants are valid instruments, the type I error rate of the MR-Egger test for pleiotropy is inflated and the causal effect underestimated. Simulation extrapolation is shown to substantially mitigate these adverse effects. We demonstrate our proposed approach for a two-sample summary data MR analysis to estimate the causal effect of low-density lipoprotein on heart disease risk. A high value of IGX2 close to 1 indicates that dilution does not materially affect the standard MR-Egger analyses for these data.Conclusions: Care must be taken to assess the NOME assumption via the IGX2 statistic before implementing standard MR-Egger regression in the two-sample summary data context. If IGX2 is sufficiently low (less than 90%), inferences from the method should be interpreted with caution and adjustment methods considered.

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Normative data and validation of a regression based summary score for assessing meaningful neuropsychological change.

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Normative data and validation of a regression based summary score for assessing meaningful neuropsychological change.

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