Presence of and correction for interviewer error on an instrument assessing cognitive function of older adults.



To determine the extent of interviewer error on the Short Portable Mental Status Questionnaire (SPMSQ), the association between interviewer-level variables and SPMSQ score, compare the prevalence of SPMSQ cognitive status categories before and after correction for interviewer error, and identify SPMSQ items prone to interviewer error.


Data of 4542 older adults from a national survey in Singapore were utilized. Multilevel models, which adjusted for respondent-level variables known to be associated with cognitive status, were utilized to determine the intraclass correlation on the SPMSQ, association of interviewer-level variables (age, ethnicity, education and number of interviews carried out) with SPMSQ and identify SPMSQ items prone to interviewer error.


The intraclass correlation, after adjusting for respondent-level variables, was 0.265. Interviewer educational status was associated with SPMSQ score. Correction for interviewer error resulted in an "improvement" in cognitive status of a substantial proportion of those initially classified as moderately or severely impaired. Two of the SPMSQ items, "Please count backward from 20 by 3" and "When were you born?" were particularly prone to interviewer error.


Investigators using the SPMSQ, and potentially, other instruments, for assessing cognitive function in surveys of older adults and using face-to-face interviews for data collection should be cognizant of the sensitivity of such instruments to interviewer error. Intensive training of interviewers to standardize instrument administration as well as assessment for interviewer error and its correction, using appropriate statistical models, such as multilevel models, is warranted.





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Publication Info

Malhotra, Rahul, Benjamin A Haaland, Choy-Lye Chei, Angelique Chan, Chetna Malhotra and David B Matchar (2015). Presence of and correction for interviewer error on an instrument assessing cognitive function of older adults. Geriatrics & gerontology international, 15(3). pp. 372–380. 10.1111/ggi.12331 Retrieved from

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David Bruce Matchar

Professor of Medicine

My research relates to clinical practice improvement - from the development of clinical policies to their implementation in real world clinical settings. Most recently my major content focus has been cerebrovascular disease. Other major clinical areas in which I work include the range of disabling neurological conditions, cardiovascular disease, and cancer prevention.
Notable features of my work are: (1) reliance on analytic strategies such as meta-analysis, simulation, decision analysis and cost-effectiveness analysis; (2) a balancing of methodological rigor the needs of medical professionals; and (3) dependence on interdisciplinary groups of experts.
This approach is best illustrated by the Stroke Prevention Patient Outcome Research Team (PORT), for which I served as principal investigator. Funded by the AHCPR, the PORT involved 35 investigators at 13 institutions. The Stroke PORT has been highly productive and has led to a stroke prevention project funded as a public/private partnership by the AHCPR and DuPont Pharma, the Managing Anticoagulation Services Trial (MAST). MAST is a practice improvement trial in 6 managed care organizations, focussing on optimizing anticoagulation for individuals with atrial fibrillation.
I serve as consultant in the general area of analytic strategies for clinical policy development, as well as for specific projects related to stroke (e.g., acute stroke treatment, management of atrial fibrillation, and use of carotid endarterectomy.) I have worked with AHCPR (now AHRQ), ACP, AHA, AAN, Robert Wood Johnson Foundation, NSA, WHO, and several pharmaceutical companies.
Key Words: clinical policy, disease management, stroke, decision analysis, clinical guidelines

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