Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Age-stratified norms for Raven's standard progressive matrices for Sri Lankan adults(Psychology Press, 2024) Dassanayake, T.L.; Ariyasinghe, D.I.; Baminiwatta, A.; Hewawasam, C.OBJECTIVE The aim of this study was to create age-stratified norms for the Raven's Standard Progressive Matrices (SPM) for Sri Lankan adults.METHODS A sample of 610 adults (age: 18-72 years; education: 1-19 years), underwent the 60-item version of the SPM under individual supervision of a test administrator. The sample was stratified into 5-year age bands, and the norms are presented as percentile tables and percentile curves.RESULTS The age-related changes were more accurately predicted by a curvilinear model (overall R2 = 0.961) than a linear regression model (R2 = 0.639). The SPM norms are presented as age-stratified percentile tables, as well as sex-, age- and education-adjusted multiple regression equations. The highest percentiles in the younger end of the age spectrum showed a ceiling effect. In the context of age-stratified US (1993) and British (1992) norms, older individuals in the Sri Lankan sample scored much lower than their Western counterparts. However, the difference narrowed in the younger age bands, showing no difference among the 18-to-22-year age bands in the three countries.CONCLUSIONS This age-by-country interaction can be partly explained by poorer education in the older individuals in the present sample compared to those in the US and UK standardization samples. SPM norms presented in this paper fill a hiatus in assessment of general intellectual ability in Sri Lankan adults. Given that Sri Lanka improves its educational, socioeconomic and health standards faster than the nations who have already reached higher standards, these norms would require re-standardization in the coming decades.Item Demographically-adjusted normative data for Symbol Digit Modalities Test (SDMT) among Sri Lankan adults(Sri Lanka College of Psychiatrists, 2021) Dassanayake, T.L.; Baminiwatta, A.; Ariyasinghe, D.I.BACKGROUND: Symbol Digit Modalities Test (SDMT) is a simple pencil-and-paper substitution task that measures divided attention, visual scanning and processing speed. It is sensitive to cognitive impairment in a wide variety of neuropsychiatric conditions. Extant normative data for the SDMT, mainly based on Western populations, may not be applicable for Sri Lankans. AIMS: We aimed to create sex-, age- and education-adjusted regression-based norms for the SDMT for Sri Lankan adults. METHODS: Four-hundred and twenty-two community-living adults (220 women, 52.1%), aged 18 to 83 years, with 5 to 23 years of education, completed the study. We conducted multiple linear regression analyses with sex, age and years of education to predict the SDMT score. RESULTS: The SDMT scores of the sample ranged from 5 to 72, with a mean (SD) score of 35.98 (12.87). The regression model [predicted SDMT score = 29.395 - (1.549 × sex) - (0.434 × age in years) + (2.207 × years of education)] explained 56.5% of the variance in SDMT scores (adjusted R2 = 0.565; F=183; p<0.001). Age explained 20.9% and years of education explained 18.8% of the SDMT score variance uniquely. Sex was not a significant predictor. CONCLUSION: We report regression-based norms for the SDMT for Sri Lankans aged 18–83 years, and supplement the regression equation with a Microsoft Excel-based calculator that produces predicted and standardized scores for individual test participants. These norms would assist clinicians in accurately interpreting SDMT test results, accounting for the variability introduced by sex, age and education. KEYWORDS: Symbol Digit Modalities Test, SDMT, regression-based norms, normative data, processing speed