Adjusting for cross-cultural differences in computer-adaptive tests of quality of life.

PURPOSE: Previous studies using the WHOQOL measures have demonstrated that the relationship between individual items and the underlying quality of life (QoL) construct may differ between cultures. If unaccounted for, these differing relationships can lead to measurement bias which, in turn, can undermine the reliability of results. METHODS: We used item response theory (IRT) to assess differential item functioning (DIF) in WHOQOL data from diverse language versions collected in UK, Zimbabwe, Russia, and India (total N = 1332). Data were fitted to the partial credit 'Rasch' model. We used four item banks previously derived from the WHOQOL-100 measure, which provided excellent measurement for physical, psychological, social, and environmental quality of life domains (40 items overall). Cross-cultural differential item functioning was assessed using analysis of variance for item residuals and post hoc Tukey tests. Simulated computer-adaptive tests (CATs) were conducted to assess the efficiency and precision of the four items banks. RESULTS: Splitting item parameters by DIF results in four linked item banks without DIF or other breaches of IRT model assumptions. Simulated CATs were more precise and efficient than longer paper-based alternatives. DISCUSSION: Assessing differential item functioning using item response theory can identify measurement invariance between cultures which, if uncontrolled, may undermine accurate comparisons in computer-adaptive testing assessments of QoL. We demonstrate how compensating for DIF using item anchoring allowed data from all four countries to be compared on a common metric, thus facilitating assessments which were both sensitive to cultural nuance and comparable between countries

Mental distress and podoconiosis in northern Ethiopia: A comparative cross-sectional study

Background The stigma, deformity and disability related to most neglected tropical diseases may lead to poor mental health. We aimed to assess the comorbidity of podoconiosis and mental distress. Methods A comparative cross-sectional study was conducted in 2012, including 346 people with podoconiosis and 349 healthy neighbourhood controls. Symptoms of mental distress were assessed using the validated Amharic translation of the Kessler-10 scale (K10). A linear regression analysis was conducted to identify factors associated with mental distress. Results The mean K10 score was 15.92 (95% CI: 15.27 to 16.57) in people with podoconiosis and 14.49 (95% CI: 13.85 to 15.12) in controls (average K10 scores 1.43 points higher [95% CI: 0.52 to 2.34]). In multivariate linear regression of K10 scores, the difference remained significant when adjusted for gender, income, alcohol use, age, place of residence and family history of mental illness. In the adjusted model, people with podoconiosis had K10 scores 1.37 points higher than controls (95% CI: 0.64 to 2.18). Other variables were also associated with high K10 scores: women had K10 scores 1.41 points higher than men (95% CI: 0.63 to 2.18). Those with family history of mental illness had K10 scores 3.56 points higher than those without (95% CI: 0.55 to 6.56). Conclusions This study documented a high burden of mental distress among people with podoconiosis compared with healthy controls. Taking this finding in the context of the high stigma and reduced quality of life, we recommend integration of psychosocial care into the current morbidity management of podoconiosis

Assessing health and well-being among older people in rural South Africa

Background: The population in developing countries is ageing, which is likely to increase the burden of noncommunicable diseases and disability. Objective: To describe factors associated with self-reported health, disability and quality of life (QoL) of older people in the rural northeast of South Africa. Design: Cross-sectional survey of 6,206 individuals aged 50 and over. We used multivariate analysis to examine relationships between demographic variables and measures of self-reported health (Health Status), functional ability (WHODASi) and quality of life (WHOQoL). Results: About 4,085 of 6,206 people eligible (65.8%) completed the interview. Women (Odds Ratio (OR) 1.30, 95% CI 1.09, 1.55), older age (OR2.59, 95% CI 1.97, 3.40), lower education (OR1.62, 95% CI 1.31,2.00), single status (OR1.18, 95% CI 1.01, 1.37) and not working at present (OR1.29, 95% CI 1.06, 1.59) were associated with a low health status. Women were also more likely to report a higher level of disability (OR1.38, 95% CI 1.14, 1.66), as were older people (OR2.92, 95% CI 2.25, 3.78), those with no education (OR1.57, 95% CI 1.26, 1.97), with single status (OR1.25, 95% CI 1.06, 1.46) and not working at present (OR1.33, 95% CI 1.06, 1.66). Older age (OR1.35, 95% CI 1.06, 1.74), no education (OR1.39, 95% CI 1.11, 1.73), single status (OR1.28, 95% CI 1.10, 1.49), a low household asset score (OR1.52, 95% CI 1.19, 1.94) and not working at present (OR1.32; 95% CI 1.07, 1.64) were all associated with lower quality of life. Conclusions: This study presents the first population-based data from South Africa on health status, functional ability and quality of life among older people. Health and social services will need to be restructured to provide effective care for older people living in rural South Africa with impaired functionality and other health problems