Socioeconomic inequality in disability among adults: a multicountry study using the World Health Survey.

OBJECTIVES: We compared national prevalence and wealth-related inequality in disability across a large number of countries from all income groups. METHODS: Data on 218,737 respondents participating in the World Health Survey 2002-2004 were analyzed. A composite disability score (0-100) identified respondents who experienced significant disability in physical, mental, and social functioning irrespective of their underlying health condition. Disabled persons had disability composite scores above 40. Wealth was evaluated using an index of economic status in households based on ownership of selected assets. Socioeconomic inequalities were measured using the slope index of inequality and the relative index of inequality. RESULTS: Median age-standardized disability prevalence was higher in the low- and lower middle-income countries. In all the study countries, disability was more prevalent in the poorest than in the richest wealth quintiles. Pro-rich inequality was statistically significant in 43 of 49 countries, with disability prevalence higher among populations with lower wealth. Median relative inequality was higher in the high- and upper middle-income countries. CONCLUSIONS: Integrating equity components into the monitoring of disability trends would help ensure that interventions reach and benefit populations with greatest need.

Social determinants of sex differences in disability among older adults: a multi-country decomposition analysis using the World Health Survey.

INTRODUCTION: Women represent a growing proportion of older people and experience increasing disability in their longer lives. Using a universally agreed definition of disability based on the International Classification of Functioning, Disability and Health, this paper examines how, apart from age, social and economic factors contribute to disability differences between older men and women. METHODS: World Health Survey data were analyzed from 57 countries drawn from all income groups defined by the World Bank. The final sample comprises 63638 respondents aged 50 and older (28568 males and 35070 females). Item Response Theory was applied to derive a measure of disability which ensured cross country comparability. Individuals with scores at or above a threshold score were those who experienced significant difficulty in their everyday lives, irrespective of the underlying etiology. The population was then divided into "disabled" vs. "not disabled". We firstly computed disability prevalence for males and females by socio-demographic factors, secondly used multiple logistic regression to estimate the adjusted effects of each social determinant on disability for males and females, and thirdly used a variant of the Blinder-Oaxaca decomposition technique to partition the measured inequality in disability between males and females into the "explained" part that arises because of differences between males and females in terms of age and social and economic characteristics, and an "unexplained" part attributed to the differential effects of these characteristics. RESULTS: Prevalence of disability among women compared with men aged 50+ years was 40.1% vs. 23.8%. Lower levels of education and economic status are associated with disability in women and men. Approximately 45% of the sex inequality in disability can be attributed to differences in the distribution of socio-demographic factors. Approximately 55% of the inequality results from differences in the effects of the determinants. CONCLUSIONS: There is an urgent need for data and methodologies that can identify how social, biological and other factors separately contribute to the health decrements facing men and women as they age. This study highlights the need for action to address social structures and institutional practices that impact unfairly on the health of older men and women.

Generating comprehensive functioning and disability data worldwide: development process, data analyses strategy and reliability of the WHO and World Bank Model Disability Survey.

BACKGROUND: Data on functioning and disability collected at population level is essential to complement mortality and morbidity, to estimate rehabilitation needs of countries and regions and to monitor the Convention on the Rights of Persons with Disabilities (CRPD) and the Sustainable Development Goals (SDGs). The objective of this paper is to briefly report the development process of the WHO Model Disability Survey, its data analysis strategy as well as its reliability and ability to measure low to high levels of functioning and disability across countries. METHODS: The development process is described in detail, and a secondary analysis using Rasch methods is conducted to report reliability and targeting using data from eight national and two regional implementations of the survey. RESULTS: The currently available versions of the Model Disability Survey are presented. The survey has good to very good internal reliability and good targeting in all included countries. CONCLUSION: The participatory and evidence-based development, consideration of the expertise of stakeholders, the availability of previously developed ICF-based surveys, and WHO tools targeting functioning and disability are reflected in its good to very good psychometric properties. The survey has been implemented to date in Afghanistan, Cameroon, Chile, Costa Rica, India, Laos, Pakistan, Philippines, Sri Lanka, and Tajikistan, and is used to inform policy-making, to monitor the CRPD and SDGs and to plan the delivery of rehabilitation services.

Measuring functioning and disability using household surveys: metric properties of the brief version of the WHO and World Bank model disability survey.

BACKGROUND: The Model Disability Survey (MDS) is the current standard recommended by WHO to collect functioning and disability data. Answering calls from countries requesting a version to be implemented as a module that could be integrated into existing surveys and be used for monitoring disability trends and for data disaggregation, WHO developed the brief MDS. The objectives of this paper are to evaluate the metric properties of the disability metrics generated with the Brief MDS and the precision of the Brief MDS in comparison with the full MDS. RESULTS: The partial credit model, a unidimensional model for polytomous data from the Rasch family, was applied to evaluate psychometric properties using data from national MDS implementations in Chile (N = 12,265) and in Sri Lanka (N = 3000). The Brief MDS generates valid metrics for measuring disability, from the perspectives of capacity and performance, thereby achieving good levels of measurement precision in comparison with its full counterpart. CONCLUSION: Given the scarcity of valid functioning and disability modules for household surveys, the Brief MDS represents a milestone in disability measurement. The Brief MDS is currently used by countries to monitor disability trends over time, which is especially important to evaluate the impact of health policies and public health interventions, to disaggregate indicators of the Sustainable Development Goals, and to monitor the implementation of the UN Convention on the Rights of Persons with Disabilities (CRPD).

Response to Madans et al. Comments on Sabariego et al. Measuring Disability: Comparing the Impact of Two Data Collection Approaches on Disability Rates. Int. J. Environ. Res. Public Health, 2015, 12, 10329-10351.

We greatly appreciate and wish to thank Madans, Mont and Loeb for the issues they raise in their Comment [1] on our paper "Measuring Disability: Using the WHO Model Disability Survey to Address the Impact of Screeners on Disability Rates" [2]. [...].

Measuring Disability: Comparing the Impact of Two Data Collection Approaches on Disability Rates.

The usual approach in disability surveys is to screen persons with disability upfront and then ask questions about everyday problems. The objectives of this paper are to demonstrate the impact of screeners on disability rates, to challenge the usual exclusion of persons with mild and moderate disability from disability surveys and to demonstrate the advantage of using an a posteriori cut-off. Using data of a pilot study of the WHO Model Disability Survey (MDS) in Cambodia and the polytomous Rasch model, metric scales of disability were built. The conventional screener approach based on the short disability module of the Washington City Group and the a posteriori cut-off method described in the World Disability Report were compared regarding disability rates. The screener led to imprecise rates and classified persons with mild to moderate disability as non-disabled, although these respondents already experienced important problems in daily life. The a posteriori cut-off applied to the general population sample led to a more precise disability rate and allowed for a differentiation of the performance and needs of persons with mild, moderate and severe disability. This approach can be therefore considered as an inclusive approach suitable to monitor the Convention on the Rights of Persons with Disabilities.