Measuring disability in population-based surveys: the interrelationship between clinical impairments and reported functional limitations in Cameroon and India

Summary

Purpose: to investigate the relationship between two distinct measures of disability: self-reported functional limitations and objectively-screened clinical impairments.

Method: we undertook an all age population-based survey of disability in two areas: north-west Cameroon (August/October 2013) and Telangana State, India (Feb/April 2014). Information was collected using structured questionnaires, observations and examinations.

Results: self-reported disability prevalence was 5.9% (95% CI 4.7-7.4) and 7.5% (5.9-9.4) in Cameroon and India respectively. The prevalence of moderate or greater clinical impairments in the same populations were 8.4% (7.5-9.4) in Cameroon and 10.5% (9.4-11.7) in India. Overall disability prevalence (self-report and/or screened positive to a moderate or greater clinical impairment) was 10.5% in Cameroon and 12.2% in India, with limited overlap between the sub-populations identified using the two types of tools. 33% of participants in Cameroon identified to have a disability, and 45% in India, both reported functional limitations and screened positive to objectively-screened impairments, whilst the remainder were identified via one or other tool only. A large proportion of people with moderate or severe clinical impairments did not self-report functional difficulties despite reporting participation restrictions.

Conclusion: tools to assess reported functional limitation alone are insufficient to identify all persons with participation restrictions and moderate or severe clinical impairments. A self-reported functional limitation tool followed by clinical screening of all those who report any level of difficulty would identify 94% of people with disabilities in Cameroon and 95% in India, meeting the study criteria.