Approaches and tools for measuring disability in low and middle-income countries

[[[ Purpose: ]]] To review the current state-of-the-art of measuring disability in the context of countries where leprosy is endemic. [[[ Background: ]]] Estimates of the prevalence of disability are often based on scanty data, collected with a myriad of different instruments. This is true for all four components of the International Classification of Functioning, Disability and Health (ICF); 1) body functions and structures, 2) activities and participation, 3) personal factors and 4) environmental factors, and for disability-related quality of life. There is an urgent need for data on leprosy-related disability, as well as for data on disability due to other causes. Data is needed as baseline for rehabilitation programmes, individual interventions, for programme monitoring and evaluation and for advocacy. [[[ Results: ]]] Measurement instruments and qualitative data collection techniques now exist which are directly applicable in the context of most leprosy-endemic countries. We discuss several instruments compatible with the ICF conceptual framework. A validated generic instrument for measuring impairment is currently not available. For measuring activity and participation, we recommend the WHODAS, the SALSA scale and the Participation Scale. We recommend an inclusive focus, where people with leprosy-related disability are seen as a sub-group of people with disability in the wider context, since many of their needs are the same as those of others. The need for validation and collection of normative reference data is also discussed. [[[ Conclusions: ]]] Programmes and research projects should choose an appropriate set of tools and methods and seek to apply these systematically. This choice should be guided by data on the validity of these tools in the concerned context. Instruments should be revalidated formally in every new context. Similarly, locally relevant normative data should be collected and applied to ensure that decisions are based on valid interpretations and conclusions.