Measures of functional status and quality of life in rheumatoid arthritis: Health Assessment Questionnaire Disability Index (HAQ), Modified Health Assessment Questionnaire (MHAQ), Multidimensional Health Assessment Questionnaire (MDHAQ), Health Assessment Questionnaire II (HAQ‐II), Improved Health Assessment Questionnaire (Improved HAQ), and Rheumatoid Arthritis Quality of Life (RAQoL)

Rheumatoid arthritis (RA) is one of the few diseases where subjective patient and physician measures are the best predictors of treatment response and future health outcomes. Arguably, the most important of these is the American College of Rheumatology core measure of function. Developed in 1978, the original Health Assessment Questionnaire Disability Index (HAQ) remains the gold standard for measuring functional status in RA (1). However, its length at 41 questions and relatively complex scoring can make clinical use difficult. We summarize the HAQ and the most common measures developed from it including the Modified HAQ, Multidimensional HAQ, HAQ-II, and Improved HAQ (2–5). Although it is not a primary measure of function, we also review the Rheumatoid Arthritis Quality of Life scale as it is the lone RA-specific quality of life measure and, whether correct or not, functional measures are often used as a substitute for quality of life in RA (6). We did not include several measures that have less recent published use and may be promising for future studies, including the visual analog scale for function (7) and the Patient-Reported Outcomes Measurement Information System computerized adaptive test for function (8). HEALTH ASSESSMENT QUESTIONNAIRE DISABILITY INDEX (HAQ)