Comparison of the Health Assessment Questionnaire (HAQ) and the modified HAQ (MHAQ) in patients with rheumatoid arthritis

Objectives. Physical disability in patients with rheumatoid arthritis (RA) is often assessed by questionnaires. We compared the Health Assessment Questionnaire (HAQ) with the modified HAQ (MHAQ) in a cohort of RA patients across various levels of disability, and examined correlations with other measures of physical function. Methods. Patients with RA (n = 182) completed self-report questionnaires assessing functional capacity. Instruments included the MHAQ and HAQ completed separately, as well as SF-36 and the Arthritis Impact Measurement Scales (AIMS). Scores from unadjusted and adjusted HAQ were compared with MHAQ at various disability levels. Results. A clear ceiling effect with aggregation of normal scores for physical function was observed for MHAQ (23%) and HAQ (12%), but not for SF-36 (4%) or AIMS (5%). The correlations between adjusted/unadjusted HAQ and MHAQ scores were 0.85/0.88. A discrepancy in HAQ and MHAQ scores was observed in patients with high levels of disability, especially when MHAQ was compared with the adjusted final HAQ score. Adjustment of HAQ by aids or help increased the final score by an average of 0.15, and both adjusted and unadjusted HAQ scores were numerically clearly higher (mean 0.45 and 0.30, respectively) than the MHAQ score. Conclusion. The present findings indicate that MHAQ and HAQ may be applicable as measures of physical capacity in RA patients, but clinicians and researchers should select the appropriate instrument for the setting, and be aware of differences in scores, especially at different disability levels.