Extraction and validation of a lower limb HAQ by comparison with objective measurement of ambulatory activity

Objectives: Both the Health Assessment Questionnaire (HAQ) and the measurement of spontaneous ambulatory activity are measures that can be used to evaluate disability in RA. Methods: A cross sectional survey was conducted of 105 RA patients where the HAQ was compared with ambulatory activity from the Numact monitor. Rank correlation was used to evaluate the relationships between activity and the complete and individual sections of the HAQ. Results: Correlation of activity with total HAQ produced significant results (r= -0.29 to-0.48). Correlation with individual sections showed the strongest association with "Hygiene", followed by "Activities", and "Walking". A lower limb HAQ was devised using these and the dressing and rising items. Conclusions: HAQ and recorded activity measure different but related aspects of disability. Activity should be used if the ability to quantify the result outweighs the extra effort involved in the study.