Objective: The Health Assessment Questionnaire (HAQ) disability index (DI) has been commonly used in rheumatology to quantify functional disability in patient groups, but current general population values of this index are not available. This study was undertaken to establish normative values for the HAQ DI in a general population and to analyze its correlates.
Methods: The HAQ DI (range of scores 0-3) was measured in a random sample of 1,530 adults in the Central Finland District. Prevalence rates of disability by strata of age, sex, education level, body mass index (BMI), and health behaviors (including smoking and exercise habits) were calculated. Pearson's product-moment correlation coefficient and ordinary least squares regression were used to analyze the data.
Results: The estimated population mean HAQ DI was 0.25 (95% confidence interval 0.22-0.28), and 32% of respondents had at least some disability. Both for men and for women, functional disability increased exponentially with age. The HAQ DI was correlated with pain (r = 0.58) and global self assessment (r = 0.61). The prevalence of disability decreased with increasing number of years of education, lower BMI, and increasing frequency of physical exercise.
Conclusion: Almost one-third of the general population has some functional disability. Functional disability is associated in part with lifestyle choices and increases with age in a nonlinear manner. The normative values of the HAQ DI that we have presented could be used as a reference benchmark for clinical and epidemiologic studies using this measure of disability.