Assessing joint pain complaints and locomotor disability in the Rotterdam Study: Effect of population selection and assessment mode

Objective: To assess the prevalence of self-assessed and physician-assessed disability and joint pain, their association, and the effect of cohort reduction and mode of assessment. Design: Cross-sectional population survey. Setting: General population, age 55 years and older. Subjects: Independently living participants of the Rotterdam Study, including 1,156 men and 1,739 women. Outcome Measures: Self-reported and physician-assessed joint complaints. Patients' self-assessment of locomotor disability was by response to questions from the Stanford Health Assessment Questionnaire; physicians assessed patients' disability by administering activity tests. Results: Reduction of the study cohort because of nonresponse and missing data had no influence on the frequency and effect measures. The physician-assessed prevalence of pain of the hips, knees, or feet was significantly lower than the self-assessed prevalence, with the percentage agreement being 83% for men and 74% for women, with kappa-values of approximately .40. The prevalence of physician-assessed locomotor disability was also significantly lower than the self-assessed disability, with the percentage agreement being 83% for men and 78% for women, with kappa values of .41 and .47, respectively. The associations of joint complaints with disability were similar for both modes of assessment. Conclusion: Cohort reduction caused by nonresponse and missing data had no influence on estimates of frequency and association. Self-assessment gives higher prevalences of joint complaints and locomotor disability than physician assessment, but the associations between complaints and disability were the same.