Impact of age and comorbidities on the criteria for remission and response in rheumatoid arthritis

Objective: To determine to what extent health status impairment in rheumatoid arthritis (RA) measured by self report of pain, global assessment, and functional disability is attributable to age and other comorbid conditions as opposed to the disease itself. Methods: Pain, global assessment, and Health Assessment Questionnaire Disability Index (HAQ-DI) were measured in a random sample of 1530 adults in the Central Finland District, Finland. Median regressions were used for multivariable analyses. Results: The mean age was 55.4 years and 72% were women. A large majority of the population reported some pain (76%) and less than perfect general health (83%). The overall mean values of pain, HAQ-DI, and general health were 20 mm, 0.25 units, and 21 mm, respectively. The most common self reported musculoskeletal comorbidities were osteoarthritis (24%) and chronic back pain (25%). Age and number of comorbidities were the only statistically significant correlates of pain and general health in multivariable analyses. Conclusions: Self reported disability, pain, and poor health were widely prevalent in the general population and are related to age and comorbid conditions. This needs to be taken into account when interpreting remission and response rates using current criteria and for future development of definitions for these end points in RA and other rheumatic diseases.