Arthritis onset and worsening self-rated health: a longitudinal evaluation of the role of pain and activity limitations.

OBJECTIVE

To longitudinally explore the hypothesized role of worsening pain and development of activity limitations as mediators in the relationship between arthritis onset and worsening self-rated health (SRH).

METHODS

Data was obtained from the 1998/1999 and 2000/2001 cycles of the population-based Canadian longitudinal National Population Health Survey (n = 10,859; ages > or = 18; response rate: time 1 = 81.6%, time 2 = 89.2%). Respondents were asked about chronic conditions, pain, activity limitations, and self-perceived health; change over time was assessed. Change in effect of arthritis onset on worsening SRH upon considering potential mediators was assessed through multivariate logistic regression, controlling for sociodemographic characteristics and onset of other conditions.

RESULTS

Worsening pain fully explained the effect of arthritis onset on worsening SRH; a portion of the effect of worsening pain was mediated by the development of activity limitation. Residual direct effect of arthritis onset was statistically insignificant. Worsening pain and development of activity limitations also mediated a portion of the effects of onset of other chronic conditions but to a lesser extent than arthritis onset.

CONCLUSION

This is the first study to examine these relationships longitudinally. Identifying the role of mediators is necessary if target areas of prevention and/or management are sought, either at the individual or population level. Our results indicate that the development of arthritis has a significant impact on worsening SRH. Pain and development of activity limitations fully account for the relationship between arthritis onset and worsening SRH. High priority should be placed on prevention and management strategies for pain among people with arthritis.