The epidemiology of chronic pain in Canadian men and women between 1994 and 2007: longitudinal results of the National Population Health Survey.

BACKGROUND: The epidemiology of chronic pain is poorly understood due to a paucity of longitudinal studies limiting the ability to develop prevention strategies for a condition resistant to many current therapies.
OBJECTIVES: To identify the incidence of and sociodemographic risk factors for chronic pain in Canadian women and men over a 12-year period.
METHODS: Using data from the National Population Health Survey, individuals who developed chronic pain, defined as the presence of "usual pain" were identified. The cumulative incidence of chronic pain was calculated separately for men and women followed from 1994 to 2007. Biannual incidence and prevalence estimates of chronic pain were calculated during the same time period. Logistic regression analysis was used to examine predictors of chronic pain in men and women.
RESULTS: The cumulative incidence over the 12-year period was 35.6% (women 39.0%; men 32.2%). Women had a higher biannual prevalence, but not incidence, of chronic pain compared with men. In women, being older, having lower education and being widowed, separated or divorced, increased the risk of chronic pain. There were no sociodemographic risk factors for chronic pain in men.
CONCLUSION: Women had a higher prevalence - but not incidence - of chronic pain compared with men, indicative of longer duration of illness in women. Risk factors also differed according to sex, supporting current literature reporting potentially different mechanisms for men and women. A better understanding of risk factors is necessary to develop population-based preventive interventions. The former can only be achieved with population-based, longitudinal studies.