The distribution and predictive validity of the stages of change for mammography adoption among Canadian women.

Objective: To examine the predictive validity of the transtheoretical model (TTM) stages of change for mammography participation in Canadian women.

Method: We examined the association between baseline TTM stage of mammography adoption and subsequent mammography participation in a representative sample of 3,125 Canadian women aged 40 and older from the longitudinal Canadian National Population Health Survey.

Results: The likelihood of having a mammogram at follow-up (1998/1999) increased with progressive stages of change at baseline (1996/1997) even after adjusting for potential confounders. Relative to women in maintenance, women in precontemplation, relapse, contemplation, relapse risk, and action were significantly less likely to report a recent mammogram during follow-up (adjusted RR of 0.41, 0.50, 0.63, 0.75, and 0.92, respectively; P(trend) < 0.01). This pattern held for women within and outside of the 50-69 target age range, and for urban and to a lesser degree rural-dwelling women.

Conclusion: Our findings support the predictive validity of the TTM stages of mammography adoption construct and the inclusion of both relapse and relapse risk categories to improve the sensitivity of the predictive model. Interventions to promote the eventual maintenance of mammography screening should also benefit from further research that aims to understand the variables that promote progressive movement through the stages.