Mammography utilization in Canadian women aged 50 to 69 - Identification of factors that predict initiation and adherence

Objective: To identify factors that predict initiation of mammography and adherence with biennial screening among Canadian women aged 50-69 years. Methods: Using data from a longitudinal panel of Canadian women interviewed in the National Population Health Survey (NPHS) in 1994/95 and 2 and 4 years later, we estimated the relative risks (RR) of mammography initiation and adherence according to socio-demographic, health and lifestyle characteristics. Results: Among 505 women with no history of mammography use at baseline, 23.0% and 41.4% initiated mammography by 2 and 4 years, respectively. Urban residence (RR=2.85) was most strongly associated with initiation by 2 years; younger age (50-54) and lower education also predicted initiation by 2 years. Younger age, birthplace outside Canada, and having a recent (< 2 years) blood pressure check were associated with initiation by 4 years. Among 873 women reporting a recent (< 2 years) mammogram at baseline, 88.7% also reported a recent mammogram within 2 years while 73.0% reported one at both the 2- and 4-year follow-up. Being a non-smoker was the strongest predictor of maintaining adherence both at the 2- (RR=1.18) and the 4-year (RR=1.37) follow-up. Interpretation: Previously identified underserved groups of Canadian women (e.g., those with lower educational levels or born outside of Canada) were most likely to initiate mammography. Approximately 1 in 6 women aged 50 to 69 years remained never-users during follow-up, and fewer than half reported recent mammograms at all three survey cycles, suggesting the need to reinforce regular screening participation.