(National Cancer Institute, unpublished data,. 1990). ... Screening, Alberta Cancer Board, Calgary, Alberta. Requests ... American Journal of Public Health 927 ...
Changes in Canadian Women's Mammography Rates Since the Implementation of Mass Screening Programs Catherine E. De Grasse, MScN, RN, Annette M. O'Connor PhD, RN, Jack Boulet, PhD, Nancy Edwards, PhD, RN, Heather Bryant, MD, PhD, and Krista Breithaupt, MA Canadian and American breast-screening guidelines for women aged 50 to 69 years include mammography every 1 to 2 years. 1-3 Recommendations for women in their 40s are more variable, reflecting the greater uncertainty regarding efficacy.3'4 Canadian guidelines do not recommend routine mammography screening,4 whereas American guidelines,5'6 which previously varied in recommendations for screening women in their 40s, now recommend routine
screening.3'7 In 1990 to 1991, only 55% of Canadian women aged 50 to 69 years reported ever having had a mammogram.811 Moreover, mammography rates among Canadian women in their 40s-an age group for whom screening was not routinely recommendedwere comparable to those of women in their 50s. In the United States, in 1990, 60% of women 40 years and older had received at least 1 mammogram during their lifetime (National Cancer Institute, unpublished data, 1990). Since the 1990/91 Canadian surveys, several organized provincial breast-screening programs have been established to increase age-appropriate screening rates by providing coordinated screening services through outreach community strategies. This study's objective was to describe changes in mammography rates between 1990 and 1994/95 among Canadian women aged 40 to 69 years, according to the presence or absence of a provincial screening
program.
Methods Changes in mammography rates among Canadian women aged 40 to 69 years were determined by comparing 2 national surveys: the 1990 Health Promotion Survey and the 1994-1995 National Population Health Survey. Changes were analyzed by age group (40-49 years and 50-69 years) and by the presence or absence of an organized provincial breast-screening program between 1990 and 1993. Both surveys used the same vali-
CCFP, FRCP,
dated questions to measure self-reported
mammography.'2"13 To obtain appropriate standard errors and confidence limits for the estimates, we had to take into account the design effects due to complex sampling in each survey (V Goel, unpublished data, 1993). We used a simple approximation method in which the population weights were divided by the average population weight to create analytic weights. The analytic weights were modified for each survey to reflect an average design effect for study variables. The design effect was selected on the basis of a review of the literature'4 and was checked against the coefficients of variation in the survey documentation. The t test was used to examine the differences in screening rates over time.'5 In the present study, the proportions and their standard errors represented estimates of continuous variables. t values less than -2 or greater than +2 were considered statistically significant (level of significance = approximately 5%).
Results The household response rates were 87.1% and 88.7% for the 1990 and 1994/95 surveys, respectively. The demographic profiles of respondents were Catherine E. De Grasse is with Clinical Services, Ottawa Regional Women's Breast Health Centre, Ottawa Hospital-Civic Campus, Ottawa, Ontario. Annette M. O'Connor and Nancy Edwards are with the School of Nursing, Faculty of Health Sciences, and Krista Breithaupt is with the Department of Epidemiology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario. Jack Boulet is with the Educational Commission for Foreign Medical Graduates, Philadelphia, PA. Heather Bryant is with the Division of Epidemiology, Prevention and Screening, Alberta Cancer Board, Calgary, Alberta. Requests for reprints should be sent to Catherine E. De Grasse, MScN, RN, Program Coordinator, Clinical Services, Ottawa Regional Women's Breast Health Centre, Ottawa Hospital-Civic Site, 200 Melrose Ave, Ottawa, Ontario, Canada KIY 4K7. This paper was accepted November 11, 1998.
American Journal of Public Health 927
Briefs
comparable in the 2 surveys. The percentof women in various categories for the 1990 and 1994/95 surveys, respectively, were as follows: 43% vs 44% in their 40s; 5% vs 7% single; 76% vs 73% married; 39% vs 30% with less than a high school education; 30% vs 35% with a high school diploma; 31% vs 35% with a college/university diploma; 48% vs 47% employed; 38% vs 34% with an income under Can $30000. The percentage of Canadian women aged 50 to 69 years who reported ever having had a mammogram (Figure 1) increased by 19% between 1990 and 1994/95 (t= 9.7, P
