Background Programmes of mammography can help to reduce socioeconomic disparities in breast cancer screening. While Switzerland has not developed a mammography programme at the national level, regional programmes were progressively introduced since 1999 and covered 38% of Swiss women in 2012. Our objective was to examine (1) the evolution of socioeconomic inequalities in breast cancer screening between 1992 and 2012 in Switzerland and (2) the impact of introduction of mammography programmes on socioeconomic inequalities.

Methods Data on 17,332 women 40–70 years old were collected by the Swiss Health Interview Survey, a nationally representative cross-sectional survey repeated 5 times from 1992 to 2012. Socioeconomic status was assessed with education, income, employment, social class and type of health insurance in case of hospitalisation. Adjusted prevalence ratios (APR) of up-to-date (last two years) mammography were estimated with Poisson regression and robust standard errors. Interaction between mammography exposure and socioeconomic status were tested. All results were weighted for sampling frame and response bias. Two periods were considered: a period without exposure to mammography programs (1992–1997) and a period with exposure (2002–2012).

Results During the period without mammography programs (1992–1997), prevalence of up-to-date mammography increased by 16% between 1992 and 1997 (APR 1.16 95% CI 1.05–1.28). Higher prevalence was associated with type of health insurance (fully private vs. basic APR 1.31 95% CI 1.14–1.51), and employment (working full time vs. out of the labour force APR 1.19 95% CI 1.04–1.35).

During the period of progressive introduction of regional programmes (2002–2012), prevalence of up-to-date mammography increased by 19% every five years (APR 1.19 95% CI 1.15–1.24). Higher prevalence was associated with exposure to mammography programmes (APR 1.52 95% CI 1.43–1.61), type of health insurance (fully private vs. basic APR 1.28 95% CI 1.17–1.40), higher income (≥6,001 Swiss francs vs. ≤2,000 Swiss francs APR 1.16 95% CI 1.01–1.) and employment (working full time vs. out of the labour force APR 1.09 95% CI 1.01–1.18). Interaction between mammography programmes and socioeconomic status were not significant (interaction p-values not shown), except for employment status (p = 0.014).

Stratifying up-to-date mammography between women exposed to programmes and women not exposed yielded similar results.

Discussion Prevalence of up-to-date mammography in Switzerland increased during the period before the introduction of mammography programmes. Progressive introduction of regional mammography programmes accelerated the increase in prevalence of up-to-date mammography but did not modify the pattern of socioeconomic inequalities, except for employment inequalities. Mammography programmes reduced employment inequalities by increasing the participation of women out of the labour force.