Impact of socio-economic status on breast cancer screening in women with diabetes: a population-based study

Aims – There is evidence to suggest that mammography rates are decreased in women with diabetes and in women of lower socio-economic status. Because of the strong association between low socio-economic status and diabetes, we explored the extent to which socio-economic status differences explain lower mammography rates in women with diabetes.

Methods – A population-based retrospective cohort study in Ontario, Canada, of women aged 50 to 69 years with diabetes between 1999 and 2010 age matched 1:2 to women without diabetes. Main outcome measure is the likelihood of at least one screening mammogram in women with diabetes within a 36-month period, starting as of either 1 January 1999, their 50th birthday or 2 years after a diabetes diagnosis, whichever came last. Outcomes were compared with those in women without diabetes during the same period as their matched counterparts, adjusting for socio-economic status based on neighbourhood income and other demographic and clinical variables.

Results – Of 504 288 women studied (188 759 with diabetes, 315 529 with no diabetes), 63.8% had a screening mammogram. Women with diabetes were significantly less likely to have a mammogram after adjustment for socio-economic status and other factors (odds ratio 0.79, 95% CI 0.78-0.80). Diabetes was associated with lower mammogram use even in women from the highest socio-economic status quintile (odds ratio 0.79, 95% CI 0.75-0.83).

Conclusions – The presence of diabetes was an independent barrier to breast cancer screening, which was not explained by differences in socio-economic status. Interventions that target patient, provider and health system factors are needed to improve cancer screening in this population.