In this analysis of a nationally representative sample of women in the US, we found that overall, women with diabetes were less likely to be concordant with cervical cancer screening; however once controlling for other predictors of concordant screening, the association with diabetes was attenuated towards the null and no longer statistically significant. Most predictors of concordant screening were similar for women with or without diabetes but we did see evidence of heterogeneity for urbanicity, income and delayed medical care. We also found little evidence that reasons for not being screened differed by diabetes status.
Most studies examining cervical cancer screening by diabetes status have been conducted outside of the US. Within the US, a previous analysis using the Behavioral Risk Factor Surveillance System (BRFSS) found a lower prevalence of cervical cancer screening among women with diabetes compared to those without even after adjustment for other factors, but that study was limited to HPV testing and if women had ever been tested. We reported on Pap smears and HPV testing combined but unlike the BRFSS analysis, once we controlled for other participant characteristics, there was no association between diabetes status and concordant screening. In the BRFSS, there was also indication of lower rates of screening in southern states while there was no evidence of regional differences in the NHIS.
Another recent retrospective cohort study conducted in Canada found lower cervical cancer screening rates among women with prevalent (but not incident) diabetes. They found women with diabetes had a 15% lower rate of concordant cervical cancer screening compared to women without diabetes. There are a number of factors that make these analyses difficult to compare. Most notably, the population demographics differ, as well as each country’s healthcare system. Since the strongest associations we found for predictors in this analysis were healthcare-related (i.e. having health insurance, a usual place for healthcare, and visiting a doctor in the past year), it is important to have data available for diabetes and cervical cancer screening in the US. In our analysis, we excluded women with incident diabetes diagnosed in the year prior to the survey because of insufficient numbers and noted detection biases.
We did not find evidence that screening concordance by race/ethnicity differed by diabetes status. This is important because the risk of being diagnosed with and dying from diabetes and cervical cancer are both higher in Hispanic and Black non-Hispanic women.[9, 14, 15] Based on this analysis, interventions targeted to increase screening in these groups would not need to consider diabetes as a modifying factor. Access to care still appears to be the biggest obstacle regardless of diabetes. This may apply to other chronic conditions also since the number of chronic conditions was not predictive of concordant screening after adjusting for other factors.
The differences we found by diabetes status for urbanicity are interesting in that women with diabetes in rural areas are more likely to be screened for cervical cancer than women in metro areas while women without diabetes in rural areas are less likely to be screened than women in metro areas. Breast and cervical cancer screening have been shown to be persistently lower in rural communities and these women face additional barriers to healthcare. Perhaps having a chronic condition, such as diabetes, helps overcome some of these barriers in rural communities but acts more of a burden in metro areas. While studies have compared barriers to cervical cancer screening in urban and rural women,[17, 18] we are unaware of any that have examined the barriers by diabetes or other chronic disease status.
A major limitation of this analysis is relying on self-reported screening, which makes it less reliable to compare Pap smears and HPV tests to each other. However, for the purposes of this analysis, the focus was on any concordant screening. Because the NHIS includes such a broad questionnaire, we were able to control for and examine many potential predictors of concordant screening. However, it should be noted that we calculated a substantial number of statistical tests and did not adjust for multiple testing. It is also important that these data were collected prior to the Covid-19 pandemic, which has provided substantial disruption to cancer screening schedules and routines. It is unclear how these results might differ as screenings begin to recover and it is unlikely that the recovery will be equal across groups, which could exacerbate existing disparities.
Cervical cancer screening rates have been declining since 2000. Because of lower survival from cervical cancer among women with diabetes and increasing prevalence of diabetes, it is important to increase cervical cancer screening in these women. Based on the results of this study, it appears that while cervical cancer screening concordance may be lower in women with diabetes compared to those without, most barriers to screening are common to all women.