Socioeconomic Disparities in Breast Cancer Screening in Hawaii

INTRODUCTION Despite evidence that breast cancer screening reduces morbidity and mortality, many women do not obtain mammograms. Our objective was to analyze the relationship between income and mammography screening for members enrolled in a large health plan in Hawaii. METHODS We analyzed claims data for women (N = 46,328) aged 50 to 70 years during 2003 and 2004. We used parametric and nonparametric regression techniques. We used probit estimation to conduct multivariate analysis. RESULTS At the 5th percentile of the earnings distribution, the probability of mammography is 57.1%, and at the 95th percentile, it is 67.7%. Movement from the 5th percentile to the 35th percentile of the earnings distribution increases the probability of mammography by 0.0378 percentage points. A similar movement from the 65th percentile to the 95th percentile increases the probability by 0.0394 percentage points. Also, we observed an income gradient within narrowly defined geographic regions where physical access to medical care providers is not an issue. CONCLUSION We observed a steep income gradient in mammography screening in Hawaii. Because of the prevalence of measurement error, this gradient is probably far greater than our estimate. We cannot plausibly attribute our findings to disparities in coverage because 100% of our sample had health insurance coverage. The gradient also does not appear to result from poorer people residing in areas that are geographically isolated from providers of medical care.