Understanding the relationship between health insurance and kidney stones: an examination of NHANES data.

ABSTRACT

INTRODUCTION: To investigate the relationship between socioeconomic factors, specifically insurance status, and kidney stones using a nationally representative cohort. MATERIALS AND METHODS: A retrospective secondary data analysis of National Health and Nutrition Examination Survey (NHANES) data from 2007 to 2014 was performed. Using univariate statistics and multiple logistic regressions, we examined the relationship between socioeconomic factors and kidney stone history. RESULTS: The weighted national prevalence of nephrolithiasis between ages 20 and 64 was 7.7% of a population of over 95.3 million. Fifty-three percent of the total population was female. The mean age was 42 years and the mean body mass index (BMI) was 28.7. The prevalence of nephrolithiasis was higher among individuals who had state-assisted insurance compared to those with private insurance (10.3% versus 7.3%, p = 0.005). On univariate regression analysis, having a college education was protective against stones compared to having less than a high-school degree (OR 0.62, 95% CI 0.43-0.84; p = 0.009). Income was also significantly associated with kidney stone prevalence. After adjusting for race, BMI, gender, water intake, income, and education level through multivariable analysis, having private insurance was associated with lower odds of developing nephrolithiasis compared to having state-assisted insurance (OR 0.62, 95% CI 0.44-0.89; p = 0.01). CONCLUSIONS: Individuals with state-assisted insurance were found to have significantly increased odds of a kidney stone compared to those with private insurance. Urologists, primary care, and policy makers should recognize this disparity exists and target opportunities to elucidate mechanisms and provide intervention for this high-risk group.