New England Section of the American Urological Association

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Investigating the Relationship between Socioeconomic Factors and Nephrolithiasis Prevalence
Kinan Bachour, BS; Amanda R. Swanton, MD; PhD; Vernon M. Pais, Jr., MD
Dartmouth-Hitchcock Medical Center, Lebanon, NH

Background: Socioeconomic factors, including type of health insurance, income, and level of education, may be associated with kidney stone formation. While some previous investigations have suggested a relationship between insurance status and kidney stone formation, to our knowledge such associations have not been made using a nationally representative cohort.  
Methods: Data was abstracted from the National Health and Nutrition Examination Survey (NHANES) from 2007 to 2014, and was weighted to represent the United States population. The variables chosen were assessed for collinearity before analyzed. Using univariate and multivariable logistic regressions on STATA, we analyzed the odds of developing kidney stones among several socioeconomic factors.
Results: The weighted national prevalence of nephrolithiasis between ages 20 and 79 was 8.5% of a population of over 156.7 million. 51% of the population was women. The mean age was 45 years old and the mean body mass index (BMI) was 28.8. The prevalence of nephrolithiasis was higher among individuals who had state-assisted insurance compared to those with private insurance (6.3% vs 1.8%, p<0.001). On univariate regression analysis, having a college education was protective against stones compared to having less than a high-school degree (OR 0.78, 95% CI 0.63-0.97; p=0.03). Income was also significantly associated with kidney stone prevalence. After adjusting for race, body mass index (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 0.60, 95% CI 0.42 0.85; p=0.005).
Conclusion: We demonstrate that certain socioeconomic variables, including health insurance, education level, and income are associated with nephrolithiasis. Individuals who have state-
assisted insurance have increased odds of developing kidney stones. Further investigation is warranted so that these discrepancies among patients with nephrolithiasis may be reduced in the future.


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