Geographic Variation in the Quality of Secondary Prevention for Nephrolithiasis

Objective To examine the variation in the quality of secondary prevention for nephrolithiasis across health care markets. Methods Using analytical files from Litholink Corporation (2003-2012), we identified adults with nephrolithiasis and abnormal urine biochemistries on 24-hour urine collection. After assigning all patients to a hospital referral region (HRR), we determined the proportion of patients in each HRR who underwent on-treatment follow-up testing (our measure of quality). We then fitted multivariate hierarchical regression models to quantify the amount of variation in this proportion across HRRs. Finally, we examined for associations between a patient's odds of on-treatment follow-up testing and the supply of primary care and specialist physicians in an HRR. Results The mean rate on-treatment follow-up testing was exceedingly low at only 11.9%. This rate has been stable over time. There was fourfold variation in this rate across HRRs from as little as 6.6% to as high as 23.4%. Those HRRs with higher on-treatment follow-up testing rates tended to have a wealthier and more educated population ( P = .01). Receipt of on-treatment follow-up testing was not associated with the number of specialists per capita. Conclusion Wide geographic variation exists in the quality of secondary prevention for patients with nephrolithiasis. Given that current guidelines recommend on-treatment follow-up testing, efforts to increase its uptake are needed.