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MON-523 Risk of Nephrolithiasis and Nephrocalcinosis in Patients with Chronic Hypoparathyroidism (HypoPT)

Year: 2019

Type: article

Abstract: Background: Chronic hypoparathyroidism (HypoPT) managed with conventional therapy (i.e., oral calcium and active vitamin D) may increase the risk of nephrolithiasis and nephrocalcinosis. This study evaluated whether HypoPT is associated with increased risk of these conditions. Methods: A retrospective cohort study was conducted to compare the risk of nephrolithiasis and nephrocalcinosis between chronic HypoPT patients (excluding those receiving parathyroid hormone) and randomly selected non-HypoPT patients over 5 years of follow-up using a large US commercial claims database (Q1 2007 - Q2 2017). The first date of follow up (i.e., index date) for HypoPT patients was the earliest HypoPT diagnosis date at least 6 months after the initial HypoPT diagnosis and for non-HypoPT patients was the date of a randomly selected medical claim. Patient characteristics at baseline (the 6 months prior to index date) were compared between cohorts. The risk of nephrolithiasis (identified by diagnosis and procedure codes) was compared between cohorts using Kaplan-Meier analysis and adjusted Cox proportional hazards models. Adjusting parameters included demographic (age, sex, race, region, and index year) and clinical (nephrolithiasis, gout, hypercalciuria, hypertension, diabetes, and thiazide diuretic use) characteristics at baseline. Similar analyses were conducted for nephrocalcinosis, among those without the condition at baseline. Adjusting parameters included demographic information and hypercalciuria. A sensitivity analysis for nephrocalcinosis was conducted among those with study period kidney imaging. Results: A total of 8,097 chronic HypoPT patients and 40,485 non-HypoPT patients were included. Compared to non-HypoPT patients, HypoPT patients were older (58.6 vs. 47.3 years), a higher proportion were female (76.2 vs. 54.4%), and higher proportions had nephrolithiasis (3.3 vs. 1.3%), nephrocalcinosis (0.6 vs. <0.1%), gout (3.0 vs. 1.2%), hypercalciuria (23.8 vs. 0.5%), type 2 diabetes (20.6 vs. 10.8%), and hypertension (43.7 vs. 25.2%) at baseline (all p <0.001). Kaplan-Meier analyses showed that HypoPT patients had increased risk of nephrolithiasis and nephrocalcinosis vs. non-HypoPT patients (p<0.001). The adjusted hazard ratios (HRs) associated with HypoPT vs. non-HypoPT were 1.81 (95% confidence interval [CI]: 1.60, 2.04) for nephrolithiasis and 6.94 (4.41, 10.92) for nephrocalcinosis (both p<0.001). In the sensitivity analysis, 2.6% of HypoPT and 0.5% of non-HypoPT patients (p<0.001) had nephrocalcinosis during the study. Conclusions: Chronic HypoPT was associated with increased risks of nephrolithiasis and nephrocalcinosis. Further research is warranted to understand the potential mechanisms for the relationship of chronic HypoPT and its management with the observed risk of these conditions. Funding: Shire

Source: Journal of the Endocrine Society

DOI: 10.1210/js.2019-mon-523