Kidney Stone Events Following Parathyroidectomy vs Nonoperative Management for Primary Hyperparathyroidism

Abstract

Context: Primary hyperparathyroidism (PHPT) is associated with an increased risk of kidney stones. Few studies account for PHPT severity or stone risk when comparing stone events after parathyroidectomy vs nonoperative management.

Objective: Compare the incidence of kidney stone events in PHPT patients treated with parathyroidectomy vs nonoperative management.

Design: Longitudinal cohort study with propensity score inverse probability weighting and multivariable Cox proportional hazards regression.

Setting: Veterans Health Administration integrated health care system.

Patients: A total of 44 978 patients with > 2 years follow-up after PHPT diagnosis (2000-2018); 5244 patients (11.7%) were treated with parathyroidectomy.

Main outcomes measure: Clinically significant kidney stone event.

Results: The cohort had a mean age of 66.0 years, was 87.8% male, and 66.4% White. Patients treated with parathyroidectomy had higher mean serum calcium (11.2 vs 10.8mg/dL) and were more likely to have a history of kidney stone events. Among patients with baseline history of kidney stones, the unadjusted incidence of ≥ 1 kidney stone event was 30.5% in patients managed with parathyroidectomy (mean follow-up, 5.6 years) compared with 18.0% in those managed nonoperatively (mean follow-up, 5.0 years). Patients treated with parathyroidectomy had a higher adjusted hazard of recurrent kidney stone events (hazard ratio [HR], 1.98; 95% CI, 1.56-2.51); however, this association declined over time (parathyroidectomy × time: HR, 0.80; 95% CI, 0.73-0.87).

Conclusion: In this predominantly male cohort with PHPT, patients treated with parathyroidectomy continued to be at higher risk of kidney stone events in the immediate years after treatment than patients managed nonoperatively, although the adjusted risk of stone events declined with time, suggesting a benefit to surgical treatment.

Keywords: kidney stones; nephrolithiasis; parathyroidectomy; primary hyperparathyroidism.

Figure 1.

Consort diagram. *Some patients met multiple exclusion criteria.

Figure 2.

Kaplan-Meier estimates of kidney stone events among inverse probability–weighted patients with PHPT treated with parathyroidectomy vs nonoperative management within 2 years, stratified according to baseline history of kidney stones.

Figure 3.

Annual rate of kidney stone events before and after treatment among inverse probability–weighted (IPW) groups of patients with PHPT and a baseline history of kidney stones treated with parathyroidectomy within 2 years vs nonoperative management.^a,b. ^aThe propensity score used for IPW in this table was based on sex, age group, race, ethnicity, Charlson Comorbidity Index, endocrinologist or nephrologist/urologist care within 6 months of PHPT diagnosis, operative indications for parathyroidectomy (history of kidney stones, osteoporosis, or stage 3 chronic kidney disease at the time of PHPT diagnosis), and risk factors for kidney stones (hypertension, diabetes, gout, body mass index). ^bRate of stone events at time 0 represents rate in year before treatment date.