Endocrine Abstracts

Background: Prior small studies have suggested increased risk of cardiovascular (CV) conditions in patients with hypoparathyroidism (HypoPT). We evaluated whether chronic HypoPT is associated with increased risk of select CV hard endpoints (i.e., myocardial infarction (MI), stroke, and a composite CV endpoint) in a large contemporary cohort.

Methods: A retrospective cohort study, based on a US commercial claims database (Q1 2007 - Q2 2017), was conducted to investigate the risk of select CV conditions associated with chronic HypoPT. The study cohort included chronic HypoPT patients (identified using diagnosis codes; excluding those receiving parathyroid hormone) and randomly selected non-HypoPT patients during 5 years of follow-up. CV outcomes (identified using diagnosis and procedure codes) included MI, stroke, and a composite CV endpoint consisting of cerebrovascular disease, coronary artery disease, heart failure, and peripheral vascular disease. For HypoPT patients, the first date of follow-up (i.e., index date) was the earliest HypoPT diagnosis date ≥6 months after the initial HypoPT diagnosis (to establish chronic HypoPT); for non-HypoPT patients, it was the date of a randomly selected medical claim. Patient characteristics at baseline (the 6 months prior to index date) were compared. The risk of each CV endpoint was compared between cohorts among patients free of the corresponding condition at baseline using Kaplan-Meier analysis and Cox proportional hazards models adjusting for demographic (age, sex, race, region, and index year) and clinical (chronic kidney disease, hypertension, and diabetes for all endpoints, and select CV comorbidities for MI and stroke) characteristics at baseline.

Results: The study included 8,097 chronic HypoPT and 40,485 non-HypoPT patients. At baseline, HypoPT patients were older than non-HypoPT patients (58.6 years vs. 47.3 years), a higher proportion were female (76.2% vs. 54.4%), and higher proportions had baseline MI (1.9% vs. 1.3%), stroke (4.6% vs. 2.4%), and any composite CV endpoint condition (19.4% vs. 9.5%) (all P<0.001). HypoPT patients had increased risk of MI, stroke, and the composite CV endpoint compared with non-HypoPT patients (all P<0.001). The adjusted hazard ratios (95% confidence interval; P-value) associated with HypoPT versus non-HypoPT were 1.19 (1.02, 1.39; P=0.029) for MI, 1.44 (1.30, 1.61; P<0.001) for stroke, and 1.64 (1.53, 1.76; P<0.001) for the composite CV endpoint.

Conclusions: Chronic HypoPT was associated with increased risk of incident MI, stroke, and the composite CV endpoint. Further research is warranted to understand the potential mechanisms for the relationship of chronic HypoPT and its management with the observed risk of CV conditions.