ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Endocrine Abstracts (2019) 63 GP149 | DOI: 10.1530/endoabs.63.GP149

Risk of chronic kidney disease (CKD) and CKD progression in patients with chronic hypoparathyroidism (HypoPT): a retrospective cohort study

Kristina Chen1, Elvira O. Gosmanova2, Gary Curhan3, Lars Rejnmark4, Fan Mu5, Elyse Swallow5, Nicole Sherry1, Monica Macheca5 & Markus Ketteler6

1Shire Human Genetic Therapies, Inc., a member of the Takeda group of companies, Cambridge, MA, USA; 2Stratton VA Medical Center and Albany Medical College, Albany, NY, USA; 3Brigham and Women’s Hospital, Boston, MA, USA; 4Aarhus University and Aarhus University Hospital, Aarhus, Denmark; 5Analysis Group Inc., Boston, MA, USA; 6Klinikum Coburg GmbH, Coburg, Germany.

Background: Previous studies of smaller size signaled heightened risk of CKD in patients with chronic HypoPT treated with conventional therapy (ie, oral calcium and active vitamin D). However, little is known about CKD progression, including progression to end-stage kidney disease (ESKD), in HypoPT patients.

Methods: A retrospective cohort study, using a large US commercial claims database (Q1 2007–Q2 2017), was conducted to compare the risk of CKD between chronic HypoPT patients (excluding those receiving parathyroid hormone) and randomly selected non-HypoPT patients over 5 years of follow-up. For HypoPT patients, the first date of follow-up (ie, index date) was the earliest HypoPT diagnosis date ≥6 months after initial HypoPT diagnosis; for non-HypoPT patients, it was the date of a randomly selected medical claim. Diagnosis codes, estimated glomerular filtration rate (based on CKD-EPI formula), and dialysis procedure codes were used to identify CKD stages. Patient characteristics at baseline (the 6 months before index date) and risk of incident CKD stage ≥3 were compared between cohorts, the latter using Kaplan-Meier analysis and Cox proportional hazards models adjusting for baseline demographic (age, sex, race, region, and index year) and clinical (heart failure, hypertension, diabetes, and medication use) characteristics. CKD progression to a higher CKD stage and to ESKD was similarly analysed among patients with baseline CKD stages 3 or 4.

Results: The study included 8097 chronic HypoPT patients and 40,485 non-HypoPT patients. At baseline, HypoPT patients were older than non-HypoPT patients (58.6 vs 47.3 years), a higher proportion were female (76.2% vs 54.4%), and higher proportions had CKD stages 3-5 (16.4% vs 3.0%) and stages 3-4 (13.6% vs 2.6%). Among those with baseline CKD stages 3-4, HypoPT patients were younger than non-HypoPT patients (70.6 vs 72.1 years), and a higher proportion were female (67.1% vs 54.8%). HypoPT patients had increased risk of CKD stage ≥3, CKD progression, and progression to ESKD compared with non-HypoPT patients (all P<0.001 based on Kaplan-Meier analyses). Adjusted hazard ratios (95% CI) associated with HypoPT vs non-HypoPT were 2.57 (2.35, 2.82) for CKD stage ≥3, 1.62 (1.29, 2.03) for CKD progression, and 1.95 (1.41, 2.70) for progression to ESKD (all P<0.001).

Conclusions: Chronic HypoPT was associated with significantly increased risk of CKD stage ≥3, CKD progression, and progression to ESKD. Further research is warranted to understand the potential mechanisms for the relationship of chronic HypoPT and its management with these observed risks.