Parathyroidectomy for Patients With Primary Hyperparathyroidism and Associations With Hypertension

Abstract

Importance: Hyperparathyroidism is associated with cardiovascular disease. However, evidence for a beneficial consequence of parathyroidectomy on hypertension is limited.

Objective: To investigate if parathyroidectomy improves hypertension in patients with primary hyperparathyroidism (PHPT).

Design, setting, and participants: In this cohort study and retrospective database review, patients with PHPT and hypertension between January 1, 2008, and December 31, 2016, were identified. The mean arterial pressure (MAP) and number of antihypertensive medications were compared between those who did and did not undergo parathyroidectomy. The setting was a large health care system. Primary hyperparathyroidism was defined using biochemical data, and hypertension was identified by International Classification of Diseases, Ninth Revision codes.

Exposure: Parathyroidectomy was identified in the database by Current Procedural Terminology codes.

Main outcomes and measures: The MAP and use of antihypertensive medications were compared for patients who underwent parathyroidectomy and those who did not at 6 months, 1 year, and 2 years. Multivariable logistic regression was used to assess the adjusted odds ratios for both increased and decreased use of antihypertensive medications.

Results: In this cohort study of 2380 participants (79.0% female), patients undergoing parathyroidectomy (n = 501) were younger (mean [SD] age, 65.3 [9.7] vs 71.9 [10.4] years; P < .001) and took fewer antihypertensive medications at baseline (mean [SD] number of medications, 1.2 [1.1] vs 1.5 [1.3], P < .001) than nonsurgical patients (n = 1879). Patients with parathyroidectomy showed greater improvement in their MAP at all follow-up time points (the median [SD] MAP change from baseline to 1 year was 0.1 [8.7] mm Hg without parathyroidectomy vs -1.2 [7.7] mm Hg after parathyroidectomy, P = .002). Nonsurgical patients were more likely vs those with parathyroidectomy to require more antihypertensive medications at 6 months (15.9% [n = 298] vs 9.8% [n = 49], P = .001), 1 year (18.1% [n = 340] vs 10.8% [n = 54], P < .001), and 2 years (17.6% [n = 330] vs 12.2% [n = 61], P = .004). By multivariable analysis, parathyroidectomy was independently associated with freedom from an increased number of antihypertensive medications at all periods (eg, adjusted odds ratio, 0.49; 95% CI, 0.34-0.70; P < .001 at 1 year). Among patients who were initially not taking antihypertensive medications, patients with parathyroidectomy were less likely vs no surgery to start antihypertensive medication treatment at all periods (eg, 10.2% [13 of 127] vs 30.4% [136 of 447], P < .001 at 1 year).

Conclusions and relevance: This study's findings suggest that, among hypertensive patients with PHPT, parathyroidectomy may be associated not only with greater decreases in their MAP but also with reduced requirements for antihypertensive medications. Parathyroidectomy decreased the number of patients who began taking antihypertensive medications. Additional study will be required to find whether there are downstream cardiovascular benefits of parathyroidectomy. Preexisting hypertension, particularly in those not already taking antihypertensive medications, should be considered when weighing surgical treatment.

Figure 1.. Derivation of the Study Cohort

MAP indicates mean arterial pressure; PHPT, primary hyperparathyroidism; and PTH, parathyroid hormone. To convert calcium level to millimoles per liter, multiply by 0.25; creatinine level to micromoles per liter, multiply by 88.4; and PTH level to nanograms per liter, multiply by 1.0. ^aThe index date is the surgery date for those with parathyroidectomy and is the index elevated calcium level date for those who did not undergo surgery.

Figure 2.. Patients Starting Antihypertensive Medication Therapy

Shown is the percentage of patients who were not taking antihypertensive medications at baseline but began taking antihypertensive medications during the study period.