Reduced fracture incidence in patients having surgery for primary hyperparathyroidism.

Objective: The indication of surgery in primary hyperparathyroidism has been controversial, as many patients experience mild disease. The primary aim was to evaluate fracture incidence in a contemporary population-based cohort of patients having surgery for primary hyperparathyroidism. The secondary aim was to investigate whether preoperative serum calcium, adenoma weight or multiglandular disease influence fracture incidence.

Design: A retrospective cohort study with population controls. Primary outcomes, defined by discharge diagnoses and prescriptions, were any fracture and fragility fracture, secondary outcomes were multiple fractures anytime and osteoporosis. Subjects were followed 10 years pre- and up to 10 years postoperatively (or 31 December 2015). Multiple events per subject were allowed. Fracture incidence rate ratios (IRRs) for patients pre- and postoperatively were tabulated and evaluated with mixed-effects Poisson regression. Secondary outcomes were evaluated using conditional logistic regression.

Patients: A Swedish nationwide cohort of patients having surgery for primary hyperparathyroidism (n = 5009) from the Scandinavian Quality Register for Thyroid, Parathyroid and Adrenal Surgery between 2003 and 2013 was matched with population controls (n = 14,983). Data were cross-linked with Statistics Sweden and the National Board of Health and Welfare.

Measurements: Preoperative serum calcium and adenoma weight at pathological examination.

Results: Patients had an increased incidence rate of any fracture preoperatively, IRR 1.27 (95% confidence interval: 1.11-1.46), highest in the last year before surgery. Fracture incidence was not increased postoperatively. Serum calcium, adenoma weight and multiglandular disease were not associated with fracture incidence.

Conclusions: Fracture incidence is higher in patients with primary hyperparathyroidism but is normalized after surgery.