Stable incidence and increasing prevalence of primary hyperparathyroidism in a population-based study in Scotland

Objective: Previous studies, including our own, have demonstrated a highly variable incidence of primary hyperparathyroidism (PHPT) from year to year. We planned to provide a current estimate of the incidence and prevalence of PHPT in a community-based study.

Design: A population-based retrospective follow up study in Tayside (Scotland) from 2007 to 2018.

Methods: Record-linkage technology (demography, biochemistry, prescribing, hospital admissions, radiology, and mortality data) was used to identify all patients. Cases of PHPT were defined as those with at least two raised serum CCA (>2.55 mmol/l) and/or hospital admissions with PHPT diagnoses and/or surgery records with parathyroidectomy during the follow-up period. The number of prevalent and incident cases of PHPT per calendar year by age and gender were estimated.

Results: A total of 2118 people (72.3% female, mean age 65 years) were identified with an incident case of PHPT. The overall prevalence of PHPT over the twelve years of the study was 0.84% (95%CI: 0.68-1.02), steadily increasing from 0.71% in 2007 to 1.02% in 2018. From 2008, the incidence of PHPT was relatively stable from 4 to 6 cases per 10,000 person-years, declining from 11.5 per 10,000 person-years in 2007. The incidence varied from 0.59 per 10,000 person-years (95%CI: 0.40- 0.77%) for those aged 20-29 years, to 12.4 per 10,000 person-years (95% CI: 11.2-13.3) in those aged 70-79 years. Incidence of PHPT was 2.5 times higher in women than in men.

Conclusions: This study is the first showing a relatively steady annual incidence of PHPT at 4-6 per 10,000 person-years. This population-based study reports a PHPT prevalence of 0.84%.