A record linkage study of outcomes in patients with mild primary hyperparathyroidism:The Parathyroid Epidemiology and Audit Research Study (PEARS)

Context Primary hyperparathyroidism (PHPT) is a common endocrine disorder, but the majority of cases are perceived to be mild and remain untreated.Objective To determine the risk of mortality and morbidities in patients with mild PHPT.Setting Tayside, Scotland, 1997-2006.Design A historical, prospective, record-linkage, population-based, matched cohort study.Patients All patients with diagnosed but untreated, mild PHPT.Method and outcome measures Each patient with PHPT was matched with five population-based comparators, by age, gender and calendar year of PHPT diagnosis, selected from the general population. Primary outcomes were all-cause mortality, fatal and nonfatal cardiovascular disease (CVD). Secondary outcomes were cancer-related deaths and other hospital admitted morbidities, including cerebrovascular disease, fractures, hypertension, psychiatric disease, renal complications, cancer and diabetes. The risk was assessed using the Cox proportional hazards model, adjusting for confounding factors of pre-existing co-morbidities, previous prescription of bisphosphonates, socio-economic deprivation score and the probability of having a calcium check.Results Compared to the matched cohort, the risk of all cause mortality, fatal and nonfatal CVD was increased in patients with asymptomatic PHPT: adjusted hazard ratios (HR) 1.64 (95% CI: 1.43-1.87), 1.64 (95% CI: 1.32-2.04) and 2.48 (95% CI: 2.13-2.89), respectively. The risk was also increased in all secondary outcomes, with the risk of renal failure and renal stones being the highest, adjusted HRs being 13.83 (95% CI: 10.41-18.37) and 5.15 (95% CI: 2.69-9.83), respectively.Conclusions Patients with mild PHPT had an increased risk of mortality, fatal and nonfatal CVD, and the risk of developing other co-morbidities was also increased.