Males with prolactinoma are at increased risk of incident cardiovascular disease.

Objective: To investigate whether the risk of incident cardiovascular disease (CVD) is increased in patients with prolactinoma.

Design: Population-based, retrospective, open-cohort study using The Health Improvement Network (THIN) database.

Patients: A total of 2233 patients with prolactinoma and 10 355 matched controls (1:5 ratio) from UK General Practices contributing to THIN were included. Sex, age, body mass index and smoking status were used as matching parameters. The primary outcome was any incident CVD, defined by Read codes suggesting myocardial infarction, angina pectoris, stroke, transient ischaemic attack or heart failure. Sex-specific-adjusted incidence rate ratios (aIRRs) were calculated with Poisson regression, using clinically relevant parameters as model covariates. Sensitivity analyses were performed to check whether a change in the initial assumptions could have an impact on the findings.

Results: During the 6-year observation period, the composite CVD outcome was recorded in 54 patients with prolactinoma and 180 "nonexposed" individuals. The incidence rate was 1.8 and 14.8 per 1000 person-years for the females and males with prolactinoma, respectively. The aIRRs for CVD were estimated at 0.99 [95% confidence interval (CI): 0.61-1.61, P = .968)] in female patients and 1.94 (95% CI: 1.29-2.91, P = .001) in male patients. These findings remained robust in sensitivity analyses restricting to patients with documented record of dopamine agonist treatment and those with newly diagnosed prolactinoma.

Conclusions: In contrast to females, men with prolactinoma have increased risk for incident CVD; the aetiology of this gender-specific finding remains to be elucidated.