The safety profile of tadalafil as prescribed in general practice in England: results from a prescription‐event monitoring study involving 16 129 patients

Abstract

To examine the safety of tadalafil as used in general practice in England, and to compare the mortality rate due to ischaemic heart disease (IHD) in tadalafil users with that in the male population in England. Patients in this observational cohort study were identified from dispensed prescriptions for tadalafil issued by general practitioners (GPs) from February 2003 to November 2004. Demographic and outcome data (clinical events) were requested from patients' GPs using a postal questionnaire. A standardized mortality ratio (SMR) was calculated using indirect standardization for deaths from IHD in the cohort (where age was known) over a 1-year observation period compared to that in the English male population (2003). A sensitivity analysis was carried out to investigate the effects of missing data for age and cause of death. Clinical information was obtained for 16 129 patients (median age 60 years, interquartile range 52-67); the age was not specified for 3212 (19.9%) patients. At least a third of the patients had diabetes mellitus and 29% had hypertension. Comparison of the mortality rate due to IHD for the patients of known age with that in the English male population provided an SMR of 0.57 (95% confidence interval 0.38-0.83) indicating fewer observed deaths in the cohort than expected. The results of the sensitivity analyses investigating the effect of missing data for age and cause of death produced similar SMR estimates. One confirmed case of non-arteritic anterior ischaemic optic neuropathy (NAION) was reported during tadalafil therapy in a patient with other risk factors for this condition. The results from this prescription-event monitoring study suggest that tadalafil is generally well tolerated when used in general practice in England. The most frequently reported adverse clinical events were in keeping with clinical trial data and include headache, dyspepsia and back pain. There was no evidence of a greater mortality rate due to IHD in the tadalafil cohort than in the general male population. However, these results are limited by the use of an external comparator group and might be explained by a 'healthy cohort effect'. One event of NAION was reported, and although a causal relationship was not established it indicates that NAION occurs rarely in patients prescribed tadalafil.