β Blockers for glaucoma and excess risk of airways obstruction: population based cohort study

Topical β blockers are the most commonly prescribed drugs in the United Kingdom for glaucoma.1 They are known to exacerbate bronchospasm in asthma and chronic obstructive pulmonary disease.2 This study examined whether topical β blockers are associated with excess respiratory disease in elderly patients not considered to be at excess risk. We used the Mediplus database to identify patients with no previous diagnosis of airways obstruction. We defined exposed patients as patients who had used ophthalmic topical β blockers for the first time in the period 1993-7. Unexposed patients were randomly selected (loosely matched by age and sex to exposed patients). For validation we inspected a random sample of 40 full longitudinal records of exposed and unexposed patients. We defined patients who had excess respiratory disease in two ways. Definition A patients were patients who in the 12 months after treatment with topical β blockers were given for the first time a drug …