Table.

Risk of developing airways obstruction in patients taking a topical β blocker for glaucoma

Diagnostic criterion	Time point after treatment with β blockers	No (%) of new cases		Unadjusted rate ratio (95% CI)	Adjusted hazard ratio (95% CI)*	No of patients needed to harm (95% CI)†
		Patients given topical β blockers (n=2645)	Control patients (n=9094)
Definition A‡	At 6 months	49 (1.9)	55 (0.6)	2.83 (1.91 to 4.20)	2.79 (1.88 to 4.15)	84 (51 to 131)
	At 12 months	81 (3.1)	112 (1.2)	2.39 (1.79 to 3.20)	2.29 (1.71 to 3.07)	55 (39 to 85)
Definition B§	At 6 months	115 (4.3)	172 (1.9)	2.16 (1.70 to 2.76)	2.18 (1.71 to 2.79)	42 (30 to 60)
	At 12 months	191 (7.2)	354 (3.9)	1.81 (1.5 to 2.16)	1.77 (1.48 to 2.12)	30 (22 to 42)

^*Adjusted analysis used a proportional hazards model, corrected for age, sex, use of systemic β blockers, use of non-steroidal anti-inflammatory drugs, use of nitrates, smoking, season of presentation, and number of visits to general practitioner after index date. 

^†Number of patients needing to be treated with topical β blockers to cause one case of airways obstruction during that time period. 

^‡Patients who were given a new prescription of a drug used in the treatment of airways obstruction. 

^§Definition A patients combined with patients who had a Read code for airways obstruction listed in their record.