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Abstract #25822 Published in IGR 12-2
Quantification of patient population impact of contra-indications: Glaucoma therapy
Maguire A; MacLachlan SPharmacoepidemiology and Drug Safety 2009; 18: S100
Background: Contraindication is a key element in harm reduction of one or more adverse events. To estimate the expected occurrence of these events we need to know the distribution of risk factors for the adverse events according to the therapeutic options. We also need the population incidence of the adverse events according to the levels of the risk factors. In glaucoma treatment, timolol maleate is contraindicated among patients with asthma/COPD and with congestive heart failure (CHF). Objectives: To describe the risk factors of asthma/COPD hospitalisation or exacerbation and CHF in glaucoma patients and to describe the distribution of these conditions according to the main therapeutic options: timolol maleate and latanoprost. Methods: The UK primary care database THIN provided glaucoma patients (on January 1st 2007). Prevalence of CHF, asthma, COPD, coronary heart disease (CHD), diabetes, hypertension, smoking, BMI ((greater-than or equal to)25) were described by glaucoma therapy. General population incidence rates of asthma/COPD hospitalisation or exacerbation and CHF according were estimated from all patients in THIN on 1st January 2006. Results: There were 2280 patients using timolol maleate and 7927 using latanoprost as unique therapy. Prevalences of CHF, asthma, COPD and CHD were all lower (p<0.001) in the timolol group as compared to latanoprost [CHF: 3% vs. 5%; asthma: 6% vs. 16%; COPD: 3% vs. 8%; CHD: 14% vs. 17%]. Prevalences of diabetes (17%), hypertension (50%), smoking (10%) and high BMI (59%) were very similar as were age and sex of the two patients populations (median age = 77 years; % male = 47%). By applying the general population incidence rates, the expected number of events per 10000 patients over 1-year was calculated and compared for timolol vs. latanoprost [CHF: 89 vs 113; COPD/asthma: 71 vs. 176]. Conclusions: The expected reduction in events is purely the result of altering the case-mix within the timolol group; effective contraindication should lead to a reduction in events greater than this. However, these estimates require scenario modeling and the incorporation of uncertainty.
A. Maguire. UBC, LondonUnited Kingdom.
Classification:
15 Miscellaneous
1.1 Epidemiology (Part of: 1 General aspects)
11.4 Prostaglandins (Part of: 11 Medical treatment)
11.3.4 Betablocker (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
