Risk of herpes zoster in patients prescribed inhaled corticosteroids: a cohort study

We identified a cohort of adult users of respiratory medications in the General Practice Research Database and carried out a nested case control analysis of inhaled corticosteroid use among 8900 new cases of herpes zoster and 88032 controls matching on age and calendar time.The adjusted odds ratio for the relationship between current use of ICS and the occurrence of herpes zoster was 1.00 (95% confidence interval (CI), 0.94-1.07). There was no increase in risk of herpes zoster even at higher ICS doses; odds ratio 1.05 (95% CI, 0.96-1.14). Among subjects with concomitant prescriptions for an ICS and an inhibitor of cytochrome P450 3A4, the point estimate for the association between herpes zoster and the use of higher doses of inhaled corticosteroids was 1.23 (95% CI, 0.81-1.88).The use of inhaled corticosteroids, even at high doses and in conjunction with inhibitors of their metabolism, was not a significant risk factor for the occurrence of herpes zoster in adults.Inhaled corticosteroids (ICS) are being increasingly used in the treatment of patients with asthma and with chronic obstructive pulmonary disease (COPD). These medications are systemically absorbed and may have systemic adverse effects such as cataracts and fractures [1,2]. The use of high doses of ICS has recently been found to increase the risk of severe pneumonia in patients with COPD [3,4]. Information on other infectious complications of ICS therapy is scant but low doses of oral corticosteroids with similar systemic potency have been linked to an excess of serious infections [5]. Moreover, ICS are metabolised via the cytochrome P450 (CYP) system which is involved in biotransformation of the vast majority of all drugs currently available [6,7]. Therefore patients often find themselves taking several medications competing for the same enzymes required for their biotransformation into inactive compounds which can then be excreted.Herpes zoster (shingles) results from reactivation of latent varicella zos