β-blockers for COPD inpatients.

For clinicians who treat patients with respiratory diseases, the use of β-blockers has, for a long time, posed a dilemma because of the potential risk of bronchospasm and neutralisation of the effectiveness of β-2 agonists. This predicament is particularly challenging for patients with chronic obstructive pulmonary disease (COPD), many of whom have substantial cardiovascular comorbidity, and in whom the avoidance of β-blockers might deprive them of substantial cardiovascular benefit. In the last few years, this restraint has been challenged, and rightfully so, in view of the general scarcity of data on this potential antagonism and, more importantly, its would-be effect on major outcomes. While caution is generally the sensible approach in drug safety, this is less the case here, as one would be withholding a treatment that has been demonstrated to be effective for cardiovascular disease. Several observational studies have examined the potential risks and benefits of β-blocker use in COPD. Most studies, to date, have looked at β-blocker use during the usual course of COPD without specifically examining their risk or benefit at the time of an acute exacerbation of COPD (AECOPD). Stefan et al address the question of the effects of β-blockers during a serious exacerbation requiring hospitalisation. The authors specifically evaluated whether β-blockers given early to patients hospitalised for AECOPD, and who also have ischaemic heart disease or heart failure, increase the risk of mortality. They used the US Premier hospitalisation database to identify a large cohort of over 35 000 patients hospitalised for COPD, and who received prednisone and inhaled β-2 agonists. The paper reports that the 29% of patients who received β-blockers during the first 2 days of the hospital stay did not have an increased risk of in-hospital mortality, readmission within 30 days, or mechanical ventilation, compared with COPD patients who did not receive β-blockers. This study has several noteworthy features. First, it is one of the first to look at the effects of β-blockers during a serious exacerbation requiring hospitalisation. This is a particularly crucial time, as COPD exacerbations are associated with high mortality in the first 1–2 weeks, likely more so if the patients also have cardiovascular comorbidity. This study suggests that β-blockers are safe during this particularly high-risk period. Second, the authors avoided the vexing problem of immortal time bias that has plagued recent observational studies of β-blockers in COPD, suggesting erroneously spectacular benefits of these drugs. This bias was present in the study by Dransfield who suggested that β-blocker use during a COPD hospitalisation was associated with an impressive 61% reduction in mortality (and an astonishing 92% reduction associated with short-acting β-agonist use). 10 The bias was also present in the study by Short et al, that reported a 22% reduction in all-cause mortality associated with β-blocker use, as noted in the related correspondence. In the present study, the authors were Center for Clinical Epidemiology, Lady Davis Research Institute, Jewish General Hospital, McGill University, Montreal, Quebec, Canada Departments of Epidemiology and Biostatistics and of Medicine, McGill University, Montreal, Quebec, Canada