BackgroundAcute urinary retention is a medical emergency which can be associated with serious complications. Previous studies have reported that the mortality rates in older men with precipitated acute urinary retention was double that of the general population [Armitage et al. 2007]. The mortality rates among men with acute urinary retention ranged from 9.5% in those aged between 45 and 54 years to 45.4% for men over 85 years of age [Armitage et al. 2007]. Hence, identification and avoidance of aetiological factors may have some impact in reducing risk of urinary retention and any associated medical complications.Acute urinary retention is typically related to the presence of prostatic disease. However, some drugs have been known to be associated with urinary retention, including antipsychotics, tricylic antidepressants, calcium channel antagonists and anticholinergic drugs [Verhamme et al. 2008].Risk of acute urinary retention associated with inhaled anticholinergics in patients with chronic obstructive lung disease: systematic review Yoon K. Loke and Sonal Singh Abstract: Inhaled anticholinergics (ipratropium bromide and tiotropium bromide) are widely used as maintenance treatment in chronic obstructive pulmonary disease. Previous studies have reported on their cardiovascular effects but relatively little is known about their effects on the bladder. Acute urinary retention is a medical emergency which can be associated with serious complications. Our objective was to evaluate the existing literature regarding the effects of inhaled anticholinergics on urinary retention among patients with chronic obstructive pulmonary disease. We searched PubMed and the United States Food and Drug Administration (FDA) adverse events database for case reports, observational studies, randomized controlled trials (or meta-analyses of such trials) that reported on the outcome of urinary retention with inhaled anticholinergics (ipratropium or tiotropium). We checked 27 published articles and identified relevant papers including two case reports, three pooled analyses, two observational studies and one randomized controlled trial. Two of the observational studies and a pooled analysis of randomized controlled trials reported a significant increase in the risk of acute urinary retention with inhaled anticholinergics. Older patients with benign prostatic hyperplasia seem to be at the highest risk of this adverse effect which tends to occur soon after treatment initiation. Although all the links in the chain have yet to be fully elucidated, the preponderance of evidence suggests the possibility of a causal relationship between inhaled anticholinergics and urinary retention. Clinicians should carefully balance these and other adverse effects of inhaled anticholinergics against their known symptomatic benefits on exacerbations, after eliciting patient preferences for various outcomes in a shared decisionmaking context.