Study design: Retrospective cohort study.
Setting: Two academic tertiary-care hospitals in the U.S.
Synopsis: The authors reviewed the electronic medication administration record of all adult patients admitted to two academic hospitals from June 1, 2010, to Aug. 31, 2010. A total of 14,411 patients (60.7%) were prescribed acetaminophen, of whom 955 (6.6%) were prescribed more than the 4g per day (the maximum recommended daily dose) at least once. In addition, 22.3% of patients >65 and 17.6% of patients with chronic liver disease exceeded the recommended limit of 3g per day. Half the supratherapeutic episodes involved doses exceeding 5g a day, often for several days. In adjusted analyses, scheduled administration (rather than as needed), a diagnosis of osteoarthritis, and higher-strength tablets were all associated with a higher risk of exposure to supratherapeutic doses.
Bottom line: A significant proportion of hospitalized patients are exposed to supratherapeutic dosing of acetaminophen.
Citation: Zhou L, Maviglia SM, Mahoney LM, et al. Supra-therapeutic dosing of acetaminophen among hospitalized patients. Arch Intern Med. 2012;172(22):1721-1728.
Longer Anticoagulation Therapy after Bioprosthetic Aortic Valve Replacement Might Be Beneficial
Clinical question: How long should anticoagulation therapy with warfarin be continued after surgical bioprosthetic aortic valve replacement?
Background: Current guidelines recommend a three-month course of anticoagulation therapy after bioprosthetic aortic valve surgery. However, the appropriate duration of post-operative anticoagulation therapy has not been well established
Study design: Retrospective cohort study.
Setting: Denmark.
Synopsis: Using data from the Danish National Registries, 4,075 subjects without atrial fibrillation who underwent bioprosthetic aortic valve implantation from 1997 to 2009 were identified. The association between different durations of warfarin therapy after aortic valve implantation and the combined end point of stroke, thromboembolic events, cardiovascular death, or bleeding episodes was examined.
The risk of adverse outcomes was substantially higher for patients not treated with warfarin compared to treated patents. The estimated adverse event rate was 7 per 100 person-years for untreated patients versus 2.7 per 100 for warfarin-treated patients (adjusted incidence rate ratio [IRR] 2.46, 95% CI 1.09 to 6.48). Patients not treated with warfarin were at higher risk of cardiovascular death within 30 to 89 days after surgery, with an event rate of 31.7 per 100 person-years versus 3.8 per 100 person-years (adjusted IRR 7.61, 95% CI 4.37 to 13.26). The difference in cardiovascular mortality continued to be significant from 90 to 179 days after surgery, with an event rate of 6.5 per 100 person-years versus 2.1 per 100 person-years (IRR 3.51, 95% CI 1.54 to 8.03).
Bottom line: Discontinuation of warfarin therapy within six months of bioprosthetic aortic valve replacement is associated with increased cardiovascular death.
Citation: Mérie C, Køber L, Skov Olsen P, et al. Association of warfarin therapy duration after bioprosthetic aortic valve replacement with risk of mortality, thromboembolic complications, and bleeding. JAMA. 2012;308(20):2118-2125.
Limited Evidence for Antimicrobial-Coated Catheters
Clinical question: Does the use of antimicrobial-coated catheters reduce the risk of catheter-associated urinary tract infection (UTI) compared to standard polytetrafluoroethylene (PTFE) catheters?
Background: UTIs associated with indwelling catheters are a major preventable cause of harm for hospitalized patients. Prior studies have shown that catheters made with antimicrobial coatings can reduce rates of bacteriuria, but their usefulness against symptomatic catheter-associated UTIs remains uncertain.
Study design: Multicenter randomized controlled trial.
Setting: Twenty-four hospitals in the United Kingdom.
Synopsis: A total of 7,102 patients >16 undergoing urethral catheterization for an anticipated duration of <14 days were randomly allocated in a 1:1:1 ratio to receive a silver-alloy-coated catheter, a nitrofural-impregnated silicone catheter, or a standard PTFE-coated catheter. The primary outcome was defined as presence of patient-reported symptoms of UTI and prescription of antibiotic for UTI. Incidence of symptomatic catheter-associated UTI up to six weeks after randomization did not differ significantly between groups and occurred in 12.6% of the PTFE control, 12.5% of the silver alloy group, and 10.6% of the nitrofural group. In secondary outcomes, the nitrofural catheter was associated with a slightly reduced incidence of culture-confirmed symptomatic UTI (absolute risk reduction of 1.4%) and lower rate of bacteriuria, but it also had greater patient-reported discomfort during use and removal.