Parallel group randomised controlled trials that enrolled adult (over 18 years) patients undergoing open heart surgery, that compared short-term (less than 24 hours) and long-term (24 hours or more) antibiotic prophylaxis were eligible, irrespective of drug regimen. Patients were excluded if they: were undergoing heart transplants; had active infections or were on systemic antibiotic treatment within 48 hours of surgery; had received immunosuppressive therapy or had known immunodeficiency syndromes; or had severe allergic reaction to antibiotics. The primary outcome was incidence of sternal surgical site infections. Secondary outcomes were deep sternal infections, overall infections and adverse events.
Drug regimens were variable and the comparison of short-term and long-term groups did not always include the same drug (details provided). Length of follow up varied from three to 540 days. Trials were conducted in North America, Europe or Australia between 1972 and 2008. The mean age of patients ranged between 40 and 70 years, where reported. Timing of first dose was 0 to 30 minutes before surgery in most trials. The short-term trials mainly gave one dose of antibiotic, while most long-term trials gave antibiotics for less than 48 or less than 72 hours. Short-term trials administered monotherapy while a few long-term trials involved combination therapy.
Two reviewers assessed study eligibility resolving discrepancies by consensus or with reference to a third reviewer.