Drainage days-an independent risk factor for serious sternal wound infections after cardiac surgery: a case control study.

Background: Postoperative sternal wound infections are a potentially devastating complication following cardiac surgery. The aim of our study was to determine risk factors associated with patients' baseline characteristics and peri- and postoperative management for the development of surgical site infections (SSIs) after cardiac surgery involving sternotomy.

Methods: Since 2009 the University Hospital of Basel, a tertiary care center in Switzerland, has participated in the national SSI-surveillance program by conducting postdischarge surveillance. We conducted a nested case-control study involving 30 consecutive patients with an organ/space SSI after cardiac surgery and 60 control patients.

Results: Receipt of antibiotics before operation (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.02-1.41; P = .032), decreased albumin levels (OR, 0.87; 95% CI, 0.76-0.99; P = .040, respectively), time on extracorporal circulation (OR, 1.02; 95% CI, 1.00-1.03; P = .012), number of drainages (OR, 9.15; 95% CI, 2.01-41.76; P = .004), length of drain retention (OR, 1.44; 95% CI, 1.10-1.90; P = .009), and resuscitation (OR, 7.30; 95% CI, 1.53-34.71; P = .012) were associated with SSIs. Incidence density drainage days-accounting for both number of drains and length of retention-were the only independent risk factor (OR, 1.12; 95% CI, 1.02-1.11; P = .018).

Conclusions: Retention of drainages in the operative site longer than 48 hours was the only independent risk factor for the development of organ/space sternal wound infections after cardiac surgery.