Walsh et al identified risk factors for surgical site infections (SSI) in patients undergoing spinal fusion surgery. These can help to identify a patient who may benefit from more aggressive management. The authors are from the University of Pittsburgh.
Patient selection: neurosurgical spinal fusion
Outcome: surgical site infection (17% MRSA, 34% MSSA), with incidence of 2.94% (161 out of 5.473)
The most important risk factor for SSI was a history of previous MRSA carriage on nares culture, with an odds ratio of 20.
Other risk factors from the multivariate analysis:
(1) hospitalization in the previous 30 days (prior to surgery), with odds ratio 5.8
(2) white race, with odds ratio 4.4 (97% of cases vs 89% controls)
(3) duration of surgery, with odds ratio 1.6 per hour
(4) ASA score 3 or 4, with odds ratio 1.8
where:
• The odds ratios for surgical duration in the univariate analysis: 1 for < 1 hour, 0.6 for 1-1.99 hours, 2.2 for 2 to 2.99 hours, 3.3 for 3 to 3.99 hours, 5.9 for 4-5 hours and 10.6 for > 5 hours.
A factor that reduced the risk for SSI was use of the anterior surgical approach with an odds ratio of 0.20.
Postoperative factors associated with risk of SSI (from the univariate analysis):
(1) postoperative hematocrite <= 36% (odds ratio 4)
(2) receipt of red blood cells or other blood products (odds ratio for red blood cells 3.5, for other blood products 2.9)