Delay in diagnosis of invasive surgical site infections following knee arthroplasties compared to hip arthroplasties
Background: The timing of diagnosis of invasive surgical site infections (SSI) following joint replacement surgery is an important criterion used to determine subsequent medical and surgical management. We aimed to characterize the relationship between site of arthroplasty (knee versus hip) and timing of diagnosis of invasive SSI.
Methods: We conducted a retrospective cohort study of surgical surveillance data from 36 acute care community hospitals and 1 ambulatory surgery center participating in the Duke Infection Control Outreach Network. Invasive (i.e., deep incisional or organ/space as defined by National Healthcare Safety Network) SSIs occurring within 365 days of knee or hip arthroplasties performed from 1/1/2007-12/31/2011 were included in the analysis. A Cox regression model was fit to estimate the association between procedure type and time to diagnosis of SSI, adjusted for age, pathogen virulence, American Society of Anesthesiologists' (ASA) score, and hospital surgical volume.
Results: 661 invasive SSIs were included in the analysis; 401 (61%) occurred following knee arthroplasties. The median time to diagnosis of SSI following knee arthroplasty was 42 days (IQR 21-114) versus 25 days (IQR 17-48) following hip arthroplasty; unadjusted HR 1.60, 95% CI 1.37-1.87, p<0.001. The time to diagnosis of invasive SSI was significantly longer for knee compared to hip arthroplasties after adjusting for age, pathogen virulence, and hospital surgical volume; HR 1.51, 95% CI 1.28-1.78, p<0.001 (Figure).
Conclusion: In our large cohort of community hospitals, the diagnosis of invasive SSI was delayed following knee arthroplasties compared to hip arthroplasties. This relationship was not fully explained by confounding due to patient age or pathogen virulence. We hypothesize that differences in symptom manifestation between the two surgical sites and disparities in access to care may contribute to the observed differential timing of diagnosis of SSIs following knee versus hip arthroplasties. Our findings have important implications for the management of these infections, as prosthesis removal is often required to cure infections diagnosed more than 90 days post-operatively.
Figure: Predicted time to SSI diagnosis, adjusted for age, pathogen virulence, and surgical volume
S. S. Lewis,
L. F. Chen, None
D. Anderson, None
D. J. Sexton, UpToDate: Editor, Royalties
National Football League: Consultant, Consulting fee and Educational grant
Cubist: Grant Investigator, Grant recipient
Johnson and Johnson: Consultant, Consulting fee
R. W. Moehring, None