|Seasonal Variation In Surgical Outcomes: The July Effect As Measured By ACS-National Surgical Quality Improvement Program|
|Michael J Englesbe*1, Shawn J Pelletier*1, John C Magee*1, Paul G Gauger*1, William G Henderson*2, Shukri F Khuri3, Darrell A Campbell, Jr.1 |
1University of Michigan, Ann Arbor, MI;2University of Colorado, Aurora, CO;3VA Boston Healthcare System, Brigham and Women's Hospital, and Harvard Medical School,, Boston, MA
|OBJECTIVE(S): We hypothesize that the systems of care within academic medical centers are sufficiently disrupted with the beginning of the academic year to affect patient outcomes following surgery.|
METHODS: This observational multi-institutional cohort study (14 academic centers) was conducted by analysis of the NSQIP - PSS database (2002-2004). The 30 day morbidity and mortality rates were compared between two periods of care: (early group: July 1 to Aug 30, N = 9941) and late group (April 15 to June 15, N = 10313). Candidate variables (first tested for bivariate associations) were included in stepwise logistic regression models. Mortality rates were compared to time of year with a linear regression analysis.
RESULTS: The patient populations in the two groups were similar. After risk adjustment, there was a 41% higher risk for mortality in the early group vs. the late group (OR 1.41, 1.11-1.80, p = 0.005, c-index 0.938). There was a significant decrease in mortality rates over the course of the academic year. There was 18% higher risk of post-operative morbidity in the early vs. the late group (OR 1.18, 95%, CI 1.07 - 1.29, p = 0.0005, c-index 0.794). There were significantly more myocardial infarctions (0.42% vs. 0.25%, p = 0.036) in the early group. The case duration was 17.4 minutes longer early in the year. (p<0.0001)
CONCLUSIONS: There are higher surgical morbidity and mortality rates early in the academic year. Further study is needed to fully describe the process of care measures related to this seasonal variation in outcome.
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