Does Circadian Rhythm Affect the Risk for Post-Operative Infectious Complications?
Author(s):
Christopher Guidry, UVA Health System; Stephen Davies, UVA Health System; Rhett N. Willis; Zachary Dietch; Puja M. Shah; Robert Sawyer, University of Virginia HSC
Background: Surgical care is delivered twenty-four hours a day, seven days a week at most institutions. Alarmingly, some authors have found that operative start times may be associated with increased morbidity and mortality. This effect has been noted in both the public and private sector. Although some of these differences may be related to process, they may also be related to the human circadian rhythm and changes in host defense.
Hypothesis: We hypothesized that the time of day would significantly impact the frequency of post-operative infectious complications.
Methods: Cases at a single tertiary care center reported to NSQIP over a 10-year period were identified. Operative start times were divided into 6-hour blocks with the time period from 6 AM to Noon serving as the reference. Standard univariate techniques were used. Multivariate logistic regression with mixed effects modeling was used to determine the relationship between operative start times and infectious outcomes controlling for surgeon clustering. For the purposes of this analysis, significance was set at p < 0.01.
Results: A total of 21,985 cases were identified. 2,764 (12.6%) were emergent. Overall 9.7% (n = 2,142) experienced some form infectious of post-operative complication. Seventy percent of these infections (n = 1506) were surgical site infections. On univariate analysis considering all cases, nighttime and evening operations had higher rates of post-operative infections compared to those in occurring during the day (9.1% from 6 AM to Noon; 9.7% from Noon to 6 PM; 14.8% from 6 PM to Midnight; and 14.4% from Midnight to 6 AM; p-value < 0.001). On multivariate analysis, operative start time was not associated with risk of post-operative infection even when emergent cases were considered independently (Table 1).
|
Odds Ratio (95% CI)
|
Start Time
|
All Cases
|
Emergent Cases
|
00:00 - 05:59
|
1.01 (0.75 - 1.36)
|
0.96 (0.68 - 1.36)
|
06:00 - 11:59
|
Ref
|
Ref
|
12:00 - 17:59
|
1.04 (0.94 - 1.16)
|
1.00 (0.73 - 1.36)
|
18:00 - 23:59
|
1.12 (0.91 - 1.38)
|
1.16 (0.85 - 1.58)
|
C-Statistic
|
0.76
|
0.71
|
Conclusions: Our data suggest operative start times have no correlation with post-operative infectious complications. Further work is required to identify the source of the time-dependent outcome variability observed in previous studies.