Seasonal variation in surgical outcomes

AORN Journal,  March, 2008  by George Allen

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Annals of Surgery

September 2007

In most academic medical centers, the months of July and August are characterized by an influx of relatively inexperienced trainees who are unfamiliar with their roles and responsibilities. The authors of this study hypothesized that a disruption in hospital systems in July and August (ie, the July effect) would be of sufficient magnitude to adversely affect surgical results.

A seasonal variation in adverse surgical outcomes has not been demonstrated previously due to the lack of a sufficiently standardized and risk-adjusted quality metric in surgery to allow valid month-to-month comparisons on a large scale. This is now possible with the institution of the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP), the first nationally validated, outcome-based, and risk-adjusted program for the enhancement of surgical quality. The system uses a set of defined comorbidities and endpoints (ie, 30-day mortality and morbidity) with a risk-adjustment process to allow for comparison of results between hospitals. The purpose of this observational, multi-institution, cohort study was to determine whether adverse surgical outcomes could be related to seasonal disruptions in hospital systems.

Records in the ACS-NSQIP database of more than 60,000 patients from 14 academic medical centers and four large, private, community-based hospitals for a three-year period were analyzed. The patients were divided into two groups: those who underwent a surgical procedure between July 1 and August 30 (ie, the early group) and those who underwent a surgical procedure between April 15 and June 15 (ie, the late group). The final two weeks in June were not included in the late group because of concerns that this period may be a transition period for hospital personnel staffing.

Morbidity was treated as a dichotomous variable, with patients categorized as having had a morbidity event if they had one or more of the 19 adverse events defined within the ACS-NSQIP data points. The mortality period was defined as occurring in the first 30 postoperative days. Common statistical procedures including the chi square test, t test, and logistic regression techniques were used to analyze the differences between the groups.

FINDINGS. The early group (n = 9,941) was well matched with the late group (n = 10,313) with respect to demographics and preoperative comorbidities. The unadjusted, 30-day morbidity rate in the early group was 14.3% compared to 13.1% in the late group (P = .008). The mean number of complications was 0.24 ([+ or -] 0.73) in the early group compared to 0.22 ([+ or -] 0.70) in the late group (P = .016). There were significantly more postoperative myocardial infarctions (0.42% versus 0.25%, P = 0.036) and urinary tract infections (3.0% versus 2.3%, P = 0.003) in the early group. Multivariate logistic regression analysis revealed that there was an 18% higher risk of postoperative morbidity in the early group versus the late group (odds ratio [OR] 1.18, 95% confidence interval [CI] 1.07-1.29, P = .000). There was a 41% higher risk of mortality in the early group compared with the late group (OR 1.41, CI 1.11-1.80, P = .005).

CLINICAL IMPLICATIONS. The results of this study suggest that higher rates of postsurgical morbidity and mortality are related to the time of year; however, the researchers pointed out that further study is needed to fully describe the etiologies of the seasonal variation in outcomes. Perioperative nurses and managers should increase their efforts to guide and support new trainees, especially during the months of July and August, to ensure that aseptic technique is maintained during all surgical procedures and antibiotic prophylaxis is administered in a timely manner.

Englesbe MJ, Pelletier SJ, Magee JC, et al. Seasonal variation in surgical outcomes as measured by the American College of Surgeons-National Surgical Quality Improvement Program (ACS-NSQIP). Ann Surg. 2007;246(3):456-465.

GEORGE ALLEN PHD, RN, CNOR, CIC

DIRECTOR OF INFECTION CONTROL

DOWNSTATE MEDICAL CENTER

BROOKLYN, NY

COPYRIGHT 2008 Association of Operating Room Nurses, Inc.
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