1403. Impact of Antibiotic Prophylaxis on Post-Cesarean Surgical Site Infections: A Time Series Analysis
Session: Oral Abstract Session: Predicting and Preventing SSIs
Sunday, October 23, 2011: 7:30 AM
Room: 157ABC
Background: Surgical site infections (SSI) following Cesarean section (C-section) are associated with maternal morbidity and higher medical costs. Time series analysis is a method for detecting whether infection prevention interventions to prevent SSI have an effect significantly greater than the underlying secular trends in patient (pt.) mix.

Methods: A 96 month retrospective cohort study of C-section pts. was done to determine patient-level risk factors for incisional SSI at a 1250 bed, tertiary care hospital. Data on pt. demographics, risk factors and obstetric complications were obtained from administrative records. SSI cases were defined using National Healthcare Safety Network (NHSN) surveillance criteria. A multivariate autoregressive integrated moving average (ARIMA) model was used to perform time series analysis on an 84 month cohort of C-section patients.

Results: There were 7683 C-section pts. between January 2004 and December 2010. 4739 (61.7%) of the pts. were African American, 2767 (36.0%) had a body mass index (BMI) ≥ 35 kg/m2 [median BMI= 32.8, (range 13.4-103.0)], 793 (10.3%) had diabetes or gestational diabetes, and median age = 26 years (range 12-53). 207 (2.7%) pts. developed SSI. In a multivariate logistic regression model, two factors were positively associated with development of SSI: BMI ≥ 35 kg/m2 [51.8% of cases vs. 36.9% of controls; adjusted odds ratio (aOR) = 1.83; 95% confidence interval (CI), 1.32-2.54] and age ≤ 18 years (14.0% vs. 8.9%; aOR= 1.71; 95% CI, 1.05-2.78). A larger cohort of 8668 C-section patients from January 2003 to December 2010 was included in the time series analysis. A non-seasonal ARIMA (0,1,1) model with a linear trend and no autocorrelation was identified. A policy to ban artificial nails and an intervention to improve OR cleaning had no effect on SSI rates. Implementation of a policy to administer prophylactic antibiotics within an hour before incision instead of at the time of cord clamp led to a 48% reduction in C-section SSI (Δ= -5.4 SSI per 100 C-sections; P <0.001).

Conclusion: Increased BMI and maternal age ≤ 18 years were independent risk factors for SSI in C-section patients. Administration of prophylactic antibiotics prior to incision resulted in a significant reduction in post-Cesarean SSIs.

Subject Category: N. Hospital-acquired and surgical infections, infection control, and health outcomes including general public health and health services research

Nupur D. Kittur, PhD, MPH1, Kathleen M. McMullen, MPH2, Anthony J. Russo, MPH2, Loie Ruhl, RN2, Helen H. Kay, MD3, Margaret Olsen, PhD, MPH1 and David K. Warren, MD, MPH1, (1)Division of Infectious Diseases, Washington University School of Medicine, St. Louis, MO, (2)Barnes-Jewish Hospital, St. Louis, MO, (3)Division of Maternal Fetal Medicine, Washington University School of Medicine, St. Louis, MO


N. D. Kittur, None

K. M. McMullen, None

A. J. Russo, None

L. Ruhl, None

H. H. Kay, None

M. Olsen, None

D. K. Warren, None

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