Good Old Summertime Not So Great for Surgical Infections
May 31st, 2017
IOWA CITY, IA — Summer isn’t just the season for swimming, cookouts, and wearing white — it also is prime time for a common healthcare-associated infection.
That’s according to new research on surgical site infections (SSI) published online by Infection Control & Hospital Epidemiology.
University of Iowa-led researchers found that sweltering heat above 90°F increased by 28.9% the odds of a post-surgical patient being hospitalized with a related infection, compared to cool temperatures lower than 40°F.
"We show that seasonality of surgical site infections is strongly associated with average monthly temperature. As temperatures rise, risk increases," explained senior author Philip M. Polgreen, MD. "However, the odds of any one person getting an infection are still small, and due to the limitations of our data, we still do not know which particular surgeries or patients are at more risk from higher temperature."
To reach their conclusion, researchers tapped into the Nationwide Inpatient Sample to identify every adult hospitalization with a diagnosis of SSI from January 1998 to November 2011.
At the same time, the study team compiled information on each hospital’s longitude and latitude to pinpoint nearby weather stations, which were used to determine monthly weather statistics.
Results indicate that SSIs are more seasonal than researchers expected. In fact, 26.5% more SSI-related hospital discharges occurred in the apex hot month of August, falling to the low point in January.
Even a 25% drop in the average number of at-risk surgeries in the months of July and August could lead to 1,700 fewer SSIs a year, the researchers suggested. The study found seasonality and incidence were fairly consistent across all regions, age groups, genders, and hospital teaching categories. However, seasonality had the most influence among patients in their 40s and 50s, the report notes.
"These results tell us that we need to identify the patients, surgeries, and geographic regions where weather-related variables are most likely to increase patients' risk for infections after surgery," added first author Christopher A. Anthony, MD, surgery resident physician at the University of Iowa Roy J. and Lucille A. Carver College of Medicine. "This way, we can identify the patients at the greatest risk for surgical site infections during warmer summer months."
