368. What is a Normal Postoperative Temperature? Group Based Trajectory Modeling in Postoperative Knee Arthroplasty Patients in a Large Health System
Session: Poster Abstract Session: HAI: Surgical Site Infections
Thursday, October 8, 2015
Room: Poster Hall
  • IDSA Wunderlich poster 2015.pdf (692.6 kB)
  • Background: Normal temperature values in the postoperative setting have not been well characterized. While fever is commonly associated with infection, a postoperative fever may be a normal physiologic response.

    Methods: We evaluated all patients who had elective knee arthroplasty and were discharged within 5 days at NorthShore University Health System in Illinois between January 1, 2007 and December 31, 2013. Inpatient temperature, gender, age and BMI measurements were extracted from the data warehouse. Group based trajectory modeling was performed to identify clusters of postoperative patients following similar progression of average temperature mapping over time with gender, age and BMI as covariates.

    Results: Five thousand six hundred patients’ postoperative temperature curves were evaluated. Three hundred sixty six (6.5%), 372 (6.7%), 225 (4.4%) and 30 (4.3%) patients had a Tmax greater than 100.4 on postoperative days 0, 1, 2 and 3 respectively (patients censored on discharge). Average temperature trajectories were created over 24 time periods (4 days), with each time period representing a 4-hour interval when temperatures were likely recorded (Figure 1). Three distinct trajectory clusters were identified with 41.1% displaying group membership to trajectory 1 (red), 49.3% to trajectory 2 (green) and 9.6% to trajectory 3 (blue). All 3 trajectories displayed cubic functional forms. Patients in trajectory 2 and 3 were younger than those in trajectory 1 (Likelihood estimates (LE) -0.027 and -0.020 respectively; p <0.001 for both) and had higher BMI (LE 0.036 and 0.061 respectively, p<0.001 for both). 

    Conclusion: Patients display different temperature trajectories following elective knee arthroplasty. Further work is needed to determine whether different trajectories indicate different likelihoods of an adverse event occurring.  Group based trajectory modeling may allow for personalizing the interpretation of a temperature in the postoperative setting.

    Figure 1: Average temperature trajectories of postoperative knee arthroplasty patients

    Nirav Shah, MD, MPH1, Ankit Dhingra, BA2, Jessica P. Ridgway, MD3, Rema Padman, PhD2 and Ari Robicsek, MD4, (1)Infectious Diseases and Global Health, University of Chicago Medicine, Chicago, IL, (2)Healthcare Informatics, Carnegie Mellon University, Pittsburgh, PA, (3)Infectious Diseases & Global Health, University of Chicago, Chicago, IL, (4)NorthShore University HealthSystem, Evanston, IL


    N. Shah, None

    A. Dhingra, None

    J. P. Ridgway, None

    R. Padman, None

    A. Robicsek, None

    Findings in the abstracts are embargoed until 12:01 a.m. PDT, Wednesday Oct. 7th with the exception of research findings presented at the IDWeek press conferences.