Age and Its Impact on Outcomes with Intraabdominal Infection

Author(s):
Drew Farmer, Baylor University Medical Center at Dallas; Jeffrey Tessier, JPS Health Network; James Sanders, JPS Health Network; Billy Moore, JPS Health Network; Therese Duane, JPS Health Network

Background:

The STOP-IT trial, published in 2015, was a prospective, multicenter, randomized controlled trial that found similar outcomes in the treatment of intraabdominal infections (IAIs) with a source control procedure in addition to short versus longer duration of antimicrobial therapy. Age has been shown to play a significant role in the etiology of IAIs, but the correlation between age and outcomes after therapy was not investigated.

Hypothesis:

Patients 65 years and older with IAI will have different outcomes than their younger counterparts.

Methods:

Data were obtained by post-hoc analysis of the STOP-IT trial database. Patients were stratified by age <65 (n=398) or ≥65 years (n=120). Characteristics of the groups including clinical indicators of disease severity (max WBC, max temperature, APACHE II score, total antibiotic days, total hospital days, isolation of enterococcus, MRSA), hospital vs. community-acquired infections, and site of the infection were analyzed. Primary outcomes were surgical site infection (SSI), recurrent IAI (RecIAI), and death, as well as a composite outcome (CO) of all three. Multivariate analysis was performed to identify independent predictors of outcomes.

Results:

Characteristics of the two groups were similar except lower maximum body temperatures (37.8 ± 0.9 vs. 37.5 ± 0.8, p= 0.002) and higher APACHE II scores (9.0 ± 5.8 vs. 13.4 ± 5.4, p =<0.0001) were observed in the older set. Rates of hospital vs. community acquired infections were similar in both groups (p=0.19). Colon or rectum as source of IAI was more common in the older group (29.9% vs. 48.3%, p=0.0002) while small intestine (16.3% vs. 6.7%, p=0.008), appendix (17.1% vs. 4.2%, p= 0.0004), and biliary tree (9.1% vs. 16.7%, p=0.02) were more commonly seen in the younger group. Other source sites within the abdomen were statistically similar in their prevalence. Among the primary outcomes, only death was significantly different between the age groups and was more prevalent in the ≥65 years group (1 [0.3%] vs. 4 [3.3%], p=0.003). SSI (7.3% vs. 9.2%, p=0.50), RecIAI (14.4% vs. 15.8%, p=0.69), and CO (20.4% vs. 26.7%, p=0.14) were statistically similar between the age groups and this remained true when controlling for other covariates.

Conclusions:

Patient age was not a predictor of SSI, RecIAI or a CO. These findings suggest that age itself does not play a significant role in predicting these outcomes, and therefore should not drive changes in management or alter the prognosis of patients with IAIs.