Association between Preoperative hs-CRP/Albumin Ratio and Postoperative SIRS in Elderly Patients: A Retrospective Observational Cohort Study

Systemic inflammatory response syndrome (SIRS) is one of the severe postoperative complications in elderly patients and seriously affects their prognosis and survival rate. Heretofore, there have been no reliable and accurate methods to predict postoperative SIRS in elderly patients. The aim of this study was to determine whether increased preoperative hs-CRP/albumin ratio (CAR) was associated with postoperative SIRS in elderly population.

The data of patients aged ≥ 65 years who underwent general anesthesia in two centers of Third Affiliated Hospital of Sun Yat-sen University between January 2015 and September 2020 were retrieved and analyzed. Based on the perioperative dataset, we used the targeted maximum likelihood estimation (TMLE) to estimate the association between preoperative CAR and postoperative SIRS in elderly population. Patients’ CAR was calculated and divided into two groups (< 0.278 and ≥ 0.278) according to its normal range in our hospital. Adjusted odd ratios (aORs) and 95% confidence intervals (CIs) were calculated respectively. Further sensitivity analyses were conducted to evaluate the robustness of the results.

A total of 16141 elderly patients were accessed and 7009 of them were enrolled in the final analysis, and 1674 (23.9%) patients developed SIRS within 3 days after surgery. Compared with non-SIRS patients, patients with SIRS had a significantly longer postoperative hospitalization, higher cost and higher risk of in-hospital mortality. Compared with patients with preoperative CAR < 0.278, we found that CAR ≥ 0.278 had a significantly higher risk for the development of postoperative SIRS after multivariable adjustment [aOR = 1.27; 95% CI (1.21, 1.33)]. The interaction effect of preoperative CAR ≥ 0.278 and SIRS was stronger among patients with the following characteristics: aged ≥ 75 years, male, comorbid with diabetes mellitus and admitted to ICU after surgery, duration of surgery < 120 minutes, underwent cerebral surgery or skin, spine and joint surgery (all P < 0.001). The above results remained robust in the sensitivity analysis.

Preoperative CAR ≥ 0.278 was significantly associated with increased risk of postoperative SIRS in elderly patients. Special attention should be paid to elderly patients with a preoperative CAR ≥ 0.278 so as to reduce the incidence of postoperative SIRS.