Preoperative hs-CRP/HDL ratio is associated with increased risk for postoperative SIRS in elderly patients: a retrospective cohort study

Background: Systemic inflammatory response syndrome (SIRS) greatly affects postoperative lives of afflicted aged patients. This study aimed to determine whether preoperative high hs-CRP/HDL ratio (CHR) was associated with an increased risk of postoperative SIRS in the elderly population. Methods: This retrospective cohort study included data on patients aged ≥ 65 years who underwent general anesthesia surgery at two clinical centers between January 2015 and September 2020. The primary exposure was preoperative CHR which was divided into two groups (≤ 12.82 and > 12.82) based on its normal range in our hospital, and the primary outcome was the incidence of postoperative SIRS. Targeted maximum likelihood estimation analyses were used to model the exposure–outcome relationship. Results: The analysis included 5595 elderly patients, of whom 1410 (25.20%) developed SIRS within three postoperative days. Targeted maximum likelihood estimation analysis revealed that elderly patients with CHR > 12.82 vs. CHR ≤ 12.82 was associated with increased risk of postoperative SIRS (aOR = 1.40, 95% CI [1.33, 1.48], P < 0.001). Those results were consistent both in subgroup analyses and sensitivity analyses. Compared with patients with CHR ≤ 12.82, patients with CHR > 12.82 had a higher prevalence of postoperative SIRS (49.06% vs. 22.70%), postoperative in-hospital mortality (3.40% vs. 0.65%), a longer hospital stay after surgery [10 (IQR, 6–16) vs. 8 (IQR, 5–11) days] and higher direct medical cost [10070 (IQR, 6878–15577) vs. 7117 (IQR, 4079–10314) euros, all P < 0.001]. Conclusions: In elderly patients, preoperative CHR > 12.82 was significantly associated with a higher risk of postoperative SIRS.