Study Finds Systemic Postoperative Inflammation Contributes to Worsened Patient Outcomes

In a recent study published in Anesthesia, researchers found significant correlations between postoperative systemic inflammation and poorer outcomes in patients recovering from major abdominal surgery.

Postoperative complications after major surgeries account for millions of deaths each year. Immunosuppression and/or hyperinflammation are suspected contributors to these outcomes, which can increase one’s vulnerability to organ disfunction, persistent disability, worsened surgery recovery, and even death. Much of this research comes to these conclusions by monitoring plasma C-reactive protein (CRP) levels; however, as the authors note, the influence of postoperative systemic inflammation on patient outcomes remains inconclusive. To address this gap in literature, researchers conducted a retrospective cohort study to explore associations between inflammation and various outcomes following major abdominal surgery.

Inflammation concept | Image Credit: picture-waterfall - stock.adobe.com

Data were gathered from the RELIEF (Restrictive Versus Liberal Fluid Therapy for Major Abdominal Surgery) trial (a multi-center study assessing different intravenous fluid regimens administered to patients) from May 2013 until September 2016. Patients with varying levels of systemic inflammation—measured with CRP—were analyzed from 47 centers across 7 countries.

Coprimary end points for this study were persistent disability or death through the 90 days following surgery, as well as 15-item scoring from a quality of recovery assessment on days 3 and 30. Secondary end points were all-cause mortality at 90 days and 1 year, acute kidney injury, septic complications, unplanned intensive care/high dependency unit (ICU/HDU) admission, total length of hospitalization; and readmission to the hospital. Researchers split the data into quartiles according to increasing maximum CRP concentration at 3 days post operation. The lowest quartile was known as the “reference group” (Q1) and the others were deemed the “inflammation groups” (Q2-Q4).

In total, 2533 patients were eligible for analysis, having received at least 1 CRP measurement to their third postoperative day. The reference group included 639 individuals with maximum levels up to day 3 < 85 mg/L^–1, which “reflects a resolving host response, promoting wound healing and tissue repair.” The highest quartile (Q4) was made up of 618 individuals that registered peak CRP to day 3 of 587 mg/L^–1.

Up to day 90 post surgery, a rising proportion of patients affected by persistent disability or who died was observed across all inflammation groups compared with the reference (10.8% [Q1] vs 13.2% [Q2] vs 18.2% [Q3] vs 25.6% [Q4]). For patients who had a maximum day-3 CRP registering above 200 mg/L^–1, and for every subsequent 100 mg/L^–1 increase, the researchers found they carried significantly greater risks for these outcomes (P < .001).

Reports of patients’ quality of recovery also increasingly diminished in the higher quartiles; the authors note that even minimal differences in postoperative inflammation correlated with significantly reduced recovery by day 3. In a similar fashion, patient risks for acute kidney injury, septic complications, unplanned admission to the ICU/HDU, longer hospital stays, and unexpected hospital readmission grew with increasing inflammation (P < .001 across each end point). Yet, at day 90 and 1 year, there were no significant differences observed between groups.

Overall, the authors note that the correlative evidence between inflammatory states and patient outcomes supports the use of maximum postoperative CRP (up to day 3) as a valuable inflammatory marker. Their findings bolster the idea that CRP should be monitored in patients who have undergone surgical procedures as a guide for discharge decisions and as an assessment tool for predicting recovery risks.

Reference

Bain CR, Myles PS, Martin C, et al. Postoperative systemic inflammation after major abdominal surgery: patient-centred outcomes. Anesthesia. Published online August 2, 2023. doi:10.1111/anae.16104