The effects of allostatic load on patients undergoing surgery: a systematic review

Allostatic load (AL) is a measure of physiologic adaptation to repetitive environmental stressors and is associated with poor health outcomes and chronic conditions, ranging from cardiovascular disease and type 2 diabetes to malignancy. Given the acute rise in physiologic stress that accompanies surgically induced trauma, AL has the potential to affect surgical outcomes, particularly for the invasive, complex, lengthy procedures common in surgical oncology. The aims of this study were to systemically review existing literature surrounding AL and surgery, and to contextualize these findings accordingly.

A systematic review was conducted in May 2024 via PubMed, Embase, Cochrane, Web of Science, and PsycINFO to identify existing literature on AL and surgery. Study quality and sources of bias were assessed via the Mixed Methods Appraisal Tool. Data from original studies were extracted and compiled, and a similar process was repeated for related review articles.

A total of 10 original research studies explored the relationship between AL and surgical topics. Eight of these studies attempted to quantify AL as either a numerical composite index or via single or multiple representative biomarkers. AL emerged as (1) a specific predictor of surgical outcomes and (2) an explanatory mechanism for racial and socioeconomic disparities in surgical populations, as AL is known to be increased in socially disadvantaged individuals. Four of 10 included studies explored surgical oncology populations exclusively.

AL appears to impact surgical care and demonstrates the potential to not only predict postoperative outcomes (i.e., postoperative complications) but also identify high-risk surgical patients. This relationship appears to be most well-defined in surgical oncology relative to any other surgical specialty. By illuminating the connections between AL and surgery, targeted interventions aimed at reducing AL may be implemented to mitigate postoperative complications and improve the quality of surgical care. Future work in this area should include prospective studies examining preoperative AL, specific postoperative outcomes, and the impact of personalized AL-centered interventions on adverse perioperative outcomes.