In the immune system, it has been observed that the preoperative neutrophil-to-lymphocyte ratio (NLR) is an index that reflects the state of inflammation and oxidative stress. In the perioperative period, NLR has been described as a predictor for patients who will develop renal injury, ischemic stroke, and myocardial injury. Since preoperative inflammation is a predictor of morbidity and mortality in patients undergoing non-cardiac surgery, a retrospective analysis of the inflammatory status of patients undergoing surgery at the center is proposed.

A retrospective analysis of patients operated on at the Clinical Hospital of the University of Chile is proposed. The search will be conducted in the electronic medical records of all patients operated on between January and December 2021, with no exclusion criteria for this analysis. Demographic data, complications, length of hospital stay, and specific characteristics such as the need for mechanical ventilation, time spent in intermediate care units, and ICU as well as total hospitalization time will be recorded. For the purpose of this study, the preoperative complete blood count of the patients will be analyzed to search for hematological variables that reflect the state of preoperative systemic inflammation.

Inclusion Criteria:

• Availability of complete blood count in electronic medical records of all patients operated on between January and December 2021

Exclusion Criteria:

• None

Emergency patients operated on at the Clinical Hospital of the University of Chile between January and December 2021