756 out of 140,756 non-obstetric surgical inpatients cared for between January 1, 2017 and December 31, 2017 met inclusion criteria (0.54%, 95% CI 0.50% to 0.58%). The average patient age was 65. 51% of patients were Male, 89% were Caucasian, 69% were Hypertensive and 36% were Diabetic requiring medication. The majority of patients were ASA-PS 3 (43.25%) and 4 (39.68%). Patient demographics and clinical characteristics are shown in Table 1. Respiratory (43.65%), cardiac (39.63%), and renal (9.5%) complications accounted for the majority of organ specific post-surgical morbidities (Table 2). 213 (28.17%) patients within this cohort died. Of these, 16 (7.51%) patients died intraoperatively, 47 (22.10%) within 48 hours of surgery, 103 (48.36%) at greater than 48 hours. For 51 patients (22.03%), the time of death could not be determined from the medical record. Out of the total population, 308 (0.22%) patients suffered perioperative cardiac arrest, of which 151 (49%) died. Intraoperative cardiac arrest (ICA) occurred in 47 (0.03%) patients, 92% of which were ASA-PS classification 3 or higher. Of those with ICA, 24 (51.1%) died: 16 (66.67%) intraoperatively, 3 (12.5%) within 48 hours, and 5 (20.83%) at greater than 48 hours. Emergency surgical admissions accounted for 158 (21%) patients. Of these patients, 145 (91.8%) were ASA-PS 3 or higher and 43 (27%) died.
According to the results of our logistic regression models (Table 3), surgeons (16.08%) were more likely to document ISRAs (P-value<0.0001; R-squared=68.23%) than anesthesiologists (4.50%) (P-value< 0.0001, R-squared 15.38%). Cardiac surgeons (25.87%) documented ISRAs more frequently than non-cardiac surgeons (16.15%) (P-value=0.0086, R-squared=0.970%). The odds of documenting ISRAs for cardiovascular procedures were 1.8123 times higher than those for non-cardiovascular procedures, 95% Confidence Interval (CI) [1.1769 to 2.7906].
Elective surgical patients (19.57%) received ISRA documentation more frequently than emergency surgery patients (12.03%) (P-value=0.0226, R-squared=0.730%). In turn, ISRA documentation was 1.7795 times more likely to occur in patients who elected to have a surgery than those who had an emergency surgery, 95% CI [1.0577 to 2.9939].
ISRAs were documented more frequently for patients 65 years and older (20.31%) than for patients under 65 (14.61%) (P-value=0.0429, R-squared=0.580%). The odds of documenting ISRAs for patients 65 and over is 1.4898 times higher than those for patients younger than 65, 95% CI (1.0076 to 2.2027).
Neither female (19.09%) nor male (16.93%) gender had a statistically significant effect on ISRA documentation [P-value=0.4397, R-squared=0.080%]. However, the odds of ISRA documentation occurring were 1.1576 times higher for female patients than for male patients, 95% CI (0.7984 to 1.6785).
ISRA documentation was not statistically different between non-Caucasians (25.29%) and Caucasians (17.04%) [P-value = 0.0701, R-squared=0.460%]. However, the odds of ISRA documentation occurring were 1.6478 times higher for non-Caucasian patients than for Caucasian patients, 95% CI (0.9760 to 2.7821).
No associations with individual risk documentation were found between ASA-PS 1 and 2 (17.82%) and ASA-PS 3, 4, and 5 (17.89%) [P-value = 0.9867, R-squared= 0%]. The odds of documenting ISRAs were only 1.0047 times higher for patients with ASA-PS 3, 4, and 5 than for patients with ASA-PS 1 and 2, 95% CI (0.5811 to 1.7369).
A significant relationship [P-value = 0.1275, R-squared=0.330%] did not exist between ISRA documentation and time of surgery (daytime surgery 18.63%; evening surgery 11.59%). The odds of documenting ISRAs were 1.7460 times higher for patients who had daytime surgery than for those who had surgery in the evening. 95% CI (0.8152 to 3.7394).
There was no significant difference between documentation of preoperative ISRA for patients who survived (17.13%) versus those who died (20.19%) [P-value = 0.3287, R-squared=0.130%]. However, the odds of documenting ISRAs for patients who died were 1.2239 higher than for those who survived surgery. 95% CI (0.8186 to 1.8299).
Group effect model design
A logistic regression model was created to analyze the group effect of four predictors (age, emergency status, race, and cardiac surgery) on the likelihood of ISRA documentation. As a group, these predictors had a significant effect on documenting ISRAs (P-value=0.0004) and explain more variability than each measure individually (R-squared=2.86%). The model positively classifies 82.01% of the records.
Parameters estimates
According to our model, 45.2% of the patients who had documented ISRAs were 65 years and older, non-Caucasian, elected to have a surgery, and underwent cardiovascular surgery.
Effect Likelihood Ratio Test
Race did not have a significant relationship upon the documentation of ISRAs (P-value=0.0701). However, it was added into the group of predictors since the probability of being a non-Caucasian and having documented ISRAs was 25.29%. According to our model, the individual effect of race (P-value=0.0138), age (P-value=0.0275), emergency status (P-value=0.0389), and cardiovascular surgery (P-value=0.0137) were significant.