Frailty index is useful for predicting postoperative morbidity in older patients undergoing gastrointestinal surgery: a prospective cohort study

BACKGROUND: Many assessment tools have been used to identify frail surgical patients. This study was designed to explore the prediction value of the frailty index (FI) for postoperative morbidity in older patients undergoing elective gastrointestinal surgery. METHODS: Between January 2019 and September 2020, we conducted a prospective study in our hospital, and patients aged over 65 years were enrolled. The FI assessment was conducted by two specialist nurses based on the 38-item scale, and patients were considered frail if the FI score was ≥ 0.25. The primary outcome was 30-day postoperative morbidity. Univariable and multivariable analyses were used to find the risk factors related to postoperative morbidity. RESULTS: A total of 246 consecutive patients were enrolled, for whom the median age was 72.0 [interquartile range (IQR): 67.0–77.0] years old, and 175 (71.1%) were male. Of these, 47 (19.1%) were frail. Patients with frailty were associated with older age (p < 0.001), higher American Society of Anesthesiologists (ASA) grade (p = 0.006), lower body mass index (p = 0.001), lower albumin (p = 0.003) and haemoglobin (p < 0.001) levels, increased blood loss (p = 0.034), increased risk of postoperative morbidity (p < 0.001), increased median length of stay (p = 0.017), and increased median postoperative hospital stay (p = 0.003). Multivariable analysis revealed that ASA grade [odds ratio (OR): 2.59, 95% confidence interval (CI) 1.19–5.64, p = 0.016], FI score (OR 7.68, 95% CI 3.19–18.48, p < 0.001) and surgical complexity (OR 22.83, 95% CI 5.46–95.51, p < 0.001) were independent predictors of 30-day postoperative morbidity. However, for patients with major surgery, FI score was the only independent predictor (OR 8.67, 95% CI 3.23–23.25, p < 0.001). CONCLUSION: Frailty was associated with adverse perioperative outcomes, and the 38-item FI scale was a useful frailty screening tool for older patients undergoing elective gastrointestinal surgery. For patients with major surgery, frailty was a more reliable predictor of postoperative 30-day morbidity than age and ASA grade. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12893-022-01471-9.