Risk factor analysis and predictive score for pneumonia after major/ultra‐major operations: A single‐centre, retrospective study from the Surgical Outcome Monitoring and Improvement Program database

Aim This study aimed to identify the significant risk factors predicting the occurrence of post-operative pneumonia after major or ultra-major operations, and construct a predictive score to identify high-risk patients for post-operative pneumonia. Patients and methods Six thousand two hundred and thirty-seven (6237) patients, received major/ ultra-major operations in a single institute, were recruited in this study. Data from one thousand seven hundred and forty-two (1742) patients who received major or ultra-major operations (OT) from 7/2012 to 6/2013 were retrieved from the SOMIP (Surgical Outcome Monitoring and Improvement Program) database. Thirty-eight variables were analyzed by using uni-variable analysis method; those significant factors with p-value < = 0.05 were further analyzed by using multi-variable logistic regression model. A scoring system was then formulated by using these significant risk factors to identify the high-risk patients. The efficacy of this scoring system was examined by applying this to other four thousands four hundred and ninety-five (4495) patients. Results Thirty-eight variables were included in this study (7 patients’ demographic variables, 20 pre-operative and 11 operative or disease related variables). Five out of thirty-eight variables were found to be significant , including (1) Dependence of activity of daily living, (2) Ascites, (3) General anaesthesia, (4) pre-operative Dyspnea and (5) ASA score > = 3. They formed the basis of the DAGDA score. Maximum DAGDA score is 18 with area under ROC curve 0.774 (95% CI: 0.711 – 0.836). Sensitivity and specificity of DAGDA score with cut-off point of 8 are 73.6 % and 73.4 % respectively. Validation of DAGDA score is examined by using another cohort group of 1329 patients (7/2010-6/2011 database), with area under ROC curve 0.751. Similar results were achieved when the scoring system was applied to 7/2013-6/2014 (1671 patients) and 7/2014-6/2015 (1495 patients) database. Conclusion Dependence of activity of daily living, ascites, general anaesthesia, pre-operative dyspnoea and ASA score > =3 are significant risk factors associated with post-operative pneumonia after major and ultra-major operations. DAGDA score can be used to predict who are the high-risk patients developing post-operative pneumonia.