LOS ANGELES – The Sequential Organ Failure Assessment (SOFA) score and the Glasgow Coma Scale (GCS) are simple, accurate tools for risk stratification of hospitalized patients with acute exacerbation of COPD, results from a single-center study showed.
“Acute exacerbations of chronic obstructive pulmonary disease often require hospitalization, may necessitate mechanical ventilation, and can be fatal,” Mohamed Metwally, MD, FCCP, said in an interview in advance of the annual meeting of the American College of Chest Physicians. “There are currently no validated disease-specific scores that measure the severity of acute exacerbation. Prognostic tools are needed to assess acute exacerbations of chronic obstructive pulmonary disease.”
Dr. Mohamed Metwally
For the 2-year study, Dr. Metwally and his associates prospectively evaluated 250 critically ill ICU AECOPD patients, mean age 65 years, at Assiut University Hospital between December 2012 and December 2014. The primary outcome was in-hospital mortality while the secondary endpoint was need for intubation and mechanical ventilation. The researchers excluded patients who died less than 24 hours after admission, those with underlying COPD who were admitted with another primary diagnosis such as an accident or a stroke, or for elective hospitalizations such as elective surgery or diagnostic procedures.
Dr. Metwally and his associates collected sociodemographic data, vital signs, and other clinical variables, and collected scores from five tools used to measure mortality prediction: the Acute Physiology and Chronic Health Evaluation (APACHE II), the SOFA score, the Early Warning Score (EWS), the GCS, and the Charlson Comorbidity Index (CCI). To assess performance of the scores, they used area under the receiver operating characteristic curve (AUC) analysis and the Hosmer-Lemeshow goodness-of-fit test for logistic regression.
Of the 250 patients, 43 (17%) died during their hospital stay and 54% required mechanical ventilation. All recorded scores were significantly higher in nonsurvivors, compared with survivors, and the risk of clinical deterioration increased with increasing scores. The discriminatory power of each score varied as measured by AUC analysis. The AUC of APACHE II, SOFA, EWS, GCS, and CCI were 0.79, 0.81, 0.76, 0.69, and 0.68, respectively “and all these models had good calibration in mortality prediction,” Dr. Metwally said. The SOFA score was the best in predicting mortality (its predicted mortality was 16%, compared with the actual mortality of 17%), while the APACHE II score overestimated mortality by at least twofold (46% vs. 17%). In addition, the EWS outperformed the GCS in predicting mortality. “This may be due to EWS containing all vital signs plus level of consciousness,” he said in an interview.
The GCS was found to be the most useful in predicting need for mechanical ventilation, with an AUC of 0.81. The AUCs of APACHE II, SOFA, EWS, and CCI were 0.79, 0.80, 0.73, and 0.61, respectively. All of the scores had good calibration in mortality prediction, Dr. Metwally said, with the exception of SOFA.
As for the APACHE II, Dr. Metwally said that instrument “can be used as a tool to predict both mortality and intubation in a specific group of patients, but with low discriminatory power.” He acknowledged certain limitations of the study, including the fact that it was limited to patients with AECOPD. “Future studies should include any critically ill respiratory patients,” he said.
He reported having no financial disclosures.