Evaluation of a Modified POSSUM Scoring System for Predicting the Morbidity in Patients Undergoing Lumbar Surgery

For most spine surgeons, operative intervention is common for the treatment of lumbar disc herniation, lumbar stenosis, lumbar fracture or lumbar spondylolisthesis. However, with the increase in lumbar surgery, the complication rate increases accordingly. Whereas the Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (POSSUM) scoring system has been widely used to predict morbidity in various surgical fields, the application of this system in lumbar surgery has not been reported. From January 2008 to January 2010, we recruited 158 patients (85 males and 73 females) with operation for lumbar disc herniation, lumbar stenosis, lumbar fracture, or lumbar spondylolisthesis. All patients were analyzed to compare the morbidity by a modified POSSUM scoring system. According to the modified POSSUM, the expected morbidity was 51 cases (32.3 %), whereas the observed mortality was 42 cases (26.6 %). The overall observed-to-expected ratio was 0.82, and the chi-squared test indicated no statistically significant difference between the expected and observed morbidities (χ (2) = 1.23, P = 0.27), suggesting that the modified POSSUM can accurately estimate the outcome. The modified POSSUM scoring system we developed is a useful tool for predicting and evaluating morbidity in lumbar surgery. Further studies are required to investigate whether this scoring system can predict mortality.