Incidence and risk factors for mortality of vertebral osteomyelitis: a retrospective analysis using the Japanese diagnosis procedure combination database

Objective To examine the incidence of vertebral osteomyelitis (VO) and the clinical features of VO focusing on risk factors for death using a Japanese nationwide administrative database. Design Retrospective observational study. Setting Hospitals adopting the Diagnosis Procedure Combination system during 2007–2010. Participants We identified 7118 patients who were diagnosed with VO (International Classification of Diseases, 10th Revision codes: A18.0, M46.4, M46.5, M46.8, M46.9, M48.9 and M49.3, checked with the detailed diagnoses in each case and all other codes indicating the presence of a specific infection) and hospitalised between July and December, 2007–2010, using the Japanese Diagnosis Procedure Combination database. Main outcome measures The annual incidence of VO was estimated. Logistic regression analysis was performed to analyse factors affecting in-hospital mortality in the VO patients. Dependent variables included patient characteristics (age, sex and comorbidities), procedures (haemodialysis and surgery) and hospital factors (type of hospital and hospital volume). Results Overall, 58.9% of eligible patients were men and the average age was 69.2？years. The estimated incidence of VO increased from 5.3/100？000 population per year in 2007 to 7.4/100？000 population per year in 2010. In-hospital mortality was 6%. There was a linear trend between higher rates of in-hospital mortality and greater age. A higher rate of in-hospital mortality was significantly associated with haemodialysis use (ORs, 10.56 (95% CI 8.12 to 13.74)), diabetes (2.37 (1.89 to 2.98)), liver cirrhosis (2.63 (1.49 to 4.63)), malignancy (2.68, (2.10 to 3.42)) and infective endocarditis (3.19 (1.80 to 5.65)). Conclusions Our study demonstrates an increasing incidence of VO, and defines risk factors for death with a nationwide database. Several comorbidities were significantly associated with higher rates of in-hospital death in VO patients