Clinical score for nonbacterial osteitis in children and adults

OBJECTIVE: To accurately differentiate nonbacterial osteitis (NBO) from other bone lesions by applying a clinical score through the use of validated diagnostic criteria. METHODS: A retrospective study was conducted to assess data on patients from a pediatric clinic and an orthopedic tertiary care clinic, using administrative International Classification of Diseases codes as well as laboratory and department records from 1996 to 2006. Two hundred twenty-four patients older than age 3 years who had either NBO (n = 102), proven bacterial osteomyelitis (n = 22), malignant bone tumors (n = 48), or benign bone tumors (n = 52) were identified by chart review. Univariate logistic regression was used to determine associations of single risk factors with a diagnosis of NBO, and multivariable logistic regression was used to assess simultaneous risk factor associations with NBO. RESULTS: NBO was best predicted by a normal blood cell count (odds ratio [OR] 81.5), symmetric bone lesions (OR 30.0), lesions with marginal sclerosis (OR 26.8), normal body temperature (OR 20.3) a vertebral, clavicular, or sternal location of lesions (OR 13.9), presence of >1 radiologically proven lesion (OR 10.9), and C-reactive protein level > or =1 mg/dl (OR 6.9). The clinical score for a diagnosis of NBO based on these predictors ranged from 0 to 63. A score for NBO of > or =39 had a positive predictive value of 97% and a sensitivity of 68%. CONCLUSION: The proposed scoring system helps to facilitate the diagnostic process in patients with suspected NBO. Use of this system might spare unnecessary invasive diagnostic and therapeutic procedures.