The University of Connecticut Osteonecrosis Numerical Scale (UCONNS): Application to a Retrospective Case Control Study

Osteonecrosis of the jaws (ONJ) is a clinical entity with diagnostic criteria set forth by various health professional societies.  All current definitions include a breach in the oral mucosa with exposed bone that fails to heal in 6-8 weeks despite conservative therapy.While the ability to predict which patients will develop ONJ is elusive and the pathophysiology of ONJ remains ill-defined, a number of clinical risk factors have been implicated. Based on the current literature, we have developed an instrument to assess and risk-stratify comorbidities that are critical for the development of ONJ, the University of Connecticut OsteoNecrosis Numerical Scale (UCONNS). This report describes a retrospective validation of this tool and a case-control study of ONJ in patients with an emphasis on benign medical conditions. 

 Twenty-four patients with ONJ and fifty-five patients without ONJ were recruited from the UCHC OMFS Clinic, Cancer Center or Osteoporosis Clinic.  Subjects were categorized according to malignant condition (soft tissue cancers, multiple myeloma) or benign condition (osteoporosis).  Among the ONJ patients, 29% (7/24) had benign conditions, while 71% (17/24) had malignant conditions. Data was extracted from patients’ healthcare records and put into 5 weighted categories: bone-modifying agents (BMAs), oral health, orofacial procedures, medical conditions and co-morbidities. A total UCONNS score was determined. Using SPSS software (Version 9.3) descriptive statistics for the mean and standard deviation were calculated. Chi-square analysis was used to compare categorical outcomes between ONJ and non-ONJ groups. A Receiver Operating Characteristic (ROC) analysis was performed using ONJ and the UCONNS score as parameters.

 The mean UCONNS score for the ONJ group was 24.36 (SD 7.06) and the mean score for the non-ONJ group was 14.18 (SD 6.76) p=0.001.  Statistically significant risk factors for ONJ included poor oral health and steroid use within the past 12 months, p=0.003. Using a sensitivity/specificity pair value of 0.8, the ROC analysis determined that a UCONNS score of 19 or above (p < 0.01) was an appropriate threshold for predicting which patients are at high risk for the development of ONJ.

The mean UCONNS score for ONJ patients with a malignant condition (ONJ/M) was 27.65 (SD 5.219) and for ONJ patients with a benign condition (ONJ/B) was 16.43 (SD 4.79, p=0.0001 t-test).  There was a significant correlation between cumulative BMAs in ONJ/M (p=0.0001, SC= -0.501), however, with ONJ/B no such correlation was shown. Total BMA mean score was 5.88 (SD 1.764) in ONJ/M and 3.43 (SD 1.397) in ONJ/B (p=0.004 parametric t-test). The comorbidities mean score was 7.88 (SD 2.5) in ONJ/M and 2.86 (SD 2.96) in ONJ/B, p=0.001 non-parametric Mann–Whitney U test. The medical conditions mean score was 4.29 (SD 1.96) in ONJ/M and 1.57 (SD 0.787) in ONJ/B, p=0.00001 non-parametric Mann–Whitney Utest. Mean scores for oral health and orofacial procedures were not significantly different between ONJ/M and ONJ/B.

 In conclusion, the UCONNS is a sensitive predictor of ONJ development among at-risk patients. Our findings are significant for a higher frequency of ONJ in benign conditions than currently reported (0.00038-0.01%). Furthermore, risk factors such as steroids and poor oral health appear to be associated with the development of ONJ.

 

1. Ruggiero, Salvatore L., et al. "American Association of Oral and Maxillofacial Surgeons Position Paper on Medication-Related Osteonecrosis of the Jaw—2014 Update." Journal of Oral and Maxillofacial Surgery (2014): 1938-956.

2. Lo, Joan C., et al. "Prevalence of Osteonecrosis of the Jaw in Patients With Oral Bisphosphonate Exposure." Journal of Oral and Maxillofacial Surgery 68 (2010): 243-53.