Background Oral bisphosphonates (BPs) have been increasingly prescribed for the treatment of and prophylaxis for osteoporosis over the past decade. More than 190 million prescriptions for oral BPs have been dispensed worldwide, and, thus, the number of patients that develop oral BP-related osteonecrosis of the jaw (BRONJ) is expected to increase in the future. Although previous studies have investigated oral BRONJ, predictive factors have not yet been identified [1].

Objectives The aim of the present study was to clarify the clinical features and predictive factors of oral BRONJ.

Methods We included 8 patients who had taken oral BPs and were diagnosed with BRONJ at Mitsui Memorial Hospital (Tokyo, Japan) between 2011 and 2016. The following details were collected for each patient from a review of medical charts: sex, age, type of BP used, duration of BP administration, co-morbidities, laboratory values at presentation including hemoglobin, albumin, and serum creatinine values, clinical stage of the lesion, site affected, and pathological findings. Laboratory values of patients with BRONJ were compared with those of 242 patients (as a control group) who were prescribed BPs in October 2016 at our hospital. The Mann-Whitney U-test and chi-squared test were used for statistical comparisons between the oral BRONJ and control groups. Risk factors for BRONJ were assessed using multivariate analyses with a logistic regression analysis. All analyses were performed using SPSS ver. 21.

Results The mean age and female ratio in the oral BRONJ and control groups were 74.5±13.8 years and 75.0%, and 71.1±12.7 years and 66.1%, respectively (p=0.26, p=0.61). The mean interval between the initiation of BP therapy and a confirmed diagnosis was 45.9±35.5 months. Seven patients had lesions in the mandibular bones and alendronate was used in six cases. Oral BPs were administered to three patients with rheumatoid arthritis or multiple sclerosis, all of whom were given a maintenance dose of corticosteroids. The remaining three out of 5 oral BP users developed BRONJ after dental extraction. Regarding laboratory results, serum albumin values were significantly lower in the oral BRONJ group than in the control group (3.7±0.3 g/dl and 4.2±0.4 g/dl, respectively, p<0.01). Serum hemoglobin levels were slightly lower in the oral BRONJ group than in the control group (11.3±1.3 g/dl and 12.4±1.7 g/dl, respectively, p =0.06). A multiple logistic regression analysis identified serum albumin levels as the only significant predictive factor for oral BRONJ (OR=0.14; 95% CI 0.03–0.71, p<0.05). A pathological examination was available in six patients, with Actinomycetes being identified as the causative species in 4.

Conclusions Oral BRONJ mainly developed in patients with long-term corticosteroid use for an underlying illness or those who underwent dental extraction, and hypoalbuminemia was the only laboratory marker identified as a predictive factor for BRONJ.

References

1. Diniz-Freitas M et al., Oral bisphosphonate-related osteonecrosis of the jaws: Clinical characteristics of a series of 20 cases in Spain. Med Oral Pathol Oral Cir Bucal 2012;17:e751.

References

Disclosure of Interest None declared