Sialadenitis May Be Associated With an Increased Risk for Osteoradionecrosis: A Nationwide Population-Based Cohort Study

Purpose: The impact of sialadenitis on osteoradionecrosis (ORN) is controversial. The aim of this study was to determine the association between sialadenitis and ORN. Materials and Methods: Participants were derived from the Taiwanese Longitudinal Health Insurance Database. From January 1, 2000 to December 31, 2008, cases of sialadenitis (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes 527.2, 527.3, 527.5 to 527.7, 527.9, and 710.2) and ORN (ICD-9-CM codes 526.89, 526.5, 730.0, and 730.1) were identified. Different treatment modalities, including surgery versus medicine, were used to distinguish the severity of sialadenitis. The primary predictor variable was sialadenitis. The secondary predictor variable was severity of sialadenitis. The primary outcome variable was time to developing ORN. Other study variables were grouped for age, gender, risk factor, and medical treatment. Cox proportional hazard regression was used to investigate the associations between sialadenitis and ORN after adjusting for statistical confounders. Results: The sample was composed of 47,385 patients with a mean age of 46.6 years (standard deviation, 19.9 yr) and 37.2% were men. Twenty percent had a diagnosis of sialadenitis and 1.13% had a diagnosis of ORN. Sialadenitis was associated with an increased risk of ORN (hazard ratio [HR] = 1.93; 95% confidence interval [CI], 1.61-2.31; P <.0001). After adjustment for confounders, sialadenitis was associated with ORN (multivariable HR = 1.83; 95% CI, 1.52-2.19; P <.0001). Severity of sialadenitis was associated with an increased risk of ORN; risks for ORN were 1.79 (95% CI, 1.49-2.16; P <.0001) and 3.52 (95% CI, 1.67-7.44; P <.001) in patients with mild and serious sialadenitis, respectively, compared with the no-sialadenitis cohort. For the joint effect of ORN between sialadenitis and malignancy type, patients with sialadenitis had 11.6-fold risk for ORN (95% CI, 5.58-23.9) compared with patients without malignancy. Conclusions: Sialadenitis markedly increased the risk to develop ORN. The severity of sialadenitis was positively correlated with the incidence of ORN.