National Trends and Associated Factors of Retropharyngeal Abscess among Adult Inpatients with Peritonsillar Abscess

Objectives: (1) Describe national trends in retropharyngeal abscess (RPA) complicating peritonsillar abscess (PTA). (2) Determine factors associated with RPA in patients with PTA. Methods: Years 2003 to 2010 of the Nationwide Inpatient Sample (Healthcare Cost and Utilization Project, Agency for Healthcare Research and Quality) were queried for PTA (ICD-9 code: 475) and RPA (ICD-9 code: 478.24) in adult patients (age ≥18 years old). The cohort was analyzed using descriptive statistics and multivariate regression modeling to identify factors associated with RPA. Results: Of the 90,941 (95% confidence interval [CI]: 86,433-95,449) patients identified with PTA, 885 (1.0%) also had a concurrently coded RPA. The annual rate of concomitant RPA doubled (P < .001) from 0.5% (95% CI: 0.3%-0.8%) to 1.4% (95% CI: 1.0%-2.0%) between 2003 and 2010. Patients with RPA were more likely to undergo tonsillectomy (23.5% vs 11.1%) and mechanical ventilation (13.2% vs 2.0%) than those without RPA (all P < .001). RPA patients were significantly (all P < .001) older (41 vs 34 years old), had a longer hospital stay (6.4 vs 2.5 days), and had more procedures (2.5 vs 0.9) compared with patients without RPA. Upon multivariate regression analysis, factors associated with RPA included age groups 40 to 64 years (odds ratio [OR] = 2.073, P < .001), 65 years and older (OR = 2.148, P = .021), and teaching hospital (OR = 1.838, P < .001). When controlling for age, sex, and hospital characteristics, general linear modeling demonstrated that RPA accounted for $27,240 (P < .001) in excess total charges per patient. Conclusions: The incidence of RPA among adult inpatients with PTA is increasing, and patients with RPA have higher in-hospital resource utilization. Further studies may help validate factors predictive of RPA to enable earlier identification.