Diseases associated with subsequent peritonsillar abscess: a case-control-study from ENT practices in Germany.

Objective: Peritonsillar abscess (PTA) is the most common deep soft tissue infection necessitating surgical intervention in the head and neck region. Potential causes include infections of the palatine tonsils, palatine glands, or branchiogenic rudiments ("acute tonsillitis hypothesis" vs. "Weber's gland hypothesis"). Understanding the currently still unknown predominant cause is crucial for guiding therapeutic strategies, such as abscess tonsillectomy versus incision and drainage alone. This study aims to investigate the pre-diagnoses associated with subsequent PTA using a nationally representative practice database in Germany.

Methods: Data were collected from 195 ENT practices across Germany utilizing the nationally representative practice database IQVIA™ Disease Analyzer. Included were patients aged 18 years and older with a first diagnosis of PTA (index date) between January 2005 and December 2022 and a minimum observation period of 12 months preceding the index date. These patients were matched (1:5) with controls without PTA, based on age, sex, and index year. Frequencies of prior diagnoses coded according to ICD-10 in the 12 months preceding the index date were computed. The association between prior diagnoses and PTA was evaluated using multivariable logistic regression (MLR) and sensitivity analysis (SA).

Results: A total of 5,325 cases were compared with 26,725 controls in the multivariable logistic regression (MLR) analysis, and 16,251 cases were compared with 81,255 controls in the sensitivity analysis (SA). Mean age was 45.3 ± 18.3 years (MLR) and 41.9 ± 16.7 years (SA). The proportion of female patients was 51.8% (MLR) and 46.9% (SA), respectively. MLR showed the strongest associations with PTA for the prior diagnoses of "acute tonsillitis" (odds ratio, OR: 6.71; 95% CI: 5.81-7.74), "chronic tonsillitis" (OR: 2.00; 95% CI: 1.58-2.52), and "acute pharyngitis" (OR: 1.74; 95% CI: 1.50-2.03). SA similarly indicated the strongest associations with PTA for the prior diagnoses of "acute tonsillitis" (OR: 5.02; 95% CI: 4.60-5.47), "chronic tonsillitis" (OR: 1.87; 95% CI: 1.64-2.12), and "acute pharyngitis" (OR: 1.27; 95% CI: 1.14-1.41).

Conclusion: The most prevalent prior diagnosis associated with PTA was acute tonsillitis, followed by chronic tonsillitis and acute pharyngitis. The association with acute pharyngitis suggests possible non-tonsillogenic causes. Other specific causes of PTA, such as inflammation of the palatine gland or branchiogenic remnants, are not captured by the ICD system or the database utilized in this study.