title: The impact of prior tonsillitis and treatment modality on the recurrence of peritonsillar abscess: a nationwide cohort study.
abstract: BACKGROUND
  Studies suggest an increased risk of peritonsillar abscess (PTA) recurrence in patients with prior tonsillitis. However, this association is inconsistent and could be confounded by different treatment modalities. This study aimed to assess the risk of recurrence among PTA patients with different degrees of prior tonsillitis and treatment modalities, and the role of tonsillectomy in current practice.
  
  
  METHODS
  All in-patients with peritonsillar abscess between January 2001 and December 2009 were identified in a nationwide, retrospective cohort study. Recurrence was defined as the first occurrence of PTA ≧30 days from the initial PTA. Factors independently associated with recurrence were analyzed using Cox proportional hazard model after adjusting for demographic and clinical data.
  
  
  RESULTS
  There were 28,837 patients, with a 5.15% recurrence rate and 4.74 years of follow-up. The recurrence rates were significantly higher among subjects with more than five prior tonsillitis or 1-4 prior tonsillitis compared to those without prior tonsillitis (adjusted hazard ratio, 2.82 [95% confidence interval, 2.39-3.33] and 1.59 [95% CI: 1.38-1.82]). The adjusted HR in patients treated with needle aspiration was 1.08 compared to those treated with incision & drainage (95% CI: 0.85-1.38). After age stratification, the adjusted HRs of more than five prior tonsillitis increased to 2.92 and 3.50 in patients aged ≦18 and 19-29 years respectively. The adjusted HR of needle aspiration only increased in patients ≦18 years old (aHR: 1.98 [95% CI: 0.99-3.97]). The overall tonsillectomy rate was 1.48% during our study period.
  
  
  CONCLUSIONS
  The risk of PTA recurrence increases with higher degrees of prior tonsillitis in all age groups and management by needle aspiration only in the pediatric population. Patients younger than 30 years old with PTA and more than five prior tonsillitis have the greatest risk of recurrence.
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Mackay Memorial Hospital, Taipei, Taiwan; Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Audiology and Speech Language Pathology and School of Medicine, Mackay Medical College, New Taipei City, Taiwan.
authors.forename: Ying-Piao
authors.initials: YP
authors.lastname: Wang
authors.affiliation: Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan; Department of Otolaryngology, Head and Neck Surgery, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Mao-Che
authors.initials: MC
authors.lastname: Wang
authors.affiliation: Department of Otolaryngology, Head and Neck Surgery, Mackay Memorial Hospital, Taipei, Taiwan; Department of Audiology and Speech Language Pathology and School of Medicine, Mackay Medical College, New Taipei City, Taiwan.
authors.forename: Hung-Ching
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Institute of Public Health and Community Medicine Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Pesus
authors.initials: P
authors.lastname: Chou
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D019152:Paracentesis; D000039:Peritonsillar Abscess / Q000209:etiology* / Q000473:pathology; D016016:Proportional Hazards Models; D012008:Recurrence; D012189:Retrospective Studies; D012306:Risk; D014068:Tonsillectomy; D014069:Tonsillitis / Q000150:complications* / Q000473:pathology / Q000601:surgery