A multivariate analysis of chronic otitis related prognostic factors in determining hearing improvement in tympanoplasty

OBJECTIVE: The aim of this study was to evaluate which factors are best predictors of hearing improvement after tympanoplasty and to evaluate best functional outcome in different forms of pathology in the tympanic cavity and mastoid in chronic otitis media. METHODS: Prospective study included 120 patients who were operated for chronic suppurative otitis media and cholesteatoma in the ENT Department University Clinic Center Banja Luka from 2006 to 2011. Multiple linear regression analysis was used to measure which factors predict better hearing improvement. MAIN OUTCOME MEASURES: A model that evaluates factors related to chronic otitis media: ossicular chain integrity, tympanic tube function, tympanic membrane perforation, type of surgery and condition of tympanic and mastoid walls was used to predict postoperative hearing improvement. Hearing outcome was measured comparing preoperative to postoperative pure-tone average (PTA) and postoperative air-bone gap (ABG). RESULTS: Out of 120 operated patients, we performed primary surgery in 106 and revision surgery in 9 cases due to recurrent cholesteatoma. We observed high correlation and statistically significant contribution of ossicular chain pathology (b=-0.310, t=-3.01, p<0.05), and mastoid bone erosion or defects (b=2.05, t=2.05 , p<0.05), on the variance of PTA. The same variables were highly correlated with ABG closure: ossicular chain pathology (b=-0.230, t=-2.14, p<0.05), and mastoid bone erosion or defects (b= 2.05, t=2.08 , P<0.05). Variance of preoperative to postoperative PTA difference explained by the model as a whole was 24,7%, F(8,119)=4.54 , p<0.01. Variance of preoperative to postoperative ABG difference explained by the model as a whole was 18,3% F(8,119)=3.1, p<0.01. The predictive model in this study included 8 variables related to middle ear pathology proved to be superior to analyzing each variable separately. CONCLUSION: A model that evaluates factors related to chronic otitis media: ossicular chain integrity, tympanic tube function, tympanic membrane perforation, type of surgery and condition of tympanic and mastoid walls has significant predictive value for hearing assessment in tympanoplasty.