[A middle to long-term clinical study on pars flaccida and pars tensa cholesteatoma using survival analysis]

The current clinical study was performed on 311 cases of pars flaccida and 89 cases of pars tensa cholesteatoma which were treated with canal wall reconstructed tympanoplasty between 1991 and 2012. The average follow-up time of these patients was 5.3 years. Since follow-up periods were different in each case and some censored patients were involved, we used survival analysis on this study to discuss the cumulative rates of disease-free successful cases and the rates of recurrent cholesteatoma throughout the postoperative course. The disease-free successful cases were defined as those cases in which patients were both out of re-operation with recurrent and residual cholesteatoma and out of revision operation with another problem, furthermore, maintained good hearing outcome. Based on the criteria set by the Japan Otological Society (2010), the cases that satisfied the following were evaluated as good hearing results; (a) a successful case in which preoperative bone conduction was used, and (b) a case in which the postoperative air-bone gap was within 20dB after tympanoplasty for chronic otitis media. The analysis results were shown for each of (a) and (b). 1. In pars flaccida cholesteatoma, the 5-year survival rate of successful case was (a) 76.1% and (b) 83.9%, the 10-year survival rate was (a) 58.9% and (b) 73.0%. In pars tensa cholesteatoma, the 5-year survival rate of successful cases was (a) 57.7% and (b) 63.5%, the 10-year rate was (a) 42.1% and (b) 56.9%. A significant difference was seen between pars flaccida and pars tensa cholesteatoma (p < 0.001). 2. In pars flaccida cholesteatoma, the 5-year recurrence rate was 7.6% and the 10-year rate was 15.3%, and the recurrence rate increased gradually throughout the follow-up period. On the other hand, in pars tensa cholesteatoma, the increase in the recurrence rate reached a peak 15.8% at 5.5 years after the surgery. A long-term follow-up is necessary when evaluating the clinical results after tympanoplasty.