Second letter
Dear Editors,
The authors of the paper titled ‘Evaluation and comparison of type I tympanoplasty efficacy and histopathological changes to the tympanic membrane in dry and wet ear: a prospective study’ rightly point out that previous studies seeking to determine whether discharge at the time of surgery has an adverse effect on the outcome of myringoplasty operations have produced conflicting results. This is because they were inadequately powered to answer this question. The same is true of Shankar and colleagues' study.
Fortunately, a study has already been published which provides a definitive answer.Reference Mills, Thiel and Mills1 When devising the study, the authors decided that, as patients with active ears benefit more from surgery than those with dry ears, the important question was whether discharge at the time of surgery was associated with an increase in the rate of persistent perforations of less than 10 per cent. A power calculation based on this premise indicated a need for a sample size of 182, with equal numbers in each group. In fact, 268 patients were enrolled, of whom 246 attended a follow-up appointment 6 months after surgery. The success rate for inactive ears was 83 per cent and that for active ears was 82 per cent. The authors concluded that: ‘There is no clinically significant difference in the success rate for myringoplasty in patients whose ears were active or inactive at the time of surgery’.Reference Mills, Thiel and Mills1
