The principal results of the validation study showed that the variables that best predicted the success of tympanoplasty were the following seven: the age at onset of symptoms (>6
years); the state of the contralateral ear (normal); prior adenoidectomy; the cause of perforation (trauma/implantation of ventilation tube); size of the perforation (<50%); state of the mucosa (normal); and the absence of craniofacial dysmorphias. By incorporating a more functional definition of success (i.e., measured by means of three criteria: integrity of graft, hearing, and adequate air-filled space in the middle ear), the rate of success fell to 56.3%, compared to that (93.8%) found when only the integrity of the implant or closure of perforation was considered (Table
). This is not an isolated finding for pediatric patients. Bluestone et al. [24
] published a success rate of 35%; Manning et al. [16
] reported 78% success for integration of the graft, but only 52% showed adequate function of the Eustachian tube. In comparison, data for adults show that closure of the perforation is achieved in approximately 80% to 90% of cases; however, only 70% have an intact tympanic membrane, without imperfections such as pockets of retraction or lateralization of the graft, so that different degrees of improvement in the auditory threshold are found in 67.2%, with improvement of >20
dB (16.4%) in three-year follow-ups [10
]. On this point, it is worth mentioning that the most acceptable definition of success in auditory gain is the closure of the air-bone gap, resulting in a gain of ≥20
]. Therefore, in this study, the auditory component of success was defined as a gain in auditory threshold of 10–20
dB, or more, and not as closure of the air-bone gap, the reason being that the latter is measured only by tonal audiometry, which was not possible to do with all the children in this study; we had technical problems with the children. For those cases in which tonal audiometry could not be done, those patients were assessed by using brainstem auditory evoked potentials.
To our knowledge, this is the first study to validate an index that predicts the result of tympanoplasty in children. In general terms, the characteristics of the patients were similar to those treated in other hospitals. For the population of the United States, the most frequent causes of perforation have been, first, a result of the placement of ventilation tubes and, second, chronic perforation due to infection [4
]. However, other reports have mentioned a high frequency of perforations with infectious etiology [16
], the frequency being equal to that reported for patients in this series.
It is important to point out that, in the present work, age at the time of surgery was excluded because this variable did not show sufficient weight in the model to predict the success of surgery. A limitation of this study would be the considering that the youngest patient included was five years of age. Using logistical regression analysis, Sckolnick et al. [3
] postulated that, as age increased, the odds ratio of success diminished, with the cut-off point placed at nine years of age; that is, the best prognosis was for 1–5
year-old patients, declining 9% for each year of age thereafter, until nine years of age when the success rate increased to a value similar to that found for those older than 16
years of age. For this reason, it is possible to identify a group of patients, 7–12
years of age, with a lower rate of success; the majority of the population studied was, on average, 7.1
years old [3
]. The present study is one of the few that evaluate the results of tympanoplasty in very young children. A study by Black et al. in 1994 included patients as young as two years of age; no statistically significant differences were encountered in the results of the surgery for these children [11
]. In the only meta-analysis that individually evaluated articles that were cited in the current study, the authors showed that, in the majority (25 of 30) of these reports, no relation was found between age and the success of surgery. This contrasts with the results of the same meta-analysis, in which a statistically significant relation was found between this factor and a successful result. The authors of this meta-analysis attributed these discrepancies to the following: the majority of the individual studies analyzed either did not include patients younger than seven years of age, used a different definition of success, or had methodological errors, such as the size of the sample or the type of study (retrospective) [1
]. In a study published in 2010, which reported (retrospective) the results of 132 tympanoplasties performed on children, ranging from 6–15
years and divided into two groups (<8 and >8
years), once again no statistically significant differences between age and successful result were found [18
]. It is of note that, in that study, the definition of success was the same as the one used in the present study; one limitation of this definition is that the frequency of success is lower than when just one factor is considered.
Another important point to consider is the age of onset of chronic otitis media. In the literature, this is used in the age of the perforation. For example, patients with retained ventilation tube, who underwent tympanoplasty during the removal of the tube and who did not suffer changes due to chronic inflammation are said to be at age “zero” of the perforation. This population differs from those whose perforation occurred either after a process of otitis, or secondary to the extrusion of a tube, but for whom a determined period of time passed before the tympanoplasty was performed [4
]. In that same study, the authors found a statistically significant relation between the age at which the ear was perforated and the result of the surgery; nevertheless, upon excluding the patients at age zero of the perforation, this relation loses significance. In other studies, no relation was found between these factors [1
]. The sample size of our study was small; however, the age of onset of chronic otitis media was associated with the success of tympanoplasty.
For patients with craniofacial dysmorphias (basically, the sequelae of cleft lip or cleft palate), the results of tympanoplasty are controversial. On one hand, Dornhoffer et al., in a series of 20 patients, with a total of 26 otological surgeries, concluded that tympanoplasty is a reasonable treatment for patients with sequelae of cleft lip or cleft palate. In that work and in the current study, the same three criteria of success were used and similar results were obtained [25
]. In a retrospective study of 26 patients who had sequelae to cleft lip or cleft palate and who underwent tympanoplasty, no statistically significant difference was found in the results for integration of the graft, hearing, and the necessary equalizing of pressure in the Eustachian tube, as compared with the results for patients of the same age without cleft palate [21
]. Despite the small sample size in our study, this variable was related with the prognoses of the patients, one reason in this study would be that the increased technical difficulty encountered in performing tympanoplasty on patients with craniofacial dysmorphia tends to negatively affect the outcome of the surgery.
One limitation of this study was that, with the seven variables included in the predictive model, it was possible to predict only 81% of the successful outcomes. In the validation study, all patients with a successful evolution could be predicted. Nevertheless, the specificity was only 67%; therefore, it was expected that this model could not predict 33% of the failures. In the present study, 17% of the patients who had been predicted to have successful outcomes had, in fact, unfavorable post-surgical evolutions. However, the predictive model produced better results than did analyzing each variable separately. The model that included the three outcome criteria was the most equilibrated of these models was the one that incorporated all three parameters of success as the outcome criterion, because it predicted a greatest number of failures without affecting the percentage of predicted successes.
As mentioned above, the sample size of this study is its main limitation; thus, it will be necessary to include a greater range of patients in order to evaluate the benefit of the prognostic index presented here. As indicated by Sackett et al. [23
], it is preferable to quantify the probability of success of a therapeutic intervention when explaining the intervention to a patient or to the patient’s family members, because a calculated value provides them with a more objective tool with which to make a decision as to whether an intervention is appropriate or not.