BACKGROUND: Otitis media with effusion (OME) has a high rate of spontaneous resolution, and a policy of waiting and watching for 3 months is justified. The decision about further treatment should be individualized, depending on duration and symptoms. Knowledge of the determinants for persistent OME would be helpful for identifying patients with a need for active treatment or increased monitoring for complications.

METHODS: A total of 433 children aged 6 months to 6 years were monitored for 3 months in the offices of 57 family physicians. A questionnaire pertaining to determinants was completed. The outcome measures were: presence of unilateral or bilateral OME or bilateral OME after 3 months. The outcome was determined on the basis of tympanometry results. We performed bivariate and multivariate analyses.

RESULTS: The presence of an upper respiratory tract infection (URTI) at the follow-up visit was associated with finding OME at that visit. When a URTI was present, no other determinants for persistent OME were found. When absent, the determinants for persistent bilateral OME were: no history of adenoidectomy, an episode of acute otitis media (AOM) in the first year of life, and month of entry into the study (June-November). For persistent unilateral or bilateral OME, the only significant determinant was an episode of AOM in the first year of life.

CONCLUSIONS: Children with 1 or more of the following factors need special attention for prevention of the sequelae of persistent OME: no history of adenoidectomy, AOM in the first year of life, and the presence of bilateral OME in the period between June and November.

In 1976, Paradise¹ concluded that uncertainty and controversy prevail over the choice and timing of treatment of otitis media with effusion (OME). Now, more than 20 years later, important issues of prognosis and treatment of persistent OME still have not been solved. The costs of medical and surgical treatment for OME are high.² There is great concern regarding the worldwide problem of multiply resistant strains of bacteria,³ and some authors believe that many patients with OME are overtreated with antibiotics.^4,5 Considering the natural course of the disease, the introduction of a waiting period before surgery and restriction of treatment to those cases with sequelae may be cost-effective.^6-8 The duration of this waiting period and the criteria for selecting those cases that should be actively followed up are not yet clear.^9-13 Persistent OME may have functional effects on hearing and cognitive-linguistic development and behavior. The identification of a set of determinants for persistent OME would help physicians identify patients who need further monitoring or treatment. Studies looking at factors associated with persistent OME show conflicting results, and none has been carried out in a family practice population. The only 2 factors on which there is agreement are young age and attendance at a daycare center.^7,14-16 The effect of other factors on the natural course of OME is not known.^15-17 In addition, such studies are difficult to compare because different criteria are used for the diagnosis of OME, and the study populations differ.^{7,14,15,17-22}

Most children with OME are initially seen in a primary care setting where a policy of “watchful waiting”^23,24 is feasible. Since there have been no previous studies of factors associated with persistent OME in family practice settings, we addressed the issue.

Methods

Subjects

Between December 1992 and August 1993, 57 family physicians selected children aged 6 months to 6 years whom they suspected of having middle ear effusion in both ears (bilateral OME) for tympanometry. Only children with bilateral OME were selected, since these are the only cases for which the Dutch College of Family Physicians recommends active treatment.²⁵ The selection criteria were based on complaints frequently associated in the literature with the occurrence of OME, including: subjective or objective hearing loss, language and speech problems, mouth breathing and snoring, a history of recurrent upper respiratory tract infection (URTI), a family history of otitis media, and acute otitis media (AOM) 6 weeks previously.^16,26,27 Children with a history of the following were excluded: antimicrobial therapy in the preceding 6 weeks, compromised immunity, craniofacial abnormalities, Down syndrome, or cystic fibrosis.

Design

After informed parental consent, a questionnaire covering demographic data and past and present history was completed, and an ear, nose, and throat (ENT) examination, including tympanometry (Welch-Allyn microtymp I), was performed. If the diagnosis of bilateral OME was confirmed, the children were entered into the study and asked to return after 3 months. No treatment for their ear problem was given.

At the 3-month follow-up visit, any current symptoms were recorded and another ENT examination, including tympanometry, was carried out. All tympanograms were printed out and classified by the first author (FvB).

Outcome Measures

Two outcome measures were studied: the presence of bilateral OME in those children who still had it at the 3-month follow-up examination, and unilateral or bilateral OME in all children with OME, whether unilateral or bilateral, at the follow-up examination.

Definitions

OME was defined as the presence of fluid in the middle ear cavity behind an intact tympanic membrane without signs or symptoms of acute infection. The presence of middle ear effusion was defined by the C2-curve and the B-curve because of their high positive predictive values (88% and 54%, respectively).^28,29 Recurrent URTI was defined as 6 or more episodes of a common cold or nasal catarrh in the past 12 months, each episode not exceeding 4 weeks. Recurrent AOM was defined as 3 or more episodes in the past 12 months. A child failed the Ewing test if he or she did not respond to the sound stimuli in any of the tests. Bottle feeding meant that no breastfeeding had been used at all.

Statistical Analysis

Bivariate analyses were carried out to test the association between determinants and outcome assessed at the 3-month follow-up visit. The strengths of the associations were expressed as odds ratios with 95% confidence interval limits.³⁰ Associations were also tested by chi-square analysis. All factors showing a P value equal to or less than 0.2, and all factors that were clinically relevant were subjected to logistic regression analysis.³¹ The goal of the regression analysis was to find a set of determinants for persistent OME. From those factors that were significant we derived a prediction score by adding the betas (eg, prediction score=bfactor1+bfactor2+bfactor3).³¹ The discriminating ability of these predictions was assessed by means of receiver operating characteristic curve analysis. The size of the area under the curve (AUC) is a measure for the discriminating capability, the ability to separate patients into groups classified according to the determinants.³² A test that does not discriminate will have an AUC of 0.5; a perfect test will have an AUC of 1.0.

Results

A total of 593 children were suspected of having bilateral OME at the initial visit, but the tympanograms were normal for 82 (14%), and no classifiable tympanogram could be obtained for 11 (2%). Sixteen of the remaining 500 children were excluded because they had been given an antibiotic in the preceding 4 weeks, and the parents of 51 children refused consent. Thus a total of 433 children (73%) were included in our study. Eighty children (18%) had more than 3 entry criteria, and 231 (53%) had more than 2. The most common combinations of complaints were subjective hearing loss with recurrent URTI (19%) and subjective hearing loss with mouth breathing and snoring (14%).

Twelve children failed to attend the 3-month follow-up visit, and in 24 no classifiable tympanogram could be obtained ([Figure]). We excluded these 36 children from the 3-month follow-up as they did not differ significantly from the evaluation group in respect to sex, age, month of entry, presence of URTI at the initial visit, or complaints at entry. Of the remaining 397 children (92%), 223 (56%) still had C2-typanogram and B-tympanogram in both ears, 81 (20%) in one ear, and 93 (24%) had A-tympanogram or C1-tympanogram. Patient characteristics at the initial visit are shown in [Table 1] (Please see pages 609 -611 for all tables.)

Persistent Bilateral OME

[Table 2] shows the results of the bivariate analysis of determinants for persistent bilateral OME. Entry into the study between June and November showed a weak association (P=.05). The presence of AOM or URTI during the examination showed a strong association with bilateral OME (P=.005 and P <.001, respectively).

[Table 3] shows the results of the logistic regression analysis. Only no adenoidectomy showed any influence on the duration of OME (P <.05). The presence of AOM or URTI at the follow-up visit was associated with bilateral OME (P <.05 and P <.001, respectively). Because of the influence of URTI on OME, logistic regression analysis was carried out both with and without URTI at the follow-up visit. When URTI was present no determinants were found. When it was absent, the following 3 determinants were prognostic of bilateral OME: (1) no adenoidectomy (P <.05; adjusted odds ratio [OR]=2.75; 95% confidence interval [CI], 1.22-6.20); (2) an episode of AOM in the first year of life (P <.05; adjusted OR=1.59; 95% CI, 1.03-2.46); and (3) entry into the study between June and November (P <.05; adjusted OR=2.07; 95% CI, 1.11-3.86). No good set of discrimant factors was found when adding together the b coefficients for an episode of URTI and AOM on follow-up, no adenoidectomy, and an episode of AOM in the first year of life (AUC=0.61; standard error [SE]=0.029).

Persistent Unilateral or Bilateral OME

[Table 4] shows the results of the bivariate analysis of determinants for persistent unilateral or bilateral OME. Absence of AOM at initial visit, attending daycare and less than 3 rooms in the house showed a weak association. The presence of URTI during examination was again associated with the presence of middle ear effusion.

Logistic regression analysis ([Table 5]) showed a significant association with the absence of AOM at the initial visit (P <.05) and with URTI at the follow-up visit (P=.001). The analysis was repeated again with and without URTI at the follow-up visit. In the presence of URTI no determinants were found; in the absence of URTI an episode of AOM in the first year of life showed a significant association (P <.05; adjusted OR=1.69; 95% CI, 1.15-2.49). Again, no good set of discrimant factors was found by adding the b coefficients of AOM at initial visit, history of AOM in the first year of life, daycare, and URTI at the follow-up visit (AUC=0.65; SE=0.03).

Discussion

Our entry criteria detected a high percentage (84%) of patients with bilateral OME. The presence of more than 1 criterion in the same child had no effect on the duration of OME. Our data show a strong association between the presence of AOM or URTI during examination and the finding of middle ear effusion. In the absence of URTI, the following were associated with persistent bilateral OME: no adenoidectomy, an episode of AOM in the first year of life, and entry into the study between June and November. An episode of AOM in the first year of life was associated with persistent unilateral or bilateral OME. It was not possible to construct a discriminant model prognostic of persistent bilateral or unilateral or bilateral OME as the AUCs of 0.61 and 0.65, respectively, were rather low.

A possible weak point in this study is that our results are based on tympanometry outcome after a 3-month interval. The 36 children excluded from the 3-month follow-up did not differ significantly from those included, so their exclusion probably had no influence on the results.

Some of the determinants identified in this study are closely related to URTI. For instance we found a weak association between attending daycare and persistent unilateral or bilateral OME in bivariate analysis, but this association disappeared in the logistic regression analysis. This could be explained by the close relationship between attending daycare and URTI-related factors in the occurrence of OME. This close association between OME and URTI has been reported before.³³ The finding of this relationship suggests that occurrence of middle ear effusion during an URTI episode is a physiologic phenomenon, probably caused by eustachian tube obstruction and needing no further treatment. If this is true, children with URTI-related OME need only close follow up and no active treatment.

The factors of no adenoidectomy, early episodes of AOM, and the prevalence of bilateral OME during the months June to November were found in the absence of URTI and suggest a different, more pathophysiologic relationship with OME than when OME is found with URTI. As adenoid size seems not to be correlated with the pathogenesis of OME,³⁴ the association with no adenoidectomy supports the viewpoint that the adenoids are an important factor in OME by providing an infectious focus in the nasopharynx or by their influence on the immunological status of the nasopharynx.^34-36

The association between AOM early in life and persistence of OME has been reported previously.³⁷ Children with early AOM episodes are frequently known as “otitis-prone.”³⁸ They also have more recurrent AOM episodes and more episodes of URTI than average.

The exact relationship between AOM and OME is not known. AOM may precede OME, but it is also more frequent in patients with OME.³⁹ Several studies have reported an association between OME and winter or early spring. This is probably the result of the increased incidence of URTI during this season. The period between June and November (summer and early autumn) is less likely to be associated with frequent episodes of URTI. Contrary to the findings of other studies, we found no association between age younger than 3 years and persistent OME.⁴⁰

In our study we found that factors associated with persistent OME differ from those that increase the risk for occurrence of OME (attending daycare, bottle feeding, passive smoking).* This is an important finding. First, the absence or presence of the determinants for persistent OME may affect the choice of treatment. A more active attitude is needed if there is a higher chance for sequelae, such as language delay caused by conductive hearing loss, atelectasis of the tympanic membrane, and cholesteatoma, as is the case in persistent OME. In the absence of determinants for persistent OME a more watchful policy may be followed, especially if the child has no severe hearing loss, does not suffer from recurrent AOM episodes, and has no tympanic membrane abnormalities. This would lead to a reduction of overtreatment and to cost reduction. In the presence of determinants for persistent OME, children should be monitored more closely. When sequelae such as language delay or recurrent episodes with AOM are present, active treatment with antibiotics, tympanostomy tub insertion,^5,9 or adenoidectomy^34-36 is needed. We also feel that future research should be focused on the pathophysiological group of otitis-prone children and not on all children with OME. If we are capable in differentiating between those children who need further treatment from those children in whom OME is a physiological reaction on a URTI, overtreatment and costs may be greatly reduced.

Acknowledgments

We thank Dr F.W.M.M. Touw-Otten who contributed much to this study but passed away in 1997. We also thank Dr H. de Glanville for his critical review of this paper.

Persistent Otitis Media with Effusion: Can It Be Predicted? A Family Practice Follow-up Study in Children Aged 6 Months to 6 Years