Acta Otorrinolaringol Esp 2005; 56: 290-294

CLINICAL RESEARCH

290

Otitis medias with effusion: association with the Eustachian tube dysfunction and adenoiditis. The case of the Central Hospital of Maputo

J. L. da Costa1,2, A. Navarro2, J. Branco Neves3, M. Martín2 1Instituto Superior de Ciências e Tecnologia de Moçambique (ISCTEM). Department of Community Health, Faculdade de Medicina UEM, Maputo. 2 Grups de Recerca d’Amèrica i Àfrica Llatines (GRAAL). Unitat de Bioestadística. Universitat Autònoma de Barcelona. 3ENT-CHM, Faculdade de Medicina UEM, Maputo.

Abstract: Introduction: Although the etiology of otitis media is known to be multifactorial, adenoid infections and Eustachian tube dysfunction have frequently been associated with the incidence of middle-ear effusion. Cases of middle-ear effusion are common in Maputo, Mozambique, and the insertion of tympanostomy tubes and an adenoidectomy, alone or with tonsillectomy, have often been used to treat children and to prevent further episodes. The objective of this study is to describe the connection of these factors to otitis media with effusion in patients that visit the ENT department of the Central Hospital of Maputo (HCM), as well as to describe the clinical and epidemiological profile of these patients. Patients and methods: A cross-sectional study was conducted. The 4,157 clinical files of all the patients who visited the ENT department at the HCM for the first time with otitis media during a 4-year period (1995 to 1998) were reviewed. Results: 23.3% of patients who visited the ENT service of Maputo with otitis media were children under the age of 3; the majority of the cases of otitis media with effusion were observed in children aged between 3 and 7 years (49.2%). Otitis media with effusion is strongly associated with a history of adenoiditis and/or Eustachian tube dysfunction in boys under the age of 7, (OR=9.53), and in older patients (OR=12.26). Conclusion: The proportion of cases of otitis media with effusion noticeably increases in patients with Eustachian tube dysfunction. Another factor that can be significant in patients under the age of 7 is the presence of adenoiditis. Key words: Otitis media with effusion. Otitis media. Adenoids. Eustachian tube. Log-linear models (public health).

Correspondence: Miguel Martín. Unitat de Bioestadística. Facultat de Medicina. Edifici M. Universitat Autònoma de Barcelona. 08193 Cerdanyola del Vallès (Barcelona). E-mail: gaton2001@yahoo.es Fecha de recepción: 4-3-2005 Fecha de aceptación: 25-4-2005

INTRODUCTION

Otitis media with effusion (OME) is the inflammation of the middle ear, characterized by the presence of liquid or effusion behind an intact tympanic membrane, without acute symptoms. For the last 40 years, owing to its habitual resistance to treatment and a tendency to persist, which in turn leads to complications and serious after-effects, OME has been the subject of ongoing research with the objective of discovering more about its etiology and physiopathology.

OME is a disease that often appears at a young age and is asymptomatic in the vast majority of cases which is why it often goes unnoticed by parents. It is therefore common that the disease is already at an advanced stage in its evolution when the parents take their children to hospital. In many countries the lack of resources in Primary Care centers does not aid an early diagnosis, which contributes to some cases becoming chronic.

Hypertrophy of the adenoids and Eustachian tube dysfunction are often considered to be causal factors of this pathology1-3. Furthermore, OME produces a complex, multifactorial process, which is why the pneumatization of the mastoids and the variation in the gaseous diffusion in circulation have an important role in the negative pressure phenomenon in the affected middle-ear4.

Nowadays it is believed that adenoidectomies, together with an myringotomy, alone or with ventilation tubes, can be effective as a preventative measure against otitis2,5.

In Maputo, adenoidectomies are common in children with OME. The hospital casuistic suggests that good results have been obtained through adenoidectomies, even though studies have not been conducted that would allow us to describe the magnitude or to quantify the association of adenoiditis and Eustachian tube dysfunction with otitis media.

The objective of this study, therefore, is to describe the association of these factors with OME in the patients that attend ENT departments in the Hospital Central of Maputo, as well as to describe their clinical and epidemiological profiles.

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MATERIAL AND METHODS

This study was conducted in Maputo, the capital of Mozambique, a country where there is a National Health Service (NHS) which is structured into 4 levels of care. Primary care covers the 1st and 2nd levels. The Hospital Central of Maputo is a 4th level sanitary unit and is the most developed in the country. Although it has many shortcomings, the best-equipped ENT department in the country is situated inside this hospital. Besides this one, there are two more ENT departments in the country. One of them is located in the North of the country and another one in the Central region, with a total of 8 ENT doctors for close to 17 million inhabitants.

The study presented here is cross-sectional. The hospital record of the first visit by patients with otitis media to the Hospital Central of Maputo, between January of 1995 and December of 1998, was used as the data source.

During the process of collecting the information, the medical histories were recompiled including data relating to age, sex, most common medical conditions, the presence or not of tonsillitis, adenoiditis, recurrent otitis media, a history of rhinitis and the physical and functional condition of the tympanic membrane.

The cases of otitis were grouped as follows: acute or purulent otitis media (AOM), otitis media with effusion (OME) and chronic otitis media (COM). The cases in which the classification was not clearly defined were considered non-specific otitis. For the classification of otitis with effusion, the tympanogram curves and the stapedial reflex, as well as the records related to the patients' history and medical examination, were assessed.

The data was processed and analyzed using the SPSS 8.06 and GLIM7 programs. The univariate description of all the variables registered was conducted using its distribution of frequencies in the case of the category variables and measures of central tendency and dispersion in the case of the quantitative variables. Then, for the cases in which the type of otitis could be classified according to clinical development, a bivariate analysis was made where the association between the type of otitis and the explicative variables was evaluated using the chi-squared test of independence. Following that, a multivariate analysis was made to investigate the simultaneous associations between the different variables of the study. This analysis was done using hierarchical log-linear models. Finally, with the logit transformation, the proportion of OME was calculated in the different observational situations. With the aim of making the interpretation of results easier, the adjustment of said models was done separately for children under the age of 7 and those older than 7. RESULTS

A total of 4,157 medical files were analyzed. The distribution of the type of otitis observed was the following: 37.2% had AOM, 29.2% OME and 17.5% COM. In the clinical files of the remaining patients, the classification was not given in 16.1% of cases, which is why these were recorded as

non-specific otitis. Therefore, among the total of cases in which the type of otitis could be identified, the proportion of OME was 34.9%.

The patients studied were aged between 6 months and 65 years and distributed into 6 groups, as displayed in table 1.

It can be seen from the data in table 1 that the group with the greatest number of patients was made up of boys and girls with an age of 3 years or less. For every four patients studied, one was aged 3. More than half the patients were under 25 and 1 in 3 was not yet 8 years old. In regard to the proportion of OME per age group, it can be seen that the figure is low for young children at 22.2%, it sharply increases in children aged 3 to 7 to 49.2%, and then falls and remains stable in the age groups that follow at around 35-39%.

Among all the individuals studied, males dominated, 64.2%, the proportion of OME being greater in this group (37.6%) than for females (29.8%) (p<0.001).

The affected ear was specified in a total of 3,505 files; it was possible to confirm that in 35.2% of these cases the otitis was bilateral. In the 2,272 cases in which affectation was unilateral, the left ear recorded a slightly higher figure (52.6%) than did the right ear (47.4%). The percentage of OME did not show differences in relation to the ear affected.

14% of all the patients examined had associated tonsillitis, 9% adenoiditis and 11.8% Eustachian tube dysfunction. The proportion of OME in patients with tonsillitis was 40.7%, and 33.7% for those who did not (p=0.003). 46.9% of patients with adenoiditis had OME compared to 33.4% of patients without adenoiditis (p<0.001). Results obtained for patients aged 7 or younger

The significant associations observed between the type of otitis and the other variables are given in table 2 in OR terms as per the adjusted model.

The results obtained indicate the association between the type of otitis, adenoiditis and age on the one hand and the type of otitis, Eustachian tube dysfunction and sex on the other. Thus, the presence of adenoiditis increases the proportion of OME for patients under the age of or aged 3 (OR=400). In children over the age of 3, adenoiditis appears to behave in a similar way, although more moderately to how it behaves in younger children. This effect, however, is not significant as it is at the border of the level established at 0.05. A similar situation is observed in reference to Eustachian tube dysfunction syndrome. The presence of this clearly increases the proportion of OME in males (OR=9.53). Furthermore, the fact that the proportion of OME is greater for children over the age of 3 than for younger children stands out in a more pronounced way in cases without adenoiditis. Finally, with regard to gender, it should be stressed that the proportion is higher for boys than for girls, especially in cases with tube dysfunction syndrome. The tonsillitis cases did not show any association with the type of otitis.

To better assess the effect of adenoiditis and Eustachian tube dysfunction on the type of otitis media, the different proportions of OME were estimated in every observational situation. These estimates are presented in table 3.

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Table 1: Distribution of the patients studied by age groups and the percentage of otitis media with effusion cases in each group

Agea Distribution of patients

Proportion of otitis

media with effusion

n %b % accumulated

%c

≤3 961 23.3 23.3 22.2 3-7 289 7.0 30.3 49.2 8-15 320 7.7 38.0 38.3 16-25 684 16.6 54.6 35.3 26-35 817 19.8 74.4 38.7 36-45 794 19.2 93.6 39.1 ≥46 265 6.4 100.0 37.3 Total 4130 100 100 34.9 aExpressed in years bOut of all the patients cWithin each age group

In this table, concentrating on the other variables, it can clearly be seen that older boys always register higher percentages of OME than younger ones and males more than females along with higher figures with the presence of adenoiditis and Eustachian tube dysfunction. Also in this table, the proportion of OME with the lowest figures can be observed among girls aged 3 or under without adenoiditis. In this case, approximately only 1 per every 10 recorded cases of otitis was OME. In contrast we have the peculiar situation for boys over the age of 3 with Eustachian tube dysfunction where for every 10 boys that had these characteristics, 9 had OME. Results obtained for patients over the age of 7

In this case, it was observed in the adjusted model that the only variables that are associated with the type of otitis were gender and Eustachian tube dysfunction (table 4).

The proportions of OME are described in table 5 where it is confirmed that the percentage increases greatly in the presence of Eustachian tube dysfunction and, more slightly in men: for every 10 patients with Eustachian tube dysfunction syndrome approximately 8 had OME, representing an increase of around 55% in the proportion observed in patients who did not have this dysfunction. DISCUSSION

The results obtained in this study in regard to the proportion of otitis media with effusion in relation to gender and age agree with those found in the literature8,9. Various epidemiological studies of otitis media show that, just as with most infections in babies and infants, the incidence of otitis media is usually greater in males than in females. It is the same with complications, as was demonstrated in the study conducted in Boston9, in which chronic forms were more common in the male sex. From the bibliography consulted, the reasons for this difference are not clear, but it is known

Table 2: Significant associations with the type of otitis Variable OR IC (95%) Adenoiditis

• In children of 3 or under:

Without adenoiditis 1 With adenoiditis 4.00 (2.66-6.02)

• In children between the ages of 3 and 7:

Without adenoiditis 1 With adenoiditis

1.68

(0.95-2.93)

Eustachian tube dysfunction • In women:

Without Eustachian tube dysfunction 1

With Eustachian tube dysfunction

1.32 (0.77-2.25)

• In men: Without Eustachian tube dysfunction 1

With Eustachian tube dysfunction

9.53

(4.55-19.96)

Age • In patients without

adenoiditis:

≤ 3 years 1 3-7 years 4.42 (2.91-6.70)

• In patients with adenoiditis:

≤ 3 years 1 3-7 years

1.85

(1.12-3.08)

Sex • In patients without

Eustachian tube dysfunction:

Female 1 Male 1.66 (1.13-2.43)

• In patients with Eustachian tube dysfunction:

Female 1 Male 11.99 (4.78-30.07)

that gender is one of the factors that contribute to the characterization of the physiopathological development of many diseases and this could be one of those diseases. However, the results from the study that we present here cannot be extrapolated to the wider community, given that the data was collected in a model national hospital. The results are therefore dependent on the admission rate of patients. Another factor to consider when interpreting the results is the fact that this study is based on retrospective data where the patients were examined for different illnesses, even for different sequelae. In this sense, it is possible that although the prevalence of otitis media is greater in males, it might not really be so in the proportion found.

In regard to age, the results of other studies were confirmed. The salient feature of these results is that a large proportion of acute otitis media cases, a greater proportion

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Table 3: Percentages of OME. Patients aged 7 or under Adenoiditis No Yes Eustachian tube dysfunction aAge Sex No Yes No Yes ≤3 Female 10.0% 12.7% 30.7% 36.8% Male 15.5% 19.4% 42.3% 49.1%3-7 Female 32.9% 39.2% 45.1% 51.9% Male 44.8% 88.5% 57.6% 90.8%aExpressed in years

Table 4: Significant associations with the type of otitis. Patients over the age of 7.

Variable OR IC (95%) Eustachian tube dysfunction Without Eustachian tube dysfunction 1

With Eustachian tube dysfunction 12.26

(9.49-15.84)

Sex Female 1 Male 1.42 (1.10-1.84) than that observed in cases of otitis with effusion, are children under the age of 3. This observation is particularly common in developing countries. It must be noted, however, that the proportion of cases of otitis media with effusion could be underestimated owing to the fact that it is frequently asymptomatic in the initial phase of the disease. This can contribute to the parents of children under the age of 3 not identifying the problem until they reach school age or when the disease is at an advanced stage.

It is known that the etiology of otitis media is multifactorial and other factors such as infection10, the functional state of the Eustachian tube11,12, the immunological state1, allergy13,14 and environmental and socioeconomic15 factors can all be involved. Of these factors, the functional state of the Eustachian tube stands out given its function of maintaining the ventilation in the middle ear and the mastoids; a fundamental condition for optimal hearing13.

Various patients included in this study visited the hospital because of rhinitis and/or recurring adenoiditis. The ENT examinations of these patients revealed OME in many cases. In this sense, the results obtained show a clear

Table 5: Percentage of OME. Patients over the age of 7

Sex Eustachian tube dysfunction

Female Male

Without Eustachian tube dysfunction 25.0% 32.1% With Eustachian tube dysfunction 80.3% 85.3%

association between the type of otitis and the presence of adenoiditis in patients under the age of 7, as well as between the type of otitis and Eustachian tube dysfunction, independently of age.

The hypothesis that Eustachian tube dysfunction is the origin of serous otitis media or otitis with effusion was first posited by Politzer more than 100 years ago. Since then many studies have been conducted, even experimenting on animals, where the importance of the functional state of the Eustachian tube has been assessed (whose function it is to ventilate and drain the eardrum) in the histopathological mechanisms of the different types of otitis media16-18, as well as in the process of the exchange of CO2 and O2 between the middle ear and the blood19. Tube dysfunction can be caused by two factors: obstruction and alteration of the permeability. The obstruction can result from mechanical barriers, from functional causes, or mixed situations in which the two mechanisms are combined. The obstruction caused mechanically can result from structural anomalies, extrinsic factors from peritubic compression due to adenoids, tumors, or to an increase in extramural pressure in supine decubitus. In this sense, hypertrophy of the adenoids reduces the ventilation of the nasopharynx, increases the accumulation of secretions and can be the focus of infection for the middle ear. This increase in secretions can produce an internal obstruction of the Eustachian tube, with a consequent reduction in the ventilation of the middle ear. Functional obstruction has been observed in various nasopharyngeal inflammatory and allergic diseases, with a drop in air pressure in the eardrum which, together with the obstruction of the tube, causes the accumulation of liquid.

The great susceptibility of children to infections in the first year of life is well known, given that they are in contact with microorganisms against which they do not have the specific antibodies required. This can be one of the reasons why children are more susceptible to suffering from otitis. Moreover, the immaturity of the immune system, already only slightly effective, increases the risk posed by anatomical factors, as the Eustachian tube is short and more horizontal. This can facilitate the propagation of infections localized in the nasopharynx of the middle ear. This immunological immaturity, together with the anatomical and functional immaturity of an infant’s ear, could constitute factors that strengthen each other and

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which would explain the seriousness of some otitis media symptoms that develop to a chronic state, even when correctly treated. References

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