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Prevalence and impact of chronic otitis media in school age children in Brazil. First epidemiologic study concerning chronic otitis media in Latin America
International Journal of Pediatric Otorhinolaryngology 61 (2001) 223– 232 www.elsevier.com/locate/ijporl
Prevalence and impact of chronic otitis media in school age children in Brazil. First epidemiologic study concerning chronic otitis media in Latin America Ricardo N. Godinho a,*, Taˆnia M.L. Gonc¸alves a, Fla´vio B. Nunes a, Celso G. Becker a, Helena M.G. Becker a, Roberto E.S. Guimara˜es a, Fabrı´cio Sanfins a, Enrico A. Colosimo c, Reynaldo G. Oliveira b, Joel A. Lamounier b a
Department of Ophthalmology-Otorhinolaryngology, School of Medicine, Federal Uni6ersity of Minas Gerais, Belo Horizonte, Brazil b Department of Pediatrics, School of Medicine, Federal Uni6ersity of Minas Gerais, Belo Horizonte, Brazil c Department of Statistics, Federal Uni6ersity of Minas Gerais, Belo Horizonte, Brazil Received 24 June 2001; received in revised form 17 August 2001; accepted 17 August 2001
Abstract Objecti6e: The first epidemiological study carried out in Latin America to investigate the prevalence of otological disease and its impact in a representative random sample of the school children population. Methods: A cross sectional epidemiological survey to investigate the epidemiology of otitis in a representative random sample of 1119 children and adolescents from a total of 486 166 elementary and high-school students, aged 6 – 18 years, regularly registered in one of the 521 public and private schools of the city of Belo Horizonte, in the state of Minas Gerais, southern Brazil. The interviews were conducted individually, in the school, by an otolaryngologist or a pediatrician. The interview included all of the personal data and also detailed questions regarding otological disorders and hearing. The otological examination was carried out with Mini-Heine otoscopes and the audiometric evaluation with the AudioScope 3™ with 25dB intensity. The questionnaire and basic procedures for medical examination had been previously tested through a pilot test in two schools. Results: The prevalence of chronic otitis media was 0.94%. Impacted wax was found in 12.3% of the students. The prevalence of abnormalities (excluding wax) in the otoscopy examination was 10.5%. It was found that 8.3% of students had a past history of otitis and 7.7% had a past history of otorrhea. These two special groups presented statistically significant associations with chronic otitis media, hearing loss and otolaryngological surgeries (when compared with the other school children). Parents and school children seemed significantly able to identify a special group of children with past history of otitis during childhood. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Audiometry; Epidemiology; Otitis media; Hearing impairment; Prevalence; School children
* Corresponding author. Present address: Rua Joaquim Coura, 347, CEMIG, Sete Lagoas, CEP 35700, Minas Gerais, Brazil. Tel.: + 55-31-3771-7314. E-mail address: [email protected] (R.N. Godinho). 0165-5876/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 1 6 5 - 5 8 7 6 ( 0 1 ) 0 0 5 7 9 - 1
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1. Introduction
2. Methods
Otitis is the most frequent pathology in children requiring antibiotic medication and is also the major cause of hearing loss and need for surgery. It is estimated that over 3 billion dollars are spent annually in US regarding otitis media treatment [1]. According to a Canadian study [2] the money spent treating otitis media represents 60% of what is necessary to treat diabetes, or 40% of what is spent treating chronic bronchitis, emphysema and asthma. Chronic otitis media is the main cause of hearing loss in developing countries [3] and may lead to severe complications, even death. Hearing loss is considered to be the main health issue which affects quality of life in approximately one third of the population of these countries [4]. The World Health Report, 1997 [5] describes hearing impairment as ‘a serious problem in young children because it retards language development and school progress-both of which have significant impact in later life’. Seely et al. [6] stated that in communities or countries where illiteracy is prevalent the ear and hearing diseases might impair a person’s capacity to participate in normal conversations, thus increasing the social and economical impact of these diseases. Based on a review of about 50 studies published in the last 30 years, Bluestone [3] classified the population in four groups according to the prevalence of suppurative chronic otitis media and he did not mention any investigation carried out in Latin America. In Brazil the prevalence of chronic otitis media is still unknown [7]. Brazil is a developing country with about 180 million people. The World Health Organization considers that chronic otitis media is an important public health problem, and prevalence data must be collected [8]. The main goal of this study is to become acquainted with the current status of otologic health in Brazil. This is the first data regarding the prevalence and impact of chronic otitis media in a representative random sample of children in South America.
This is an epidemiological cross sectional study of the prevalence of otological pathologies in school age children of elementary and junior high schools in the city of Belo Horizonte, fourth largest city of Brazil and capital of the state of Minas Gerais (16 672 613 inhabitants). It is strategically located among the principal political and economic centers in the country, the Rio-Sa˜ o Paulo and Brası´lia axis. It occupies an area of 335.5 km2 within the Metallurgical Zone, one of the richest areas in the state. It has an altitude of 858 m. The tropical climate includes a dry winter and a rainy summer, with an average annual temperature of 21 °C. Belo Horizonte was the first planned city in Brazil and it was chosen as the ‘city with the best quality of life in Latin America’ by the Population Crisis Committee, organ of the UN. The population of Belo Horizonte was of 2 091 371 inhabitants (711 234 between 7 and 19 years of age) in the 1996 census and grows at a rate of 2.5% a year. Inside the metropolitan area, there are 531 schools, 56 hospitals and 9769 hospital beds. This is a corroborative study brought forth by the joint efforts of otolaryngologists, audiologists and speech therapists and a group of pediatricians who also evaluated other important childhood problems: arterial hypertension, obesity and nutrition, headaches, and accidents with children. The study is in accordance with the Helsinki Declaration and with the ethical standards of the Ethical Committee of the Universidade Federal de Minas Gerais (UFMG).
2.1. Sample planning A survey was carried out which mapped a population of 486 166 students spread in 521 schools (136 municipal public schools, 218 state public schools, three federal public schools and 164 private schools). Based on the epidemiological characteristics and the sampling needs of the many topics being investigated it was decided that the number of students to be included had
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to be approximately 1000. The pilot test pointed to an 80% rate of compliance from the mothers (20% would refuse to participate); therefore, over 1250 students were selected. To tailor the methodology to the unit investigated, a ‘class of students’ (classroom) was studied, instead of an ‘isolated student’. After the necessary sampling calculations, taking into account a confidence interval of 95, 3% accuracy, delineation effect (sample per cluster), and using the data found in the pilot test, it was decided to split the sample into 40 classrooms from 20 schools. This would provide enough statistical power for our investigation. At the end of this selection process, a sample of 1305 eligible students, 40 classrooms (two from each of the 20 schools) was defined. Table 1 shows the comparison between the data of the total children population and the sample population.
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the questions. Thus, the questions about each subject (arterial hypertension, obesity and nutrition, headaches, and accidents with children) were asked by six physicians, who were previously trained, the topic researcher him/herself included, in an attempt to reduce the bias of each investigator on the set of data obtained.
2.3. Identifying the children with pre6ious past history of otitis media during childhood and that with past history of otorrhea In order to correctly identify the children with past history of otitis and the children with past history of otorrhea, two multiple-choice questions were presented. The answer options were classified in categories.
2.4. Identifying the main ear pathologies 2.2. The inter6iew and the questionnaire The questionnaire was very carefully prepared, as it is one of the most important tool in the data collection process. In order to devise the best way to ask a question and to stratify and code the answers, the questionnaire was strenuously tested. The necessary changes were all made during the pilot phase of the study. Aiming at improving the quality of the method, the otolaryngologists and pediatricians responsible for the various modes of this joint study should be the ones who would ask
Through otoscopic examination, the main otoscopic abnormalities in the eardrum were identified and then grouped according to the most common ear diseases. A set of selected pictures showing the normal ear drum and otoscopic pathological findings was used as a guideline for the otoscopic examinations. Together with the examination, the student was asked seven questions about the topics being studied aiming at matching theses answers with the ones provided by the interviewee.
2.5. Identifying the children with chronic otitis media Table 1 Comparing the percentage distribution ofjunior and senior high school students of Belo Horizonte and in the selected sample General total Private Schools State Public Schools Municipal Public Schools Total
Whole Sample Whole Sample Whole Sample Whole Sample
21.1% 23.8% 48.8% 39.3% 29.3% 36.9% 100% 100%
All of the children who presented at least one of the following abnormalities in the tympanic membrane were classified as children with chronic otitis media: perforation with or without otorrhea, cholesteatoma and the presence of ventilation tubes.
2.6. Audiometry with the Audioscope 3™ Both otologic and audiologic examinations were carried out in the most quiet room of the school, with the maximum background noise of 50 dB, measured by decibelimeter.
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Table 2 Age descriptive statistics Statistics
Age
Average Median Standard deviation (S.D.) Minimum age Maximum age
11.3 11.0 3.1 6.0 18.0
Welch Allyn Inc, Skaneateles Falls, NY, produce an instrument called AudioScope 3™ [9] which couples a fiber optic otoscope to an audiometer for screening purposes, powered by a rechargeable battery. The AudioScope 3™ allows for a hearing screening at the frequencies of 500, 1000, 2000 and 4000 Hz, and at a fixed level of decibels. The screening protocol with the audioscope specifies training or an acquaintance period, at which the person hears at higher intensity levels and learns to raise one’s hand when the sound is heard. The most adequate size for the ear speculum was carefully selected in order to obtain acoustic sealing. In our investigation, the audioscope was used at a test intensity of 25 dB.
2.7. Data organization and statistical analysis of the results EpiInfo and SPSS software were used for data input and systematic organization, and also for the statistical analysis. A P B0.05 or 5% (h B 0.05) was used as a statistically significant level for a null hypothesis for all the tests.
views) or the father (6.2%) or someone else responsible for the child (8.5%). The 16-year-old students and those above this age (13.4%) were interviewed personally.
3.2. Otologic pathologies About 118 (11.3%) children had wax occluding their external right ear canal and 120 (11.5%) children had it in their left external ear canal. Seventy one (6.8%) children had bilateral wax accumulation. About 167 (16%) children had wax obstruction in at least one ear. Excluding wax in the ear canal, 46 (5.7%) children had bilateral abnormalities in their otoscopy, 70 (8.7%) with right ear abnormalities and 67 (8.3%) with left ear abnormalities. The abnormalities found at otoscopy are listed in Table 3. Nineteen children had reduced transparency of the tympanic membrane in both ears. One child had a ventilation tube in his left tympanic membrane and two children had already undergone a tympanoplasty (successful unilateral outcome in one child and bilaterally in another). One child had otorrhea coupled with tympanic membrane perforation, one with unilateral cholesteatoma and another with an osteoma in his right ear canal. Perforation in the tympanic membrane, which was also classified as chronic otitis media, was found in 14 ears, and three children had bilateral perforations. The prevalence of chronic otitis media of 0.94% was calculated through valid information from Table 3 Abnormalities in the tympanic membrane (TM) and/or middle ear at the otoscopic exam
3. Results
3.1. Characteristics of the sample studied About 1005 children were examined, 512 (50.95%) males and 493 (49.05%) females, with an average age of 11.36 years (Table 2), thus forming a truly representative sample of the school age children population of the city of Belo Horizonte. Each set of questions was asked by one of the investigators to the mother (71.9% of the inter-
Tympanic membrane alteration
Right ear
Left ear
Perforated Retracted TM retracted and with reduced transparency TM with reduced transparency TM hyperaemic MT bulged Middle ear effusion Tympanosclerosis
7 15 4
7 19 7
32 6 1 12 6
32 6 2 5 6
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Table 4 Association between the children with chronic otitis media compared with those without chronic otitis media
Table 5 Association between the children with a past history of otitis compared with the children without a past history of otitis
Variable
P-value
Variable
P-value
Right side COM Left side COM
Past history of otorrhea Hearing loss at 500 Hz Hearing loss at 1000 Hz Hearing loss at 2000 Hz Hearing loss at 4000 Hz Right side otoscopic abnormalities Left side otoscopic abnormalities Chronic right side otitis media Chronic left side otitis media Ear surgery Otolaryngologic surgery Hearing loss awareness
B0.001 0.006 0.007 B0.001 B0.001 0.030 0.018 0.002* 0.001* 0.010* 0.025* 0.023
Past of otitis Past of otorrhea Hearing loss at 500 Hz Hearing loss at 1000 Hz Hearing loss at 2000 Hz Hearing loss at 4000 Hz Surgery Hearing loss awareness
0.002* B0.001* B0.001*
B0.001* B0.001* B0.001*
B0.001*
0.001*
0.012*
0.006
0.002*
B0.001*
0.801* 0.011*
0.776* 0.011*
*, value calculated by the exact Fisher teat.
otoscopy in 1900 ears. Table 4 shows the associations between the children with chronic otitis media in comparison with the children without chronic otitis media. Only the association between the children with chronic otitis media and those operated upon, compared with the children without chronic otitis media was not statistically significant.
3.3. Past history of otitis and past history of otorrhea Amongst the 974 children with information matching the diagnosis of a past history of otitis, 32 (3.3%) did not know of any otitis during childhood. Eighty one (8.3%) had previous events of otitis, of these 72 (7.4%) started having ear infections before 6 months of age. The association of children with a past history of otitis and other variables investigated are listed on Table 5. All associations presented statistically significant values. Seventy five (7.71%) children had a past history of otorrhea in their childhood. In order to representatively evaluate this group, the past history of otorrhea was related with other variables investigated according to Table 6. All of the associations were statistically significant, including ear surgery.
*, value calculated by the exact Fisher test.
4. Discussion
4.1. In6estigation method One of the most important aspects of this paper was the sampling process used, which guaranteed an adequate representation of all the school children population of a large city. Through the process adopted it was made possible that each one of almost half a million students could have the same chance of participating in the study. This characteristic together with the high level of community participation (about 90% of the eligible Table 6 Association between the children with a past history of otorrhea compared with the children without a past history of otorrhea Variable
P-value
Past of otitis Hearing loss at 500 Hz Hearing loss at 1000 Hz Hearing loss at 2000 Hz Hearing loss at 4000 Hz Right side otoscopic abnormalities Left side otoscopic abnormalities Ear surgery Otolaryngologic surgery Hearing loss awareness
B0.001 B0.001 B0.001 B0.001 B0.001 B0.003* B0.001* 0.005* 0.047* B0.001*
*, value calculated by the exact Fisher test.
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were investigated) led its conclusions to encompass all the population of students of elementary and junior high schools of the city of Belo Horizonte.
4.2. Characteristics of the samples assessed in other population studies The sampling selections in population studies of otitis and hearing loss do not always involve a representative group of children of all school grades and simultaneously of all social and economic layers in a large city, as in our investigation. This is an important limitation to compare the results. The lack of epidemiological studies in South America also makes the comparisons very difficult. These difficulties in characterizing a population, especially in developing countries, further complicate the selection of samples that may adequately represent all of the population of a city, or even a country. Therefore, the external validity of the collected data, which is very important in population and prevalence surveys, may be compromised. The studies with children may be classified in such a way that the values obtained from small samples, as long as they are chosen by correct statistical processes, may be extrapolated to a much larger universe, as in our investigation— 1005 children representing a universe of almost half a million school children in one of the most important capitals of Brazil. The observation that the prevalence of otologic disease in school children may not reflect exactly what happens in the community, but it points to what may be expected. The prevalence in the community should be higher than the one found among the school children, as long as some children are not enrolled in schools and those children with important hearing loss and important ear diseases will less likely go to school when compared with their healthy peers [10].
4.3. The 6alidity of questionnaires in pre6alence studies The morbidity investigations in a community have collected information about population sam-
ples in two ways: through interviews and through examinations [11]. Although there is a number of advantages in obtaining information about diseases of a specific population from interviews and examinations, the lack of accuracy and the variety of information always present problems. These difficulties must be considered when dealing with the data about morbidity investigations. In a study carried out by Stephenson [12], both children and parents were questioned about happenings from 15 to 20 years in the past and there was an agreement in the answers of the adults regarding ear problems and hearing during childhood. In an investigation by Alho et al. [13], they compared infection data based on a questionnaire to medical files in order to assess the validity of the questionnaire data about previous episodes of acute otitis media. The cumulated incidence of otitis media in those over the age of 2 years in the questionnaire data was lower than that found among the data files. The number of occurrences by child, by year, and the incidence rate for recurrent episodes was considerably higher in the questionnaire data. Daly et al. [14] compared the answers of the parents with medical events. Previous insertions of ventilation tubes and premature birth were carefully remembered. However, there was a substantial amount of information loss regarding the actual age when the first episode of otitis media happened, occurrence of otitis media in previous summers, and regarding the number of episodes in the previous 18 months. The parents who remembered six or more past episodes with their children, overestimated the number, compared with the medical files, whilst those who remembered a lower rate of occurrence underestimated it. Remembering the number of episodes and the age of the first episode may become easier if the answer options are classified in categories (e.g.: 0– 2, 3–5, 6– 8, \ 8). This technique was used in our questionnaire. Daly et al. conclude that the reasonable agreement among the individuals, parents and family doctors suggests that only one of these information sources is required in certain histories of otitis media.
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According to Lilienfeld [11], an important method to validate a research through interviews is to compare the information obtained in the interview with that obtained through the physical examination. In our investigation, the data from the questionnaire and from the physical examination were compared determining special groups of children with past history of otitis and past history of otorrhea.
4.4. Otoscopic e6aluation The presence of obstructing wax was the main abnormality found in the otoscopic exam in most of the investigations that mentioned the prevalence of such finding. In some the wax was removed. In our investigation, obstructing wax was found in 12.3% of the children. Similar values were found in Swaziland [15], Kenya [10] and Malaysia [16]. The group of children who had wax obstructing the ear canal presented significantly higher numbers of hearing loss when compared with the other children. These results showed us that wax is an important preventable cause of hearing loss. According to Hatcher et al. [10], the obstruction of the external ear canal by wax is relatively common, because in the great majority of cases it is asymptomatic and, therefore, it is not an indication to visit the doctor. However, the wax obstruction is a cause of reduction in the hearing and is preventable. Tympanometry is a simple method to assess the presence of effusion in the middle ear, due to its high sensitivity in the diagnosis of otitis media with effusion. The cost of the portable device used to perform the exam in the children made its use impossible in our investigation, which may be considered the major limitation of this work in terms of its data acquisition, most specially regarding the prevalence of otitis media with effusion. Therefore, the prevalence of otitis media with effusion may be estimated only based on the morphologic abnormalities of the tympanic membrane. Ninteen children had tympanic membranes with their transparencies bilaterally reduced, and this may be due to constitutional alteration of these membranes and not due to any pathology.
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4.5. Chronic otitis media The sampling characteristics are of extreme importance in order to assess the prevalence of chronic otitis media. In the Korean [17] sample, the prevalence in the age range from 0 to 15 years was of 0.26% whilst between 16 and 34 years it was 1.74%. Therefore, in the same country, different prevalence values were found due to the age range in which they were calculated. In Malaysia, Saim et al. [16] assessed only kindergarten age children, therefore, the low prevalence of 0.17% is mainly due to the age range studied. In Spain (0.7%) [18], Malaysia (0.17%) [16] and Jamaica (0.16%) [19] the prevalence was very low. With the prevalence ranging between 1 and 2%: Gambia (1.7%) [20], Thailand (1.7%) [21] and Riad [22] in Saudi Arabia (1.5%). In another study performed by Zakzouk et al. [23] in Al-Ariah, in the central region of Saudi Arabia, the prevalence of chronic otitis found was 5.5%. This may be due to the fact that the population lives in villages without primary medical care and primary health care programs, which are already well established in Riad, the capital of the country. A prevalence between 2 and 3% was found in Korea (2.19%) [17], South Africa (2.2%) [24], Tanzania (2.6%) [25] and Sierra Leone (2.8%) [6]. A prevalence of 3% or higher was found in Nepal (3%) [26], Swaziland (3.1%) [15] and Kenya (3.5%) [10]. In Greenland [27], the prevalence of chronic otitis media in the city of Nuuk was of 18.5% and of 4.7% in Sisimiut. In Norway, Andersen et al. [28] showed 6% of chronic otitis media (0.73% of tympanic perforation) among the citizens of Svalbard. Data mentioned by Kim et al. [17], showed a prevalence of 5.6% of otitis media (chronic and acute otitis media) in Chileans and of 8% in Mexicans, and this may reflect the prevalence of these diseases in Latin America. Another study available from investigations carried out in America is from Jamaica [19] (0.16%). Very high prevalence values were found in India [29], 7.8%, where the highest prevalence of ear wax and hearing loss was also found. The prevalence of chronic otitis media in the city of Belo Horizonte could be estimated from the prevalence in school age children [30]. The
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prevalence of perforation in the tympanic membrane in our study could be comparable to that found in the schools of Thailand [21], Kuwait [3] and South Korea [17]. According to the classification proposed by Bluestone [3], this prevalence could be classified as low, sharing the same levels as those found in Korea, India and Saudi Arabia.
4.6. Past history of otitis and past history of otorrhea Most of the studies analyzed did not consider a questionnaire targeting the children’s parents. Only those investigations carried out in South Africa [24], Thailand [21], Greece [31], Iceland [32] and Spain [18] used small questionnaires that did not always involved the parents or all of the children surveyed. In our investigation, a questionnaire was designed aiming at identifying those children who really had an important past history of ear infection in their early childhood, therefore, a very specific group in relation to the children who had otitis in their childhood: 81 (8.3%) had previous events of otitis, of these 72 (7.4%) started having ear infections before 6 months of age. According to Rasmussen et al. [33] 12% of the Swedish children, prospective followed up until 7 years of age, had at least five episodes of acute otitis media. In a prospective study developed in Finland, by Rahko et al. [34], until the age of 13.5 years, 35.2% of the children had had eight or more episodes of acute otitis media and when they were 5 years old, 5.2% had hearing abnormalities. In Belo Horizonte, Brazil, 75 (7.71%) children had a past history of otorrhea in their childhood. In Spain [18], they estimated the prevalence of children with a past history of otorrhea in the range of 6.81%, through a questionnaire. In Gambia [20], the history of past infection was estimated throughout otoscopic examination, reaching a prevalence of 15.1%. In Sierra Leone [6], the presence of discharge for over one month was statistically significantly linked to hearing loss. The questionnaire’s approach was valid enough to distinguish the ‘extremes’ in past occurrences of otitis media, reaching a point at which the interviewed children were classified as a special group
of school children. Therefore, the parents provided enough information enabling the investigators to identify a special group of children and this may be used to devise programs to reach this population.
4.7. Hearing loss When performing hearing screenings, it is very important to check the room conditions. When there is an excess of noise in the room during the test, the examiner must consider the cut-off alteration in the sound intensity, which will inevitably have an impact in the tests’ specificity and sensitivity. This may pose as a serious problem to the examiner regarding the evaluation rooms in developing countries, for not being adequate in terms of soundproof treatment. Many authors criticize the audiometric screening with high decibel level in children (\ 30 dB), leading to a high number of false negatives, having in mind that 15 dB is considered normal in children [35–38]. Sorri et al. [39] and Rahko et al. [34] reported that the effects caused by the infection during childhood are of low intensity. Therefore, in our investigation the audioscope was used at a test intensity of 25 dB. The audioscope is used by many professionals who work with pediatric health [35]. In general, the audioscope was considered light, portable, easy to use, and it did not scare the little patients who even found the exam ‘kind of fun’. The viewing conditions of the tympanic membrane were thought to be adequate. All users thought that the audioscope examination could very easily fit in their health assessment routine and become a convenient and reproducible screening tool. The audioscopic exam is simple and fast. The device is less expensive than a screening audiometer and it does not require sound insulation when used in a sufficiently silent room. 5. Conclusions The prevalence of chronic otitis media in school age children of Belo Horizonte is 0.94%. This is the first data regarding prevalence and impact of chronic otitis media in a representative random sample of children in South America.
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School children with chronic otitis media present with more hearing loss, past history of otitis and past history of otorrhea when compared with children without chronic otitis media. 8.3% of children with a past history of otitis and 7.71% of children with a past event of otorrhea form a special group of children with an important history of childhood ear infection and significant otoscopic and hearing abnormalities. The prevalence of wax in the external ear canal is 12.3%. Both parents and students proved to be significantly able to spot a special group of children with a past history of otitis or otorrhea.
[8]
[9] [10]
[11] [12]
[13]
Acknowledgements The authors wish to thank the pediatricians Andre´ a Deborah Barreto Oliveira, Marcela Dama´ sio Ribeiro and Jose´ Sabino de Oliveira for their important participation. We are grateful to Ana Cristina Cortes Gama, Ana Paula Campolina, Roberta C. Ferreira, Cristina G.R. Cury, Maria Aparecida Silva, Fabrı´cio Sanfins, Antoˆ nio Braz Pereira Ju´ nior for their support during the audiological examination.
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[24] C.H. Rooy van, J.G. Swart, J. Op’T Ho, A.C. Vlantis, P.H. Ahmed, P.H. Venter, Diagnosis and treatment of ear disease among children in the Ellisras district, An outreach programme, South Afr. Med. J. 85 (7) (1995) 675 – 677. [25] B.M. Minja, A. Machemba, Prevalence of otitis media, hearing impairment and cerumen impaction among school children in rural and urban Dar es Salaam, Tanzania, Int. J. Pediatr. Otorhinolaryngol. 37 (1) (1996) 29 – 34. [26] P. Little, A. Bridges, R. Guragain, D. Friedman, R. Prasad, N. Weir, Hearing impairment and ear pathology in Nepal, J. Laryngol. Otol. 107 (5) (1993) 395 – 400. [27] P. Homoe, R.B. Christensen, P. Bretlau, Prevalence of otitis media in a survey of 591 unselected Greenlandic children, Int. J. Pediatr. Otorhinolaryngol. 36 (3) (1996) 215 – 230. [28] A.B. Andersen, G. Ag, L.E. Stenfors, Occurrence of otitis media in an arctic region, Acta Otolaryngol. Suppl. Stockh., 529 (1997) 11 –13 Ryding, M. [29] A. Jacob, V. Rupa, A. Job, A. Joseph, Hearing impairment and otitis media in a rural primary school in south India. Int. J. Pediatr. Otorhinolaryngol. 39 (2) (1997) 133 – 138, 6. [30] S. Bermans, Otitis media in developing countries, Pediatrics 95 (1 pt 1) (1995) 126 –131.
[31] K. Apostolopoulos, J. Xenelis, A. Tzagarvoulakis, D. Kandiloros, J. Yotakis, K. Papafragou, The point prevalence of otitis media with effusion among school children in Greece, Int. J. Pediatr. Otorhinolaryngol. 44 (3) (1998) 207 – 214. [32] B. Benediktsdottir, Upper airway infections in preschool children— frequency and risk factors, Scand. J. Prim. Health Care 11 (3) (1993) 197 – 201. [33] F. Rasmussen, Recurrence of acute otitis media at preschool age in Sweden, J. Epidemiol. Commun. Health 48 (1) (1994) 33 – 35. [34] T. Rahko, P. Laitila, M. Sipila, M. Manninen, P. Karma, Hearing and acute otitis media in 13-year-old children, Acta Otolaryngol. Stockh. 115 (2) (1995) 190 – 192. [35] J. Gershel, B. Kruger, D. Giraudi-Perry, Accuracy of the Welch Allyn AudioScope and traditional hearing screening for children with known hearing loss, J. Pediatr. 106 (1985) 15 – 20. [36] O. Nietupska, N. Harding, Auditory screening of school children: fact or fallacy?, Br. Med. J. 284 (1982) 717 – 720. [37] L. Petrocchi, Hearing screening in pre-school children. B.A. thesis, 1988. [38] A. Greville, Preschool ear screening (letter), New Zealand Med. J. 108 (993) (1995) 8 – 44. [39] M. Sorri, T.E. Maki, O.P. Alho, Otitis media and longterm follow-up of hearing, Acta Otolaryngol. Stockh. 115 (2) (1995) 193 – 195.
Prevalence and impact of chronic otitis media in school age children in Brazil. First epidemiologic study concerning chronic otitis media in Latin America Ricardo N. Godinho a,*, Taˆnia M.L. Gonc¸alves a, Fla´vio B. Nunes a, Celso G. Becker a, Helena M.G. Becker a, Roberto E.S. Guimara˜es a, Fabrı´cio Sanfins a, Enrico A. Colosimo c, Reynaldo G. Oliveira b, Joel A. Lamounier b a
Department of Ophthalmology-Otorhinolaryngology, School of Medicine, Federal Uni6ersity of Minas Gerais, Belo Horizonte, Brazil b Department of Pediatrics, School of Medicine, Federal Uni6ersity of Minas Gerais, Belo Horizonte, Brazil c Department of Statistics, Federal Uni6ersity of Minas Gerais, Belo Horizonte, Brazil Received 24 June 2001; received in revised form 17 August 2001; accepted 17 August 2001
Abstract Objecti6e: The first epidemiological study carried out in Latin America to investigate the prevalence of otological disease and its impact in a representative random sample of the school children population. Methods: A cross sectional epidemiological survey to investigate the epidemiology of otitis in a representative random sample of 1119 children and adolescents from a total of 486 166 elementary and high-school students, aged 6 – 18 years, regularly registered in one of the 521 public and private schools of the city of Belo Horizonte, in the state of Minas Gerais, southern Brazil. The interviews were conducted individually, in the school, by an otolaryngologist or a pediatrician. The interview included all of the personal data and also detailed questions regarding otological disorders and hearing. The otological examination was carried out with Mini-Heine otoscopes and the audiometric evaluation with the AudioScope 3™ with 25dB intensity. The questionnaire and basic procedures for medical examination had been previously tested through a pilot test in two schools. Results: The prevalence of chronic otitis media was 0.94%. Impacted wax was found in 12.3% of the students. The prevalence of abnormalities (excluding wax) in the otoscopy examination was 10.5%. It was found that 8.3% of students had a past history of otitis and 7.7% had a past history of otorrhea. These two special groups presented statistically significant associations with chronic otitis media, hearing loss and otolaryngological surgeries (when compared with the other school children). Parents and school children seemed significantly able to identify a special group of children with past history of otitis during childhood. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Audiometry; Epidemiology; Otitis media; Hearing impairment; Prevalence; School children
* Corresponding author. Present address: Rua Joaquim Coura, 347, CEMIG, Sete Lagoas, CEP 35700, Minas Gerais, Brazil. Tel.: + 55-31-3771-7314. E-mail address: [email protected] (R.N. Godinho). 0165-5876/01/$ - see front matter © 2001 Elsevier Science Ireland Ltd. All rights reserved. PII: S 0 1 6 5 - 5 8 7 6 ( 0 1 ) 0 0 5 7 9 - 1
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1. Introduction
2. Methods
Otitis is the most frequent pathology in children requiring antibiotic medication and is also the major cause of hearing loss and need for surgery. It is estimated that over 3 billion dollars are spent annually in US regarding otitis media treatment [1]. According to a Canadian study [2] the money spent treating otitis media represents 60% of what is necessary to treat diabetes, or 40% of what is spent treating chronic bronchitis, emphysema and asthma. Chronic otitis media is the main cause of hearing loss in developing countries [3] and may lead to severe complications, even death. Hearing loss is considered to be the main health issue which affects quality of life in approximately one third of the population of these countries [4]. The World Health Report, 1997 [5] describes hearing impairment as ‘a serious problem in young children because it retards language development and school progress-both of which have significant impact in later life’. Seely et al. [6] stated that in communities or countries where illiteracy is prevalent the ear and hearing diseases might impair a person’s capacity to participate in normal conversations, thus increasing the social and economical impact of these diseases. Based on a review of about 50 studies published in the last 30 years, Bluestone [3] classified the population in four groups according to the prevalence of suppurative chronic otitis media and he did not mention any investigation carried out in Latin America. In Brazil the prevalence of chronic otitis media is still unknown [7]. Brazil is a developing country with about 180 million people. The World Health Organization considers that chronic otitis media is an important public health problem, and prevalence data must be collected [8]. The main goal of this study is to become acquainted with the current status of otologic health in Brazil. This is the first data regarding the prevalence and impact of chronic otitis media in a representative random sample of children in South America.
This is an epidemiological cross sectional study of the prevalence of otological pathologies in school age children of elementary and junior high schools in the city of Belo Horizonte, fourth largest city of Brazil and capital of the state of Minas Gerais (16 672 613 inhabitants). It is strategically located among the principal political and economic centers in the country, the Rio-Sa˜ o Paulo and Brası´lia axis. It occupies an area of 335.5 km2 within the Metallurgical Zone, one of the richest areas in the state. It has an altitude of 858 m. The tropical climate includes a dry winter and a rainy summer, with an average annual temperature of 21 °C. Belo Horizonte was the first planned city in Brazil and it was chosen as the ‘city with the best quality of life in Latin America’ by the Population Crisis Committee, organ of the UN. The population of Belo Horizonte was of 2 091 371 inhabitants (711 234 between 7 and 19 years of age) in the 1996 census and grows at a rate of 2.5% a year. Inside the metropolitan area, there are 531 schools, 56 hospitals and 9769 hospital beds. This is a corroborative study brought forth by the joint efforts of otolaryngologists, audiologists and speech therapists and a group of pediatricians who also evaluated other important childhood problems: arterial hypertension, obesity and nutrition, headaches, and accidents with children. The study is in accordance with the Helsinki Declaration and with the ethical standards of the Ethical Committee of the Universidade Federal de Minas Gerais (UFMG).
2.1. Sample planning A survey was carried out which mapped a population of 486 166 students spread in 521 schools (136 municipal public schools, 218 state public schools, three federal public schools and 164 private schools). Based on the epidemiological characteristics and the sampling needs of the many topics being investigated it was decided that the number of students to be included had
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to be approximately 1000. The pilot test pointed to an 80% rate of compliance from the mothers (20% would refuse to participate); therefore, over 1250 students were selected. To tailor the methodology to the unit investigated, a ‘class of students’ (classroom) was studied, instead of an ‘isolated student’. After the necessary sampling calculations, taking into account a confidence interval of 95, 3% accuracy, delineation effect (sample per cluster), and using the data found in the pilot test, it was decided to split the sample into 40 classrooms from 20 schools. This would provide enough statistical power for our investigation. At the end of this selection process, a sample of 1305 eligible students, 40 classrooms (two from each of the 20 schools) was defined. Table 1 shows the comparison between the data of the total children population and the sample population.
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the questions. Thus, the questions about each subject (arterial hypertension, obesity and nutrition, headaches, and accidents with children) were asked by six physicians, who were previously trained, the topic researcher him/herself included, in an attempt to reduce the bias of each investigator on the set of data obtained.
2.3. Identifying the children with pre6ious past history of otitis media during childhood and that with past history of otorrhea In order to correctly identify the children with past history of otitis and the children with past history of otorrhea, two multiple-choice questions were presented. The answer options were classified in categories.
2.4. Identifying the main ear pathologies 2.2. The inter6iew and the questionnaire The questionnaire was very carefully prepared, as it is one of the most important tool in the data collection process. In order to devise the best way to ask a question and to stratify and code the answers, the questionnaire was strenuously tested. The necessary changes were all made during the pilot phase of the study. Aiming at improving the quality of the method, the otolaryngologists and pediatricians responsible for the various modes of this joint study should be the ones who would ask
Through otoscopic examination, the main otoscopic abnormalities in the eardrum were identified and then grouped according to the most common ear diseases. A set of selected pictures showing the normal ear drum and otoscopic pathological findings was used as a guideline for the otoscopic examinations. Together with the examination, the student was asked seven questions about the topics being studied aiming at matching theses answers with the ones provided by the interviewee.
2.5. Identifying the children with chronic otitis media Table 1 Comparing the percentage distribution ofjunior and senior high school students of Belo Horizonte and in the selected sample General total Private Schools State Public Schools Municipal Public Schools Total
Whole Sample Whole Sample Whole Sample Whole Sample
21.1% 23.8% 48.8% 39.3% 29.3% 36.9% 100% 100%
All of the children who presented at least one of the following abnormalities in the tympanic membrane were classified as children with chronic otitis media: perforation with or without otorrhea, cholesteatoma and the presence of ventilation tubes.
2.6. Audiometry with the Audioscope 3™ Both otologic and audiologic examinations were carried out in the most quiet room of the school, with the maximum background noise of 50 dB, measured by decibelimeter.
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Table 2 Age descriptive statistics Statistics
Age
Average Median Standard deviation (S.D.) Minimum age Maximum age
11.3 11.0 3.1 6.0 18.0
Welch Allyn Inc, Skaneateles Falls, NY, produce an instrument called AudioScope 3™ [9] which couples a fiber optic otoscope to an audiometer for screening purposes, powered by a rechargeable battery. The AudioScope 3™ allows for a hearing screening at the frequencies of 500, 1000, 2000 and 4000 Hz, and at a fixed level of decibels. The screening protocol with the audioscope specifies training or an acquaintance period, at which the person hears at higher intensity levels and learns to raise one’s hand when the sound is heard. The most adequate size for the ear speculum was carefully selected in order to obtain acoustic sealing. In our investigation, the audioscope was used at a test intensity of 25 dB.
2.7. Data organization and statistical analysis of the results EpiInfo and SPSS software were used for data input and systematic organization, and also for the statistical analysis. A P B0.05 or 5% (h B 0.05) was used as a statistically significant level for a null hypothesis for all the tests.
views) or the father (6.2%) or someone else responsible for the child (8.5%). The 16-year-old students and those above this age (13.4%) were interviewed personally.
3.2. Otologic pathologies About 118 (11.3%) children had wax occluding their external right ear canal and 120 (11.5%) children had it in their left external ear canal. Seventy one (6.8%) children had bilateral wax accumulation. About 167 (16%) children had wax obstruction in at least one ear. Excluding wax in the ear canal, 46 (5.7%) children had bilateral abnormalities in their otoscopy, 70 (8.7%) with right ear abnormalities and 67 (8.3%) with left ear abnormalities. The abnormalities found at otoscopy are listed in Table 3. Nineteen children had reduced transparency of the tympanic membrane in both ears. One child had a ventilation tube in his left tympanic membrane and two children had already undergone a tympanoplasty (successful unilateral outcome in one child and bilaterally in another). One child had otorrhea coupled with tympanic membrane perforation, one with unilateral cholesteatoma and another with an osteoma in his right ear canal. Perforation in the tympanic membrane, which was also classified as chronic otitis media, was found in 14 ears, and three children had bilateral perforations. The prevalence of chronic otitis media of 0.94% was calculated through valid information from Table 3 Abnormalities in the tympanic membrane (TM) and/or middle ear at the otoscopic exam
3. Results
3.1. Characteristics of the sample studied About 1005 children were examined, 512 (50.95%) males and 493 (49.05%) females, with an average age of 11.36 years (Table 2), thus forming a truly representative sample of the school age children population of the city of Belo Horizonte. Each set of questions was asked by one of the investigators to the mother (71.9% of the inter-
Tympanic membrane alteration
Right ear
Left ear
Perforated Retracted TM retracted and with reduced transparency TM with reduced transparency TM hyperaemic MT bulged Middle ear effusion Tympanosclerosis
7 15 4
7 19 7
32 6 1 12 6
32 6 2 5 6
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Table 4 Association between the children with chronic otitis media compared with those without chronic otitis media
Table 5 Association between the children with a past history of otitis compared with the children without a past history of otitis
Variable
P-value
Variable
P-value
Right side COM Left side COM
Past history of otorrhea Hearing loss at 500 Hz Hearing loss at 1000 Hz Hearing loss at 2000 Hz Hearing loss at 4000 Hz Right side otoscopic abnormalities Left side otoscopic abnormalities Chronic right side otitis media Chronic left side otitis media Ear surgery Otolaryngologic surgery Hearing loss awareness
B0.001 0.006 0.007 B0.001 B0.001 0.030 0.018 0.002* 0.001* 0.010* 0.025* 0.023
Past of otitis Past of otorrhea Hearing loss at 500 Hz Hearing loss at 1000 Hz Hearing loss at 2000 Hz Hearing loss at 4000 Hz Surgery Hearing loss awareness
0.002* B0.001* B0.001*
B0.001* B0.001* B0.001*
B0.001*
0.001*
0.012*
0.006
0.002*
B0.001*
0.801* 0.011*
0.776* 0.011*
*, value calculated by the exact Fisher teat.
otoscopy in 1900 ears. Table 4 shows the associations between the children with chronic otitis media in comparison with the children without chronic otitis media. Only the association between the children with chronic otitis media and those operated upon, compared with the children without chronic otitis media was not statistically significant.
3.3. Past history of otitis and past history of otorrhea Amongst the 974 children with information matching the diagnosis of a past history of otitis, 32 (3.3%) did not know of any otitis during childhood. Eighty one (8.3%) had previous events of otitis, of these 72 (7.4%) started having ear infections before 6 months of age. The association of children with a past history of otitis and other variables investigated are listed on Table 5. All associations presented statistically significant values. Seventy five (7.71%) children had a past history of otorrhea in their childhood. In order to representatively evaluate this group, the past history of otorrhea was related with other variables investigated according to Table 6. All of the associations were statistically significant, including ear surgery.
*, value calculated by the exact Fisher test.
4. Discussion
4.1. In6estigation method One of the most important aspects of this paper was the sampling process used, which guaranteed an adequate representation of all the school children population of a large city. Through the process adopted it was made possible that each one of almost half a million students could have the same chance of participating in the study. This characteristic together with the high level of community participation (about 90% of the eligible Table 6 Association between the children with a past history of otorrhea compared with the children without a past history of otorrhea Variable
P-value
Past of otitis Hearing loss at 500 Hz Hearing loss at 1000 Hz Hearing loss at 2000 Hz Hearing loss at 4000 Hz Right side otoscopic abnormalities Left side otoscopic abnormalities Ear surgery Otolaryngologic surgery Hearing loss awareness
B0.001 B0.001 B0.001 B0.001 B0.001 B0.003* B0.001* 0.005* 0.047* B0.001*
*, value calculated by the exact Fisher test.
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were investigated) led its conclusions to encompass all the population of students of elementary and junior high schools of the city of Belo Horizonte.
4.2. Characteristics of the samples assessed in other population studies The sampling selections in population studies of otitis and hearing loss do not always involve a representative group of children of all school grades and simultaneously of all social and economic layers in a large city, as in our investigation. This is an important limitation to compare the results. The lack of epidemiological studies in South America also makes the comparisons very difficult. These difficulties in characterizing a population, especially in developing countries, further complicate the selection of samples that may adequately represent all of the population of a city, or even a country. Therefore, the external validity of the collected data, which is very important in population and prevalence surveys, may be compromised. The studies with children may be classified in such a way that the values obtained from small samples, as long as they are chosen by correct statistical processes, may be extrapolated to a much larger universe, as in our investigation— 1005 children representing a universe of almost half a million school children in one of the most important capitals of Brazil. The observation that the prevalence of otologic disease in school children may not reflect exactly what happens in the community, but it points to what may be expected. The prevalence in the community should be higher than the one found among the school children, as long as some children are not enrolled in schools and those children with important hearing loss and important ear diseases will less likely go to school when compared with their healthy peers [10].
4.3. The 6alidity of questionnaires in pre6alence studies The morbidity investigations in a community have collected information about population sam-
ples in two ways: through interviews and through examinations [11]. Although there is a number of advantages in obtaining information about diseases of a specific population from interviews and examinations, the lack of accuracy and the variety of information always present problems. These difficulties must be considered when dealing with the data about morbidity investigations. In a study carried out by Stephenson [12], both children and parents were questioned about happenings from 15 to 20 years in the past and there was an agreement in the answers of the adults regarding ear problems and hearing during childhood. In an investigation by Alho et al. [13], they compared infection data based on a questionnaire to medical files in order to assess the validity of the questionnaire data about previous episodes of acute otitis media. The cumulated incidence of otitis media in those over the age of 2 years in the questionnaire data was lower than that found among the data files. The number of occurrences by child, by year, and the incidence rate for recurrent episodes was considerably higher in the questionnaire data. Daly et al. [14] compared the answers of the parents with medical events. Previous insertions of ventilation tubes and premature birth were carefully remembered. However, there was a substantial amount of information loss regarding the actual age when the first episode of otitis media happened, occurrence of otitis media in previous summers, and regarding the number of episodes in the previous 18 months. The parents who remembered six or more past episodes with their children, overestimated the number, compared with the medical files, whilst those who remembered a lower rate of occurrence underestimated it. Remembering the number of episodes and the age of the first episode may become easier if the answer options are classified in categories (e.g.: 0– 2, 3–5, 6– 8, \ 8). This technique was used in our questionnaire. Daly et al. conclude that the reasonable agreement among the individuals, parents and family doctors suggests that only one of these information sources is required in certain histories of otitis media.
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According to Lilienfeld [11], an important method to validate a research through interviews is to compare the information obtained in the interview with that obtained through the physical examination. In our investigation, the data from the questionnaire and from the physical examination were compared determining special groups of children with past history of otitis and past history of otorrhea.
4.4. Otoscopic e6aluation The presence of obstructing wax was the main abnormality found in the otoscopic exam in most of the investigations that mentioned the prevalence of such finding. In some the wax was removed. In our investigation, obstructing wax was found in 12.3% of the children. Similar values were found in Swaziland [15], Kenya [10] and Malaysia [16]. The group of children who had wax obstructing the ear canal presented significantly higher numbers of hearing loss when compared with the other children. These results showed us that wax is an important preventable cause of hearing loss. According to Hatcher et al. [10], the obstruction of the external ear canal by wax is relatively common, because in the great majority of cases it is asymptomatic and, therefore, it is not an indication to visit the doctor. However, the wax obstruction is a cause of reduction in the hearing and is preventable. Tympanometry is a simple method to assess the presence of effusion in the middle ear, due to its high sensitivity in the diagnosis of otitis media with effusion. The cost of the portable device used to perform the exam in the children made its use impossible in our investigation, which may be considered the major limitation of this work in terms of its data acquisition, most specially regarding the prevalence of otitis media with effusion. Therefore, the prevalence of otitis media with effusion may be estimated only based on the morphologic abnormalities of the tympanic membrane. Ninteen children had tympanic membranes with their transparencies bilaterally reduced, and this may be due to constitutional alteration of these membranes and not due to any pathology.
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4.5. Chronic otitis media The sampling characteristics are of extreme importance in order to assess the prevalence of chronic otitis media. In the Korean [17] sample, the prevalence in the age range from 0 to 15 years was of 0.26% whilst between 16 and 34 years it was 1.74%. Therefore, in the same country, different prevalence values were found due to the age range in which they were calculated. In Malaysia, Saim et al. [16] assessed only kindergarten age children, therefore, the low prevalence of 0.17% is mainly due to the age range studied. In Spain (0.7%) [18], Malaysia (0.17%) [16] and Jamaica (0.16%) [19] the prevalence was very low. With the prevalence ranging between 1 and 2%: Gambia (1.7%) [20], Thailand (1.7%) [21] and Riad [22] in Saudi Arabia (1.5%). In another study performed by Zakzouk et al. [23] in Al-Ariah, in the central region of Saudi Arabia, the prevalence of chronic otitis found was 5.5%. This may be due to the fact that the population lives in villages without primary medical care and primary health care programs, which are already well established in Riad, the capital of the country. A prevalence between 2 and 3% was found in Korea (2.19%) [17], South Africa (2.2%) [24], Tanzania (2.6%) [25] and Sierra Leone (2.8%) [6]. A prevalence of 3% or higher was found in Nepal (3%) [26], Swaziland (3.1%) [15] and Kenya (3.5%) [10]. In Greenland [27], the prevalence of chronic otitis media in the city of Nuuk was of 18.5% and of 4.7% in Sisimiut. In Norway, Andersen et al. [28] showed 6% of chronic otitis media (0.73% of tympanic perforation) among the citizens of Svalbard. Data mentioned by Kim et al. [17], showed a prevalence of 5.6% of otitis media (chronic and acute otitis media) in Chileans and of 8% in Mexicans, and this may reflect the prevalence of these diseases in Latin America. Another study available from investigations carried out in America is from Jamaica [19] (0.16%). Very high prevalence values were found in India [29], 7.8%, where the highest prevalence of ear wax and hearing loss was also found. The prevalence of chronic otitis media in the city of Belo Horizonte could be estimated from the prevalence in school age children [30]. The
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prevalence of perforation in the tympanic membrane in our study could be comparable to that found in the schools of Thailand [21], Kuwait [3] and South Korea [17]. According to the classification proposed by Bluestone [3], this prevalence could be classified as low, sharing the same levels as those found in Korea, India and Saudi Arabia.
4.6. Past history of otitis and past history of otorrhea Most of the studies analyzed did not consider a questionnaire targeting the children’s parents. Only those investigations carried out in South Africa [24], Thailand [21], Greece [31], Iceland [32] and Spain [18] used small questionnaires that did not always involved the parents or all of the children surveyed. In our investigation, a questionnaire was designed aiming at identifying those children who really had an important past history of ear infection in their early childhood, therefore, a very specific group in relation to the children who had otitis in their childhood: 81 (8.3%) had previous events of otitis, of these 72 (7.4%) started having ear infections before 6 months of age. According to Rasmussen et al. [33] 12% of the Swedish children, prospective followed up until 7 years of age, had at least five episodes of acute otitis media. In a prospective study developed in Finland, by Rahko et al. [34], until the age of 13.5 years, 35.2% of the children had had eight or more episodes of acute otitis media and when they were 5 years old, 5.2% had hearing abnormalities. In Belo Horizonte, Brazil, 75 (7.71%) children had a past history of otorrhea in their childhood. In Spain [18], they estimated the prevalence of children with a past history of otorrhea in the range of 6.81%, through a questionnaire. In Gambia [20], the history of past infection was estimated throughout otoscopic examination, reaching a prevalence of 15.1%. In Sierra Leone [6], the presence of discharge for over one month was statistically significantly linked to hearing loss. The questionnaire’s approach was valid enough to distinguish the ‘extremes’ in past occurrences of otitis media, reaching a point at which the interviewed children were classified as a special group
of school children. Therefore, the parents provided enough information enabling the investigators to identify a special group of children and this may be used to devise programs to reach this population.
4.7. Hearing loss When performing hearing screenings, it is very important to check the room conditions. When there is an excess of noise in the room during the test, the examiner must consider the cut-off alteration in the sound intensity, which will inevitably have an impact in the tests’ specificity and sensitivity. This may pose as a serious problem to the examiner regarding the evaluation rooms in developing countries, for not being adequate in terms of soundproof treatment. Many authors criticize the audiometric screening with high decibel level in children (\ 30 dB), leading to a high number of false negatives, having in mind that 15 dB is considered normal in children [35–38]. Sorri et al. [39] and Rahko et al. [34] reported that the effects caused by the infection during childhood are of low intensity. Therefore, in our investigation the audioscope was used at a test intensity of 25 dB. The audioscope is used by many professionals who work with pediatric health [35]. In general, the audioscope was considered light, portable, easy to use, and it did not scare the little patients who even found the exam ‘kind of fun’. The viewing conditions of the tympanic membrane were thought to be adequate. All users thought that the audioscope examination could very easily fit in their health assessment routine and become a convenient and reproducible screening tool. The audioscopic exam is simple and fast. The device is less expensive than a screening audiometer and it does not require sound insulation when used in a sufficiently silent room. 5. Conclusions The prevalence of chronic otitis media in school age children of Belo Horizonte is 0.94%. This is the first data regarding prevalence and impact of chronic otitis media in a representative random sample of children in South America.
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School children with chronic otitis media present with more hearing loss, past history of otitis and past history of otorrhea when compared with children without chronic otitis media. 8.3% of children with a past history of otitis and 7.71% of children with a past event of otorrhea form a special group of children with an important history of childhood ear infection and significant otoscopic and hearing abnormalities. The prevalence of wax in the external ear canal is 12.3%. Both parents and students proved to be significantly able to spot a special group of children with a past history of otitis or otorrhea.
[8]
[9] [10]
[11] [12]
[13]
Acknowledgements The authors wish to thank the pediatricians Andre´ a Deborah Barreto Oliveira, Marcela Dama´ sio Ribeiro and Jose´ Sabino de Oliveira for their important participation. We are grateful to Ana Cristina Cortes Gama, Ana Paula Campolina, Roberta C. Ferreira, Cristina G.R. Cury, Maria Aparecida Silva, Fabrı´cio Sanfins, Antoˆ nio Braz Pereira Ju´ nior for their support during the audiological examination.
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