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Otitis media and academic achievements
International Journal of Pediatric Otorhinolaryngology 57 (2001) 31 – 40 www.elsevier.com/locate/ijporl
Otitis media and academic achievements Ingrid Augustsson a,*, Ingemar Engstand b a
Department of Oto-Rhino-Laryngology, O8 rebro Medical Center Hospital, 70129 O8 rebro, Sweden b Lindesberg General Hospital, Lindesberg, Sweden
Received 2 February 2000; received in revised form 20 September 2000; accepted 25 September 2000
Abstract Objecti6e: This is a study of whether there are any long-term differences in academic achievements between children with and without observed or treated middle ear disease in a population with a stable long-standing treatment policy. Methods: A birth cohort of 2156 children was previously studied through a questionnaire to the parents at 4 years of age, follow-up after audiometric screening at 4, 7, 11 and 14 years of age, and study of records from all Ear, Nose and Throats departments in the area; 2095 of these still lived in the area and received academic grades on leaving the ninth year of the state school system. We have compared these grades, and the choice of high school course for children with different experiences of otitis media. Results: A history of treatment for bilateral secretory otitis media was correlated to minor group difference in the mean of grades, but not to any significant difference in the individual grades or in the choice of further studies. Having many episodes of acute otitis before the age of four was uncorrelated to lower grades and to less tendency to continue with theoretical studies. Conclusions: No harmful effect of middle ear disease could be shown in a large sample, suggesting that Swedish children do not suffer long-term effects on learning from otitis media. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Acute otitis media; Secretory otitis media; Treatment policy; School grades; Long-term effects; Academic achievements; Study program; Population study; Screening
1. Introduction If there is a substantial long-term effect of otitis media upon concentration, learning and academic achievements, then children who have experienced long periods with otitis media would have lower grades; they would also be less likely to choose a theoretical course in high school. If, on the other hand, we have managed to identify the more severe cases and treated them successfully, no such effect * Corresponding author.
would be seen, even if the untreated disease could cause poorer academic achievements. This is a study of whether there are any long-term differences in academic achievements between children with and without middle ear disease in a population where the treatment policy has been stable. The treatment policy in O8 rebro county has been largely unchanged for 20 years, and the public handling of health care leads to a high penetration with treatment. The policy is similar to that later agreed at a Swedish Consensus Conference on Otitis Media in 1991 [1].
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 0 ) 0 0 4 3 1 - 6
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Table 1 Mean of grades for children with treated SOM/mild SOM/healthy children Outcome measure
Mean of grades
Healthy (n= 1574)
Mild SOM (n = 413)
Treated SOM (n =106)
Girls
Boys
All
Girls
Boys
All
Girls
Boys
All
3.4172
3.0594
3.2365
3.3909
3.0726
3.2082
3.2979
2.9236
3.0104
The policy can be summarized as follows: For a known duration of less than 3 months, the children were followed without intervention. For a known duration of between 3 and 6 months, children with bilateral, socially limiting loss of hearing were treated with ventilation tubes, and the others were followed without intervention. For a known duration of more than 6 months, the children were treated with ventilation tubes. In the beginning of the studied period, myringotomy was often carried out after 3 months. Adenoidectomy was only carried out in children who also had some degree of nasal obstruction. Secretory otitis media (SOM) is a very common disease with a varying spontaneous course. At least 80% of the episodes resolve spontaneously within 2 months [2,3], and thus only the children with SOM of long duration should be treated. On the other hand, only 10% of the children with SOM and documented bilateral hearing loss for at least 3 months heal spontaneously within 3 years [4]. We have shown earlier that, at the age of four, the majority of the children in need of treatment for SOM in our area are known to the Ear, Nose and Throat (ENT) clinics [5]. We have also shown that the children who had known ear disease at the age of four continued to have episodes with impaired hearing during a long time while few of those who had no evidence of ear disease at the age of four needed treatment later on [6]. This leads us to believe that very few children, who were not known to the ENT clinics and had normal hearing at the first screening, had suffered long-standing, bilateral SOM that would have qualified them for treatment before the age of four.
The immediate positive effect on the hearing from treatment with ventilation tubes is indisputable. The preventive effect of treatment upon the risk of poor language development is more difficult to demonstrate [7], but a recent report provides some short-term evidence for such an effect [8]. An early, much quoted study reported small groups of children with and without a history of early otitis media tested with different language development scales suggesting a negative effect of otitis media (OM) on language development, reading and academic achievement [9]. Many other authors have since then tried to refine the study techniques in different ways and have found weak trends in the same direction [10–12]. There are an increasing number of prospective studies trying to demonstrate differences in verbal abilities between children with and without episodes of OM. Some of them report differences [8,13–18] and others do not [19–22]. The emphasis on language has distracted from the possible general negative effect on concentraTable 2 Linear regression analysis of means of grades for children with treated SOM/healthy children and for children with mild SOM/healthy childrena Variable
Regression coefficient (B)
Significance (P)
Treated SOM Days hospitalized Sex
−0.128 −0.05195
0.051 0.204
−0.360
0.000
Mild SOM Days hospitalized Sex
−0.025 −0.042
0.477 0.259
−0.353
0.000
a
The model controls for days hospitalized and for sex.
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Table 3 Proportion of low grades, proportion of basic levels and proportion of theoretical program for children with treated SOM/mild SOM/healthy children Outcome measure
% % % % % %
Low grade Swedish Basic level English Low grade English Basic level mathematics Low grade mathematics Theoretical program
Healthy (n= 1574)
Mild SOM (n = 413)
Treated SOM (n = 106)
Girls
Boys
All
Girls
Boys
All
Girls
Boys
10 12 16 20 21 45
32 22 28 24 28 38
21 17 22 22 25 42
12 11 15 19 26 48
36 18 35 19 31 43
26 15 26 19 29 46
13 8 15 11 21 45
29 26 36 28 31 42
tion and learning [22]. However, one small study on sustained attention could not demonstrate any difference [23]. The relatively small numbers of studied cases limit all the prospective studies. Another way to study long-term effects is to study educational outcomes in populations. In these studies, like in ours, the information on the otitis exposition is less exact. A large longitudinal study from New Zealand concluded that treated SOM was associated with delayed reading ability up to the age of 15 years [24]. A recent Finnish study concluded that many episodes of acute otitis media (AOM) during the first 3 years have long-term effects on learning and attention skills, at least up to the age of 9 years in spite of active treatment [25]. By far the largest study is a birth cohort study from the UK. It reports on association between parental report on ear discharge and suspected or verified hearing loss and psychosocial and cognitive/educational outcomes. An association between history of ear disease and poorer outcomes was seen at 5 years of age and, to a lesser extent, at 10 years of age [26]. The grades on leaving the ninth year of the state school system provide the first general assessment of the academic achievements of Swedish children. They are based on national standardizing exams and performance markings on schoolwork, but also to some extent on the teachers rating of the student’s classroom behavior and attitude. At this stage, the choice of further study course also says something about
All 21 18 26 25 26 43
the student’s adaptation to school and about his/ her motivation for studies. These things of course are more dependent on other factors than on history of OM. Factors well known to affect grades are sex and social group, or more specifically the education of the mother. Swedish girls have higher grades than boys [27,28]. Since OM is more prevalent in boys according to many reports [29–32], sex has to be controlled for as a confounding factor. An association between prevalence of OM and social class has not been clearly shown within the compressed range seen in Scandinavian countries, and thus it might not be a confounding factor in a material of this size. Generally poorer health could be associated both to the prevalence of OM and to the grades. We therefore controlled for confounding of other diseases measured as total days spent in hospital care.
2. Material During many years, all Swedish children were screened with audiometry at the well baby clinics at the age of four, and at school in first, fourth and seventh grade, at approximately 7, 11 and 14 years of age. For one birth cohort in the O8 rebro area, we have undertaken a systematic follow-up of these screenings. In connection to the screening at the well-baby clinic, we also asked the parents a few questions about their child’s hearing and about treated episodes of AOM. One hundred
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and twenty children (5.7%) did not come to the screening or were not accompanied by a guardian who could answer the questionnaire. This loss consists of two distinct groups, namely those who have declined the hearing test because the child had already had a hearing test at the ENT clinic in connection with middle ear disease (26), and those who usually do not come to health controls
(94). The children that constitute our material are born in 1980 and have been living in the area between 1984 and 1995. Children who had impaired hearing in the screening test were examined at the ENT clinic after 6–8 weeks. The diagnosis of SOM was established by the specialist and based on oto-microscopy, audiometry and tympanometry. Chil-
Table 4 Logistic regression analysis of proportion of low grades, proportion of basic level and proportion of theoretical program for children with treated SOM/healthy children and for children with mild SOM/healthy childrena Outcome measure
Variable
Odds ratio (OR)
Significance (P)
Low grade English
Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex
1.2325 1.3243 2.2131 1.2524 1.1300 2.2332 0.9309 1.4425 4.2283 1.1921 1.1982 4.2242 1.0657 1.2083 1.5365 1.2523 1.1392 1.4431 1.0981 0.9493 0.7891 1.1724 1.0131 0.7891 1.0837 −0.0479 0.7814 0.8981 0.9937 2.0265 1.1806 1.0731 1.2662 0.8985 1.0126 1.2152
0.3777 0.0583 0.0000 0.0716 0.3591 0.0000 0.7824 0.0159 0.0000 0.1744 0.1835 0.0000 0.7853 0.1879 0.0002 0.0595 0.3060 0.0005 0.6462 0.6867 0.0186 0.1400 0.9097 0.0049 0.7625 0.7799 0.0000 0.4656 0.9669 0.0000 0.4750 0.6371 0.0480 0.1144 0.9278 0.0771
Low grade English
Low grade Swedish
Low grade Swedish
Low grade mathematics
Low grade mathematics
Theoretical programa
Theoretical programb
Basic level English**
Basic level Englishc
Basic level mathematicsc
Basic level mathematicsc
a
The model controls for days hospitalized and for sex. Theoretical program =1, practical program = 0. c Basic level = 1, higher level = 0. b
Mean of grades
Outcome measure
3.403
3.0296
3.2220
3.4283
3.0349
Boys 3.2157
All
Girls
All
Girls
Boys
1–3 AOM (n = 731)
0 AOM (n =955)
3.4669
Girls 3.1681
Boys 3.2923
All
\3 AOM (n= 284)
3.2125
Girls
3.2100
Boys
3.2115
All
3.1805
Girls
3.0528
Boys
3.1085
All
Missing questionnaire, ENT patients Missing questionnaire, not ENT (n= 26) patients (n=94)
Table 5 Mean of grades for children different number of AOM episodes at 0–4 years of age and for children with missing questionnaires
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Table 6 Linear regression analysis of mean of grades for children with different numbers of treated episodes of AOM at 0–4 years of agea Variable
Regression coefficient (B)
Significance (P)
AOM episodes Days hospitalized Sex
0.04457 −0.03892
0.030 0.288
−0.369
0.000
a
The model controls for days hospitalized and for sex.
dren who were not already under surveillance for SOM and received this diagnosis were examined in the same way 12– 14 weeks after the screening. Those who then still had SOM were followed and
treated according to the policy already summarized. There are only two ENT clinics in the district offering surgical treatment. The general practitioners and pediatricians in the area have agreed to refer all children with SOM if it has not resolved after 3 months. They also refer children who have SOM when they come for a check 3 months after having AOM. The medical records at the two ENT clinics for all children born in 1980 were studied retrospectively at the end of 1994. We registered contact for ear disease and treatment with ventilation tubes in the right and the left ear in each 2-year period up to the age of 14 years. Thus, there are medical records for children who have had impaired hearing due to SOM at one or more of four screening occasions
Table 7 Proportion of low grades and proportion of theoretical program for children with different numbers of AOM episodes. Outcome measure
% % % %
Low grade Swedish Low grade English Low grade mathematics Theoretical program
0 AOM (n= 955)
\3 AOM (n = 284)
1–3 AOM (n = 731)
Girls
Boys
All
Girls
Boys
All
Girls
Boys
11 16 21 45
35 35 28 37
23 24 24 41
10 14 22 46
34 30 32 41
23 23 27 43
5 13 18 50
25 26 23 43
All 17 20 21 46
Table 8 Logistic regression analysis of proportion of low grades and of proportion of theoretical program for children with different numbers of treated episodes of AOM at 0–4 years of agea Outcome measure
Variable
Odds ratio
Significance (P)
Low grade English
Number of AOM Days hospitalized Sex Number of AOM Days hospitalized Sex Number of AOM Days hospitalized Sex Number of AOM Days hospitalized Sex
0.9059 1.1351 2.4579 0.9232 1.2564 4.5316 1.1496 1.1387 1.5781 1.1131 0.9986 0.7602
0.2307 0.3423 0.0000 0.0054 0.0948 0.0000 0.0720 0.3118 0.0000 0.2836 0.9901 0.0028
Low grade Swedish
Low grade mathematics
Theoretical programb
a
The model controls for days hospitalized and for sex. Mean of grades for children with treated SOM/mild SOM/healthy children. b Theoretical program =1, practical program = 0.
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and for children who have consulted a doctor because of symptoms, and whose SOM has not resolved in 3 months. Statistics Sweden (the Government statistical office) keeps a file of grades and of the chosen high-school program for all individuals graduating from the ninth grade of the ordinary school. Of the 2127 children, 2095 who, as far as we know, have attended the compulsory nursery and middle school could be retrieved in this file. All students have basically the same curriculum in the first nine grades, but they can choose between two levels, basic or higher, in mathematics and English. The grades are 1–5, where 5 is the best grade. After the ninth grade, almost all students go on to some kind of upper secondary school, either to a study program that prepares them for university studies (theoretical) or to a study program that prepares them for vocational training (practical).
3. Methods From our file on these 2127 children, we selected data on different aspects of their otitis history. We tried to select data that would make it possible for us to compare the results with the results of other authors. Two variables came from a questionnaire to the parent when the child came to the well-baby clinic for audiometric screening at the age of four: 1. number of treated episodes of AOM up to that time; 2. whether the child had a planned visit for ear disease at that time. Five variables came from the medical records at the ENT clinics: 1. whether the child had visited the ENT clinic due to ear disease at the age of 0 – 4 years according to the medical records at the ENT clinic; 2. number of 2-year periods with planned visits for ear disease in right and/or left ear at the age of 0–14 years; 3. whether the child had any planned visits at an ENT clinic for bilateral or unilateral ear disease at the age of 0 – 14 years;
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4. number of 2-year periods with ventilation tubes in right and/or left ear at the age of 0–14 years; 5. whether the child had bilateral or unilateral treatment with ventilation tubes at the age of 0–14 years. The following outcome measures were taken from the file of grades: 1. mean of grades/scores; 2. level of mathematics course; 3. grade in mathematics; 4. grade in Swedish; 5. level of English course; 6. grade in English; 7. choice of course (program) for further studies. A file with the otitis variables was merged into the file of grades giving 2095 matches. The file thus created was anonymous. We controlled for possible confounding from sex and from generally poor health, measured as days spent under hospital care up to the age of 14 years. This information was taken from another file of health information on children in our area. First, each of the otitis variables’ possible association with all outcome measures was tested by an analysis of variance. No clear pattern could be seen, but there could be a weak trend towards association between treatment with ventilation tubes and mean of grades, and between number of AOM episodes up to 4 years of age and grades. Since the variables on contact with the ENT clinic and on the treatment of SOM are interconnected, we made a cluster analysis. This resulted in three groups of children. One group was characterized by bilateral treatment with ventilation tubes. No contact with the ENT clinics and no treatment at the age of 0–14 years and no planned visit for ear disease at the time of the questionnaire characterized another group. The first group is called ‘Treated SOM’ and comprises 106 children, and the second is called ‘Healthy’ and comprises 1529 children. The third group comprises 413 children, who were not treated with bilateral ventilation tubes but had some evidence of ear disease. In this group are the children whom we considered having a milder disease with shorter duration and less hearing loss, and thus followed without intervention. The group is called
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‘Mild SOM’, although it also contains a few children who have been referred to us because of other ear problems. In the analysis, the group ‘Healthy’ was compared with the two SOM groups separately. We also analyzed the association between the parental report on AOM episodes at the age of 0 – 4 years and the outcome measures more closely. Since the loss was influenced by contact with the ENT clinics, we also analyzed the missing group. Linear regression analysis was carried out for the mean of grades and logistic regression analysis for the other outcome measures. For logistic regression, grades in mathematics, English and Swedish were coded 1 if B 3 and else 0. In the comparisons of grades, five children who did not receive any grades when leaving the ninth grade are treated as missing. Thus, we can report on the association between SOM at 0–14 years of age, episodes of AOM up to 4 years of age and grades and choice of further studies.
4. Results Table 1 shows that the mean of grades for the children treated for SOM is slightly lower than the mean of grades for the healthy children and for the children with mild SOM. Table 2 shows that the difference between healthy children and children treated for SOM almost reaches a significant level and that there is no such trend in the comparison between the healthy children and the children with mild SOM. When we look at the proportions of low grades in the individual subjects, there seems to be a trend towards an association between treated SOM and low grades in English for boys, especially since they have chosen the basic level more often (Table 3). The regression analysis, however, shows that mainly sex is significantly associated with low grades and basic level. There is also a significant association between low grade in Swedish and days hospitalized (Table 4). A history of mild or treated SOM does not influence the choice of high school program (Tables 2 and 4).
Table 5 surprisingly shows that the children with many AOM episodes have somewhat higher mean of grades than the children with none or few episodes. The children with missing questionnaire have lower grades than those children for whom a questionnaire was filled in. However, the children who did not come to the screening because they were already patients at the ENT clinic did not have especially low grades. Table 6 shows that the difference in the mean of grades is a small but significant. There is also a significant difference in Swedish to the advantage of those with many episodes (Tables 7 and 8). No significant difference is found in their choice of high school program (Tables 7 and 8).
5. Discussion The sequelae of defined degrees of SOM on specific abilities have been studied [7–22] as well as the results on middle ear status and hearing of defined treatments for SOM [4,33–35]. But in the next step, when conclusions are drawn on how treatment policy can help avoid difficulties in learning, many more factors come into the picture [36]. Is the treatment given to the right individuals? Is it effective in clinical practice? We wanted to evaluate one aspect of the impact of health care for middle ear disease by looking at possible sequelae of SOM on learning, measured by school results, for a population group. The age of the studied children is most similar in the Dunedin study [24]. The authors show a big difference between treated and healthy children in reading ability at the age of 15. We can see several possible explanations for the difference between their and our results. The treated group in the New Zealand study could have been more seriously affected by SOM than our treated group, or they could have been less intensively treated. If the Burt reading test was used with the common scale for boys and girls, confounding from sex could contribute to the difference. The reading test in their study measures a more specific ability than the grade in Swedish in our study. The results of our study are consistent with those of the study by Bennett and Haggard [26].
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They find significant association between ear discharge/hearing loss and behavioral problems at the age of 10, but only weak signs of association between ear disease and language abilities. In the part where the effect of treated episodes of AOM before 4 years of age is studied, the most similar study is that by Loutonen et al. [25]. The conclusion in this study differs from ours. The non-response in the Finnish study was 11.3% and that in ours was 5.7%. Our parental reports should be more accurate, since they were given in closer connection to the reported period. The results are reported for 8 and 14 years of age, respectively, which could account for the differences. Nevertheless, the differences in results are smaller than the differences in conclusions, and we fare that Loutonen et al. might draw too wide conclusions from the results. The outcome measure in our study, the school grades, is more compound and less specific than the measures used in the cited studies. School grades are not scientifically validated measures, but still we feel that they more closely measure what we are really interested in, namely the future prospects of the young person. A weakness of our study is that we have no way of knowing whether the parents with higher educational levels have a greater tendency to seek and obtain treatment for their children. We do know that the screenings at 4 and 7 years of age identify few new cases of SOM in need of treatment, but we do not know whether the social background of those who have come to treatment before 4 years of age differs from that of the general population. The higher grades for children with many episodes of AOM before the age of four could suggest that parents with higher education more often seek medical care for their children. If this is the case, this could confound the relation between otitis media and grades. The assumption that there are few unknown cases of long-standing SOM in this cohort of course can be seen as a weak point. It rests partially on theoretical implications but also upon our thorough knowledge of this population and its healthcare.
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6. Conclusion Children observed or treated for otitis media according to current Swedish policy do not have significantly poorer grades than their peers, and they choose theoretical high school courses to the same extent as unaffected students. That no harmful effect can be shown in a material of this size suggests that Swedish children do not get important negative long-term effects on learning from otitis media.
Acknowledgements The county council of O8 rebro supported this work. We thank Cecilia Lundholm for her committed work with the statistics.
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[23] E. Arcia, J.E. Roberts, Otitis media in early childhood and its association with sustained attention in structured situations, J. Dev. Behav. Pediatr. 14 (3) (1993) 181 – 183. [24] I. Stewart, P.A. Silva, Otitis media with effusion, in: P.A. Silva, W.R. Stanton (Eds.), From Child to Adult: The Dunedin Multidisciplinary Health and Development Study, Oxford University Press, Auckland, 1996, pp. 113 – 129 (reprint 1998). [25] M. Loutonen, M. Uhari, L. Aitola, A.M. Lukkaroinen, J. Loutonen, M. Uhari, A nation-wide, population-based survey of otitis media and schoolachievement, Int. J. Pediatr. Otorhinolaryngol. 43 (1) (1998) 41 – 51. [26] K. Bennett, M. Haggard, Behaviour and cognitive outcomes from middle ear disease, Arch. Dis. Child. 80 (1999) 28 – 35. [27] G. Westin-Lindgren, Physical and Mental Development in Swedish Urban Schoolchildren. Studies in Education and Psychology 5, Stockholm Institute of Education, Department of Educational Research, Liber, Stockholm, 1979, pp. 42 – 43. [28] C. Stage, Gender Differences on the SweSat. A Review of Educational Measurement, Department of Education, University of Umea˚, EM No. 7, 1993, p. 14. [29] D.W. Teele, J. O. Klein, B.A. Rosner, Epidemiology of otitis media during the first seven years of life in children in greater Boston: a prospective, cohort study, J. Infect. Dis. 160 (1) (1989) 83 – 94. [30] K.A. Daly, S.S. Rich, S. Levine, R.H. Margolis, C.T. Le, B. Lindgren, G.S. Giebrink, The family study of otitis media: design and disease and risk factor profiles, Genet. Epidemiol. 13 (5) (1996) 451 – 468. [31] B.P. Lanpher, R.S. Byrd, P. Auinger, C.B. Hall, Increasing prevalence of recurrent otitis media among children in the United States, Pediatrics 99 (3) (1997) E1. [32] C. Stenstro¨m, L. Ingvarsson, Otitis-prone children and controls: a study of possible predisposing factors. 1. Heredity, family background and perinatal period, Acta Otolaryngol. (Stockh.) 117 (1) (1997) 87 – 93. [33] G.A. Gates, C.A. Avery, T.J. Prihoda, J.C. Cooper, Effectiveness of adenoidectomy and tympanostomy tubes in the treatment of chronic otitis media with effusion, N. Engl. J. Med 317 (1987) 1444 – 1451. [34] N.A. Black, C.F.B. Sanderson, A.P. Freeland, M.P. Vessey, A randomised controlled trial of surgery for glue ear, Br. Med. J. 300 (1990) 1551 – 1556. [35] J.H. Dempster, G.G. Browning, S.G. Gatehouse, A randomized study of the surgical management of children with persistent otitis media with effusion associated with a hearing impairment, J. Laryngol. Otol. 107 (1993) 284 – 289. [36] A. Long, Evidence based practice at a managerial and clinical practice level, in: J. Vang, M. Kristenson (Eds.), Outcome Measuring, Swedish Institute for Health Services Development, Stockholm 1998, p. 310.
Otitis media and academic achievements Ingrid Augustsson a,*, Ingemar Engstand b a
Department of Oto-Rhino-Laryngology, O8 rebro Medical Center Hospital, 70129 O8 rebro, Sweden b Lindesberg General Hospital, Lindesberg, Sweden
Received 2 February 2000; received in revised form 20 September 2000; accepted 25 September 2000
Abstract Objecti6e: This is a study of whether there are any long-term differences in academic achievements between children with and without observed or treated middle ear disease in a population with a stable long-standing treatment policy. Methods: A birth cohort of 2156 children was previously studied through a questionnaire to the parents at 4 years of age, follow-up after audiometric screening at 4, 7, 11 and 14 years of age, and study of records from all Ear, Nose and Throats departments in the area; 2095 of these still lived in the area and received academic grades on leaving the ninth year of the state school system. We have compared these grades, and the choice of high school course for children with different experiences of otitis media. Results: A history of treatment for bilateral secretory otitis media was correlated to minor group difference in the mean of grades, but not to any significant difference in the individual grades or in the choice of further studies. Having many episodes of acute otitis before the age of four was uncorrelated to lower grades and to less tendency to continue with theoretical studies. Conclusions: No harmful effect of middle ear disease could be shown in a large sample, suggesting that Swedish children do not suffer long-term effects on learning from otitis media. © 2001 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Acute otitis media; Secretory otitis media; Treatment policy; School grades; Long-term effects; Academic achievements; Study program; Population study; Screening
1. Introduction If there is a substantial long-term effect of otitis media upon concentration, learning and academic achievements, then children who have experienced long periods with otitis media would have lower grades; they would also be less likely to choose a theoretical course in high school. If, on the other hand, we have managed to identify the more severe cases and treated them successfully, no such effect * Corresponding author.
would be seen, even if the untreated disease could cause poorer academic achievements. This is a study of whether there are any long-term differences in academic achievements between children with and without middle ear disease in a population where the treatment policy has been stable. The treatment policy in O8 rebro county has been largely unchanged for 20 years, and the public handling of health care leads to a high penetration with treatment. The policy is similar to that later agreed at a Swedish Consensus Conference on Otitis Media in 1991 [1].
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 0 ) 0 0 4 3 1 - 6
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Table 1 Mean of grades for children with treated SOM/mild SOM/healthy children Outcome measure
Mean of grades
Healthy (n= 1574)
Mild SOM (n = 413)
Treated SOM (n =106)
Girls
Boys
All
Girls
Boys
All
Girls
Boys
All
3.4172
3.0594
3.2365
3.3909
3.0726
3.2082
3.2979
2.9236
3.0104
The policy can be summarized as follows: For a known duration of less than 3 months, the children were followed without intervention. For a known duration of between 3 and 6 months, children with bilateral, socially limiting loss of hearing were treated with ventilation tubes, and the others were followed without intervention. For a known duration of more than 6 months, the children were treated with ventilation tubes. In the beginning of the studied period, myringotomy was often carried out after 3 months. Adenoidectomy was only carried out in children who also had some degree of nasal obstruction. Secretory otitis media (SOM) is a very common disease with a varying spontaneous course. At least 80% of the episodes resolve spontaneously within 2 months [2,3], and thus only the children with SOM of long duration should be treated. On the other hand, only 10% of the children with SOM and documented bilateral hearing loss for at least 3 months heal spontaneously within 3 years [4]. We have shown earlier that, at the age of four, the majority of the children in need of treatment for SOM in our area are known to the Ear, Nose and Throat (ENT) clinics [5]. We have also shown that the children who had known ear disease at the age of four continued to have episodes with impaired hearing during a long time while few of those who had no evidence of ear disease at the age of four needed treatment later on [6]. This leads us to believe that very few children, who were not known to the ENT clinics and had normal hearing at the first screening, had suffered long-standing, bilateral SOM that would have qualified them for treatment before the age of four.
The immediate positive effect on the hearing from treatment with ventilation tubes is indisputable. The preventive effect of treatment upon the risk of poor language development is more difficult to demonstrate [7], but a recent report provides some short-term evidence for such an effect [8]. An early, much quoted study reported small groups of children with and without a history of early otitis media tested with different language development scales suggesting a negative effect of otitis media (OM) on language development, reading and academic achievement [9]. Many other authors have since then tried to refine the study techniques in different ways and have found weak trends in the same direction [10–12]. There are an increasing number of prospective studies trying to demonstrate differences in verbal abilities between children with and without episodes of OM. Some of them report differences [8,13–18] and others do not [19–22]. The emphasis on language has distracted from the possible general negative effect on concentraTable 2 Linear regression analysis of means of grades for children with treated SOM/healthy children and for children with mild SOM/healthy childrena Variable
Regression coefficient (B)
Significance (P)
Treated SOM Days hospitalized Sex
−0.128 −0.05195
0.051 0.204
−0.360
0.000
Mild SOM Days hospitalized Sex
−0.025 −0.042
0.477 0.259
−0.353
0.000
a
The model controls for days hospitalized and for sex.
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33
Table 3 Proportion of low grades, proportion of basic levels and proportion of theoretical program for children with treated SOM/mild SOM/healthy children Outcome measure
% % % % % %
Low grade Swedish Basic level English Low grade English Basic level mathematics Low grade mathematics Theoretical program
Healthy (n= 1574)
Mild SOM (n = 413)
Treated SOM (n = 106)
Girls
Boys
All
Girls
Boys
All
Girls
Boys
10 12 16 20 21 45
32 22 28 24 28 38
21 17 22 22 25 42
12 11 15 19 26 48
36 18 35 19 31 43
26 15 26 19 29 46
13 8 15 11 21 45
29 26 36 28 31 42
tion and learning [22]. However, one small study on sustained attention could not demonstrate any difference [23]. The relatively small numbers of studied cases limit all the prospective studies. Another way to study long-term effects is to study educational outcomes in populations. In these studies, like in ours, the information on the otitis exposition is less exact. A large longitudinal study from New Zealand concluded that treated SOM was associated with delayed reading ability up to the age of 15 years [24]. A recent Finnish study concluded that many episodes of acute otitis media (AOM) during the first 3 years have long-term effects on learning and attention skills, at least up to the age of 9 years in spite of active treatment [25]. By far the largest study is a birth cohort study from the UK. It reports on association between parental report on ear discharge and suspected or verified hearing loss and psychosocial and cognitive/educational outcomes. An association between history of ear disease and poorer outcomes was seen at 5 years of age and, to a lesser extent, at 10 years of age [26]. The grades on leaving the ninth year of the state school system provide the first general assessment of the academic achievements of Swedish children. They are based on national standardizing exams and performance markings on schoolwork, but also to some extent on the teachers rating of the student’s classroom behavior and attitude. At this stage, the choice of further study course also says something about
All 21 18 26 25 26 43
the student’s adaptation to school and about his/ her motivation for studies. These things of course are more dependent on other factors than on history of OM. Factors well known to affect grades are sex and social group, or more specifically the education of the mother. Swedish girls have higher grades than boys [27,28]. Since OM is more prevalent in boys according to many reports [29–32], sex has to be controlled for as a confounding factor. An association between prevalence of OM and social class has not been clearly shown within the compressed range seen in Scandinavian countries, and thus it might not be a confounding factor in a material of this size. Generally poorer health could be associated both to the prevalence of OM and to the grades. We therefore controlled for confounding of other diseases measured as total days spent in hospital care.
2. Material During many years, all Swedish children were screened with audiometry at the well baby clinics at the age of four, and at school in first, fourth and seventh grade, at approximately 7, 11 and 14 years of age. For one birth cohort in the O8 rebro area, we have undertaken a systematic follow-up of these screenings. In connection to the screening at the well-baby clinic, we also asked the parents a few questions about their child’s hearing and about treated episodes of AOM. One hundred
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and twenty children (5.7%) did not come to the screening or were not accompanied by a guardian who could answer the questionnaire. This loss consists of two distinct groups, namely those who have declined the hearing test because the child had already had a hearing test at the ENT clinic in connection with middle ear disease (26), and those who usually do not come to health controls
(94). The children that constitute our material are born in 1980 and have been living in the area between 1984 and 1995. Children who had impaired hearing in the screening test were examined at the ENT clinic after 6–8 weeks. The diagnosis of SOM was established by the specialist and based on oto-microscopy, audiometry and tympanometry. Chil-
Table 4 Logistic regression analysis of proportion of low grades, proportion of basic level and proportion of theoretical program for children with treated SOM/healthy children and for children with mild SOM/healthy childrena Outcome measure
Variable
Odds ratio (OR)
Significance (P)
Low grade English
Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex Treated SOM Days hospitalized Sex Mild SOM Days hospitalized Sex
1.2325 1.3243 2.2131 1.2524 1.1300 2.2332 0.9309 1.4425 4.2283 1.1921 1.1982 4.2242 1.0657 1.2083 1.5365 1.2523 1.1392 1.4431 1.0981 0.9493 0.7891 1.1724 1.0131 0.7891 1.0837 −0.0479 0.7814 0.8981 0.9937 2.0265 1.1806 1.0731 1.2662 0.8985 1.0126 1.2152
0.3777 0.0583 0.0000 0.0716 0.3591 0.0000 0.7824 0.0159 0.0000 0.1744 0.1835 0.0000 0.7853 0.1879 0.0002 0.0595 0.3060 0.0005 0.6462 0.6867 0.0186 0.1400 0.9097 0.0049 0.7625 0.7799 0.0000 0.4656 0.9669 0.0000 0.4750 0.6371 0.0480 0.1144 0.9278 0.0771
Low grade English
Low grade Swedish
Low grade Swedish
Low grade mathematics
Low grade mathematics
Theoretical programa
Theoretical programb
Basic level English**
Basic level Englishc
Basic level mathematicsc
Basic level mathematicsc
a
The model controls for days hospitalized and for sex. Theoretical program =1, practical program = 0. c Basic level = 1, higher level = 0. b
Mean of grades
Outcome measure
3.403
3.0296
3.2220
3.4283
3.0349
Boys 3.2157
All
Girls
All
Girls
Boys
1–3 AOM (n = 731)
0 AOM (n =955)
3.4669
Girls 3.1681
Boys 3.2923
All
\3 AOM (n= 284)
3.2125
Girls
3.2100
Boys
3.2115
All
3.1805
Girls
3.0528
Boys
3.1085
All
Missing questionnaire, ENT patients Missing questionnaire, not ENT (n= 26) patients (n=94)
Table 5 Mean of grades for children different number of AOM episodes at 0–4 years of age and for children with missing questionnaires
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Table 6 Linear regression analysis of mean of grades for children with different numbers of treated episodes of AOM at 0–4 years of agea Variable
Regression coefficient (B)
Significance (P)
AOM episodes Days hospitalized Sex
0.04457 −0.03892
0.030 0.288
−0.369
0.000
a
The model controls for days hospitalized and for sex.
dren who were not already under surveillance for SOM and received this diagnosis were examined in the same way 12– 14 weeks after the screening. Those who then still had SOM were followed and
treated according to the policy already summarized. There are only two ENT clinics in the district offering surgical treatment. The general practitioners and pediatricians in the area have agreed to refer all children with SOM if it has not resolved after 3 months. They also refer children who have SOM when they come for a check 3 months after having AOM. The medical records at the two ENT clinics for all children born in 1980 were studied retrospectively at the end of 1994. We registered contact for ear disease and treatment with ventilation tubes in the right and the left ear in each 2-year period up to the age of 14 years. Thus, there are medical records for children who have had impaired hearing due to SOM at one or more of four screening occasions
Table 7 Proportion of low grades and proportion of theoretical program for children with different numbers of AOM episodes. Outcome measure
% % % %
Low grade Swedish Low grade English Low grade mathematics Theoretical program
0 AOM (n= 955)
\3 AOM (n = 284)
1–3 AOM (n = 731)
Girls
Boys
All
Girls
Boys
All
Girls
Boys
11 16 21 45
35 35 28 37
23 24 24 41
10 14 22 46
34 30 32 41
23 23 27 43
5 13 18 50
25 26 23 43
All 17 20 21 46
Table 8 Logistic regression analysis of proportion of low grades and of proportion of theoretical program for children with different numbers of treated episodes of AOM at 0–4 years of agea Outcome measure
Variable
Odds ratio
Significance (P)
Low grade English
Number of AOM Days hospitalized Sex Number of AOM Days hospitalized Sex Number of AOM Days hospitalized Sex Number of AOM Days hospitalized Sex
0.9059 1.1351 2.4579 0.9232 1.2564 4.5316 1.1496 1.1387 1.5781 1.1131 0.9986 0.7602
0.2307 0.3423 0.0000 0.0054 0.0948 0.0000 0.0720 0.3118 0.0000 0.2836 0.9901 0.0028
Low grade Swedish
Low grade mathematics
Theoretical programb
a
The model controls for days hospitalized and for sex. Mean of grades for children with treated SOM/mild SOM/healthy children. b Theoretical program =1, practical program = 0.
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and for children who have consulted a doctor because of symptoms, and whose SOM has not resolved in 3 months. Statistics Sweden (the Government statistical office) keeps a file of grades and of the chosen high-school program for all individuals graduating from the ninth grade of the ordinary school. Of the 2127 children, 2095 who, as far as we know, have attended the compulsory nursery and middle school could be retrieved in this file. All students have basically the same curriculum in the first nine grades, but they can choose between two levels, basic or higher, in mathematics and English. The grades are 1–5, where 5 is the best grade. After the ninth grade, almost all students go on to some kind of upper secondary school, either to a study program that prepares them for university studies (theoretical) or to a study program that prepares them for vocational training (practical).
3. Methods From our file on these 2127 children, we selected data on different aspects of their otitis history. We tried to select data that would make it possible for us to compare the results with the results of other authors. Two variables came from a questionnaire to the parent when the child came to the well-baby clinic for audiometric screening at the age of four: 1. number of treated episodes of AOM up to that time; 2. whether the child had a planned visit for ear disease at that time. Five variables came from the medical records at the ENT clinics: 1. whether the child had visited the ENT clinic due to ear disease at the age of 0 – 4 years according to the medical records at the ENT clinic; 2. number of 2-year periods with planned visits for ear disease in right and/or left ear at the age of 0–14 years; 3. whether the child had any planned visits at an ENT clinic for bilateral or unilateral ear disease at the age of 0 – 14 years;
37
4. number of 2-year periods with ventilation tubes in right and/or left ear at the age of 0–14 years; 5. whether the child had bilateral or unilateral treatment with ventilation tubes at the age of 0–14 years. The following outcome measures were taken from the file of grades: 1. mean of grades/scores; 2. level of mathematics course; 3. grade in mathematics; 4. grade in Swedish; 5. level of English course; 6. grade in English; 7. choice of course (program) for further studies. A file with the otitis variables was merged into the file of grades giving 2095 matches. The file thus created was anonymous. We controlled for possible confounding from sex and from generally poor health, measured as days spent under hospital care up to the age of 14 years. This information was taken from another file of health information on children in our area. First, each of the otitis variables’ possible association with all outcome measures was tested by an analysis of variance. No clear pattern could be seen, but there could be a weak trend towards association between treatment with ventilation tubes and mean of grades, and between number of AOM episodes up to 4 years of age and grades. Since the variables on contact with the ENT clinic and on the treatment of SOM are interconnected, we made a cluster analysis. This resulted in three groups of children. One group was characterized by bilateral treatment with ventilation tubes. No contact with the ENT clinics and no treatment at the age of 0–14 years and no planned visit for ear disease at the time of the questionnaire characterized another group. The first group is called ‘Treated SOM’ and comprises 106 children, and the second is called ‘Healthy’ and comprises 1529 children. The third group comprises 413 children, who were not treated with bilateral ventilation tubes but had some evidence of ear disease. In this group are the children whom we considered having a milder disease with shorter duration and less hearing loss, and thus followed without intervention. The group is called
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‘Mild SOM’, although it also contains a few children who have been referred to us because of other ear problems. In the analysis, the group ‘Healthy’ was compared with the two SOM groups separately. We also analyzed the association between the parental report on AOM episodes at the age of 0 – 4 years and the outcome measures more closely. Since the loss was influenced by contact with the ENT clinics, we also analyzed the missing group. Linear regression analysis was carried out for the mean of grades and logistic regression analysis for the other outcome measures. For logistic regression, grades in mathematics, English and Swedish were coded 1 if B 3 and else 0. In the comparisons of grades, five children who did not receive any grades when leaving the ninth grade are treated as missing. Thus, we can report on the association between SOM at 0–14 years of age, episodes of AOM up to 4 years of age and grades and choice of further studies.
4. Results Table 1 shows that the mean of grades for the children treated for SOM is slightly lower than the mean of grades for the healthy children and for the children with mild SOM. Table 2 shows that the difference between healthy children and children treated for SOM almost reaches a significant level and that there is no such trend in the comparison between the healthy children and the children with mild SOM. When we look at the proportions of low grades in the individual subjects, there seems to be a trend towards an association between treated SOM and low grades in English for boys, especially since they have chosen the basic level more often (Table 3). The regression analysis, however, shows that mainly sex is significantly associated with low grades and basic level. There is also a significant association between low grade in Swedish and days hospitalized (Table 4). A history of mild or treated SOM does not influence the choice of high school program (Tables 2 and 4).
Table 5 surprisingly shows that the children with many AOM episodes have somewhat higher mean of grades than the children with none or few episodes. The children with missing questionnaire have lower grades than those children for whom a questionnaire was filled in. However, the children who did not come to the screening because they were already patients at the ENT clinic did not have especially low grades. Table 6 shows that the difference in the mean of grades is a small but significant. There is also a significant difference in Swedish to the advantage of those with many episodes (Tables 7 and 8). No significant difference is found in their choice of high school program (Tables 7 and 8).
5. Discussion The sequelae of defined degrees of SOM on specific abilities have been studied [7–22] as well as the results on middle ear status and hearing of defined treatments for SOM [4,33–35]. But in the next step, when conclusions are drawn on how treatment policy can help avoid difficulties in learning, many more factors come into the picture [36]. Is the treatment given to the right individuals? Is it effective in clinical practice? We wanted to evaluate one aspect of the impact of health care for middle ear disease by looking at possible sequelae of SOM on learning, measured by school results, for a population group. The age of the studied children is most similar in the Dunedin study [24]. The authors show a big difference between treated and healthy children in reading ability at the age of 15. We can see several possible explanations for the difference between their and our results. The treated group in the New Zealand study could have been more seriously affected by SOM than our treated group, or they could have been less intensively treated. If the Burt reading test was used with the common scale for boys and girls, confounding from sex could contribute to the difference. The reading test in their study measures a more specific ability than the grade in Swedish in our study. The results of our study are consistent with those of the study by Bennett and Haggard [26].
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They find significant association between ear discharge/hearing loss and behavioral problems at the age of 10, but only weak signs of association between ear disease and language abilities. In the part where the effect of treated episodes of AOM before 4 years of age is studied, the most similar study is that by Loutonen et al. [25]. The conclusion in this study differs from ours. The non-response in the Finnish study was 11.3% and that in ours was 5.7%. Our parental reports should be more accurate, since they were given in closer connection to the reported period. The results are reported for 8 and 14 years of age, respectively, which could account for the differences. Nevertheless, the differences in results are smaller than the differences in conclusions, and we fare that Loutonen et al. might draw too wide conclusions from the results. The outcome measure in our study, the school grades, is more compound and less specific than the measures used in the cited studies. School grades are not scientifically validated measures, but still we feel that they more closely measure what we are really interested in, namely the future prospects of the young person. A weakness of our study is that we have no way of knowing whether the parents with higher educational levels have a greater tendency to seek and obtain treatment for their children. We do know that the screenings at 4 and 7 years of age identify few new cases of SOM in need of treatment, but we do not know whether the social background of those who have come to treatment before 4 years of age differs from that of the general population. The higher grades for children with many episodes of AOM before the age of four could suggest that parents with higher education more often seek medical care for their children. If this is the case, this could confound the relation between otitis media and grades. The assumption that there are few unknown cases of long-standing SOM in this cohort of course can be seen as a weak point. It rests partially on theoretical implications but also upon our thorough knowledge of this population and its healthcare.
39
6. Conclusion Children observed or treated for otitis media according to current Swedish policy do not have significantly poorer grades than their peers, and they choose theoretical high school courses to the same extent as unaffected students. That no harmful effect can be shown in a material of this size suggests that Swedish children do not get important negative long-term effects on learning from otitis media.
Acknowledgements The county council of O8 rebro supported this work. We thank Cecilia Lundholm for her committed work with the statistics.
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