Antibiotic Treatment for First Episode of Acute Otitis Media Is Not Associated with Future Recurrences
Antibiotic Treatment for First Episode of Acute Otitis Media Is Not Associated with Future Recurrences
Marthe te Molder 0 1 2 3
Marieke L. A. de Hoog 0 1 2 3
Cuno S. P. M. Uiterwaal 0 1 2 3
Cornelis K. van der Ent 0 1 3
Henriette A. Smit 0 1 2 3
Anne G. M. Schilder 0 1 2 3
Roger A. M. J. Damoiseaux 0 1 2 3
Roderick P. Venekamp 0 1 2 3
0 Funding: The WHISTLER-project was supported by grants from The Netherlands Organization for Health Research and Development (ZonMw; Grant No.: 200111322 ), by the University Medical Center Utrecht , and by an unrestricted grant from GlaxoSmithKline , The Netherlands. The evidENT
1 Data Availability Statement: Data are extracted from the WHISTLER dataset accessable upon a request to the WHISTLER datamanager at the University Medical Center. For the (SPSS) analyses MH or RV may be contacted at Julius Center for Health Sciences and Primary Care
2 Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht , Utrecht , The Netherlands , 2 Department of Pediatric Pulmonology, Wilhelmina Children's Hospital, University Medical Center Utrecht , Utrecht , The Netherlands , 3 Department of Otorhinolaryngology, University Medical Center Utrecht , Utrecht , The Netherlands , 4 Ear Institute, University College London , London , United Kingdom
3 Editor: Lamberto Manzoli, University of Chieti , ITALY
Antibiotic treatment of acute otitis media (AOM) has been suggested to increase the risk of
future AOM episodes by causing unfavorable shifts in microbial flora. Because current
evidence on this topic is inconclusive and long-term follow-up data are scarce, we wanted to
estimate the effect of antibiotic treatment for a first AOM episode occurring during infancy
on AOM recurrences and AOM-related health care utilization later in life.
years of life.
We obtained demographic information and risk factors from data of the Wheezing Illnesses
Study Leidsche Rijn, a prospective birth cohort study in which all healthy newborns born in
Leidsche Rijn (between 2001 and 2012), The Netherlands, were enrolled. These data were
linked to children’s primary care electronic health records up to the age of four. Children
with at least one family physician-diagnosed AOM episode before the age of two were
included in analyses. The exposure of interest was the prescription of oral antibiotics (yes
vs no) for a child’s first AOM episode before the age of two years.
848 children were included in analyses and 512 (60%) children were prescribed
antibiotics for their first AOM episode. Antibiotic treatment was not associated with an increased
risk of total AOM recurrences (adjusted rate ratio: 0.94, 95% CI: 0.78–1.13), recurrent
AOM ( 3 episodes in 6 months or
4 in one year; adjusted risk ratio: 0.79, 95% CI: 0.57–
1.11), or with increased AOM-related health care utilization during children’s first four
team at UCL, United Kingdom, is supported by a
National Institute for Health Research (NIHR),
Research Professorship Award. The funders had no
role in study design, data collection and analysis,
decision to publish, or preparation of the manuscript.
Oral antibiotic treatment of a first AOM episode occurring during infancy does not affect the number of AOM recurrences and AOM-related health care utilization later in life. This information can be used when weighing the pros and cons of various AOM treatment options.
Acute otitis media (AOM) is one of the most common reasons for primary care consultations
during early childhood and a prime indication for antibiotic prescriptions.[
] In general, AOM
has a favorable natural course with symptoms settling spontaneously within a few days in most
] However, serious suppurative complications such as mastoiditis, meningitis and
intracranial abscess occur in a small subset of children.[
Although antibiotics have been shown to reduce AOM symptoms more quickly than
], AOM practice guidelines[
] advice a judicious use of antibiotics in this condition
because of its limited effect on preventing suppurative complications [
] and the potential
harms related to its use. Oral antibiotics are associated with an increased risk of systemic side
effects such as vomiting, diarrhea and rash and their routine use enhances the risk of
] Furthermore, it has been hypothesized that antibiotics put children at
risk for future infections.[
] Several studies showed that antibiotics affect the
nasopharyngeal microbial flora, which in turn has been suggested to enhance overgrowth and spread
of potential pathogens.[
] Moreover, recent studies showed that biofilm formation
occurred 2–5 times faster in patients treated with antibiotics compared with those that did not
receive antibiotic treatment.[
] Since the biofilm serves as a bacterial reservoir in which
bacteria are 1000 times more resistant to the action of antibiotics than their planktonic counterparts,
biofilm formation has been associated with an increased risk of recurrent infections.[
Thus far, only one study assessed the long-term (>12 months) impact of antibiotic
treatment on future AOM episodes.[
] This placebo-controlled trial showed that treatment with
oral antibiotics of AOM at young age was associated with a 50% increase in the risk of AOM
recurrences at long term follow-up.[
] However, the response rate was only 70% and data
were collected retrospectively. Other randomized controlled trials, comparing antibiotics with
placebo or watchful waiting in children with AOM, did not find any differences in AOM
recurrences at short term follow-up (up to 12 months).[
More research is needed to determine whether antibiotic treatment for AOM during infancy
puts children at risk of developing further AOM recurrences later in life. We linked our large,
prospective birth cohort data to children’s primary care electronic health records to estimate
the long-term effects of antibiotic treatment of a first AOM episode occurring during infancy
on AOM occurrence and AOM-related health care utilization during children’s first four years
Study design and participants
Data were collected as part of the WHeezing Illnesses STudy LEidsche Rijn (WHISTLER), a
prospective birth cohort study. Parents of healthy newborns, born between December 2001
and December 2012, living in Leidsche Rijn (district of Utrecht, The Netherlands) were invited
to participate within three weeks after their child’s birth. Exclusion criteria were gestational age
<36 weeks, major congenital abnormalities and neonatal respiratory disease. Prior to
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enrollment, written informed consent was obtained from parents of participating children.
Study design and rationale of WHISTLER are described in detail elsewhere.[
was approved by the pediatric medical ethics committee of the University Medical Center
Utrecht (project approval number 01/176).
For this study we used (i) baseline data on prenatal risk factors and parental characteristics,
and (ii) prospectively collected data on postnatal risk factors from monthly questionnaires
during the child’s first year of life. Additionally, (iii) four years of follow-up data were extracted
from primary care electronic health records for all participating children with a family
physician practicing within the Leidsche Rijn research district, using uniform codes for diagnoses
and treatments according to the International Classification of Primary Care (ICPC) and
Anatomical Therapeutical Chemical (ATC) coding systems. We extracted data on AOM (ICPC
H71) episodes, AOM-related health care utilization including consultations, antibiotic
prescriptions and specialist referrals, and data on all-cause antibiotic prescriptions prior to the
first AOM episode.
The exposure variable of interest was the prescription of oral antibiotics (ATC code J01, yes vs
no) for a child’s first AOM episode occurring before two years of age and presented to the
family physician. ‘No oral antibiotics’ was chosen as reference category.
The primary outcome was the total number of AOM recurrences during children’s first four
years of life seen by a family physician. A new episode of AOM (ICPC H71) was documented
after an interval of at least 28 days without AOM-related consultations. Secondary outcomes
included (i) the occurrence of recurrent AOM (yes vs no) defined as three or more episodes of
AOM within six months, or four episodes within 12 months [
], and (ii) AOM-related health
care utilization (consultations, antibiotic prescriptions and specialist referrals) during the first
four years of life.
We considered the following characteristics as confounders: gender, season of birth, parental
education level, duration of exclusive breastfeeding, number of older siblings,
householdsmoking, daycare attendance, age of first AOM episode and number of oral antibiotics prior to
the first AOM episode (irrespective of indication).
Parental education level, as a proxy for socio-economic status, was based on the highest
completed education of the child’s parents. If at least one of the parents was highly educated
(professional degree or bachelor’s degree or higher), education level was defined as ‘high’.
Otherwise it was defined as ‘middle/low’. Household-smoking was categorized in number of
months of the first year of life of household-smoking (of at least half a day per week). Daycare
attendance was based on the age of first daycare visit (of at least half a day per week).
Because of missing values in parental- and child-related factors, we first imputed missing
values using the multiple imputation by chained equations (MICE) procedure in SPSS.[
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created 10 imputed data sets. A pooled analysis was performed to give a single mean estimate
and adjusted standard errors according to the Rubin’s rule.[
Next, we compared characteristics of children who did and did not receive oral antibiotics
for their first AOM episode using Chi-squared tests, Mann-Whitney U tests and independent
We then studied the association between oral antibiotic treatment (yes vs no) for a child’s
first AOM episode occurring during the first two years of life and our outcome variables of
interest. Associations between antibiotic treatment and count outcomes (total number of AOM
recurrences, number of AOM-related consultations and antibiotic prescriptions) were
calculated using negative binomial regression analyses. These regression coefficients reflect rate
ratios. Associations between antibiotic treatment and dichotomous outcomes (incidence of
recurrent AOM, incidence of AOM-related specialist referrals) were estimated using Poisson
regression analyses with robust standard errors[
]. The regression coefficients derived from
these analyses reflect risk ratios.
In all analyses, follow-up duration was used as the offset variable to indicate exposure time.
Follow-up duration was estimated as the time in months from the first family physician
diagnosed AOM episode until the last known date of follow-up in primary care, or until children’s
All models were adjusted for potential confounders and all statistical analyses were
performed with SPSS version 21.0 (IBM SPSS, Armonk, NY, USA).
During the WHISTLER recruitment period (December 2001 to December 2012), parents of
9236 children were invited of whom 2463 children were enrolled after obtaining full written
informed consent. 2314 (94%) had a family physician inside the research district and at least
one day of follow up, which allowed us to extract relevant primary care health electronic
records data. 848 of 2314 children (37%) experienced a family physician diagnosed AOM episode
before the age of two years (Fig 1). Of those, 190 (22%) had missing confounders data which
were imputed using multiple imputation techniques.
Baseline characteristics of the 848 included children are summarized in Table 1. 512
(60%) children were prescribed oral antibiotics for their first AOM episode before the age
of two years. Children receiving antibiotics were significantly older at the time of first
AOM episode (mean age 11.3 (SD 5.2) vs 9.9 months (SD 5.1), p<0.001) than those in
which antibiotics were not prescribed. Half of the children (60/120) having their first
AOM episode before the age of six months were treated with antibiotics. Moreover, the
number of older siblings was significantly higher in children receiving antibiotics than in
those who did not receive antibiotics (median number of siblings 1 (IQR 0–1) vs 0 (IQR
0–1), p = 0.02).
Of the children who received antibiotics for their first AOM episode, 60.7% had one or
more AOM recurrences after the first AOM episode in the first four years of life (range 1–10
recurrences) and 12.3% developed recurrent AOM. Of the children not treated with antibiotics,
62.8% had one or more AOM recurrences (range 1–11 recurrences) and 16.7% developed
recurrent AOM. Antibiotic treatment of the first AOM episode was neither associated with an
increased risk of total AOM recurrences (adjusted rate ratio: 0.94, 95% CI: 0.78–1.13) and the
occurrence of recurrent AOM (adjusted risk ratio: 0.79, 95% CI: 0.57–1.11) (Table 2), nor with
the number of AOM-related consultations (adjusted rate ratio: 0.88, 95% CI: 0.74–1.03),
antibiotic prescriptions (adjusted rate ratio: 0.93, 95% CI: 0.75–1.16) and specialist referrals (adjusted
risk ratio: 0.75 (0.51–1.10)) (Table 3).
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Fig 1. Flow chart of study population Abbreviations: AOM, acute otitis media. SES, socio-economic status.
Oral antibiotic treatment for a first AOM episode occurring during infancy did not affect the
total number of AOM recurrences, the occurrence of recurrent AOM and AOM-related health
care utilization later in life.
Our findings are in agreement with results of randomized controlled trials assessing the
short-term (1.5–12 months) impact of oral antibiotic treatment on AOM recurrences.[
Furthermore, our findings are in line with placebo-controlled trials results of other common
respiratory infectious diseases including tonsillitis and acute sinusitis[
no impact of antibiotics on recurrence rates. However, our results are conflicting with the
only long-term follow-up study performed thus far. This double-blind, placebo-controlled
randomized trial of Bezáková et al. found an increased risk of AOM recurrences up to 3.5
years after randomization in children treated with antibiotics. This latter study has,
however, some important limitations which may hamper the interpretation of the results: data
on the outcomes were collected retrospectively by a parental reported questionnaire with a
response rate of only 70% and this is likely to introduce a substantial risk of recall and
When interpreting our results, it should be taken into account that amoxicillin 40mg/kg is
the first line antibiotic in AOM in the Netherlands; a safe and efficient dose according to
current antibiotic resistance patterns in this country.[
] Bezáková et al. used the same dosage in
] However, in many other countries, including the US, a higher dose of
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First episode of AOM treated with oral antibiotics
No (n = 336) Yes (n = 512) p-value
amoxicillin (up to 90mg/kg) is recommended.[
] Further research is needed to determine
whether the effect of oral antibiotics on AOM recurrences is dose-dependent.
In our study, 848 of 2314 participants (37%) had at least one AOM episode by 2 years which
is relatively low. There are, however, various explanations for this. First, we included all
newborns who had at least one day of follow-up by their family physician. A substantial number of
children (n = 242) were followed for less than two years and were therefore less likely to have
an AOM episode recorded by their family physician during their first two year of life. Second,
we focused on family physician diagnosed AOM. Previous research, however, indicated that
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parents consult their family physician with their child in case of AOM symptoms only in about
half of the episodes.[
] As such, the community incidence of AOM is likely to be much higher
than the estimate found in our study.
We found children receiving antibiotics to be significantly older at the time of first AOM
episode than children who did not receive antibiotics. Although current guidance recommends
immediate antibiotics in all children aged below six months with AOM, only half of our
children were actually treated with antibiotics. Further studies are warranted to confirm this
finding, but this suggests that future studies on guideline adherence should not only focus on
overtreatment with antibiotics but also on under treatment in specific at-risk groups.
The major strengths of our study are the large sample size and the prospective, observational
data collection. Moreover, results were adjusted for a large amount of well-established
Still, some methodological limitations deserve further attention. First, although family
physicians were trained to use of the ICPC coding system and strict diagnostic and treatment
criteria are provided by the Dutch family physician AOM practice guideline, we cannot rule out
that variability between individual family physicians and physician-related factors (years of
experience, available time per patient) influenced coding and management strategies.[
However, this potential variability may lead to non-differential misclassification but is unlikely
to produce biased estimates of the associations.
Second, our study is an observational study so antibiotics were not randomly prescribed to
children with AOM. Children receiving antibiotics for their first AOM episode may have been
Crude risk ratio (95% CI) Adjusted risk ratioa (95% CI)
0.81 (0.55–1.17) 0.75 (0.51–1.10)
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more severely ill and may have a worse prognosis compared with those who did not receive
antibiotics, resulting in confounding by indication. This may have led to an overestimation of
the number of AOM recurrences in children who were treated with antibiotics for their first
AOM episode. Although many confounders were taken into account to minimize the risk of
confounding, residual confounding cannot be entirely excluded. For example, we had no
information of pacifier use which has been previously associated with an increased risk of recurrent
Third, we only measured family physician diagnosed AOM episodes which is, as mentioned
previously, likely to underestimate the burden of AOM in the community.[
] It is likely that
not all parents of participating children did consult their family physician when their child
suffered from AOM symptoms. This would not necessarily bias our results if health seeking
behavior of parents of children with AOM in both exposure groups would be similar. However,
it has been shown that AOM-related antibiotic prescriptions are associated with higher doctor
consultation rates in case of recurrent episodes.[
] Our study results may therefore
overestimate the number of AOM recurrences in children who did receive oral antibiotics for their first
Fourth, we collected ATC codes to measure exposure status (oral antibiotics, yes vs no).
However, prescribing antibiotics does not necessarily imply that the child actually took the
prescribed drug. A previous study on the use of antibiotics among ambulatory pediatric patients
reported a compliance rate of 78.9%.[
] It is unlikely that this non-compliance introduced a
differential bias, but it may have caused non-differential misclassification of the exposure. As
such, it may have weakened the differences between the two groups.
If those last three limitations would have affected our results, the “true” risk of AOM
recurrences could actually be lower after antibiotic treatment, and thereby be in the opposite
direction of the previously mentioned results of Bezáková et al.[
Concluding, antibiotic treatment of a first AOM episode occurring during infancy is neither
associated with an increased risk of AOM recurrences, nor with increased AOM-related health
care utilization during children’s first four years of life. This information can be used when
weighing the pros and cons of various treatment options in children experiencing their first
AOM during life infancy.
We thank the parents of all participating children and primary care physicians for their
Conceived and designed the experiments: RD MH RV MM CU CE.
Performed the experiments: MM MH RV.
Analyzed the data: MM MH RV.
Contributed reagents/materials/analysis tools: CE CU MH RV MM.
Wrote the paper: RD MH RV MM CE CU AS HS.
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