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Objective--To consider whether earlier detection of otitis media with effusion (OME) in asymptomatic children in the first 4 years of life prevents delayed language development.
Methods--MEDLINE and other databases were searched and relevant references from articles reviewed. Critical appraisal and consensus development were in accordance with the methods of the Canadian Task Force on Preventive Health Care.
Results--No randomised controlled trials assessing the overall screening for OME and early intervention to prevent delay in acquiring language were identified, although one trial evaluated treatment in a screened population and found no benefit. The "analytic pathway" approach was therefore used, where evidence is evaluated for individual steps in a screening process. The evidence supporting the use of tools for early detection such as tympanometry, microtympanometry, acoustic reflectometry, and pneumatic otoscopy in the first 4 years of life is unclear. Some treatments (mucolytics, antibiotics, steroids) resulted in the short term resolution of effusions as measured by tympanometry. Ventilation tubes resolved effusions and improved hearing. Ventilation tubes in children with hearing loss associated with OME benefited children in the short term, but after 18 months there was no difference in comparison with those assigned to watchful waiting. Most prospective cohort studies that evaluated the association betw een OME and language development lacked adequate measurement of exposure or outcome, or suffered from attrition bias. Findings with regard to the association were inconsistent.
Conclusions--There is insufficient evidence to support attempts at early detection of OME in the first 4 years of life in the asymptomatic child to prevent delayed language development.
(Arch Dis Child 2001;85:96-103)
Keywords: odds media with effusion; language development disorders; speech disorders; child development
Otitis media with effusion (OME) is common, with a prevalence of about 20% at age 2 years. [1 2] It is often asymptomatic. Some studies have found an association between OME and delayed language development,  and this finding has led to the implementation of programmes for earlier detection of OME, although the evidence supporting attempts at earlier detection has been questioned.  Clinicians conducting periodic health examinations or child health surveillance may question whether attempts at earlier diagnosis of OME should be included as a routine part of these examinations. Using the methods of the Canadian Task Force on Preventive Health Care,  we considered the evidence for and against assessing asymptomatic children for OME. Our focus was the first 4 years of life because this is the period of most rapid language acquisition.
The "causal (analytic) pathway" approach considers evidence for an entire programme for early detection; if this is not available, evidence is considered for each step in an analytic pathway (fig 1).  Regarding programmes for earlier detection of OME, the analytic pathway involved examining evidence for the effectiveness of screening the general population for OME in the first 4 years of life to prevent delayed language development (step 1). If such evidence was lacking, the remaining steps in the pathway were considered as follows:
* Is there a suitable tool for early detection (step 2)?
* Is treatment effective in clearing effusions (step 3)?
* Does treating OME improve language related outcomes (step 4)?
* Is there is an association between OME and delayed language development (step 5)?
The guidelines for rules of evidence established by the Canadian Task Force on Preventive Health Care were used to classify the quality of study designs in a hierarchical fashion (box l). [8,9]
MEDLINE was searched from 1966 to July 2000, focusing on screening (in general and in the early years), treatment (and subsequent language related outcomes), and the relation between OME and language delay. Key search terms used included otitis media with effusion (OME), middle ear effusion, developmental disabilities, learning disorders, child development, language development disorders, speech disorders, mass screening, sensitivity, and specificity. The Cochrane database of systematic reviews and controlled trials register, as well as the NHS centre for reviews and dissemination database were also searched for relevant studies and meta-analyses.
Further studies were identified from manual searching of the indexes of studies identified by electronic searchers, from indexes of review studies, and from the index of the systematic review by the New Zealand health technology assessment clearing house for health outcomes and health technology assessment (http://nzhta.chmeds.ac.nz/screen.htm). If a meta-analysis of suitable quality was found, only relevant individual trials published after the meta-analysis were sought.
Studies were excluded for the following reasons:
* assessment of exposure that was retrospective or inadequate;
* use of samples other than the general population, for example studies that included only graduates of neonatal units, children with cleft palate, high risk children in day care, or specific ethnic groups;
* evaluation of OME after the first 4 years of life;
* findings published in abstract form or in conference proceedings only.
The evidence was systematically reviewed using the methods of the Canadian Task Force on Preventive Health Care. Two authors extracted information from and assessed the quality of the individual studies. The task force of expert clinicians/methodologists from a variety of medical specialities used a standardised evidence based method for evaluating the effectiveness of screening interventions. The full methodology is described by Woolf et al. 
STEP 1: DOES SCREENING THE GENERAL POPULATION OF CHILDREN IN THE FIRST 4 YEARS OF LIFE PREVENT DELAYED LANGUAGE DEVELOPMENT?
We identified no trials assessing the entire screening process for OME (early detection and intervention), where subjects were randomised to be screened and treated if early abnormality is detected, or not screened. However, one trial assessed the impact of screening a general population of children aged 2 years and those with persistent effusions invited to participate in a randomised trial. [1 10 11] Owing to small numbers, the study lacked sufficient power to detect a clinically important effect.
Three other "screening" studies were excluded because audiometry was the screening tool and subjects were not randomised. [12-14] Two of these studies focused on older children. [12 13] Three studies were excluded because referral rate was the outcome measure. [15-17] Given the lack of evidence for or against screening for OME in the general population, we then explored the remaining steps in the analytic pathway (fig 1).
STEP 2: IS THERE A SUITABLE TOOL FOR EARLY DETECTION?