The Evaluation and Treatment of Children with Acute Otitis Media

Journal of Family Practice, May, 2001 by JOHN R. McCONAGHY

KEY POINTS

* Certain combinations of symptoms are highly predictive of acute otitis media (AOM).

* Uncomplicated AOM resolves spontaneously in 80% of children.

* Most children may be safely treated initially with analgesics in the first few days and without antibiotics, provided that close follow-up can be ensured.

* If antibiotics are used, a 5-day course of standard-dose amoxicillin (40 mg/kg/day) is the most appropriate.

* No outcomes evidence supports the use of double-dose amoxicillin in the empiric routine treatment of AOM.

Between 1993 and 1995 more than 20 million visits were provided to children younger than 15 years for otitis media; 77% of these were for children aged 4 years and younger.[1] Acute otitis media (AOM) is the most frequent primary diagnosis in preschool children and accounts for almost 20% of ambulatory care visits in this age group. By the age of 3 months, 10% of children will be given at least 1 diagnosis of otitis media and more than 90% by the age of 2 years.[2] Peak incidence occurs between the ages 6 and 15 months, although there is a second peak at approximately age 5 years that is thought to be associated with entrance into school[3] In the mid1990s, treatment of otitis media cost $3.8 billion per year[4]; 20% of the more than 110 million prescriptions for oral antibiotics are for otitis media[5]

The most important contributor to AOM is a dysfunction of the eustachian tube, allowing reflux of fluid and bacteria into the middle ear space from the nasopharynx.[6] This dysfunction is usually multifactorial and is likely a combination of anatomy (shorter and more flexible eustachian tubes) and function (inefficiency at clearing secretions and equilibrating negative intratympanic pressures) in younger children.[7] Acute viral upper respiratory infections create inflammation and secretions that magnify this eustachian tube dysfunction and predispose to or induce AOM.

The 3 most common bacteria in AOM are Streptococcus pneumoniae, Haemophilus species, and Branhamella catarrhalis. A recent study showed that both bacteria and viruses were isolated in the middle ear fluid of 65% of children with otitis media. In fact, 35% had viruses isolated as the sole middle ear pathogen.[8] Other studies have failed to identify a specific infectious agent in a significant number of middle ear fluid aspirates.[9]

DIAGNOSIS

The diagnosis of AOM in children is often based on a combination of symptoms and physical findings. It is usually defined as bulging or opacification of the tympanic membrane with or without erythema, middle ear effusion, marked decrease or absence of tympanic membrane mobility, and accompanied by at least one of the following signs and symptoms of acute infection: fever, otalgia, irritability, otorrhea, lethargy, anorexia, vomiting, or diarrhea.[10] Although the best reference standard for the diagnosis of AOM is myringotomy or tympanocentesis, no published studies were identified in which this reference was performed in all study patients. Most published studies use pneumatic otoscopy combined with tympanocentesis or myringotomy as the reference standard when middle ear effusion is suspected.

Most symptoms are not specific for AOM. In a survey of patients seeing general practitioners in Finland,[11] the symptoms that most increased the likelihood of diagnosing AOM were earache (relative risk [RR]=5.4; 95% confidence interval [CI], 3.3-8.%, rubbing of the ear (RR=5.0; 95% CI, 2.9-8.6), and excessive crying (RR=2.8; 95% CI, 1.8-4.3). Although fever, earache, or excessive crying were present in 90% of children considered to have AOM, one or. more of these symptoms were also present in 72% of children who did not have otitis media. In another survey of children aged younger than 4 years with a diagnosis of AOM, 40% did not have otalgia, and 30% did not have fever.[12]

Physical examination findings are of variable reliability. Findings that physicians rely on to diagnose AOM, such as a bulging or erythematous tympanic membrane, may occasionally be found in normal ears.[13] One study compared the 3 most commonly documented otoscopic findings (color, position, and mobility of the tympanic membrane) with those of pneumatic otoscopy and myringotomy.[14] Only 65% of patients with a distinctly red tympanic membrane and 16% with a slightly red tympanic membrane had AOM. A cloudy tympanic membrane was the most predictive color change, with an 80% positive predictive value (PPV), the percentage of patients with the symptom who have AOM. A bulging tympanic membrane was most predictive of AOM (PPV=89%), despite its 27% false-negative rate. Retraction was found in only 19% of children with AOM and had a PPV of only 500/0. Distinctly impaired mobility was predictive of otitis media (PPV=78%), but diminished mobility was also found in 30% of children without middle ear effusion. These data and those presented in Table 1 show that each of these otoscopic examination elements (color, position, mobility) alone is inadequate for discriminating between cases in which the diagnosis of AOM is uncertain.