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Centre for Evidence-
Based Medicine

Tympanometry is a moderate predictor of audiometric hearing loss in school children

Clinical Bottom Line

Tympanometry is moderately helpful in the assessment of possible childhood hearing problems, but cannot rule out problems (sensitivity 58%).

Citation

Holty I, Forster DP. Evaluation of pure tone audiometry and impedance screening in infant schoolchildren. J Epidemiol Community Health 1992; 46: 21-25.

Clinical Question

What is the accuracy of microtympanometry for the diagnosis of hearing loss from a middle ear effusion in young children?

Search Terms

(tympanomet* OR impedance) AND (otitis media OR middle ear) AND audiomet* (MEDLINE)

The Study

The study attempted to screen 610 school aged children with both audiometry and tympanometry done 5 days apart (half in each sequence) by different examiners unaware of the previous result. 94.1% had both tests.

The Evidence

Target Disorder (abnormal audiometry) Totals
Present Absent
Diagnostic Test Result
(tympanometry)
Positive
(type B or C)

99

a

92

b

191

a + b

Negative
(type A)

73

c

310

d

383

c + d

Totals

a + c

172

b + d

402

a + b + c + d

574

Sensitivity = a/(a+c)
= 99/172
= 58%

Specificity = d/(b+d)
= 310/402
= 77%

Likelihood Ratio for a positive test result (LR+) = sens/(1-spec)
= 58%/23%
= 2.5

Likelihood Ratio for a negative test result (LR-) = (1-sens)/spec
= 42%/77%
= 0.54

Comparison of the 94.1% of children who completed both tympanometry and audiometry showed a sensitivity (for hearing loss) of 58% and a specificity of 77%, suggesting only a modest accuracy for tympanometry. However, the same study showed that audiometry had a test-retest repeatability of 67%. This inaccuracy in the reference standard will lead to an underestimate of the accuracy of tympanometry.

Comments

The results for Type B and Type C tympanometries have been combined here as "abnormal", but may have differential accuracy.

Appraised By

Paul Glasziou

Expiry Date

When someone has completed a systematic review.