Sensitivity and specificity of eustachian tube function tests in adults

Abstract

Importance: The study demonstrates the utility of eustachian tube (ET) function (ETF) test results for accurately assigning ears to disease state.

Objectives: To determine if ETF tests can identify ears with physician-diagnosed ET dysfunction (ETD) in a mixed population at high sensitivity and specificity and to define the interrelatedness of ETF test parameters.

Design, setting, and participants: Through use of the forced-response, inflation-deflation, Valsalva, and sniffing tests, ETF was evaluated in 15 control ears of adult subjects after unilateral myringotomy (group 1) and in 23 ears of 19 adult subjects with ventilation tubes inserted for ETD (group 2). Data were analyzed using logistic regression including each parameter independently and then a step-down discriminant analysis including all ETF test parameters to predict group assignment. Factor analysis operating over all parameters was used to explore relatedness.

Exposures: ETF testing.

Main outcomes and measures: ETF parameters for the forced response, inflation-deflation, Valsalva, and sniffing tests measured in 15 control ears of adult subjects after unilateral myringotomy (group 1) and in 23 ears of 19 adult subjects with ventilation tubes inserted for ETD (group 2).

Results: The discriminant analysis identified 4 ETF test parameters (Valsalva, ET opening pressure, dilatory efficiency, and percentage of positive pressure equilibrated) that together correctly assigned ears to group 2 at a sensitivity of 95% and a specificity of 83%. Individual parameters representing the efficiency of ET opening during swallowing showed moderately accurate assignments of ears to their respective groups. Three factors captured approximately 98% of the variance among parameters: the first had negative loadings of the ETF structural parameters; the second had positive loadings of the muscle-assisted ET opening parameters; and the third had negative loadings of the muscle-assisted ET opening parameters and positive loadings of the structural parameters.

Conclusions and relevance: These results show that ETF tests can correctly assign individual ears to physician-diagnosed ETD with high sensitivity and specificity and that ETF test parameters can be grouped into structural-functional categories.

Figure 1

Schematic diagram of the instrument used to test ETF (a), and idealized ME pressure (MEP) and trans-ET Flow versus time waveforms for the Forced-Response test (FRT), MEP versus time waveforms for the Inflation-Deflation test (IDT), and MEP and nasal pressure (NP) versus time waveforms for the Valsalva and Sniffing tests (b). “S” indicates a swallow. PO=ET opening pressure, PS=ET steady-state pressure, PC=ET closing pressure, AP=applied pressure, PP=peak pressure, RP=residual pressure, QS=steady-state flow and QA=peak flow during a swallow. See Methods for a complete description.

Figure 2

Absolute loading of the ETF test parameters onto each of the three factors identified by Factor Analysis after Varimax Rotation. Factors are listed in an arbitrary sequence corresponding to those that capture structural measures of the ET (Factor 1), functional measures of the ET (Factor 2) and mixed measures (Factor 3). See Table I for parameter definitions.