Comparison of Spectral Gradient Acoustic Reflectometry and Tympanometry for Detection of Middle-ear Effusion in Children

Background: Spectral gradient acoustic reflectometry (SGAR) and tympanometry are handy methods to aid in the diagnostics of middle-ear diseases, but no prior studies have directly assessed the correlation between SGAR and tympanometry readings in children. Methods: We compared SGAR and tympanometry in 2152 otoscopic examinations among 600 children aged 0.6-14 years, who were examined for signs and symptoms of respiratory infection in a primary care setting; 677 (31.5%) of the ear examinations were in children <3 years of age. We further determined the test characteristics of these methods for the detection of middle-ear effusion (MEE) using pneumatic otoscopy as the gold standard. All examinations were performed by trained physicians. Results: SGAR and tympanometry indicated probable absence of MEE in 1896 (88.1%) and 1937 (90.0%) of the 2152 ears, respectively. SGAR levels 1-2 were observed in 95.7% of ears with type A/As tympanogram and in 58.1% of ears with type B tympanogram. The frequency of type B tympanogram increased with increasing SGAR levels, from 4.8% at SGAR level 1 to 67.7% at SGAR level 5. The observed agreement between the 2 methods was 86%. The test characteristics of SGAR and tympanometry for the detection of MEE diagnosed by pneumatic otoscopy were comparable. Conclusions: The high specificities and negative predictive values of SGAR and tympanometry make them useful aids particularly in ruling out MEE in children with respiratory infections. The low cost, easy portability and absence of need for an airtight seal support the use of SGAR also for screening purposes at home.