Can changes in parentally measured acoustic reflectometry levels predict the middle ear status?

OBJECTIVE: Spectral gradient acoustic reflectometry (SG-AR) may be used to detect middle ear effusion. Our aim was to investigate whether increasing SG-AR levels between two SG-AR examinations indicate deterioration from a healthy middle ear to acute otitis media (AOM).

METHODS: We enrolled 185 children (age 6-35 months) whose parents were willing to use the SG-AR at home daily. Measurement pairs of parental home SG-AR examination results were generated and analyzed. There was one SG-AR examination result obtained within ±1 day of the reference visit and another result within ±1 day of the subsequent visit. We defined the SG-AR level as increasing when the difference between two measurements was ≥2 levels from a lower to a higher level, suggesting development of AOM. When the SG-AR level difference was ≤1, we defined this no change of the SG-AR level. The middle ear diagnosis was determined by pneumatic otoscopy at the study clinic.

RESULTS: 361 paired SG-AR home measurements were obtained. The reference measurement was related to a healthy middle ear as determined by pneumatic otoscopy. Increasing SG-AR levels (59/361), were 63% (95% CI 50%-74%) sensitive and 94% (91%-97%) specific for deterioration of a healthy middle ear to AOM. The positive predictive value was 71% (58%-82%) and the negative predictive value was 92% (88%-95%). When there was no SG-AR level difference between the SG-AR examinations, the corresponding figures were 88% (95% CI 84%-92%), 69% (56%-79%), 93% (89%-95%) and 57% (45%-68%), respectively.

CONCLUSIONS: This study shows that increasing SG-AR levels might not be sufficiently sensitive to detect deterioration of the middle ear status from healthy middle ear to AOM in symptomatic children. Importantly, however, the development of AOM seems to be unlikely in an initially healthy middle ear when there is no difference between the SG-AR levels in two separate measurements.