Concurrent Validity of the IOPI and Tongueometer Orofacial Strength Measurement Devices

Abstract

Objective(s): This study examined the concurrent validity of two orofacial strength manometers: (1) the Iowa Oral Performance Instrument (IOPI) - the current, gold standard orofacial manometer; and (2) the Tongueometer - a newly-available, lower cost, orofacial manometer.

Methods: This study compared IOPI and Tongueometer pressure readings across three experimental conditions. Experiment 1 compared full setup (manometer + tongue bulb) pressure readings between the IOPI and Tongueometer. Experiment 2 compared IOPI tongue bulb and Tongueometer tongue bulb pressure readings, while controlling for manometer. Experiment 3 compared IOPI manometer and Tongueometer manometer pressure readings, while controlling for tongue bulb. Pressures were applied manually within a laboratory setting. Lin's concordance correlation (ρ_c ) was used to calculate level of agreement, with ρ_c interpreted as 'poor' if <0.90, 'moderate' if 0.90 to <0.95, 'substantial' if 0.95 to <0.99, and 'excellent' if ≥0.99.

Results: 539 trials were analyzed. There was a median absolute difference of 2.4 kPa in pressure readings between the IOPI and Tongueometer full setups (manometer + tongue bulb). Correlations revealed substantial agreement between IOPI and Tongueometer full setups (experiment 1: n = 292; ρ_c = 0.986), tongue bulbs (experiment 2: n = 146; ρ_c = 0.987-0.992), and manometers (experiment 3: n = 101; ρ_c = 0.970).

Conclusions: Differences in pressures were consistently observed between the Tongueometer and IOPI. Despite these differences, substantial agreement was present. These data suggest the Tongueometer may be a valid, lower cost alternative to the IOPI for objectively assessing orofacial strength in clinical practice.

Level of evidence: Level 2 Laryngoscope, 133:3123-3131, 2023.

Keywords: Iowa oral performance instrument (IOPI); dysphagia; orofacial; strength; swallowing; tongueometer.