Reliability and Validity of Maximal Respiratory Pressures

BACKGROUND: Maximal respiratory pressure is used to assess the inspiratory and expiratory muscles strength by using maximal inspiratory pressure (P Imax ) and maximal expiratory pressure (P Emax ). This study aimed to summarize and evaluate the reliability and validity of maximal respiratory pressure measurements. METHODS: This systematic review followed the Consensus-based Standards for the Selection of Health Measurement Instruments (COSMIN) recommendations and was reported by using the PRISMA checklist. Studies published before March 2023 were searched in PubMed and EMBASE databases. RESULTS: A total of 642 studies were identified by using the online search strategy and manual search (602 and 40, respectively). Twenty-three studies were included. The level of evidence for test-retest reliability was moderate for P Imax and P Emax (intraclass correlation coefficient > 0.70 for both), inter-rater reliability was low for P Imax and very low for P Emax (intraclass correlation coefficient > 0.70 for both), and the measurement error was very low for P Imax and P Emax . In addition, concurrent validity presented a high level of evidence for P Imax and P Emax (r > 0.80). CONCLUSIONS: Only concurrent validity of maximal respiratory pressure measured with the manometers evaluated in this review presented a high level of evidence. The quality of clinical studies by using maximal respiratory pressure would be improved if more high-quality studies on measurement properties, by following well established guidelines and the COSMIN initiative, were available.