Confiabilidad de la fuerza muscular respiratoria y flujos espiratorios forzados en adolescentes sanos

Abstract

Inspiratory and expiratory muscle strength (MIP and MEP) assessment, and peak expiratory flow (PEF) and peak cough flow (PCF) measurements are often used to assess patients with respiratory diseases. Notwithstanding, there are few reports about reliability of these measurements. The aim of this study is to determine the intra-observer reliability of MIP, MEP, PCF and PEF in healthy adolescents. The study design was test retest. A sample of students from a public school of Talcahuano (Chile) were studied. MIP, MEP, PEF and PCF were recorded twice by the same appraiser, with an interval of 8 weeks. Intraclass correlation coefficient (ICC) was used as an index of reliability. Analysis of individual differences was performed by Bland and Altman’s method and the probability of discordance between test and retest was evaluated. A p value < 0.05 was considered significant. 23 students (9 males), ageing 16.3 ± 0.5 years-old entered to the study. ICC of MIP, MEP, PEF and PCF were 0.7; 0.78; 0.86 and 0.63 respectively. Bland-Altman analysis shows that the average discrepancy between the test and retest was -5 (95% CI: 35.6 to -52.6), -9.1 (95% CI: 20.2 to -38.4), -7.8 (95% CI: 107.7 to -123.2) and -28.5 (95% CI: 131.9 to -189.1) in MIP, MEP, PEF and PCF respectively. There was no significant difference in probability of discordance between parameters with the same unit of measure. Respiratory function variables show a moderate to high level of reliability, considering eight weeks of time interval between test and retest. PEF and MEP were the variables with the best performance.