Test–Retest Reliability of Handgrip Strength in Patients with Chronic Obstructive Pulmonary Disease

The purpose of this study was to investigate the intra-rater reliability and agreement of handgrip strength (HGS) measurement using a hydraulic hand dynamometer in patients with chronic obstructive pulmonary disease (COPD). A sample of 19 COPD patients (18 males and 1 female; mean ± SD age, 66.9 ± 6.3 years) was evaluated using a hand dynamometer by the same rater in two different testing sessions with a 7-d interval. During each session, patients were asked to exert three maximal isometric contractions on the dominant hand and the mean value of the 3 efforts (measured in kilogram-force [Kgf]) was used for data analysis. The intraclass correlation coefficient (ICC2,1), the standard error of measurement (SEM), the minimal detectable change (MDC), and Bland–Altman methods were used to estimate the degree of test–retest reliability and the measurement error, respectively. HGS in COPD patients revealed an ICC2,1 score of 0.99, suggesting excellent test–retest reliability. The calculated SEM was relatively small (0.59 Kgf), and the MDC presented a clinically acceptable value of 1.64 Kgf. These findings, in conjunction with the narrow width of the 95% limits of agreements (95% limits of agreement, −2.5–2.1 Kgf) in the Bland–Altman plot, reflected the measurement precision and the narrow variation of the differences during the 2 testing sessions. The results of this study demonstrated an excellent test–retest reliability of HGS measurement, indicating that this method is reliable for repeated monitoring of peripheral muscle strength in patients with COPD.