Assessment of Inter-Instrument Reliability for Dominant Handgrip Dynamometry and Spirometry

Purpose: The aim of this study was to determine the inter-instrument reliability different dynamometers and spirometers commonly used in clinical practice. Methods: involved 113 healthy volunteers across three facility sites. At each site, dominant handgrip strength (DHGS), lung function (forced expiratory volume one second [FEV1], forced vital capacity [FVC] peak flow rate [PEFR]), were compared using a local reference device. Assessments randomized with five minutes rest between measurements. Significant differences devices assessed paired t-test while relative determined via intra-class correlations (ICC). Accuracy index variability measurements technical error measurement (TEM%) coefficient variation (CV), respectively. Agreement Bland Altman’s plot limits agreement (LOA). Results: recorded significantly (p1 (3.1%-8.4%), FVC (3.1%-13%) devices. Good-excellent (ICC=0.89-0.96), unacceptable CV (5.8-9.9%) TEM% (6.6-9.9%), large mean biases (3-9kg) LOA (3-23kg) identified dynamometers. Excellent (ICC=0.91-0.99), mostly for PEFR. Compared device, all showed (-0.134 -0.536 liters) acceptable (-0.12 0.05 liters/second) PEFR, Conclusion: Unacceptable measuring DHGS indices, Across settings, comparing brands may lead reporting erroneous results corrective adjustments required