Comparing the digital dynamometer and Martin vigorimeter for handgrip strength: reliability, agreement, and prognostic value

Handgrip strength (HGS) measurement is vital for clinical assessment in older adults, yet comparative performance of different devices in Asian populations remains understudied. Prior validation focused mainly on healthy adults, but this is the first comprehensive comparison in institutionalized older adults with cognitive impairment and ADL disability. To compare the measurement properties and prognostic value of a digital dynamometer and Martin vigorimeter in Chinese nursing home residents, especially those with ADL disability and cognitive impairment. A multicenter longitudinal study of 772 residents (502 men, 270 women; median age 71.0 vs. 80.5 years) from 15 nursing homes. HGS was measured with both devices per standardized protocols. Test-retest and inter-rater reliability were evaluated using ICC, CV, SEM, MDC, and Spearman’s ρ. Device agreement was assessed via Bland-Altman, and prognostic value for 30-month mortality was analyzed with Cox regression, adjusting for multiple covariates. Both devices showed excellent test-retest reliability (digital ICC: 0.945; Martin ICC: 0.943). The Martin vigorimeter performed better in participants with ADL disability (CV: 10.48% vs. 14.01%; SEM: 8.6% vs. 11.6%; MDC: 23.0% vs. 25.7%). Inter-rater reliability favored the Martin device (ICC: 0.790 vs. 0.664). Strong correlations were observed (R = 0.60–0.62). Both devices had comparable prognostic value for mortality (adjusted HR: digital 4.50; Martin 2.77), despite different measurement principles. Both devices are reliable mortality predictors in older adults, but the Martin vigorimeter offers superior properties in those with ADL disability. These findings inform device selection for vulnerable older populations.