Exploring the ability of strength and dexterity tests to detect hand function impairment in individuals with Parkinson’s disease

Parkinson's disease (PD) can affect hand function since the beginning of the motor symptoms.To compare the ability of different hand function tests to: 1) distinguish individuals with PD from healthy controls; 2) differentiate stages of the disease; and 3) indicate changes over time due to disease progression.Twenty-four individuals with PD (Hoehn and Yahr: I-III) and 24 age- and sex-matched controls performed the Jebsen-Taylor Hand Function Test (JTHFT), the Nine-Hole Peg Test (9HPT), and the maximum grip and the maximum pinch strength tests using their right and left hands. Eight individuals with PD (six females and two males) were reassessed after 18 months. The ROC analyses and Mann-Whitney U tests (for disease progression) using the average performance of the hands were done.Individuals with PD presented worse test performances than controls, except for the writing subtest of the JTHFT and the grip strength test. The JTHFT without the writing subtest (JTHFTnoW) was the most accurate to discriminate PD from controls (AUC = 0.899; sensitivity 75% and specificity 95.8%). The 9HPT and the simulated feeding and moving large, light objects JTHFT subtests were sensitive to distinguish stages, while the 9HPT, the moving small, common objects JTHFT subtest, and the grip strength were sensitive to changes with disease progression.The JTHFTnoW was highly discriminative of the hand function impairments in PD. TwoJTHFT subtests were the most sensitives to distinguish PD stages (i.e. simulated feeding JTHFT subtest) and disease progression (i.e. moving small, common objects JTHFT subtest).