Objective: To investigate the test-retest reproducibility and smallest real difference (SRD) of 3 hand strength tests (grip, palmar pinch, and lateral pinch) and 2 dexterity tests (the Box and Block test [BBT] and the Nine Hole Peg test [NHPT]) in patients with stroke.
Methods: The 5 tests were administered on 62 stroke patients in 2 sessions, 3 to 7 days apart. The intraclass correlation coefficient (ICC) was used to determine the level of reproducibility between measurements on 2 sessions. The SRD was used to determine the extent of measurement error because of chance variation in individual patients. SRD percentage (SRD relative to mean score) was used to compare test-retest reliability across tests. We analyzed the group as a whole, then in 2 subgroups (hand spasticity vs none).
Results: The test-retest reproducibility of all 5 tests was high for all the patients, with ICCs ranging from 0.85 to 0.98. The SRDs for the more/less affected hand were: 2.9/4.7 kg for the grip test; 1.2/1.3 kg for the palmar pinch test; 1.4/1.0 kg for the lateral pinch test; 5.5/7.8 blocks/minute for the BBT; and 32.8/6.2 seconds for the NHPT. Unacceptably high SRD percentages (>30%) were found for the affected hand using the NHPT (54%), palmar pinch (35%), and lateral pinch (34%). When comparing these indices for participants with spasticity versus none for all 5 tests, the ICCs were lower and the SRD and SRD percentage were higher for the spasticity group.
Conclusions: All 5 tests demonstrated satisfactory test-retest reproducibility for a diverse group of patients with stroke. However, all tests showed higher levels of measurement error when performed with the more affected hand and in patients with hypertonicity of that hand. Thus, baseline and postrehabilitation change scores using these common tests of strength and dexterity must be interpreted with some caution, especially in poorly controlled clinical trials. Repeated measures ought to be incorporated to examine reliability within a trial that includes participants with a hypertonic hand.