Test-retest reliability and preliminary reference data for the Virtual Eggs Test in healthy adults

Rehabilitation professionals rely on hand assessment to select the proper therapy and monitor the recovery process over time. The Virtual Eggs Test (VET) is a unique assessment tool that evaluates both fine and gross hand dexterity, taking into account not only the speed in performing an action but also the accuracy in regulating the grip force. The VET was preliminary validated with amputees and healthy individuals, demonstrating construct validity, but also highlighting some weaknesses that required a protocol revision. Here, we present the update version of the protocol and of the outcomes measure (Fine Dexterity Index - FDI - and Gross Dexterity Index - GDI). We carried on a clinical trial involving 79 healthy participants, stratified by age groups, to collect normative data and evaluate test-retest reliability. The FDI and the GDI demonstrate no significant difference between test and retest. FDI showed excellent reliability (ICC was 0.90 and 0.91 for the dominant and non-dominant hand, respectively). While GDI demonstrated moderate reliability (ICC was equal to 0.63 and 0.64 for the dominant and non-dominant hand, respectively). The findings indicate that the VET is reliable over time for the evaluation of hand function in tasks involving fragile objects.