Five-position grip strength measures in individuals with clinical depression

Case-control study.

To compare the results of 5-position grip strength testing between a group of individuals newly diagnosed with clinical depression and a group of age-matched and sex-matched individuals without depression.

Clinicians often employ 5-position (or 5-rung) grip strength dynamometry as a measure of sincerity of effort. However, patients with clinical depression are known to show altered performance on motor skill tests. Therefore, the results of 5-position grip strength dynamometry in the clinically depressed may be subject to misinterpretation.

Consecutive patients newly diagnosed with clinical depression (n = 45) and age- and sex-matched individuals without clinical depression (n = 45) were recruited over a 3-month period. Each group underwent identical 5-position grip strength testing of both hands. Measures were analyzed using a statistical analysis method based on an 8.5-lb (3.83-kg) SD cutoff and visual analysis of force curve plots by clinicians naïve to the participants' diagnosis.

Participants with clinical depression had an SD equal to or less than 8.5 lb in 60 of 90 hands tested, while the participants in the control group had an SD equal to or less than 8.5 lb in 1 of 90 hands. Clinicians who analyzed force plots considered participants with depression to have exerted "limited effort" in 70% of cases and those who were not depressed to have exerted limited effort in 18% of cases.

A high percentage of individuals diagnosed with clinical depression produced statistical and graphical representations of 5-position grip strength measures that suggested poor volitional effort, which is often interpreted as lack of sincerity of effort. Clinicians unaware of the presence of clinical depression in patients could misinterpret the results of 5-position grip strength testing in this population.