The Effect of Priming With Questionnaire Content on Grip Strength in Patients With Hand and Upper Extremity Illness

Background: Grip strength is a performance-based measure of upper extremity function that might be influenced by priming (the influence of a response to a stimulus by exposure to another stimulus). This study addressed the influence of questionnaire content on performance measurements such as grip strength between patients who complete the standard Pain Catastrophizing Scale (PCS) compared with patients who complete a positively adjusted PCS. Methods: Between June 2015 and August 2015, we enrolled 122 patients who presented to 3 hand surgeons at 3 outpatient offices. They were randomized to 2 groups: the control group, which completed the PCS, and the intervention group, which completed a positively phrased version of the PCS. Before and after completion of the questionnaire, we measured each patient’s grip strength 3 times by alternating between hands. Two patients were excluded after participation. We calculated both the preintervention and postintervention mean and maximum grip strengths. Results: There was no significant difference between groups on mean or maximum grip strength before completion of the questionnaires. There was a greater improvement in mean grip strength of both hands in the intervention group compared with the PCS group. This improvement was statistically significant in the affected hand. The maximum grip strength showed a statistically significant greater improvement in both hands in the positive PCS group compared with the control group. Conclusions: Positive priming through a questionnaire leads to an increase in mean and maximum grip strength when compared with the standard questionnaire that uses negative terms rather than positive.