Simultaneous Bilateral Testing: Validation of a New Protocol to Detect Insincere Effort During  Grip and Pinch Strength Testing

Darrell Schapmire, MS, Industrial Rehabilitation Consultants, Hopedale, IL; James D. St. James, PhD, Department of Behavioral Sciences, Millikin University, Decatur, IL; Rob Townsend, MS, Work Conditioning Systems, Palos Heights, IL; Tom Stewart, PT, Allegheny and Chesapeake Physical Therapists, Ebensburg, PA; Steven Delheimer, MD (Neurosurgeon), Peru, IL; Dan Focht, OT, MA, Tri-State Occupational Health, Dubuque, IA

The detection of feigned weakness in hand-grip strength assessment is difficult. We review several proposed methods and their weaknesses. A comparison of unilateral testing and simultaneous bilateral testing with the Jamar™ dynamometer and the Baseline™ pinch gauge is demonstrated as a solution. An experiment employed 100 asymptomatic subjects tested twice, once under instructions to give a full effort and once under instructions to feign weakness. Seven statistical criteria of noncompliance were chosen. Defining noncompliance as failing two or more of the seven criteria, 99% of the instructed-noncompliant subjects were correctly classified as noncompliant. No subjects were incorrectly classified as noncompliant during instructed compliant testing. Twelve subjects failed a single criterion. On retesting, all but one were correctly classified. One subject in the instructed-noncompliant group passed all criteria. Including retesting of the 12 "grey-zone" subjects, accuracy was 99.5%.

"No single grip strength test has yet been described which unequivocally detects malingerers." (Tredgett et al., British Journal of Hand Surgery, 1999)

"The CV is not an appropriate method for determining whether an effort is sincere." (Shechtman, American Journal of Hand Therapy, 2000)

"One of the most important things is sincerity.  If you can fake that, you can do just about anything." (Kinky Friedman, Greenwich Killing Time, 1986)