Sincerity of effort versus feigned movement control of the cervical spine in patients with whiplash-associated disorders and asymptomatic persons: a case-control study.

STUDY
DESIGN: Cross-sectional design.
OBJECTIVES: To investigate whether the Fly Test can be used to differentiate patients with whiplash-associated disorders (WAD) from asymptomatic persons who deliberately feign symptoms and from WAD patients exaggerating symptoms.
BACKGROUND: The lack of valid clinical tests makes it difficult to detect a justifiable cause for compensation claims in traumatic neck-pain disorders.
METHODS: The Fly Test recorded the accuracy of neck movements in patients with WAD (n = 34) and asymptomatic persons (n = 31). The participants followed a moving "Fly" on a computer screen with a cursor from sensors mounted on the head. Two conditions were tested, sincere versus feigned efforts. In the former, the participants moved their neck as accurately as possible. In the latter, a short text was presented describing a fictitious accident (asymptomatic group) or imagining more intense pain/suffering (WAD group), and the test was performed as affected by these more serious conditions. Amplitude accuracy (AA), time on target (ToT) and jerk index (JI) were compared across patterns, conditions and groups.
RESULTS: The sincere effort in the WAD group was significant compared to the feigned effort of the asymptomatic group (p < 0.001). For AA, correct categorization of 81.5% of the performances was made, where a mean score above 5.5 mm differentiated feigned versus sincere efforts in asymptomatic and WAD groups (sensitivity 79.4%, specificity 67.7%). For ToT, score above 11% indicated correctly categorized WAD patients (sensitivity 82.4%, specificity 64.5%).
CONCLUSION: The Fly Test can provide clinicians a clue when patients with mild to moderate pain/disability are feigning or exaggerating symptoms.