Psychological factors in the use of the neck disability index in chronic whiplash patients.

STUDY DESIGN: Cross-sectional clinical study.

OBJECTIVE: Determine if psychological factors "fear avoidance behavior" and "pain amplification," along with age, gender, duration, and pain severity correlate with scores of self-rated disability in chronic whiplash sufferers.

SUMMARY OF BACKGROUND DATA: The Fear Avoidance Model has gained acceptance in the understanding of whiplash-associate disorders (WAD). While the variables important in this model have been studied in acute/subacute samples and some small chronic samples, no study has explicitly investigated the role these and other psychosocial variables play in the self-ratings of neck-related disability in chronic WAD sufferers.

METHODS: Chronic WAD sufferers (>3 months) were recruited from private practice. No WAD IV subjects were included. Subjects completed a Neck Disability Index (NDI), Tampa Scale for Kinesiophobia (TSK), pain visual analogue scale, and pain diagram. Clinical and demographic data were also obtained. Univariate correlations were obtained with the Spearman rank correlation coefficient. Items achieving statistical significance on univariate analysis were loaded in a step-wise linear regression analysis.

RESULTS: One hundred seven subjects were investigated (54 females), with a mean age of 45.4 (17) years and a mean duration of 13.4 (14.6) months. Fair to moderately strong correlations were obtained between the NDI and the TSK, pain visual analogue scale and pain drawing scores, but not with "duration." The Pain Diagram correlated with NDI scores and pain severity. A multivariate model accounting for 31% of the variance of the NDI scores (P < 0.001) was obtained with the TSK, pain severity, and pain drawing.

CONCLUSION: It appears that important psychological factors (fear avoidance beliefs and pain amplification) do have some influence on self-ratings of disability in chronic WAD sufferers. This does not appear to be larger than that found in studies of acute/subacute subjects. The influence of these factors may plateau fairly early in the post-WAD period. There is some evidence that the Pain Diagram may provide insight into nonorganic pain behavior.