Background: The term whiplash associated disorders (WAD) includes a wide range of complaints, with neck pain as predominating symptom. Living with long term pain influences quality of life. In previous studies of other chronic pain patients, subgrouping has been made according to thermal pain thresholds measured in quantitative sensory testing (QST).

Aims: The aims of the present study are threefold, (1) to evaluate thermal pain thresholds and health related quality of life in WAD patients compared to healthy pain-free individuals, (2) to explore whether subgrouping of the WAD patients is possible according to thermal pain thresholds over trapezius, and if so (3) to explore differences between the subgroups.

Methods: Twenty-six patients with WAD and 18 healthy pain-free controls took part in the study. Thermal pain thresholds were measured in two sites (over the thenar and the trapezius muscle) using quantitative sensory testing (QST). Health related quality of life (HRQoL) was assessed using the SF-36. The visual analogue scale was used to rate pain intensity and unpleasantness related to the experimental situation.

Results: WAD patients are more sensitive to thermal pain, and scored lower on the SF-36 in all scales when compared with healthy pain-free individuals. After analyzing clusters (K-means algorithm) two subgroups of WAD emerge, pain insensitive and pain sensitive. The pain insensitive group differed significantly from the pain sensitive group in the Role Emotional subscale of SF-36 (p=0.025).

Conclusions: Thermal pain hyperalgesia, especially for cold, seems to be a determinant for subgrouping WAD patients. These results support that such a classification of a heterogenous group could be of importance in tailoring treatment and early interventions.