Identification of homogeneous subgroups of patients with chronic whiplash-associated disorders on the basis of common clinical features may aid the development and assessment of treatments for this condition.
The lack of efficacy of rehabilitative approaches to the management of chronic whiplash-associated disorders (WAD) may be in part due to heterogeneity of the clinical presentation of this patient population. The aim of this study was to identify homogeneous subgroups of patients with chronic WAD on the basis of symptoms of PTSD and sensory hypersensitivity and to compare the clinical presentation of these subgroups. Successive k-means cluster analyses using 2, 3 and 4 cluster solutions were performed by using data for 331 (221 female) patients with chronic (>3 months) WAD. The 4 cluster solution was identified as the most clinically relevant, yielding 4 distinct clusters: no to mild posttraumatic stress symptoms and no sensory hypersensitivity (nPnH), no to mild posttraumatic stress symptoms and sensory hypersensitivity (nPH), moderate to severe posttraumatic stress and no sensory hypersensitivity (PnH) and moderate to severe posttraumatic stress and sensory hypersensitivity (PH). The nPnH cluster was the largest cluster, comprising 43.5% of the sample. The PH cluster had significantly worse disability, pain intensity, self-reported mental health status and cervical range of motion in comparison to the nPnH and nPH clusters. These data provide further evidence of the heterogeneity of the chronic WAD population and the association of a more complex clinical presentation with higher disability and pain in this patient group.