A systematic literature review of psychological factors and the development of late whiplash syndrome.

This systematic literature review aims to assess the prognostic value of psychological factors in the development of late whiplash syndrome (LWS). We included prospective cohort studies that provided a baseline measure of at least one psychological variable and used outcome measures relating to LWS (i.e. pain or disability persisting 6 months post injury). A search of electronic databases (Pubmed, Medline, Cinahl, Embase and Psychinfo) up to August 2006 was done using a predetermined search strategy. Methodological quality was assessed independently by two assessors. Data extraction were carried out using a standardised data extraction form. Twenty-five articles representing data from 17 cohorts were included. Fourteen articles were rated as low quality with 11 rated as adequate quality. Meta-analysis was not undertaken due to the heterogeneity of prognostic factors, outcome measures and methods used. Results were tabulated and predefined criterion applied to rate the overall strength of evidence for associations between psychological factors and LWS. Data on 21 possible psychological risk factors were included. The majority of findings were inconclusive. Limited evidence was found to support an association between lower self-efficacy and greater post-traumatic stress with the development of LWS. No association was found between the development of LWS and personality traits, general psychological distress, wellbeing, social support, life control and psychosocial work factors. The lack of conclusive findings and poor methodological quality of the studies reviewed highlights the need for better quality research. Self-efficacy and post-traumatic distress may be associated with the development of LWS but this needs further investigation.