Longitudinal Changes and Associations Between Quantitative Sensory Testing and Psychological Factors in Whiplash-associated Disorders: A Systematic Review and Meta-analyses-based Data Synthesis

Whiplash-associated disorders (WAD) represent a multifactorial condition often accompanied by altered nociceptive processing and psychological factors. This systematic review on acute and chronic WAD aimed to investigate the relationship between quantitative sensory testing (QST) and psychological factors and quantify whether their trajectories over time follow a similar pattern to disability levels. Eight databases were searched until October 2022. When 2 prospective studies examined the same QST or psychological variable, data synthesis was performed with random-effects meta-analysis by pooling within-group standardized mean differences from baseline to 3-, 6-, and 12-month follow-ups. From 5,754 studies, 49 comprising 3,825 WAD participants were eligible for the review and 14 for the data synthesis. Altered nociceptive processing in acute and chronic WAD, alongside worse scores on psychological factors, were identified. However, correlations between QST and psychological factors were heterogeneous and inconsistent. Furthermore, disability levels, some QST measures, and psychological factors followed general positive improvement over time, although there were differences in magnitude and temporal changes. These results may indicate that altered psychological factors and increased local pain sensitivity could play an important role in both acute and chronic WAD, although this does not exclude the potential influence of factors not explored in this review. PERSPECTIVE: Acute WAD show improvements in levels of disability and psychological factors before significant improvements in nociceptive processing are evident. Facilitated nociceptive processing might not be as important as psychological factors in chronic WAD-related disability, which indicates that chronic and acute WAD should not be considered the same entity although there are similarities. Nonetheless, pressure pain thresholds in the neck might be the most appropriate measure to monitor WAD progression.