The effect of changes in pain expectations on persistent pain following a road traffic crash.

BACKGROUND: Recovery expectations can influence outcomes after injury, but little is known about the course of expectations over time or factors predicting changes in expectations. This study aimed to describe how expectations of persistent pain change over time following a non-catastrophic injury sustained in a road traffic crash (RTC); identify the early predictors of change in expectations over time; and examine whether change in expectations predicted pain at 24 months post-RTC.

METHODS: One hundred and seventy-seven participants (Mage = 49.25; SD = 14.15; 66.1% female) reported their expectations of persistent pain (1 = no risk that pain will become persistent, 10 = highest risk) at approximately 6, 12 and 24 months post-injury via survey. Measures of pain, emotional distress, post-traumatic stress, fear avoidance beliefs, social support and quality of life were also measured via survey at each time point.

RESULTS: Cluster analysis revealed four clusters: 42% of participants showed a pattern of stable expectations (stable high-risk, n = 74), whereas 58% of participants showed changes in expectations over time (decreasing risk, n = 31; increasing risk, n = 44; risk peaking at 12 months, n = 28). Hierarchical linear regression models demonstrated that the clusters were a better statistical predictor of pain at 24 months than a single measure of expectation taken at 6 months post-injury. Pain, anxiety, depression and physical health-related quality of life at 6 months were associated with cluster affiliation.

CONCLUSIONS: Assessment of patterns of pain expectancy change is a superior means of determining long-term pain levels. Understanding expectancy change patterns will help provide more nuanced targets for pain intervention.

SIGNIFICANCE: This study extends previous work by investigating persistent pain expectancies over time in a compensation-seeking cohort with non-catastrophic injuries. It identifies factors that are associated with changing expectations, providing targets for clinical intervention. The study shows that expectations can change over time. Conversations with patients about their expectations should be ongoing.