Background and purpose Ambulance workers could benefit from a method for early identification of incidents likely to result in long-term emotional sequelae. There is evidence that persistence of some measures of anxiety beyond the first week after an incident is associated with sequlae. In this study we test the hypothesis that persistence of self-identifiable components of the acute stress reaction as early as a few days post-incident is associated with sequelae.

Method 228 ambulance workers volunteered to complete surveys on occurrence and persistence of physiological, behavioural and emotional responses to an index critical incident in the past, as well as symptoms of depression, post-traumatic stress, somatisation and burnout at the time of the survey. Data were analysed for associations between duration of each reaction and present symptoms. Using cut-off scores for the outcomes, we tested the RR of high scores in each of three situations: occurrence of the reaction, persistence of reaction beyond one night and persistence beyond 1 week.

Results Prolonged duration of all five acute stress reaction components was associated with all four outcomes, with the strongest associations being with post-traumatic stress and depression symptoms. The occurrence of physical symptoms of arousal is an immediate predictor of long-term sequelae. Three other components—disturbed sleep, irritability and social withdrawal—provide potential indicators of long-term emotional sequelae as early as 2 days post-incident.

Conclusion Four easily identifiable responses to a critical incident can potentially be used for early self-identification of risk of later emotional difficulties. These findings should be submitted to prospective testing.