Introduction Improved early pain control may affect the longer-term prevalence of persistent pain. In a previous randomised, controlled trial, we found that the administration of ketamine on hospital arrival decreased pain scores to a greater extent than morphine alone in patients with prehospital traumatic pain. In this follow-up study, we sought to determine the prevalence of persistent pain and whether there were differences in patients who received ketamine or morphine.

Methods This study was a long-term follow-up study of the prehospital, prospective, randomised, controlled, open-label study comparing ketamine with morphine in patients with trauma and a verbal pain score of >5 after 5 mg intravenous morphine. Patients were followed-up by telephone 6–12 months after enrolment, and a questionnaire including the SF-36 (V.2) health-related quality of life survey and the Verbal Numerical Rating Scale for pain was administered.

Results A total of 97/135 (72%) patients were able to be followed-up 6–12 months after enrolment between July 2008 and July 2010. Overall, 44/97 (45%) participants reported persistent pain related to their injury, with 3/97 (3%) reporting persistent severe pain. The prevalence of persistent pain was the same between study groups (22/50 (44%) for the ketamine group vs 22/47 (46%) for the morphine group). There was no difference in the SF-36 scores between study arms.

Conclusions There is a high incidence of persistent pain after traumatic injury, even in patients with relatively minor severity of injury. Although decreased pain scores at hospital arrival are achieved with ketamine compared with morphine, this difference does not affect the prevalence of persistent pain or health-related quality of life 6 months after injury. Further larger studies are required to confirm this finding.

Trial Registration Number Australian and New Zealand Clinical Trials Registry (ACTRN12607000441415).