AIMS: To describe patterns of multiple symptom illness (MSI) in New Zealand military veterans, defined as clusters of "medically unexplained" symptoms not fitting within a specific medical diagnosis, and to investigate the relationship with exposure to traumatic events.

METHODS: We designed an online cross-sectional survey. The participants of interest were the 3,874 currently serving veterans who had been deployed to a conflict zone, but all veterans were eligible to participate. A modified Centers for Disease Control (CDC) 54-item symptom checklist identified MSI, the post-traumatic checklist-military version (PCL-M) identified symptoms of post-traumatic stress disorder (PTSD) and the brief trauma scale assessed "war zone" service. Factor analysis was used to identify unobserved "latent factors" in the data, factor severity scores and the number of symptoms being calculated for each respondent.

RESULTS: The CDC questionnaire was completed by 1,819 veterans, with 1,672 completing the PCL-M. The factor analysis revealed three factors, explaining 86% of the variation in the data. Factor 1 symptoms were of an arthro-neuromuscular nature, Factor 2 cognitive and Factor 3 psycho-physiological. Discriminant function analysis showed that the factors could discriminate between those with and without PTSD but could not discriminate between those who did and did not serve in a war zone.

CONCLUSIONS: In veterans, multiple symptoms including pain, sleep disorders, cognitive problems and avoidance, especially when severe, may be worthy of further investigation by health professionals because of the possible association with PTSD.