Title: Prospective Study of Functional Status in Veterans at Risk for Unexplained Illness
Principal Investigator: Karen Quigley, PhD
Background: Previous deployments like that to the Persian Gulf in 1991 produced veterans with post-deployment symptom-based health problems with no medical explanation. This was termed Gulf War illness or medically unexplained illness. If previous wars are any indication, some soldiers currently deployed to hostile areas also will return home with unexplained symptom-based illnesses. However, there is virtually no pre-war, prospective data on risk and resilience factors associated with medically unexplained illness. This study will attempt to fill that gap.
Objectives: Our goals are to: (a) determine the pre- and immediate post-deployment factors predicting later medically unexplained illness and poor functional status, (b) improve previous methodological problems (e.g., selection bias, recall bias and lack of baseline controls) in studies of medically unexplained illness, and (c) relate pre-deployment risk factors (e.g., stressor reactivity, exposure history, personality) and resilience factors (e.g., coping style, social support) to post-deployment functional status.
Research Plan: Veteran and civilian individuals will be recruited for one of several studies assessing (a) risk perceptions of a vaccine, (b) symptoms and psychological distress following a vaccine, and (c) the effectiveness of a vaccine. Other studies will be used to design the vaccine information sheets and to test a computerized risk/benefit task.
Methods: This study uses a prospective, longitudinal observational design to assess risk and resilience factors for post-war medically unexplained illness in Reserve and National Guard enlisted personnel. A stratified random sample of 700 subjects will be drawn from those undergoing pre- and post-mobilization readiness processing at Fort Dix, New Jersey. Personnel will be tested pre-mobilization (Phase 1), immediately after mobilization Phase 2) and at 3 months and 1 year post-deployment (Phases 3 & 4). Primary predictor variables include personality, social support, coping style, current symptoms, sympathetic cardiac stress reactivity, and cortisol (i.e., hormonal) stress reactivity. Other variables include prior traumatic events, current distress, PTSD symptoms, body mass index, deployment experiences, environmental exposures and demographics (e.g., age, gender). Outcome variables include functional status, health care utilization, and medically unexplained illness status (using CDC criteria for chronic multisymptom illness developed after the first Gulf War).
Results: We are currently completing a pilot study to demonstrate the feasibility of our methods where we are comparing 3 groups: (a) healthy controls, (b) individuals with chronic fatigue syndrome (CFS), and (c) veterans with symptoms indicating chronic multisymptom illness (CMI) using measures that will be used in Phase 1 of the prospective study with soldiers. Our initial pilot study results show that the procedures are feasible and the response burden on subjects is reasonable. Further results are pending the completion of data collection. An interesting early finding is that most subjects showed one of two patterns of cortisol response. One pattern was characterized by peak cortisol levels occurring approximately 10-20 minutes after the completion of the stressor tasks (a relatively typical responder pattern). The other pattern was revealed in subjects who had high cortisol levels at the beginning of the session, but no subsequent response to stressors (non-responder pattern). Notably, all of the individuals in the small group of CFS/CMI subjects for whom we have analyzed cortisol data (N=4) fit the non-responder pattern.
Status: Project is ongoing.
Impact:The larger, prospective study with soldiers will help us to identify pre- and early post-deployment risk and resilience factors important in medically unexplained illness, functional status, and health care utilization. There is an urgent need for both pre- and post-deployment predictors of later medically unexplained illness. If we are to understand how to best treat veterans presenting with unexplained symptoms, then we need to know which factors, occurring at what time in the illness process (including pre-illness factors) are most important. Understanding these could help us to develop appropriate pre-deployment inoculation strategies, and focus resources on particular "at risk" individuals soon after symptom onset when dysfunction and disability can be treated more effectively.