Hospitalizations for all causes of US military service members in relationto participation in Operations Joint Endeavor and Joint Guard, Bosnia-Herzegovina, January 1995 to December 1997

Since December 1995, the United States has deployed military forces to Bosn ia-Herzegovina to participate for varying periods in peacekeeping operation s, Throughout the operations, medical surveillance data have been routinely integrated in the Defense Medical Surveillance System. For this analysis,; lll individuals who served in the U,S, armed forces between January 1995 an d December 1997 were characterized as participants or nonparticipants in th e Bosnia-Herzegovina operations, Each participant's service was divided int o predeployment, deployment, and postdeployment phases. End points for anal yses were hospitalizations (all causes) in military hospitals, The crude ho spitalization rate among nonparticipants (80.9 per 1,000 person-years [p-yr s]) exceeded the rate among participants (56.6 per 1,000 p-yrs), Among part icipants, the crude hospitalization rate during deployment (84.4 per 1,000 p-yrs) exceeded the rates before deployment (54.7 per 1,000 p-yrs) and afte r deployment (49.9 per 1,000 p-yrs). Proportional hazards regression proced ures were used to control for confounding effects in comparisons of partici pants and nonparticipants, to account for transitions in deployment-phase e xposures at appropriate calendar times, and to adjust for changes in hospit alization criteria that were implemented during the study. Although the cru de hospitalization rate after deployment was lower than the rate before dep loyment, adjusted relative risks were elevated during and after deployment (relative to before deployment).