Objective: Health care utilization studies of mental disorders focus largely on the ICD-9 category 290-319, and do not generally include analysis of visits for mental health problems identified under V-code categories. Although active duty service members represent a large young adult employed population who use mental health services at similar rates as age-matched civilian populations, V-codes are used in a larger proportion of mental health visits in military mental health care settings than in civilian settings. However, the utilization of these diagnoses has not been systematically studied. The purpose of this study is to characterize outpatient behavioral health visits in military health care facilities prior to Operation Iraqi Freedom, including the use of diagnoses outside of the ICD-9 290-319 range, in order to evaluate the overall burden of mental health care. This study establishes baseline rates of mental health care utilization in military mental health clinics in 2000 and serves as a comparison for future studies of the mental health care burden of the current war.
Methods: All active duty service members who received care in military outpatient clinics in 2000 (n = 1.35 million) were included. Primary diagnoses were grouped according to mental health relevance in the following categories: mental disorders (ICD-9 290-319), mental health V-code diagnoses (used primarily by behavioral health providers that were indicative of a potential mental health problem), and all other diagnoses. Rates of service utilization within behavioral health clinics were compared with rates in other outpatient clinics for each of the diagnostic groups, reported as individuals or visits per 1,000 person-years. Cox proportional hazard regression was used to produce hazard ratios as measures of association between each of the diagnostic groups and attrition from military service. Time to attrition in months was the difference between the date of military separation and the date of first clinic visit in 2000. Data were obtained from the Defense Medical Surveillance System.
Results: The total number of individuals who utilized behavioral health services in 2000 was just over 115 per 1,000 person-years, almost 12% of the military population. Out of every 1,000 person-years, 57.5 individuals received care from behavioral health providers involving an ICD-9 290-319 mental disorder diagnosis, and an additional 26.7 per 1,000 person-years received care in behavioral health clinics only for V-code diagnoses. Attrition from service was correlated with both categories of mental health-related diagnoses. After 1 year, approximately 38% of individuals who received a mental disorder diagnosis left the military, compared with 23% of those who received mental health V-code diagnoses and 14% of those who received health care for any other reason (which included well visits for routine physicals).
Conclusions: This study establishes baseline rates of pre-war behavioral healthcare utilization among military service members, and the relationship of mental health care use and attrition from service. The research indicates that in the military population the burden of mental illness in outpatient clinics is significantly greater when V-code diagnoses are included along with conventional mental disorder diagnostic codes.