This is the first national study of VA non-mental health medical service utilization in veterans returning from Iraq and Afghanistan. In this population, those diagnosed with mental disorders had significantly greater utilization of all types of non-mental health outpatient, emergency, and inpatient medical services than those receiving no mental health diagnoses. Veterans diagnosed with PTSD had the greatest utilization in all service categories. In adjusted analyses, compared with those with no mental health diagnoses, total utilization of outpatient non-mental health services was 55% greater in veterans with mental health diagnoses other than PTSD and 91% greater in veterans with PTSD. Though mental health diagnostic status was the strongest independent predictor of utilization, female sex and lower rank were also associated with significantly greater utilization.
The higher rates of utilization among OEF/OIF veterans with mental disorders are notable because this is a relatively young population. The mean age in our study was 31
9 years old, and only 4% were over 50 years of age. Comparing our results to utilization in non-VA populations is challenging because the demographic characteristics and categorization of services differ somewhat. Nevertheless, data from the 2004 United States National Ambulatory Medical Care Survey estimated that men aged 18–44 years (the closest demographic group to our population) had 1.36 general and specialty physician office visits per person.25
In our study, those with no mental health diagnoses had 1.52 primary care or medical/surgical subspecialty visits per year. Thus, VA non-mental health service utilization in OEF/OIF veterans with no mental disorders may approximate that of the general population, underscoring the increased need for veterans with mental disorders.
Our findings expand upon studies of mental disorders and utilization of medical services conducted in veterans of prior wars.11,15–19
In a study of 2,508 female veterans receiving care at an urban VA medical center between 1996 and 2000, Dobie and colleagues found that after adjusting for demographics, smoking, service access, and medical comorbidities, those who screened positive for PTSD had a significantly greater likelihood of having a medical or surgical hospitalization (OR 1.37, 95% CI 1.04–1.79).11
They were also significantly more likely to be in the highest quartile of utilization for emergency room, primary care, and ancillary services. Another study of 996 veterans, primarily from the Vietnam era, evaluated between 1992 and 1998, demonstrated that those who met criteria for PTSD had significantly greater utilization of non-mental health outpatient services than those without PTSD (median of 18 versus 10 visits per year).15
Other studies have demonstrated that the increase in health services utilization in veterans with PTSD is not due to co-morbid psychiatric conditions, such as anxiety and depression.26,27
Our study adds to this prior research by using national-level data, adjusting for several additional military service characteristics, and exploring utilization in OEF/OIF veterans, a group for which data are very limited.6
There are several possible explanations for our finding of increased utilization of non-mental health services in OEF/OIF veterans with mental disorders, particularly PTSD. First, exposure to combat or other traumatic events that resulted in mental health disorders may have also caused physical problems such as traumatic brain injury or musculoskeletal injuries.20,21
Second, mental disorders are frequently associated with somatic symptoms, and these physical symptoms as well as stigma surrounding mental health issues might prompt patients to seek care in non-mental health clinics.6
Third, mental disorders and PTSD may cause biological and behavioral changes that increase the risk of physical disease, leading to greater medical utilization.28, 29,12–14,30–34
Finally, there may be an increased likelihood of detection of medical problems in veterans with mental health problems, for example, through symptoms identified by mental health providers. Veterans with comorbid mental and physical problems may also be more likely to enroll in primary care, which could lead to increased utilization of other services, such as preventive screening through laboratory and diagnostic tests. However, we explored the influence of mental health and primary care visits in sensitivity analyses and found that these had only a modest effect on utilization.
Beyond mental health status, we examined several sociodemographic and military service characteristics as predictors of utilization. It is unclear whether the gender and racial differences in utilization seen in this study reflect disparities in general health, trauma exposure, preferences for VA care, or access to non-VA care.22,35
Prior studies have demonstrated that military sexual trauma is more common in female veterans and is associated with mental and physical comorbidities.36
Though we did not have data on military sexual trauma, it would be interesting to explore how this impacts gender differences in utilization. Our finding that active duty and lower rank veterans had increased utilization may be explained by the greater exposure to combat-related trauma in these veterans who were likely on the front lines.37
Other factors, such as differential access to private insurance in these generally younger veterans, could also affect utilization of VA care.38
Our results should be interpreted in light of several limitations. First, because we examined only OEF/OIF veterans who have accessed VA care, our findings may not generalize to all OEF/OIF veterans. Examining the effects of mental health conditions on utilization of non-VA services will provide valuable information for the many other systems that provide care to returning veterans. A second limitation is our use of ICD-9-CM diagnostic codes to classify veterans by mental health status. ICD-9-CM codes may be used by clinicians as “rule out” rather than definitive mental health diagnoses. However, in a prior study, we found that the majority of these diagnoses were confirmed on subsequent visits and by mental health providers.3
Still, reliance on ICD-9-CM codes could have led to over- or under-diagnosis of mental health conditions.
Third, because we defined mental health status by diagnoses made over the entire study period, some of a veteran’s utilization may have occurred prior to the date of diagnosis. However, it is well established that due to barriers in seeking and obtaining care, patients typically experience mental health symptoms for years prior to their date of diagnosis.38–40
In addition, we cannot determine the direction of the association between mental disorders and increased non-mental health service utilization. Finally, though our analyses provide information on veterans’ use of VA services, detailed economic analyses and analyses of the VA’s capacity to meet demand for services were beyond the scope of this study.
Despite these limitations, our findings have important implications for healthcare systems that care for returning OEF/OIF veterans and for future research directions. We found that mental health disorders and several demographic and military factors were associated with increased use of outpatient, emergency, and inpatient non-mental health services. As more veterans return home, many with mental and physical injuries, evaluating the capacity of the VA and other healthcare systems to meet these needs will be increasingly important. Future work should also explore how new models of care affect utilization in veterans with comorbid mental and physical health problems. For example, integrating mental health and primary care is a priority in the VA as it can reduce stigma and improve access to mental health treatment. Though such integration of care has been found to improve clinical outcomes, its affect on utilization deserves further study.9
This information could be used to improve the quality and efficiency of care for returning veterans and to guide allocation of resources to ensure the medical needs of the growing veteran population are met.