Predicting and Planning for Musculoskeletal Service-Connected Disabilities in VA Using Disability for Active Duty OEF/OIF Military Service Members

Introduction Musculoskeletal (MSK) conditions are commonly seen among military service members (SM) and Veterans. We explored correlates of award of MSK-related service-connected disability benefits (SCDB) among SM seeking care in Veterans Affairs (VA) hospitals. Materials and Methods Department of Defense data on SM who separated from October 1, 2001 to May 2017 were linked to VA administrative data. Using adjusted logistic regression models, we determined the odds of receiving MSK SCDB. Results A total of 1,558,449 (79% of separating SM) had at least one encounter in VA during the study period (7.8% disability separations). Overall, 51% of this cohort had at least one MSK SCDB (88% among disability separations, 48% among normal). Those with disability separations (as compared to normal separations) were significantly more likely to receive MSK SCDB (odds ratio 2.37) as were females (compared to males, odds ratio 1.15). Conclusions Although active duty SM with disability separations were more likely to receive MSK-related service-connected disability ratings in the VA, those with normal separations also received such awards. Identifying those at highest risk for MSK-related disability could lead to improved surveillance and prevention strategies in the Department of Defense and VA health care systems to prevent further damage and disability.

Keywords: awards and prizes; kidney; sponge; military personnel; veterans; disability

Musculoskeletal (MSK) conditions involving upper and lower extremities and the vertebral column are currently among the most commonly treated disorders in Department of Defense (DoD) military treatment facilities[1] and U.S. Department of Veterans Affairs (VA) medical facilities.[2] Both deployed and nondeployed service members (SM) experience these conditions caused by acute traumatic injuries (battle and nonbattle), overuse, sprains, and strains.[3],[4] For deployed SM, the dramatic improvement in care of battle injuries sustained in recent conflicts has saved lives, leaving them with sequelae and disabilities of acute and chronic orthopedic injuries involving the extremities, head/neck, thorax, and abdomen.[3],[5] Similarly, nonbattle MSK injuries are an underrecognized problem among SM[4] and are among the leading causes of medical encounters among military personnel.[1] Once the SM enter Veteran status and seek medical care in the VA, these conditions account for a majority (on average 61%) of outpatient and inpatient visits in VA medical facilities; the top diagnoses being MSK ailments comprising joint and back disorders.[2]

With injuries being a hallmark of military service and management of these and associated conditions to be expected in Veterans, the VA has developed particular expertise in caring for short- and long-term sequelae of injuries and MSK arising from overuse and strain. As the recent conflicts in Iraq and Afghanistan are now extending to over 18 years and the medical needs of Veterans are expected to peak in the year 2035, the costs are estimated to be close to a trillion dollars.[6] This includes planning for personnel resources such as clinical providers from various disciplines such as primary care, internal medicine, general and orthopedic surgery, physical medicine and rehabilitation, physical/occupational therapy, and rheumatology among others. Veterans also require brick and mortar health care centers for their care and material resources such as prosthetics, walking aids, and other services. An important aspect of caring for Veterans is a national policy that provides them with disability benefit awards for loss of function/injury or mental health conditions that are a direct result of or are aggravated by their military service.[7] Benefits include a tax-free monthly monetary compensation and access to free health care in VA, along with vocational rehabilitation and employment services. In 2013, nearly 3.5 million Veterans were receiving compensation totaling about $54 billion a year[8] for service-connected disability benefits (SCDB) and MSK accounts for nearly a third of SCDB among new compensation recipients.[9]

Apart from assuming that all Veterans will require disability compensation for injuries sustained or worsened during military service, the VA has few resources to predict the nature and level of disability benefits anticipated for newly enrolled Veterans from the recent conflicts in Iraq and Afghanistan. One predictor for future resource needs may be the separation category of SM. The DoD assigns each active duty SM an interservice separation code that indicate the circumstances related to discharge from service. Although most SM separate under routine or normal circumstances, a significant minority are separated for disability. We performed this study to address the hypothesis that future MSK service-connected (SC) disability determinations in the VA could be predicted by disability separations from the military.

We conducted this research with approval of the University of Utah Internal Review Board (IRB #00091744), the Research & Development Committee at the VA Salt Lake City Health Care System, and according to regulatory requirements of the Veterans Informatics and Computing Infrastructure (VINCI).

The study population comprised the entire cohort of active duty SM listed in the VA Defense Manpower Data Center file (VA/DoD Identity Repository [VADIR]) who separated from the military from October 1, 2001 to May 2017. VA administrative data were accessed using the VINCI,[10] and the VADIR file was imported into VINCI after appropriate regulatory approvals. Unique identifiers from VADIR were used to link the SM to VA administrative data to determine SC disability for MSK in the VA up to March 2018 using the "VARatedDisability" file from the VA Corporate Data Warehouse. The extension of the study period to March 2018 was to allow for at least 10 months of observation after military separation for adjudication of disability benefits.

The primary outcome for our study was the award of SCDB by the VA for any MSK condition at any percent from 0 to 100. We identified SC disability conditions as a set of MSK conditions using an inclusive definition for MSK by expert opinion of the study team. Independent variables for our analyses were extracted from VADIR and included demographics such as sex, year of birth, race, level of education, branch of service, enlisted (E1–9), warrant officer (W1–5) or officer (O1–10) pay grades, combat flag (whether they received hazard pay for serving in a combat zone), and marital status.

We used logistic regression models to estimate the odds of receiving an SCDB for MSK conditions with the key independent predictor variable for test of our hypothesis as the disability type of separation from the military as compared to normal (or routine) separations. The interservice separation codes were from VADIR and were classified as routine vs. nonroutine based on prior work.[11],[12] Disability separations were comprised of five subcategories: condition existing before service; disability, severance pay; permanent disability retirement; temporary disability retirement; and disability, no condition existing before service, no severance pay. If there was more than one type of separation for an SM during the study period, the separation type assigned to the SM was one of potential greatest influence on MSK conditions is this order (as determined by discussion among study team): disability, disqualified, early, misconduct, or normal. Models were adjusted for demographic variables listed above. Significance was set at the P = 0.05 level or lower.

The distribution of MSK disability conditions (by anatomy and disease process) that were the basis for the disability benefits were compared between normal and disability separations using the Chi-square statistic. Analyses were performed using R Version 3.5.1.[13]

From October 2001 to May 2017, a total of 1,969,724 SM experienced 3,472,031 separations from the military. Nearly half of the separation codes were either null, unknown, or applicable (likely representing National Guard/Reserve SM as only active duty SM receive an interservice separation code). Of the total SM, 1,558,449 (79%) had at least one encounter in VA administrative data during the study period (Table I). The racial/ethnic distribution of the study cohort generally followed the distribution of Veterans seen in the VA with non-Hispanic Whites forming the majority. Half of the cohort was from the Army (51%), and the majority (1,175,494, 75%) had a normal or routine separation. Of the nonroutine separations (disability, disqualified, early, and misconduct), a total of 121,314 SM (7.8%) separated for disability; these and other Veterans filed disability claims in the VA postdeployment (Fig. 1). Of the total SM seen in the VA, 794,371 (51%) received an MSK SCDB. Eighty eight percent of those with disability separations, 52% of those with early separations, 48% of those with normal and disqualified separations, and 39% of those with misconduct separations received an MSK disability benefit in the VA.

TABLE I Demographic Characteristics and VA MSK Service-Connected Disability Status of 1,558,449 SM Who Separated From the Military From October 1, 2001 to May 2017 and Had At Least One Encounter in the VA During the Study Period (up to March 2018)

Graph: FIGURE 1 Process flow of SM's deployment, separation from the military and award of disability claims in the VA.

Graph: FIGURE 2 Distribution of MSK-related disability conditions of those receiving VA SCDB for MSK conditions, by anatomy and disease process. Normal separations: 1,175,494 SM (75% of all separations), Disability separations: 121,314 SM (7.8% of all separations). "Other condition" includes vascular issues, embolism, and urticaria.

As shown in Table II, female Veterans were more likely than males to receive an MSK SCDB (odds ratio [OR] 1.15, P < 0.001). Black and Hispanic Veterans were marginally more likely to receive these awards (OR 1.04 and 1.03, respectively, P < 0.001). Other demographic characteristics were found to be significant in predicting MSK SCDB; married and divorced Veterans were more likely to receive awards (OR 1.16 and 1.13, respectively, P < 0.001), and those with education levels above high school (referent) were more likely to receive an award than lower education levels (highest OR 1.15 for those with associates degree).

Deployment demographics were also significant in that those with a positive combat flag were marginally less likely to receive MSK disability benefits (OR 0.96, P < 0.001). Time in service was also significant: all active duty SM from Air Force (OR 1.08), Army (OR 1.09), Marine Corps (OR 1.11), and Navy (OR 1.08) with longer time in service were more likely to receive MSK benefits. Those in the National Guard/Reserve from all branches were marginally less likely to receive these benefits (All OR estimates are between 0.95 and 0.98 and P < 0.001). The pay grade of the SM was significant in that enlisted, warrant officers, and officers were more likely to have an MSK SCDB with higher rank.

Those with disability separations were significantly more likely to receive MSK SCDB (OR 2.37, P < 0.001) as compared to those with normal separations. Other nonroutine separations were less likely to receive MSK disability benefits in the adjusted analysis.

The most common MSK diagnoses by anatomy involved the spine, followed by ankle, feet, arm, and general joints (Fig. 2). By pathology, conditions were either limited motion/impairment, arthritis, inflammation, or "other" that included vascular issues, embolism, and urticaria. The distribution of the MSK disability diagnoses were fairly similar for those with normal and disability separations in most categories; those with normal separations had a higher rate of disabilities associated with general joints and hands and lower rate of thigh-related disabilities.

MSK conditions are among the most prevalent of all medical diagnoses in SM and Veterans alike.[12] This prevalence is reflected in just over half of nearly 1.6 million SM who were seen in the VA receiving MSK SCDB from the VA. Our hypothesis was supported as we were able to demonstrate a significantly higher odds of receiving MSK disability benefits for those with disability separations. This is likely reflected by MSK conditions accounting for a large proportion of medical discharges from the military.[14],[15]

TABLE II Results of Logistic Regression Models for Award of SCDB for MSK Conditions in the VA for 1,558,449 SM Who Separated From the Military From October 1, 2001 to May 2017 and Had At Least One Encounter in the VA During the Study Period (up to March 2018)

1 aOmits the nonstatistically significant "Unknown" level.

2 bOmits levels annulled, separated, and widowed in the model that had small counts and were not statistically significant for brevity.

The MSK disability benefits were noted in large proportions in SM from all separation categories. The demonstration that 48% of those with normal separations received MSK SCDB in the VA is an interesting finding. The proportion of disability conditions by anatomy and disease process were largely similar to those with disability separations; there was an increase in hand and general joint conditions. While battle injuries may be contributing to these disability benefits, it is likely that the benefits are being awarded for chronic MSK conditions that may have been worsened during military service. With normal separations accounting for 75% of all separations, this signals an otherwise unexpected demand on resources in the VA and merits further study with the goal of preventing and mitigating injuries and strain while in the military.[16],[17]

The concordant results of time in service and higher rank among active duty SM being associated with increased likelihood of receiving disability benefits likely indicates these variables being correlated. The association of higher education is also likely related to either higher rank or time in service.

Females were more likely to receive MSK SCDB as compared to male Veterans; this supports descriptive studies of increased rate of injuries in female SM.[18] The marginal increase noted for receiving MSK disability benefits by Black and Hispanic Veterans may indicate differences in military occupations among racial/ethnic minorities. The association of marital status with an increased likelihood is interesting and merits further study.

We acknowledge several limitations. Because of the nature of the administrative data used in our study, we are not able to determine who filed claims for disability and those who were denied. Studies have demonstrated that those denied disability benefits are more vulnerable, likely lack social support, and generally have poorer health.[19],[20] We may have excluded a set of SM who have received disability benefits and have not received care in the VA, though the proportion of such SM would likely be low as the VA has established a reputation for caring for Veterans with MSK conditions. From our current dataset, the combat flag indicates hazard pay while deployed in a combat zone and does not necessarily distinguish between those who were in battle. Another limitation is that we are not able to distinguish between battle and nonbattle injuries leading to MSK disabilities. With the current battle-injured count from recent conflicts in Iraq and Afghanistan in the 50,000 to 60,000 range,[21] it is likely that most of the disabilities may be nonbattle injuries or worsened during deployment.

Although active duty SM with disability separations were more likely to receive MSK-related SC disability ratings in the VA, those with normal separations were also among those who received such ratings. Of interest, those with a combat flag were less likely to receive MSK-related SC disability ratings. Thus, the separation type is not sufficient to predict SC disability status that is determined postdeployment in the VA. The top disability conditions noted are fairly constant across various service eras and represent foundational VA services that need to be fully staffed and resourced, especially for MSK-related conditions. Further research is needed to identify demographic and military-specific predictors such as military occupation codes as a marker of MSK-related SC disabilities.[22] The etiology and mechanisms of MSK-related SC disabilities among active duty SM with normal separations merits further study. Understanding the magnitude and impact of SC disability conditions diagnosed in the VA after deployment has a direct bearing on force readiness and attrition among active duty and reserve component SM. Furthermore, identifying those at highest risk for MSK-related disability could lead to improved surveillance and prevention strategies in the DoD and VA health care systems to prevent further damage and disability.

Funding for this project was provided by grant F3Z4537031GW01 (Travis Air Force Base, PIs: I.J.S. and A.V.G.), and VA Center of Innovation Award #I50HX001240 from the Health Services Research and Development of the Office of Research and Development of the U.S. Department of Veterans Affairs.

Presented as a poster presentation at the 2018 Military Health System Research Symposium, August 2018, Kissimmee, FL; abstract #MHSRS-18-1121.

The views expressed in this article are those of the authors and do not necessarily represent the position or policy of the U.S. Department of Veterans Affairs, U.S. Army, U.S. Air Force, Department of Defense, or the U.S. government. The authors declare no conflicts of interest