HSR&D Home » Research » DHI 09-237 – HSR&D Study
Identifying and Validating Complex Comorbidity Clusters in OEF-OIF Veterans
Mary Jo V Pugh, PhD EdM MA
South Texas Health Care System, San Antonio, TX
San Antonio, TX
Funding Period: October 2010 - September 2015
The growing body of research on Veterans deployed in support of Operations Enduring Freedom, Iraqi Freedom and New Dawn (OEF/OIF/OND) suggests that there are patterns of comorbid conditions that cluster together. A systematic identification of common comorbidity clusters is needed to understand the long-term comorbidity patterns and health care needs of this veteran cohort.
1. Identify comorbidity clusters among OEF/OIF/OND veterans and describe comorbidity trajectories over the first 3 years of VA care.
2. Identify risk factors for trajectories of comorbidity.
3. Compare VA health care utilization for individuals with different comorbidity trajectories.
4. Examine differences in resilient coping, social support and measures of mental health for OEF/OIF/OND VA patients in a random sample stratified to represent comorbidity trajectories.
This prevalent cohort study first identified individuals deployed in support of the wars in Afghanistan and Iraq from the OEF/OIF roster, and combined data from VA national inpatient, outpatient and pharmacy data repositories, survey data, and national VistA Web chart abstraction. We identified specific comorbidities using ICD-9-CM codes each year during the first three years of VA care. We used latent class analysis (LCA) stratified by gender to identify trajectories of comorbidity among individuals first seen in VA care (FY02-09), and examined health care utilization patterns by trajectories. We then identified a random sample of individuals by comorbidity trajectory, oversampling women and individuals in small trajectories, to conduct more comprehensive examination using survey and chart abstraction data. Generalized linear models were used to examine the associations between comorbidity trajectory and resilient coping, social support, and measures of mental health.
Aim 1: We first identified comorbidity trajectories using LCA using a derivation and validation cohort. To determine if documentation of mild TBI affected the pattern of comorbidity trajectories, the derivation cohort included those first receiving care in FY07-FY09 due to initiation of TBI screening in FY07; the validation cohort included those who entered VA care in FY02-06. LCA of care-seeking Iraq and Afghanistan Veterans who received 3 or more years of care (FY07-FY11) stratified by gender indicated that a five-trajectory solution best fit the data for women (n=20,216) and a seven-trajectory solution best fit the data for men (n=147,002); a validation cohort of those entering VA care FY02-FY06 revealed the same trajectory patterns. Examination of trajectories revealed that five were similar for men and women: (1) Healthy (~40%), (2) Chronic Disease (hereafter Chronic ~10%), (3) Mental Health (~22%), (4) Pain (~13%), and (5) PCT (TBI, PTSD, and pain; ~15%). The two additional trajectories found for men were (6) Minor Chronic: mostly healthy with significantly higher probabilities of obesity, chronic lung disease, and hearing/vision conditions than the Healthy trajectory but far lower probabilities of these conditions than the Chronic trajectory; and (7) PCT+Chronic based on significantly higher probabilities of obesity, insomnia and hypertension than the PCT-only trajectory.
We further examined patterns of CNS-acting medication use by trajectory as a count at baseline (CNS-Baseline: 0, 1-3; 4+) and CNS-Change (year 3-year 1; reduced, stable, increased), to describe stability within each trajectory. At baseline, individuals in the Healthy and Chronic trajectories were significantly more likely to receive zero CNS medications (88% and 79%, respectively) compared to PCT/PCT+Chronic (36% and 40%, respectively). Those in PCT/PCT+Chronic trajectories were more likely to have 4+ unique CNS medications (19% each) compared to all other trajectories (range 0.3 [Healthy] to 7.5% [Mental Health]). Within all trajectories there was evidence of stability (range: Healthy 76% to PCT/PCT+Chronic 18%), reduced CNS (range: healthy 9.1%, PCT/PCT+Chronic 23% and 21%, respectively), and increased CNS (range healthy 15%, PCT/PCT+Chronic 60% each).
Aim 2: Demographic risk factors for comorbidity trajectories include age and race/ethnicity. Patients in trajectories of chronic disease (Chronic, Minor Chronic, PCT+Chronic) were older overall, regardless of sex. With regard to race/ethnicity, African American men and women were more likely to be included in Chronic, Minor Chronic, and PCT+Chronic trajectories. White men were more likely to be represented in Mental Health and PCT trajectories, and white women were more likely to be represented in the Mental Health trajectory. Those who served in the enlisted forces were more likely to be in Mental Health and PCT/PCT+Chronic Trajectories. Those who served in the National Guard were more likely than expected to be in the PCT+Chronic and Pain trajectories; those who served in the Reserve/National Guard were more likely to be in the Chronic and Healthy trajectories. Those deployed as Active Duty were more likely to be in Minor Chronic, Mental Health and PCT trajectories.
Aim 3: Using VA outpatient (clinic code) and inpatient records, we found that health care utilization in year four of VA care was significantly associated with comorbidity trajectories assessed in the first three years of VA care. Emergency department care, and care in mental health and substance abuse clinics, was significantly less likely in the Healthy, Minor Chronic, Chronic and Pain trajectories than Mental Health and PCT/PCT+Chronic trajectories. Similarly, hospitalization was significantly more likely in Mental Health and PCT/PCT+Chronic trajectories compared to other trajectories. However, on average PCT/PCT+Chronic trajectories also had significantly higher utilization of primary care (Median=2; IQR=3) than the Healthy and Minor Chronic trajectories (Median=1; IQR=2), suggesting overall high healthcare utilization.
Aim 4: Survey respondents had a mean age of 40.7 years (SD = 10.3) in 2014 (3-6 years after data for trajectory identification) and 55% were male (n=1,075). Results of general linear model analyses found no significant interactions with gender, so results are presented by trajectory. Trends across resilient coping, measures of social support and measures of mental health were consistent with those in the Healthy trajectory reporting the most positive scores, and those in the Mental Health, PCT, and PCT+Chronic reporting the least positive scores. Notable findings were related to scores on the health status measure, depression, and pain scores. First, self-rated health in the Healthy Trajectory was only rated as "good." Second, scores on the CES-D for the Healthy Trajectory was 9.3; CES-D scores of 10 or greater are considered "depressed." Finally, the mean pain score of 3.9 for the Healthy trajectory reflects self-reported pain near VA's "clinically significant" cutpoint of 4.
Far from illustrating a 'healthy warrior effect,' our findings suggest that a significant portion of OEF/OIF/OND Veterans in VA care are experiencing morbidity 5-10 years after entering VA care. These findings suggest a need for additional longitudinal study to monitor well-being over time and longitudinal evaluation of healthcare received by those considered less vulnerable to determine if current structures are meeting their needs.
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NIH ReporterGrant Number: I01HX000329-01A1
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DRA: Acute and Combat-Related Injury, Brain and Spinal Cord Injuries and Disorders, Military and Environmental Exposures, Mental, Cognitive and Behavioral Disorders
DRE: Diagnosis, Prognosis
MeSH Terms: none