Assessing the Effect of the VHA PCMH Model on Utilization Patterns Among Veterans With PTSD

This study utilizes a validated instrument to create case and control groups to measure the effect of the Veterans Health Administration (VHA)’s patient-centered medical home (PCMH) model on utilization patterns among veterans with posttraumatic stress disorder (PTSD).
Published Online: May 18, 2017
Ian Randall, PhD; Charles Maynard, PhD; Gary Chan, PhD; Beth Devine, PhD; and Chris Johnson, PhD

The Veterans Health Administration (VHA) implemented a patient-centered medical home (PCMH)-based Patient Aligned Care Teams (PACT) model in 2010.
We examined its effects on the utilization of health services among US veterans with posttraumatic stress disorder (PTSD).

Study Design: We analyzed VHA clinical and administrative data to conduct an interrupted time series study. Encounter-level data were obtained for the period of April 1, 2005, through March 31, 2014. We identified 642,660 veterans with PTSD who were assigned to either a high- or low-PCMH implementation group using a validated VHA PCMH measurement instrument.

Methods: We measured the effect of high-PCMH implementation on the count of hospitalizations and primary care, specialty care, specialty mental health, emergency department (ED), and urgent care encounters compared with low-PCMH implementation. We fit a multilevel, mixed-effects, negative binomial regression model and estimated average marginal effects and incidence rate ratios. 

Results: Compared with patients in low-PCMH implementation clinics, patients who received care in high-PCMH implementation clinics experienced a decrease in hospitalizations (incremental effect [IE], –0.036; 95% confidence interval [CI], –0.0371 to –0.0342), a decrease in specialty mental health encounters (IE, –0.009; 95% CI, –0.009 to –0.008), a decrease in urgent care encounters (IE, –0.210; 95% CI, –0.212 to –0.207), and a decrease in ED encounters (IE, –0.056; 95% CI, –0.057 to –0.054).

Conclusions: High PCMH implementation positively affected utilization patterns by reducing downstream use of high-cost inpatient and specialty services. Future research should investigate whether a reduction in utilization of health services indeed results in higher levels of virtual and non–face-to-face access, or if the PACT model has reduced necessary access to care.
Takeaway Points

This study provides several key contributions to the body of literature measuring the effectiveness of the patient-centered medical home (PCMH) model: 
  • Veterans with posttraumatic stress disorder (PTSD) comprise a particularly vulnerable patient subgroup. Results can help inform delivery system redesigns that target patients with mental health issues. 
  • Understanding changing utilization patterns among veterans with PTSD provides information about resource needs and constraints for policy makers and delivery system leaders considering PCMH adoption. 
  • This research sheds light on the effectiveness of the PCMH model in reducing inpatient and specialty care for veterans with PTSD. 
The Veterans Health Administration (VHA) provides care to nearly 6 million veterans each year at more than 1000 clinics across the country.1 On April 1, 2010, the VHA implemented a patient-centered medical home (PCMH)-based Patient Aligned Care Teams (PACT) model across the VHA system. Key goals of the PACT initiative include enhancing patient access, improving care coordination, and redesigning clinical teams.2 To achieve these goals, VHA clinics have developed multidisciplinary care teams, increased their staffing ratios, expanded virtual access for patients, and implemented new health information technology tools, among other steps, to drive care coordination and expand access.3 Although the VHA PACT initiative has been described in greater detail elsewhere,3-6 more detail about PACT elements are outlined in Table 1.

Literature reviews have found that elements of the PCMH, such as enhanced chronic disease management, longitudinal relationships with patients assigned to clinician panels, and multidisciplinary care teams, have been successful in improving access to primary physical and behavioral healthcare7-9 and reducing the number of specialty visits10 and emergency department (ED) utilization.11 However, there is a lack of conclusive evidence that the PCMH model improves care for vulnerable patient populations with chronic conditions.7,8,12 One such vulnerable subgroup is veterans with posttraumatic stress disorder (PTSD), a condition that is often related to combat trauma13 and prevalent among veterans.14 Our research focuses on how PACT has affected the utilization patterns of veterans with PTSD at the VHA. The study population was selected because veterans suffer from PTSD at higher rates than the general public.14,15 Patients with PTSD suffer disproportionately from psychiatric and physical comorbidities,16 utilize health services at elevated rates,17 and face distinctive barriers to receiving mental health care.18,19 Furthermore, patients who suffer from mental illness, and PTSD specifically, face unique barriers to adhering to treatment plans and complying with their medication regimens.20,21 

The PCMH model has shown the potential to reduce high-intensity healthcare utilization for high-needs patients.8,22 Because this model intensifies primary care, a heightened need exists for physicians to effectively diagnose and treat patients with mental illness23 and link these patients with mental health care specialists.24 Additionally, better integration of primary and mental health care has been shown to lower costs. We hypothesized that PACT would increase the rate of primary care encounters and, subsequently, reduce rates of hospitalizations and specialty out-patient, urgent care, and ED encounters.

In the United States, mental illness cases are the fastest-growing component of ED utilization. Patients presenting to the ED with mental illness often have complex psychiatric, medical, and social histories.25 Subsequent downstream encounters, such as inpatient admissions and ED visits, are often indicative of suboptimal care and may reflect encounters that could have been prevented with better primary care.26 Untreated mental illness, such as PTSD, can lead to the exacerbation of other mental and physical ailments. Likewise, the development of physical illness can subsequently worsen the severity of PTSD symptoms,27 creating adverse feedback loops for patients’ health status. Overall, patients with mental health disorders have higher rates of unexplained medical complaints, utilize more specialty care, and incur nearly 2-fold higher medical costs.14 However, if mental health can be treated more effectively, there are opportunities to improve health outcomes among veterans with mental illness28 and achieve savings from decreased utilization of downstream encounters.29,30 

Previous PCMH studies have often been constrained by methodological limitations, including inconsistent definitions of what constitutes a PCMH, an inability to define the level of PCMH implementation, and small sample sizes that limited generalizability.31 Moreover, PCMH research has often been hampered by an inability to decouple the PCMH model from other practice transformation initiatives and the confounding influence of electronic health records.10,12 Many PCMH studies have also been conducted using pre-post study designs, used short time periods of data, or measured several interventions simultaneously.8,12 Short time periods, in particular, are problematic because research indicates that the longer a PCMH model has been implemented, the more discernible are any true effects.7 As a result, it is difficult to infer causality from many previous studies about the PCMH model. Finally, there is a limited number of studies that have focused on the relationship between PACT and utilization patterns among vulnerable patient populations with mental health conditions, such as veterans with PTSD.7,32 

The ability to assess causation in this study is aided by a number of factors, including an enhanced ability to measure the extent of PACT implementation at VHA clinics, longer time periods to better assess causal relationships, and larger anticipated effect sizes due to higher rates of utilization among veterans with PTSD. Heterogeneous levels of PACT implementation at VHA clinics and the subsequent development of a validated instrument to measure PACT implementation at individual VHA clinics present a unique opportunity to detect potential causal effects of PACT. Lastly, this study was able to control for the potential confounding effects of Primary Care Mental Health Integration (PC-MHI), a model to embed behavioral health care in the primary care setting, implemented at a subset of VHA clinics in 2007.33,34 


Data and Subjects

Data were collected from VHA administrative databases for the period between April 1, 2005, and March 31, 2014. We collected clinical and administrative data on veterans assigned to 1006 VHA hospital and community-based clinics, with each provider site being considered a unique clinic. We screened records from 11,546,562 veterans to assess whether they were diagnosed with PTSD. International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify patients with PTSD as well as for risk adjustment using the Elixhauser method.35 Veterans with at least 1 inpatient or 2 outpatient encounters that included the PTSD ICD-9-CM code 309.81 within 1 year of a respective quarter were identified as having PTSD in that quarter.

Of all veterans screened, 1,455,295 were identified as having PTSD in at least 1 quarter of the research period. From this group, we identified veterans who received care at a clinic that was designated as either a low- or high-PACT implementation clinic. A low-PACT implementation clinic is one with a composite score on the PACT Implementation Progress Index (PI2) in the bottom quartile of the PI2 score distribution, while a high-PACT implementation clinic is one with a composite score in the top quartile of the PI2 score distribution. The PI2 was developed by VHA researchers to measure the extent of PACT implementation at individual VHA clinics.36 The PI2 measures the level of implementation across key domains that reflect meaningful adoption of the PCMH model. 

Veterans were only included in the sample population if they were part of the Primary Care Management Module (PCMM), an indicator of receiving empaneled primary care from an assigned provider team. Only veterans in the PCMM were included because they would have had at least 1 primary care visit and would be able to receive the potential benefits of the PACT initiative in the primary care setting. At the clinic level, we utilized administrative data to assign a binary marker for whether a clinic had implemented the PC-MHI initiative.

The final study sample, which included 1,405,185 veterans who were identified as having PTSD, was an imbalanced longitudinal (eg, a repeated cross-sectional) sample. The average veteran included in this sample was in the data set for an average of 30 quarters, or 7.5 years, indicating that the majority was tracked over a significant period and had been in the data set in both the pre- and post-PACT periods. Based on the PTSD inclusion criteria, this equates to 12.2% of veterans having PTSD. This figure is slightly lower than other estimates of PTSD prevalence among veterans,14 but can be explained by this study’s more stringent inclusion criteria. 

Main Measures

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