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Spatiotemporal Spread of Newer Antipsychotics for Bipolar Disorder and PTSD
Mark S Bauer, MD
VA Boston Healthcare System Jamaica Plain Campus, Jamaica Plain, MA
Funding Period: July 2011 - June 2014
Previous research indicates that patient, provider, and health system characteristics are important factors in the adoption of healthcare innovations, including new prescribing patterns and/or medication utilization. We propose that interventions to enhance evidence-based prescribing can be focused for maximal effectiveness and efficiency, and that doing so depends on knowledge of the flow of information and influence among providers working within a specific organizational context with specific types of patients.
Such knowledge requires, specifically: (a) early identification of change in prescribing behavior (surveillance), (b) identification of characteristics of prescribers with a propensity to early adoption while controlling for confounding factors (including patient characteristics), and (c) identification of specific methods of intervention by determining the relative importance of social vs. administrative factors in a provider's decision to prescribe. Study of the emerging use of second generation antipsychotics (SGAs) for bipolar disorder and PTSD in the 2000s provided an opportunity to investigate these issues.
This study focused on (a) conducting basic pharmacoepidemiologic research to identify patterns of use of SGAs for bipolar disorder and PTSD, and (b) identifying spatiotemporal clusters (STCs) that describe the spread of prescribing SGAs for these disorders. Focusing on SGAs in bipolar disorder took advantage of several discrete events in 2004-new FDA indications for bipolar disorder-that anchored the investigation of diffusion. PTSD provided an important complementary disorder by which to study innovation spread since SGAs have become widely used for PTSD-though without FDA indications.
The study Specific Aims were: (1) to identify and characterize the dynamics of STCs of early adopter providers prescribing SGAs for bipolar disorder including to evaluate: (1a) the demographic characteristics of prescribers; (1b) the demographic characteristics of the patients who receive prescriptions, and (1c) the structural and cultural organizational characteristics at the VISN, VAMC, and CBOC levels within which the prescribing occurs; and (2) to characterize the robustness of early adopter prescriber profiles by: (2a) determining the consistency of early adopter characteristics across SGAs and (2b) determining whether the same characteristics that identify early adopters for bipolar disorder also identify early adopters for PTSD; and (3) to develop an integrated model that characterizes the relative strength of diffusion-based versus organizational factors in prescribers' likelihood of adopting SGAs for bipolar disorder.
We employed fundamental pharmacoepidemiologic methods to describe the spread of SGAs for bipolar disorder and PTSD, and then utilized geographic information systems (GIS) methods to identify STCs for these disorders. We worked with national VHA data from Decision Support System, Personnel and Accounting Integrated Dataset, and related VA databases to identify STCs of early adopter providers prescribing SGAs for bipolar disorder, and within these STCs to evaluate demographic characteristics of prescribers and patients who received prescriptions, along with the structural and cultural organizational characteristics at VISN, VAMC, and CBOC levels within which the prescribing occurred. Finally, we developed an integrated model that characterized the relative strength of diffusion-based versus organizational factors in prescribers' likelihood of adopting SGAs for bipolar disorder. We hypothesized that both geographic factors, consistent with classic diffusion theory, and organizational factors, as articulated in more recent applications of diffusion theory to dissemination within healthcare organizations, shaped SGA spread and, therefore, identified opportunities for intervention.
Our pharmacoepidemiologic studies indicated that the number of subjects with bipolar disorder using SGAs nearly doubled between 2003 and 2010, resulting in an average increase in SGA use of about 7% per year. Subjects with prior psychiatric hospitalizations, psychotic features and a sleep disorder diagnosis were more likely to initiate SGA treatment, although SGA initiation increased over time among those with milder symptoms. Subjects located in the southern region of the country were more likely to initiate SGA treatment. Most medical comorbidities were only modestly associated with SGA initiation as a whole, although significant findings emerged for individual SGAs.
Further, among 732,085 Veterans with PTSD, 27.6% received an intentional trial of an SGA in 2003-2010. The annual number treated with SGAs almost doubled (45,268 to 84,197), despite decreasing prescribing rates (28.6% to 21.5%) in this rapidly expanding population. In multivariate analyses, strongest clinical associations were with prior diagnosis of depression, substance use disorders, and other anxiety disorders as well as cardiovascular risk factors. Veterans previously deployed to Iraq/Afghanistan had lower likelihood of SGA receipt. Substantial regional differences were demonstrated (South>Northeast; Midwest and West
STC analyses revealed discrete clusters of early prescribing of the SGA aripiprazole for bipolar disorder, with counts of new prescribers (raw numbers) centering in New England and the Midwest. Utilizing rates, somewhat different clusters emerged, as expected, with two clusters identified in the Midwest and the Southwest. Hierarchical linear analyses to identify provider factors associated with early prescribing, while controlling for patient factors, are underway at the time of this writing. Complementary analyses are also underway to determine whether social-spatial or administrative factors predominate in influencing prescribers by investigating CBOC vs. parent VAMC differences in prescribing. At present, analyses indicate that there is a strong relationship between VAMC and CBOC without strong impact of hypothesized geographic factors (i.e., distance between sites, same/different state of sites). However, these analyses are still ongoing so conclusions cannot yet be drawn.
In addition to the specific importance to the VA of understanding the spread of these expensive medications for two high-priority disorders , this investigation represents two methodologic advances that are applicable beyond these specific disorders and medications: (a) the linking of prescriber data to prescription, patient, and facility data to identify correlates of prescriber behavior after controlling for patient and facility characteristics, and (b) the integrated analysis of innovation spread through both spatial-social and administrative space. This knowledge will both guide the targeted development and implementation of provider behavior change strategies for the VHA, and will test and refine the diffusion-based theory for applying these techniques within and beyond our healthcare system. What is notable at this point in time is that there is no evidence of "runaway" prescribing of SGAs in these populations. Rather, the rates of SGA prescribing have declined somewhat for both bipolar disorder and PTSD. The increase in number of prescription is driven primarily by increase in the population, most dramatically for PTSD..
Moreover, STCs can be used as surveillance methods in close-to-real-time to detect trends in prescribing and to delineate their "contagion routes" through social-spatial and administrative space. Further, since academic detailing is costly, identifying STCs of early prescribing can segment the "market" for more effective deployment of academic detailing.
External Links for this Project
NIH ReporterGrant Number: I01HX000520-01
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DRA: Mental, Cognitive and Behavioral Disorders
DRE: Treatment - Observational, Research Infrastructure
MeSH Terms: none