Access, utilization, and outcomes of physical therapy services among injured workers with back pain in Washington State

Abstract

Back pain is a complex and multidimensional health problem that is highly prevalent and costly for the working population and society. It is one of the leading causes of disability in the US adult population and the primary reason to file a workers’ compensation (WC) claim. Clinical guidelines recommend use of physical therapy (PT) services, which include active interventions, passive modalities, and manual therapy services as first-line treatments over pain medications and surgical procedures for patients experiencing back pain. While evidence suggests that patients with back pain who receive early and active PT interventions experience greater improvements in disability, pain intensity, and functional status, patients do not always receive recommended PT treatments and the variability in PT care may potentially lead to varied outcomes. Furthermore, patients living in rural areas experience greater barriers of access to medical providers including PT providers compared to their urban counterparts and the factors associated with receiving PT services remain unclear in the working population. Knowledge about the factors associated with PT use and non-use as well as the associations between various measures of access to PT services in rural and urban areas will assist policy makers, health care providers, and researchers in characterizing and better understand why workers are more likely to see a PT provider or not. These results may be used in addressing potential health disparities that may exist at the worker or systematic level that may impede timely and accessible PT care. This dissertation, which covers three specific research aims, uses administrative claims, medical billing, and provider data from the WA Department of Labor and Industries Workers Compensation System (L&I WC) to examine WA state population trends in access, utilization, and outcomes of PT services among injured workers with back pain. In Chapter 2, we conducted descriptive analyses of L&I WC data from 2016 to 2019 to examine the variation in travel distance to the nearest PT provider and timing to PT services by rural and urban areas. In Chapter 3, we performed bivariate and multivariate logistic regression models to investigate factors that may be associated with PT use and non-use from a cohort of injured workers with back pain using data from the Disability Risk Identification Study Cohort (D-RISC), which combines L&I WC administrative claims data with self-reported information on worker characteristics including socio-demographic, pain and function, psychosocial, clinical, health behaviors and employment-related factors. In Chapter 4, we conducted linear and logistic regression models to test the associations between intensity of PT services in the first 4 weeks after injury on work disability and self-reported measures for work status, pain intensity, and function scores at 1-year follow-up for injured workers with back pain using data from the D-RISC study. In summary, this dissertation presents the methodology conducted for three specific aims and the research findings associated with each of these studies. First, we examine the variation in access to PT services for injured workers with back pain living in rural versus urban areas. Secondly, we identified factors associated with PT use and non-use. And lastly, we investigate the impact of intensity of PT services on work and health outcomes among injured workers with back pain in WA. Demonstrating these differences in access, utilization, and outcomes of PT services has the potential to transform current approaches by informing key stakeholders including medical providers, policymakers, educators, researchers, and the working population. The findings from this dissertation may also improve clinical care coordination, pain management efforts, and return-to-work (RTW) prospects for WA workers experiencing back pain.