title: Opioid Use as a Predictor of Health Care Use and Pain Outcomes: Analysis of Clinical Trial Data.
abstract: OBJECTIVE
  To examine effects of pre-enrollment opioid use on outcomes of a 12-month collaborative pain care management trial. We hypothesized that participants with opioid use would have worse pain at baseline; use more health care services and analgesics; and have worse pain outcomes during the trial.
  
  
  METHODS
  Secondary analysis of randomized controlled trial data.
  
  
  METHODS
  Veterans Affairs (VA) primary care.
  
  
  METHODS
  Patients age 18-65 years with chronic pain of at least moderate severity who were enrolled in a 12-month pragmatic trial of a telephone-based collaborative care intervention for chronic musculoskeletal pain.
  
  
  METHODS
  Participants were categorized as opioid users (n = 84) or non-users (n = 166) at baseline and trial randomization was stratified by opioid use. We used logistic regression to examine cross-sectional associations with baseline opioid use and mixed-effect models for repeated measures to examine baseline opioid use as a predictor of Brief Pain Inventory (BPI) scores over 12 months.
  
  
  RESULTS
  At baseline, 33.6% reported use of prescribed opioids. Baseline opioid users had higher baseline BPI scores and higher health-related disability than non-users. Baseline opioid users also had more outpatient visits (15.0 vs. 10.1; p = 0.001) and received more analgesics (p < 0.001) during the trial. In the final multivariable model examining effects of baseline opioid use on BPI over 12 months, opioid users and nonusers had a non-significant difference of 0.25 points (p = 0.098). In conclusion, although baseline opioid users had worse pain at baseline and used more health care during the study, response to the intervention was not significantly modified by pre-existing opioid therapy.
authors.affiliation: *Center for Chronic Disease Outcomes Research, Minneapolis VA Health Care System, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, USA.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Krebs
authors.affiliation: Center for Health Information and Communication, Roudebush VA Medical Center, Department of Medicine, Regenstrief Institute, Inc., Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: Kurt
authors.initials: K
authors.lastname: Kroenke
authors.affiliation: Department of Epidemiology and Biostatistics, College of Public Health, Temple University, Philadelphia, Pennsylvania, USA.
authors.forename: Jingwei
authors.initials: J
authors.lastname: Wu
authors.affiliation: Center for Health Information and Communication, Roudebush VA Medical Center, Department of Medicine, Regenstrief Institute, Inc., Indiana University School of Medicine, Indianapolis, Indiana, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Bair
authors.affiliation: Department of Pharmacy Practice, Purdue University College of Pharmacy, Indianapolis, Indiana, USA.
authors.forename: Mary Ann
authors.initials: MA
authors.lastname: Kozak
authors.affiliation: Shanghai Jiaotong-Yale Joint Center of Biostatistics, Shanghai Jiaotong University, Shanghai, PR China.
authors.forename: Zhangsheng
authors.initials: Z
authors.lastname: Yu
keywords: Chronic Pain; Opioid Analgesics; Primary Care