title: Redaction of Substance Abuse Claims in Medicare Research Files Affects Spending Outcomes for Nearly One in Five Beneficiaries with Serious Mental Illness.
abstract: To assess the impact of substance abuse claims redaction on Medicare spending estimates for beneficiaries with serious mental illness.
  
  
  
  The 2012 claims and unredacted beneficiary-level Medicare spending totals from CMS's Chronic Conditions Warehouse.
  
  
  
  We identified beneficiaries with claims affected by the redaction by comparing claims-based spending estimates to unredacted spending totals. Differences in characteristics of beneficiaries with and without redacted claims were examined in bivariate analyses.
  
  
  
  Claims-based spending totals differed from unredacted totals for 19.7 percent of the cohort. Part A spending for those with redacted claims was underreported by 57.0 percent. Characteristics of beneficiaries with and without redacted claims differed significantly.
  
  
  
  Researchers who rely on Medicare claims to analyze spending outcomes for beneficiaries with serious mental illness should be aware of the potential for bias due to nonrandom redaction of substance abuse data.
authors.affiliation: Department of Pharmaceutical Health Services Research, University of Maryland School of Pharmacy, Baltimore, MD.|Policy & Research Department, PhRMA, Washington, DC.
authors.forename: Pamela
authors.initials: P
authors.lastname: Roberto
authors.affiliation: Department of Pharmacy Practice and Science, University of Maryland School of Pharmacy, Baltimore, MD.
authors.forename: Nicole
authors.initials: N
authors.lastname: Brandt
authors.affiliation: Department of Pharmaceutical Health Services Research, University of Maryland School of Pharmacy, Baltimore, MD.
authors.forename: Eberechukwu
authors.initials: E
authors.lastname: Onukwugha
authors.affiliation: Department of Pharmaceutical Health Services Research, University of Maryland School of Pharmacy, Baltimore, MD.
authors.forename: Bruce
authors.initials: B
authors.lastname: Stuart
mesh_terms: D000368:Aged; D035843:Biomedical Research; D005260:Female; D005102:Health Expenditures; D006302:Health Services Research; D006801:Humans; D007345:Insurance Claim Review; D008297:Male; D006278:Medicare; D001523:Mental Disorders / Q000628:therapy*; D019966:Substance-Related Disorders / Q000523:psychology*; D014481:United States
keywords: Medicare spending; Substance abuse claims redaction; selection bias