In 2013 a reinterpretation of the federal regulation governing the confidentiality of drug and alcohol treatment and prevention records caused the Centers for Medicare and Medicaid Services (CMS) to redact any health care encounter that included a diagnosis or procedure code related to substance abuse from the Medicare and Medicaid research identifiable files.1 This created important and difficult-to-identify gaps in claims data, especially those related to use of inpatient services.2 The research community was relieved when in 2017 the Substance Abuse and Mental Health Services Administration announced changes to the Confidentiality of Substance Use Disorder Patient Records regulations3 restoring access to previously redacted Medicaid and Medicare claims.4,5 However, this relief does not acknowledge the legacy left by incomplete files already in use for analyses spanning the implementation of the Affordable Care Act (ACA), a time period characterized by new insurance coverage, payment, and delivery models in health care and falling US life expectancy.
The gap in data coincides with the accelerating epidemic of drug overdose and resulting deaths, which increased from 41,000 in 2012 to 64,000 in 2016, largely due to opioids.6 Our analysis of Medicare data for 2007–14 demonstrates a steep drop in the prevalence of treatment for nonfatal opioid overdose (exhibit 1). We observed a 26.4 percent decline in such overdoses in beneficiaries ages sixty-five and older and a 41.7 percent decline in beneficiaries younger than age sixty-five between 2012 and 2013. Unfortunately, this decline is an artifact of redaction, since any overdose event with a diagnosis or procedure related to substance abuse is absent from the data. At a time when the opioid epidemic accelerated, Medicare claims suggest the opposite.
Despite laudable efforts by CMS to make “gap files” available, the months required to receive an amended data use agreement, high fees for gap files (the specific price depends on the agreement), and the time required to process files issued in a new format all create barriers to updating data. Researchers may be unwilling or unable to make the effort for studies that don’t specifically target addiction. But redaction can affect a wide range of studies. Prior analyses highlighting this issue were limited to Medicaid recipients2 or a subset of Medicare recipients with serious mental illness;7 the impact on the full Medicare population is unknown.
To more fully illustrate the impact of missing substance abuse claims in Medicare, we describe the effect of redaction on prevalence estimates of common chronic conditions and on inpatient use and spending overall, by age, and for selected inpatient diagnoses.