Long-Term Implications Of A Short-Term Policy: Redacting Substance Abuse Data

We used complete fee-for-service Medicare claims for 2012, the last year of claims available before redaction was implemented. To estimate the impact of redaction, we created a new version of the 2012 cohort by removing any claim that included a substance abuse–related diagnosis or procedure code that was redacted in 2013, as specified by the Research Data Assistance Center(ResDAC). Our analysis used the full 2012claims and the redacted version.We estimated the prevalence of thirteen chronic conditions by age, comparing unredacted and redacted data (exhibit 2). Following previously published work, we constructed chronic conditions based on International Classification of Diseases, Ninth Revision(ICD-9), codes corresponding to a subset of hierarchical classification categories used to risk adjust payments to Medicare Advantage health plans. We focused on a subset of conditions that are relatively common among Medicare beneficiaries or were likely to be affected by redaction.Next, we computed inpatient utilization in the redacted and unredacted data. We estimated inpatient admissions per 100 beneficiaries and inpatient spending per beneficiary, overall and by age (exhibit 3). To characterize how redaction might affect studies that created diagnostic cohorts in inpatient settings, we calculated the population rates of admission per 100 beneficiaries (and, separately, psychiatric hospital admissions) for selected diagnoses likely to be affected(serious mental illness, depression, and hepatitis C) and less likely to be affected (diabetes) by redaction (exhibit 4).