Researchers at Boston’s Brigham and Women’s Hospital examined the impact of the recent Centers for Medicare & Medicaid Services (CMS) policy of suppressing substance abuse-related claims on diagnostic rates for conditions unrelated to substance abuse in Medicaid data. They found the policy didn’t affect those rates, but caused substantial reductions in the reported rates of hepatitis C and HIV, conditions frequently associated with drug abuse.
Such artificially reduced rates, the researchers warned, could have a significant and negative impact on future research and evaluations of clinical care. The study, “Suppression of Substance Abuse Claims in Medicaid Data and Rates of Diagnoses for Non–Substance Abuse Conditions” was published in JAMA.
In a change from long-lasting practice, the CMS has started to suppress claims linked to conditions related to substance abuse in the Medicare and Medicaid Research Identifiable Files. The change was enacted to comply a 1987 federal regulation preventing third-party payers releasing information, without the consent of patients, from federally funded substance abuse treatment programs.
But when the CMS removes claims with a diagnostic or procedure with a substance-abuse code, the whole encounter captured by the claim is removed. Consequently, study authors hypothesized, important clinical diagnoses related to substance abuse might also be removed.
Researchers compared Medicare data for 2000-2006, before the claim suppression policy was implemented, and the data for 2007-2010, following its implementation.
The analyses included the annual inpatient and outpatient rates of diagnosis of human immunodeficiency virus, cirrhosis, hepatitis C, depression, anxiety, and tobacco use, all conditions that usually co-occur with substance abuse. Conditions not related to substance abuse, such as kidney disease, type II diabetes, hypertension, and stroke, were also included.
Results found no association between the CMS suppression practices and diagnosis rates for conditions unrelated to substance abuse. However, the policy implementation coincided with substantial decreases in the rates of inpatient diagnoses for substance abuse co-occurring conditions. For anxiety, significant reductions were found in outpatient diagnosis rates.
“Underestimation of diagnoses has the potential to bias health services research studies and epidemiological analyses for which affected conditions are outcomes or confounders. In studies of health care utilization, the number of missing claims may vary in a nonrandom fashion between groups defined by demographics, disease, or locality. Comparisons between groups may lead to spurious conclusions — a hospital that regularly admits substance abusers will have artificially low rates of readmission, giving a false appearance of better performance,” the researchers said in a news release.