Evaluating short- and long-term impacts of a Medicaid "lock-in" program on opioid and benzodiazepine prescriptions dispensed to beneficiaries

Drug Alcohol Depend. 2018 Jan 1:182:112-119. doi: 10.1016/j.drugalcdep.2017.10.001. Epub 2017 Nov 14.


Background: Insurance-based "lock-in" programs (LIPs) have become a popular strategy to address controlled substance (CS) (e.g., opioid) misuse. However, little is known about their impacts. We examined changes in CS dispensing to beneficiaries in the 12-month North Carolina Medicaid LIP.

Methods: We analyzed Medicaid claims linked to Prescription Drug Monitoring Program (PDMP) records for beneficiaries enrolled in the LIP between October 2010 and September 2012 (n=2702). Outcomes of interest were 1) number of dispensed CS prescriptions and 2) morphine milligram equivalents (MMEs) of dispensed opioids while a) locked-in and b) in the year following release.

Results: Compared to a period of stable CS dispensed prior to LIP enrollment, numbers of dispensed CS during lock-in and post-release were lower (count difference per person-month: -0.05 (95% CI: -0.11, 0.01); -0.23 (95% CI: -0.31, -0.15), respectively). However, beneficiaries' average daily MMEs of opioids were elevated during both lock-in and post-release (daily mean difference per person: 18.7 (95% CI: 13.9, 23.6); 11.1 (95% CI: 5.1, 17.1), respectively). Stratification by payer source revealed increases in using non-Medicaid (e.g., out-of-pocket) payment during lock-in that persisted following release.

Conclusion: While the LIP reduced the number of CS dispensed, the program was also associated with increased acquisition of CS prescriptions using non-Medicaid payment. Moreover, beneficiaries acquired greater dosages of dispensed opioids from both Medicaid and non-Medicaid payment sources during lock-in and post-release. Refining LIPs to increase beneficiary access to substance use disorder screening and treatment services and provider use of PDMPs may address important unintended consequences.

Keywords: Controlled substance; Lock-in; Medicaid; Narcotic; Opioid; Prescription drug abuse.

Publication types

  • Observational Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Analgesics, Opioid / adverse effects
  • Analgesics, Opioid / therapeutic use*
  • Benzodiazepines / adverse effects
  • Benzodiazepines / therapeutic use*
  • Controlled Substances / standards*
  • Drug Prescriptions / standards
  • Female
  • Health Expenditures / standards
  • Humans
  • Male
  • Medicaid / standards*
  • Medicaid / trends
  • Middle Aged
  • North Carolina / epidemiology
  • Prospective Studies
  • Substance-Related Disorders / diagnosis*
  • Substance-Related Disorders / epidemiology*
  • Substance-Related Disorders / prevention & control
  • Time Factors
  • United States / epidemiology


  • Analgesics, Opioid
  • Controlled Substances
  • Benzodiazepines