The importance of data source in prescription drug monitoring program research.

OBJECTIVE To develop a legal research protocol for identifying various measures of prescription drug monitoring program (PDMP) start dates, apply the protocol to create a useable PDMP database, and test whether the different legal databases that are meant to contain the same information produce divergent results when used in an illustrative empirical exercise. DATA SOURCES Original research from state statutes, regulations, policy statements, and interviews; alternative PDMP data from the National Alliance for Model State Drug Laws and Prescription Drug Abuse Policy System; claims from a 40 percent random sample of Medicare beneficiaries, 2006-2014. STUDY DESIGN Collaborative research effort among a group of lawyers to develop protocol. Legal research to produce an original database of dates state PDMP laws: (a) were enacted, (b) became operational, and (c) required query before prescribing controlled substances. Descriptive analyses characterize differences in dates of enactment, operation, and must query requirements. Regression analyses estimating, for each beneficiary annually any opioid prescription received in a calendar year, among other measures. Estimates conducted on under age 65 and full Medicare population. DATA COLLECTION/EXTRACTION METHODS PDMP legal databases were linked to annual Medicare claims. PRINCIPAL FINDINGS An original database differs from commonly used, publicly available data. Outcomes tested depend on the measure of PDMP date used and differ by data source. Must-query laws show the largest effects among all the laws tested. CONCLUSIONS Data choices likely have had large consequences for study results and may explain contradictory outcomes in prior research. Researchers must understand and report protocol for dates used in PDMP research to ensure that results are internally consistent and verifiable.