Data Source

This retrospective cohort study was conducted utilizing data from the Truven MarketScan Commercial and Medicare Supplemental health care claims databases for the period between January 1, 2006, and December 31, 2012. The databases include information from commercial health insurance claims (inpatient and outpatient medical and outpatient pharmacy) and enrollment data from large employers and health plans across the United States. The MarketScan Medicare Supplemental and Coordination of Benefits (Medicare) database contains the inpatient medical, outpatient medical, and outpatient prescription drug information of retirees with Medicare supplemental insurance paid for by employers. These databases provide detailed cost, use, and outcomes data for health care services performed in inpatient and outpatient settings. The medical claims are linked to outpatient prescription drug claims and person-level enrollment data through the use of unique enrollee identifiers.

These databases are fully compliant with the Health Portability and Accountability Act of 1996 (HIPAA), meet the criteria for a limited-use dataset and contain none of the data elements prohibited by HIPAA for limited-use datasets. All data are de-identified to protect the privacy of patients and providers. Accordingly, institutional review board and ethics committee approval were not required for the study.

Overall, MarketScan covered approximately 158 million patients from 2000 to 2012. For the year 2012, it included approximately 51 million eligible subjects. The regional representation of this commercial claims database in the United States is as follows: Northeast, 5.44%; North Central, 23.05%; South, 38.61%; West, 19.89%; and Unknown, 2.98%. Medicare does not track patients’ regions. In the period from 2000 to 2012, 85.3% of the subjects included in the database were commercially insured, and 6.5% belonged to Medicare (n = 10,459,149). Codes used in MarketScan are International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for disease, Current Procedural Terminology/Healthcare Common Procedure Coding System codes, and National Drug Code numbers for drugs.