Development and evaluation of a record linkage protocol for Utah's Controlled Substance Database.

Utah's Controlled Substance Database prescription registry does not include master identifiers to link records for individual patients. We describe and evaluate a linkage protocol for Utah's Controlled Substance Database. Prescriptions (N = 22,401,506) dated 2005-2009 were linked using The Link King software and patient identifiers (e.g. names, dates of birth) for 2,232,725 patients. Review of 998 randomly selected record pairs classified 46 percent as definitely correct links and 54 percent as probably correct links. A correct link could not be confirmed for <1 percent. None were classified as probably incorrect links or definitely incorrect links. Record set reviews (N = 100 patients/set for 10 set sizes, randomly selected) classified 27-49 percent as definitely correct links and 39-63 percent as probably correct links. Fewer had too little information to confirm a link (5%-22%) or were probably incorrect (0%-6%). None were definitely incorrect. Overall, results suggest that Utah's Controlled Substance Database records were correctly linked. These data may be useful for cross-sectional and longitudinal studies of patient-controlled substance prescription histories.