Record linkage strategies, outpatient procedures, and administrative data.

By understanding the range of approaches implicit in modern record linkage, epidemiologists and health services researchers can better decide its suitability for their needs. The authors discuss a small record linkage project, providing a sense of where mistakes were made. The research first uses existing identification numbers as a gold standard for linking hospital abstracts and physician claims to investigate whether or not coronary angiography was performed on a given individual. Even if identification numbers are not available, a successful linkage (with more than 95% of the cases matched) may be possible under some circumstances. The linkage process highlights problems with the consistent recording of coronary angiography in inpatient and outpatient hospital abstracts. Our approach should prove useful when the same procedure is recorded in more than one place on a single file and when validating a procedure (or other event) across files is important. Given the growing number of health care databases and ongoing changes in the delivery of care, record linkage often can provide quality control and expand research opportunities in a timely fashion.