Objective: To link the administrative data of a large dental carrier and an integrated health plan in Washington State to conduct an observational study of diabetes and periodontal disease.
Study design: Evaluation of variable suitability, testing of linkage variables, and performing an n - 1 deterministic linkage strategy.
Methods: We examined a variety of administrative data variables for their consistency over time and their information richness to use as matching variables. After choosing social security number, date of birth, first name, and last name, we tested their reliability as linking variables among a population with dual dental and medical insurance. Lastly, we performed four n - 1 deterministic linkage steps to obtain our study population.
Results: With a success match rate of more than 96% with the 4 test variables, we extracted the entire population who met the study criteria with the understanding that only a subset would successfully link. We linked 78,230 individuals (55.2% of the Group Health Cooperative population). Of these matches more than 50% occurred within a last name-first name-birth date deterministic match.
Conclusions: Employer groups who provide dental-medical benefits for their employees send identical administrative data to dental and healthcare plans. The n - 1 deterministic linkage was accomplished by using a relatively straightforward approach because these data were fairly homogeneous and of high quality. Until medical care and dental care are integrated, it is possible to link these data to assess the impact of oral disease on overall health.