The increasing availability of nationwide data organized in distinct information systems requires the development of linkage methodologies to identify the relationships between the same variables in different databases. This article describes and analyzes the linkage methodology between two countrywide databases: the Brazilian Mortality System and the database of the population covered by private health insurance. Death registrations and the records of individuals covered by private health insurance in 2004 were analyzed. 92,566 deaths were identified in those covered by private health insurance. The strictness in specificity instead of sensitivity in the method employed did not lead to selection biases that could have compromised the resulting analyses. The standardized mortality ratio (SMR) indicates underestimation of the number of deaths, in addition to showing differences in the risk of death between the populations analyzed; however, different life and health situations may have affected the results.
Mortalidade; Record linkage; Health information systems; Private health insurance; Mortality