Andy Stergachis

Record linkage studies for postmarketing drug surveillance: data quality and validity considerations.

Large automated databases are the source of information for many record linkage studies, including postmarketing drug surveillance. Despite this reliance on prerecorded data, there have been few attempts to assess data quality and validity. This article presents some of the basic data quality and validity issues in applying record linkage methods to postmarketing surveillance. Studies based on prerecorded data, as in most record linkage studies, have all the inherent problems of the data from which they are derived. Sources of threats to the validity of record linkage studies include the completeness of data, the ability to accurately identify and follow the records of individuals through time and place, and the validity of data. This article also describes techniques for evaluating data quality and validity. Postmarketing surveillance could benefit from more attention to identifying and solving the problems associated with record linkage studies.

Vaginal spermicides and miscarriage seen primarily in the emergency room

Among 813 women who had obtained a vaginal spermicide within 48 weeks of the estimated date of fertilization (EDF), 47 (5.8%) had an early miscarriage. Among women who had obtained oral contraceptives, 35/1,127 (3.1%) miscarried, and among women who obtained neither, 140/4,231 (3.3%) miscarried. The risk ratio estimate comparing spermicide users with nonusers was 1.8 (90% confidence interval 1.4, 2.3). The association was strongest among women who had obtained a spermicide within 12 weeks of the EDF. Examination of abortus material revealed that the association with spermicides was strongest among those where an abnormal fetus was present.

A Comparison of Wax Matrix and Microencapsulated Potassium Chloride in Relation to Upper Gastrointestinal Illness Requiring Hospitalization

The frequency of hospitalization for documented upper gastrointestinal illness among recipients of either wax matrix or microencapsulated potassium chloride was similar in a study in which clinics were randomly assigned to dispense one or the other preparation. The results indicate that there is no material difference between the two preparations in relation to serious upper gastrointestinal illness.