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March 9, 1984

Intrauterine Devices and Pelvic Inflammatory Disease-Reply

Author Affiliations

Boston University School of Medicine School of Public Health

JAMA. 1984;251(10):1278-1279. doi:10.1001/jama.1984.03340340020012

In Reply.—  We set out to compare the Dalkon Shield with other IUDs because there was a specific hypothesis concerning this device. It is correct that there were more total Saf-T-Coil users; however, when the Dalkon Shield is contrasted with the Saf-T-Coil, the age-adjusted relative risk estimate of 4.7 (95% confidence interval, 0.9 to 23.1) does not alter the conclusions in our article.The discrepancy between the numbers of controls using the Dalkon Shield in our two studies is accounted for by more rigorous diagnostic criteria in the second study; this was feasible because there were more potential controls available. Thus, a patient eligible as a control in the first study may have been excluded from the second on the basis of her diagnosis. An example of such a diagnosis is colitis: this diagnosis is nonspecific, and the condition may be chronic. The selection of controls was made without knowledge