Was the Dalkon Shield a safe and effective intrauterine device? the conflict between case-control and clinical trial study findings
Mumford, S.D.; Kessel, E.
Fertility and Sterility 57(6): 1151-1176
1992
ISSN/ISBN: 0015-0282 PMID: 1601137 DOI: 10.1016/s0015-0282(16)55068-7Document Number: 556597
2 researchers searched MEDLARS databases for articles on clinical trials of the Dalkon Shield to compare the results of case control and cohort studies which identified its relationship with pelvic inflammatory disease (PID) with those of other clinical trials. They identified 71 useful reports. The results of clinical trials not used to incriminate the A.H. Robins Company, the manufacturer of the Dalkon Shield, showed that the Dalkon Shield was indeed safe and effective when inserted by a skilled and experienced clinician. In addition, the Dalkon Shield compared favorably with other IUDs. Further the pregnancy rate and removal rate for pain and bleeding matched those of other IUDs. Moreover the expulsion rate for the Dalkon Shield was better than that of other IUDs. In those studies that examined PID, the PID rates were essentially the same as the expected rates of other IUDs in their clinic populations. Besides, even though the case control studies suggested a considerable increased PID rates with the Dalkon Shield, increased rates of removals for pain and bleeding did not occur. Furthermore pregnancy and expulsion rates improved as did the skill and experience of the physicians who inserted the Dalkon Shield. In fact, the best rates occurred in trials conducted in centers where only a few clinicians inserted 1000 Dalkon Shields. For example, the removal rate for pain or bleeding was as low as 0.9%. This rate among inexperienced clinicians was as high as 27%. The fact that the litigation case against A.H. Robins used the results of the weaker case control studies rather than the superior randomized clinical trial resulted in removal of a safe and effective contraceptive. Further IUD studies should incorporate clinician skill as a variable to better assess the IUD's efficacy and safety.