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Title: Was the Dalkon Shield a safe and effective intrauterine device? The conflict between case-control and clinical trial study findings.
Author: Mumford SD, Kessel E.
Journal: Fertil Steril; 1992 Jun; 57(6):1151-76. PubMed ID: 1601137.
Abstract:
OBJECTIVE: To compare the findings of the case-control and cohort studies used to indict the Dalkon Shield (A.H. Robins Company, Inc., Richmond, VA) with the findings of the Dalkon Shield clinical trials. DATA IDENTIFICATION: All published reports on the Dalkon Shield were identified through MEDLARS system (United States National Library of Medicine) searches and by cross checking all references in these reports. The same approach was used to identify all case-control and cohort studies of the purported relationship between intrauterine devices (IUDs) and pelvic inflammatory disease (PID). STUDY SELECTION: Only studies of interval patients that included 50 or more women and 6 or more months of follow up that computed standard IUD event rates (rates of pregnancy and expulsion and removal for pain and bleeding) were selected for this study. All case-control and cohort studies identified were included except two case-control studies that included women with sterile chronic salpingitis. RESULTS: The 16 case-control and 2 cohort studies found or suggested that the Dalkon Shield increased the risk of PID. The 71 clinical trials of the Dalkon Shield show that when this device is inserted by an experienced clinician it is a safe and effective contraceptive method, comparable with other IUDs used at the time. There was no evidence of an increased risk of PID found in these clinical trials. CONCLUSIONS: This study offers convincing evidence that the indictment of the Dalkon Shield was a mistake. Additionally, this study shows that physician skill and experience is far more important to successful IUD insertion than previously recognized, a finding with considerable implications for IUD study designs and for marketing strategies. 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.

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