(BSPOT13) Does an additional gold or silver alloy provide any benefit over copper-only intrauterine devices? Insights from the EURAS-LCS12 study

Background: Some copper intrauterine devices (IUDs) contain copper wires with an additional gold or silver core which was promoted to prolong safe use of IUDs as they reduce breakage of the wire by fragmentation in the corrosion process. Other copper IUDs carry gold clips on the horizontal arms which should increase sonographic visualization of the IUD. Furthermore, copper-gold alloys tend to have an antibacterial effect which should further minimize the risk of pelvic inflammatory diseases. However, studies investigating these potential benefits of copper-gold and copper-silver alloys are lacking.

Objectives: To evaluate potential benefits of copper-gold and copper-silver alloys over copper-only IUDs with respect to the occurrence of product technical complaints, pelvic inflammatory diseases, and unintended pregnancies.

Methods: This secondary analysis comprised copper-only, copper-gold and copper-silver IUD users enrolled in the EURAS-LCS12 study from ten different European countries (Germany, Spain, Austria, United Kingdom, France, Italy, Poland, Finland, Sweden, Czech Republic). The occurrence of product technical complaints, pelvic inflammatory diseases, and unintended pregnancies were descriptively compared between copper IUD subtypes. Incidence rates with corresponding 95% confidence intervals were calculated.

Results: Overall, we included 144 different copper IUD models in our analysis which were used by a total of 32,826 study participants. Of those, most devices (23,863; 72.6%) contained solely copper followed by 7,790 (23.7%) copper-silver IUDs and 1,173 (3.6%) copper-gold IUDs. During a follow-up period of up to 66 months, 126 product technical complaints were reported with a higher proportion seen in copper-gold IUD users (n=36; 3.1%) compared to users of copper-only (n=55; 0.2%) and copper-silver IUDs (n=35; 0.4%). Overall, most (>90%) complaints were due to broken horizontal arms of the device. Quality issues with the copper wire was reported by one study participant using a copper IUD with gold clips. The incidence of unintended pregnancies was similar across copper IUD subtypes (copper-only: 0.5 [95% CI, 0.41–0.54]; copper-gold: 0.5 [95%, 0.25–0.83]; copper-silver: 0.4 [95% CI, 0.27–0.47] per 100 women-years [WY]). In total, we observed 29 events of pelvic inflammatory disease with no substantial differences between IUD subtypes (copper-only: 20/44,759 WY; copper-silver: 8/14,213 WY; copper-gold: 1/2,509 WY).

Conclusions: We did not observe any benefits of copper-gold or copper-silver alloys over copper-only IUDs. Product technical complaints were very rare and mostly due to breakage of horizontal arms rather than a fragmented copper wire. Clinicians may choose to use these data when counseling patients.