Copper IUD Users May Have Lower Risk of High-Grade Cervical Neoplasms

March 19, 2020

Copper intrauterine device users were found to have a lower risk of high-grade cervical neoplasms compared with levonorgestrel-releasing intrauterine system users.

Copper intrauterine device (IUD) users were found to have a lower risk of high-grade cervical neoplasms compared with levonorgestrel-releasing intrauterine system (LNG-IUS) users, according to a study published in Obstetrics & Gynecology.1

However, the relative risk of cervical neoplasms of LNG-IUS users compared with the general population remains unknown. 

“Copper and hormonal IUDs may have different physiological effects on the female genitourinary system,” lead author Matthew Spotnitz, MD, MPH, a postdoctoral research scientist within the Department of Biomedical Informatics at Columbia, said in a press release.2 “Consequently, the risk of cervical neoplasms may be different for copper and hormonal IUD users. Our findings may help patients and healthcare providers make informed decisions about whether the benefits of hormonal IUD use, compared to copper IUD use, are greater than the risks.”

Researchers performed a retrospective cohort analysis of 10,674 patients who received IUDs at Columbia University Medical Center. These data were transformed to a common data model and are part of the Observational Health Data Sciences and Informatics (OHDSI). The patients and outcomes were identified by a combination of procedure codes, condition codes, and medication exposures in billing and claims data. Moreover, the researchers adjusted for confounding with propensity score stratification and propensity score 1:1 matching.

Before adjusting the propensity score, the copper IUD cohort included 8,274 patients and the LNG-IUS cohort included 2,400 patients. Notably, more than 95% of the LNG-IUS cohort used a device with 52 mg LNG. Moreover, before propensity score adjustment, the researchers identified 114 cervical neoplasm outcomes. Overall, 77 (0.9%) cervical neoplasms were in the copper IUD cohort and 37 (1.5%) were in the LNG-IUS cohort.

The propensity score matching analysis identified 7,114 copper IUD users and 2,174 LNG-IUS users, with covariate balance achieved over 16,827 covariates. The diagnosis of high-grade cervical neoplasia was found to be 0.7% in the copper IUD cohort and 1.8% in the LNG-IUS cohort (2.4 [95% CI, 1.5-4.0] cases/1,000 person-years and 5.2 [95% CI, 3.7-7.1] cases/1,000 person-years, respectively). Further, the relative risk of high-grade cervical neo- plasms among copper IUD users was 0.38 (95% CI 0.16–0.78; P = .02) compared with LNG-IUS users. By inspection, the Kaplan-Meier curves for each cohort diverged over time. 

“The proportions of women who use copper and hormonal IUDs may vary among institutions,” Spotnitz said. “Overall, IUD use has become more popular over the past 20 years. Copper IUD use has remained constant whereas hormonal IUD use has increased. The rising popularity of hormonal IUDs may be related to the fact that they decrease the pain and bleeding of menses.”

The authors noted that further toxicology studies regarding the effects of copper IUDs and LNG-IUS are warranted. Additionally, a direct comparison between LNG-IUS users and women who do not use intrauterine contraception would be relevant. However, women who do not use intrauterine contraception are dissimilar from those who do. 

“The association between IUD usage and high-grade cervical neoplasm incidence has implications for public health on a global scale,” the authors wrote. “More than 100 million women use IUDs as contraception worldwide. An approximate 1% difference in high-grade cervical neoplasm incidence between LNG-IUS and Cu IUD users, as observed in this analysis, could have large worldwide effects, especially in those areas with the highest incidence of cervical cancer.”

Looking forward, Spotnitz indicated that the research team hopes to lead a network study across other databases within the OHDSI network.

Reference:

1. Spotnitz ME, Natarajan K, Ryan PB, Westhoff CL. Relative Risk of Cervical Neoplasms Along Copper and Levonorgestrel-Releasing Intrauterine System Users. Obstetrics & Gynecology. doi:10.1097/AOG.0000000000003656.

2. Columbia study evaluates cervical cancer risks of IUDs [news release]. New York, NY. Published March 10, 2020. eurekalert.org/pub_releases/2020-03/dsia-cse031020.php. Accessed March 17, 2020.