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The Effect of Study Design Biases on the Diagnostic Accuracy of MRI Evaluation of Silicone Breast Implant Ruptures: A Meta-Analysis
Jae W. Song, MD, MS, H. Myra Kim, ScD, Lilly Bellfi, BA, Kevin C. Chung, MD, MS.
University of Michigan, Ann Arbor, MI, USA.
PURPOSE: In 2006, the Food and Drug Administration (FDA) re-approved the use of silicone breast implants in the U.S., ending a 15 year ban. However, in parallel with the re-approval, recommendations to screen all recipients with MRI 3 years after implantation and biannually thereafter were also instituted. These recommendations affect a large number of women undergoing breast augmentation. An estimated 1 million women underwent augmentation with silicone gel implants between 1963 and 1988 prior to the ban, and from 2008-2009, nearly 50% of all women undergoing breast augmentation used silicone implants. With a growing number of women being implanted with silicone gel implants, serial screening throughout the implant’s lifetime raises concerns regarding MRI as an optimal screening modality. Despite the reported MRI sensitivity of 89% for detecting a silent rupture, we hypothesize that this value may be an over-estimation, given the inherent study design biases in the published literature evaluating the use of MRI in diagnosing silicone breast implant rupture.
METHODS: Studies investigating the diagnostic accuracy of MRI and ultrasound in evaluating ruptured silicone breast implants were identified through a systematic search of the literature using MEDLINE, EMBASE, ISI Web of Science, and Cochrane library databases. Eligible studies reported sufficient data to compute sensitivities and specificities, reported the number of silicone breast implants, confirmed ruptures with surgical explantation, and reported at least 10 patients. Two reviewers screened potential studies for inclusion and independently extracted the data. Study design biases were assessed using the Quality Assessment of Studies of Diagnostic Accuracy Studies (QUADAS) checklist.
RESULTS: Among 1175 identified articles, 21 met the inclusion criteria. Most studies using MRI (n= 10 of 16) and ultrasound (n=10 of 13) examined symptomatic subjects (Figure 1). Meta-analyses revealed that MRI studies evaluating symptomatic subjects had 14-fold higher diagnostic accuracy estimates compared to studies using an asymptomatic sample (RDOR 13.8; 95% CI 1.83-104.6) and 2-fold higher diagnostic accuracy estimates compared to studies using a screening sample (RDOR 1.89; 95% CI 0.05-75.7) (Figure 2).
CONCLUSION: Many of the published studies utilizing MRI or ultrasound to detect silicone breast implant rupture are flawed with methodological biases, particularly because of the use of only symptomatic samples. These methodological shortcomings may result in overestimated MRI diagnostic accuracy measures. Given these results, the FDA’s recommendations to use MRI as a screening test to detect ruptured silicone breast implants warrant further evaluation in the context of the high cost associated with serial screening and the number of false positive cases that may result in unnecessary breast implant explantation.
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