Background: A 2000 meta-analysis indicated no overall association between breast implants and risk of connective-tissue diseases (CTDs). However, a large retrospective cohort study we previously conducted suggested, instead, a small increased risk of CTDs. Because of limitations inherent to the retrospective cohort study design, we sought clarification by conducting a prospective cohort study of the association of breast implants with CTD risk.
Methods: Participants were 23 847 US women (mean age 56.6 years), 3950 of whom had breast implants and 19 897 did not. Women reported their breast implant status at baseline in 2001 and were followed for a median of 3.63 years. During follow-up, women reported incident CTD, confirmed using a CTD screening questionnaire (CSQ) and medical records.
Results: In multivariate analyses, the rate ratios for self-reported CTD (113 vs 377 cases in the implanted and non-implanted group, respectively) were 1.60 [95% confidence interval (CI) 1.28-2.00], for CSQ-confirmed CTD (77 vs 226 cases), 1.80 (1.37-2.38) and for medical record confirmed CTD (21 vs 74 cases), 1.39 (0.82-2.35).
Conclusions: Although this prospective cohort study represented a stronger design than the retrospective cohort study, the present data should still be viewed cautiously because of remaining methodological limitations, including the potential for differential self-reporting of CTD and CTD symptoms among women with and without breast implants, the difficulty of obtaining medical records for women reporting CTD and the low and possibly differential confirmation of self-reported disease against medical records. A reasonable conclusion is the lack of a large increase in CTD risk (e.g. ≥2-fold) associated with breast implants.