Authors' objectives

To investigate the possible relation between silicone breast implants and the risk of autoimmune conditions or connective tissue diseases.

Searching

Searches were conducted of MEDLINE (January 1966 to May 1998), Toxline (January 1985 to May 1998), Current Contents Search (July 1997 to May 1998), and Dissertation Abstracts Online (January 1992 to May 1998). Keywords included 'breast implant', 'breast augmentation', 'breast reconstruction', 'mammoplasty' and 'mammaplasty', 'rheumatic diseases', 'connective tissue disease', 'autoimmune disease', 'systemic sclerosis', 'scleroderma', 'lupus', 'dermatomyositis', 'sarcoidosis', 'rheumatoid arthritis', 'fibromyalgia', 'Sjogren', and 'polymyosistis'. Citations in other meta-analyses and reviews were also used as a source of studies. All searches were limited to reports published in English.

Study selection

Assessment of study quality

No systematic assessment of quality was undertaken, although aspects of quality were mentioned.

Data extraction

Data were abstracted independently by two reviewers using standardised data abstraction forms. Disagreements were resolved by discussion.

Methods of synthesis

Results of the review

Nine cohort studies (including 14,542 women with implants and 103,778 women without implants), nine case-control studies (including 3715 cases and 11,474 controls), and two cross-sectional studies (including 26,562 cases and 387,246 controls) were included.

The summary adjusted RR of individual connective tissue diseases associated with breast implants was 1.04 (95% CI 0.72, 1.51) for rheumatoid arthritis (7 studies), 0.65 (95% CI 0.35, 1.23) for lupus erythromatosus (4 studies), 1.01 (95% CI 0.59, 1.73) for scleroderma or systemic sclerosis (4 studies), 1.42 (95% CI 0.65, 3.11) for Sjogren's syndrome (3 studies), and 1.52 (95% CI 0.97, 2.37) for dermatomyositis or polymyosistis (1 study). The summary adjusted RR of all definite connective tissue disease combined, associated with breast implants, was 0.80 (95% CI 0.65, 3.11), and for other autoimmune or rheumatic conditions was 0.95 (95% CI 0.74, 1.25). There was no evidence, therefore, that breast implants were associated with a significant increase in any of these categories. Nor was there any evidence of significantly increased risk in the unadjusted analyses or in the analyses restricted to silicone-gel-filled implants. Funnel plots showed no evidence of publication bias.

Authors' conclusions

There was no evidence of an association between breast implants in general, or silicone-gel-filled implants specifically, and any of the individual connective tissues diseases, all definite connective tissue diseases combined, or other autoimmune or rheumatic conditions.

CRD commentary

The review addresses a clear question. The search strategy is adequate, although there is potential for language bias. The authors did investigate publication bias and found no evidence of it. The individual studies included in the review are presented clearly in tables, although it would have been helpful to have listed the type of implant used in each study. It is not explicit whether the tabulated outcome events were mutually exclusive within each study. There was no apparent systematic assessment of the quality of the included studies, although relevant aspects are mentioned in the results and discussion. The methods used for data analysis are clearly described and appear to be appropriate. Homogeneity was investigated whenever data were pooled in meta-analyses, and potential sources of heterogeneity were explored. In order to judge the strength of the evidence, it would have been helpful if the number of participants and the type of studies included in each meta-analysis, not only the number of studies, was presented. The conclusions do appear to be supported by the evidence presented.

Implications of the review for practice and research

Practice: The authors state that the elimination of implants would not be likely to reduce the incidence of connective tissue disease.

Research: The authors do not state any implications for research.

Funding

Administrative Office of the U.S. Courts, grant number USCA 79004.

Bibliographic details

Janowsky E C, Kupper L L, Hulka B S. Meta-analysis of the relation between silicone breast implants and the risk of connective tissue diseases. New England Journal of Medicine 2000; 342(11): 781-790. [PubMed: 10717013]

Original Paper URL

http://content.nejm.org/

Indexing Status

Subject indexing assigned by NLM

MeSH

Autoimmune Diseases /etiology; Breast Implants /adverse effects; Case-Control Studies; Cohort Studies; Confounding Factors (Epidemiology); Connective Tissue Diseases /etiology; Cross-Sectional Studies; Female; Humans; Odds Ratio; Rheumatic Diseases /etiology; Risk; Silicone Gels /adverse effects

AccessionNumber

12000008201

Database entry date

31/05/2001

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.