Breast Implant Illness: Are We Measuring What Matters? A Systematic Review of Symptom Variability and the Impact of Methodology.

BACKGROUND: Breast Implant Illness (BII) refers to a wide range of symptoms reported by women with breast implants. Its underlying etiopathology remains unclear, and it is not officially recognized as a medical diagnosis, resulting in divergent perspectives among clinicians and patients. This systematic review provides a comprehensive overview of symptoms associated with BII and highlights the influence of methodology on the reported spectrum. METHODS MATERIAL: Multiple electronic databases were searched using the term "Breast Implant Illness". Of 871 identified studies, 23 were included in the qualitative analysis. From these, 19 were used to conduct a quantitative trend analysis of the "Top 20 BII-symptoms surveyed" and the "Top 20 BII-symptoms reported", along with their distribution across organ systems. In addition, the specific tools and strategies used for symptom collection were analyzed. RESULTS: A total of 98 symptoms were identified. "Fatigue" was most frequently reported, followed by "arthralgia/joint pain" and "myalgia/muscle pain". Symptoms affecting the nervous system and sensory organs predominated. Substantial methodological variability was observed, with only four studies using standardized questionnaires. CONCLUSION: The extensive range of symptoms reflects not only clinical heterogeneity but also methodological inconsistencies. The frequent presence of secondary diagnoses further complicates attribution to implants. A way forward includes the use of standardized, validated questionnaires and instruments addressing psychological domains, administered at predefined time points. Achieving international consensus on such tools is crucial to minimize bias, improve comparability, and enable prospective studies to clarify causal links and support the recognition of BII as a distinct clinical entity.