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Background: The majority of women undergoing risk-reducing mastectomy have implant-based breast reconstruction, with capsular contracture being one of the most common complications. The primary aim of this study was to establish the national incidence rate of severe capsular contracture requiring surgery following risk-reducing mastectomy with implant-based breast reconstruction. The secondary aim was to establish the incidence rate of other complications and associated risk factors.

Methods: Women undergoing implant-based breast reconstruction following risk-reducing mastectomy were identified from the Swedish Breast Implant Register. Data were extracted from the Swedish Breast Implant Register and the National Patient Register on women undergoing implant-based breast reconstruction from 2014 to 2021. The primary outcome was severe capsular contracture corresponding to Baker grade III-IV requiring surgery, and the secondary outcomes were other complications observed perioperatively.

Results: In total, 656 women with 1095 implant-based breast reconstructions were included in the analysis. Median follow-up was 3.5 (interquartile range 1.5-5.4) years. Capsular contracture was observed in 39 of 1095 breasts (3.6%), and the cumulative incidence increased from 1.9% at 1 year to 4.7% after 5 years. Stratified by implant type, the estimated risk of capsular contracture increased for patients with a permanent tissue expander compared with a permanent fixed-volume implant (adjusted hazard ratio 19.33, 95% confidence interval 3.92 to 95.43; P < 0.001).

Conclusion: This study has highlighted that the risk of developing severe capsular contracture requiring surgery seems to differ between implant types, emphasizing the need for further investigation regarding permanent tissue expanders. Moreover, the continuous increase in capsular contracture incidence rates over 5 years underscores the importance of long-term follow-up.