75 Implant loss and associated risk factors following implant-based breast reconstruction Table 5. Risk model Accumulating number of risk factors and corresponding predicted implant loss rates. Additionally, the observed implant loss rates are summarized. Risk factors Predicted risk Observed risk 0 < 3.6% 2% 1 8.4%–13.0% 10.5% 2 21.9%–32.5% 23.0% 3 47.5%–59.3% 60.0% 4 > 78.2% — DISCUSSION The risk of implant loss following an implant-based breast reconstruction in this study was 11.8%, with a yearly variation of 5.5%–18.3%. A growing body of literature has estimated several risk factors for implant loss, most of which are consistent with our findings. Six individual risk factors were associated with implant loss: obesity, a bra cup size larger than C, an active smoking status, a nipple-preserving procedure, a DTI approach, and a lower surgeon’s volume. Obesity is well known as a risk factor for complications following implantbased reconstructions. According to a theory proposed by Hirsch et al.14 this might be caused by a proportionally larger breast with larger mastectomy flaps, accompanied by a decreased blood supply, more postoperative dead space, and prolonged duration of surgery, which increase the potential for complications. Our result is consistent with this theory, as obesity and a bra cup size larger than C were both significant risk factors for implant loss. A breast cup size larger than C has also been reported by Francis et al. as a risk factor for implant loss.15 Smoking is known to have an adverse effect on outcomes following implant-based breast reconstructions,16, 17 which is in line with our findings. This is probably due to the negative effect of nicotine as a vasoconstrictor that reduces nutritional blood flow to the skin.18 Furthermore, previous studies have shown that complication rates after using a DTI approach are higher than after performing a two-stage procedure.10 Our results confirm a significant relationship between the DTI approach and implant loss. This relationship also appears in the yearly variation of implant loss in this study. The highest incidence of implant loss (18.3%) was in the first year, in which in 53.7% of the procedures, a DTI approach was used. This high rate resulted in a shift toward two-stage reconstructions in the following years. Nipple-preserving surgery appeared to be the most significant risk factor for implant loss in this study. A review of the literature showed that this is the first time that nipple preservation proved to have a negative effect on surgical outcomes, specifically on implant loss. The most common complication that led to a surgical 5
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