122 Chapter 8 factors were treated as dichotomous variables, and the predicted probability of implant loss ranged from 4.5% in the absence of any risk factors to 38% in the case of four risk factors. Since the model was subsequently internally validated, the model could be expanded to the Dutch reconstructive population at large. Several studies in literature already assessed the risk on implant loss. One study created an evidence-based intervention bundle with a multidisciplinary team. After implementing this protocol, the implant loss rate in 3 months decreased from 14% to 0%. Among other things, a patient selection was introduced where no more than one risk factor was allowed (BMI>30 kg/m2, smoker, diabetes, radiotherapy, neoadjuvant chemotherapy) and only implants <500 cc were placed.24 The Dutch national guideline also recommends patient selection, suggesting not to perform immediate implant-based breast reconstruction in patients with more than two risk factors (smoking, BMI≥30 kg/m2, age >55 years, larger breast, bilateral surgery). Moreover, the guideline recommends preferably not to perform immediate implant reconstruction if there is a high chance of postoperative radiotherapy.30 This guideline was partly based on the study of Fischer et al, where risk factors for implant loss were identified and odds ratios were used to assign weighted risk scores in three categories, low, intermediate and high risk.23 Although this is the largest study assessing outcomes in IBR associated with implant loss, they only covered ‘early’ implant loss within the first 30 postoperative days, with a very low overall implant loss rate of 0.8%. This was a much lower rate compared to the study in chapter 7, reporting on 5260 implant-based breast reconstructions included from the DBIR, with an implant loss rate of 6.7%. Moreover, the study in chapter 7 reported a median time to surgical removal of the implant of 42 days (IQR: 21 to 83 days). Based on these results, a substantial part of patients who will suffer from implant loss will be missed with a 30 day follow-up. Some literature even suggest that follow-up should be at least one year for infectious complications, which can lead to implant loss.31 Following the results of this thesis, we can conclude that in different cohorts, different risk factors for implant loss were identified. If we compare the study in chapter 5, including data of two medical centers in the Netherlands, with the risk factors derived from the DBIR database in chapter 7, just two risk factors are consistent, which were smoking and obesity. One risk factor, a lower volume of the oncological surgeon, could not be derived from the DBIR database, but could be linked to another important factor. The quality and vascularization of the mastectomy skin flaps are the most important aspects in a successful IBR and could be influenced by the experience of the surgeon. Additionally, until experience is gained establishing skin perfusion, for inexperienced surgeons a two-stage reconstruction is a safer option compared to a DTI reconstruction.21
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