S. Tuinder

Predictors of complications after direct-to-implant breast reconstruction with an acellular dermal matrix from a multicentre randomized clinical trial: Complications after direct-to-implant breast reconstruction with an acellular dermal matrix

In the multicentre randomized trial BRIOS (Breast Reconstruction In One Stage), direct‐to‐implant (DTI) breast reconstruction with an acellular dermal matrix (ADM) was associated with a markedly higher postoperative complication rate compared with two‐stage tissue expander/implant breast reconstruction. This study aimed to identify factors that contribute to the occurrence of complications after DTI ADM‐assisted breast reconstruction.

Reply to the Letter to the Editor by Wade et al. "The importance of the Unit of Analysis". Commentary on: Beugels J et al. Complications in unilateral versus bilateral deep inferior epigastric artery perforator flap breast reconstructions: A multicentre study.

Interestingly, when we performed ‘per patient’ analyses, major complications occurred significantly more often in bilateral DIEP flap breast reconstructions and the true relative risk of major complications is somewhere between 1.15 and 3.23 (with 95% confidence). Similarly, total flap loss occurred in 6.7% of bilateral reconstructions compared to 2.8% in the unilateral group; note that the confidence interval for the relative risk of total flap loss spans from 1 (meaning the groups are the same) to 6 (meaning that bilateral reconstruction is 6 times as risky as unilateral reconstructions). The true relative risk of total flap loss in the population (as this is an estimate from a sample) is plausibly somewhere between 1 and 6 but the reason there is no statistically significant difference in this comparison is likely due to lack of power. To detect a 4% proportional difference in total flap loss, a power calculation (aZ 0.05, b Z 0.80) suggests that a sample size of approximately 932 would be required. We appreciate that recruitment of such a large sample of women seeking breast reconstruction is extremely difficult and equally don’t intend to devalue the findings of this otherwise excellent work. We think it is useful to show how changing the unit of analysis from ‘per patient’ to ‘per flap’ underestimates the risks of adverse outcomes for women undergoing bilateral DIEP flap breast reconstruction. Therefore, although this studywas performed and reported to a high standard, we are concerned that the conclusion “bilateral DIEP flap breast reconstructions can be performedwith the same percentage of complications” is not supported by their data or the established literature and so may mislead some readers.