(286) LEARNING CURVE OF ANTEROLATERAL THIGH FLAP PHALLOPLASTY (ALT) FOR TRANSMASCULINE GENDER AFFIRMATION SURGERY

Abstract Introduction The anterolateral thigh flap phalloplasty (ALTP) offers the advantages of an easily hidden scar, security of vascular supply and improved flexibility in the length of the flap. Objective The aim of the study is to define for the first time the surgical learning curve of ALTP. Methods To compute the surgical learning curve for ALTP we defined as the surgical outcome measure all complications that occurred after the phalloplasty, excluding complications related to the join-up and erectile device to avoid confounding. 30-day complications, total/partial flap loss, urethral strictures, and urethral fistulas were included. The number of cases performed was used as a proxy for surgical experience. To build the curve we first fitted a multivariable logistic regression model including all clinically significant covariables (case number, flap area, age, presence of urethra, number of vascular pedicles > = 2) and then proceeded with the stepwise backward variable selection to obtain a model with only significant covariables. We then built the surgical learning curve by graphing the marginal predicted complications probability over the number of cases performed, ordered in chronological order, adjusted by the number of vascular pedicles. Results From 2009 87 patients underwent ALTP. The median age was 31 (IQR 26-43) and median BMI was 23.5 (21.0-26.0). The cohort had few comorbidities where only 3 patients had diabetes mellitus and none had cardiovascular disease. The median follow up of the cohort was 64 months (43-80). Eighty-one (93%) patients had a pedicled flap, with the remainder requiring free flap transfer. Overall, 31 patients experienced at least one complication as defined previously for the surgical outcome. The multivariable regression model found the case number and the number of vascular pedicles predictors of all complications after the phalloplasty (respectively: OR = .97, p = .003, 95% CI = .95-.99; OR = 4.19, p = .036; 95% CI = 1.09-15.9). More specifically, the probability of complications decreases as more cases are performed and increases when the flap has > = 2 vascular pedicles. The surgical learning curve shows a constant decrease in the adjusted probability of complications from an initial 65% to 10%. Although there was a slight horizontal trend in the last cases, a clear plateau was not reached. Conclusions ALTP is a difficult procedure performed only is specialized centers. The learning curve takes several years to accomplish, and we may have not reached its end yet. The relatively low number of cases performed over an extended period may have affected the rendering of the curve. Disclosure No.