Abstract: We identified eight trials that met the inclusion criteria. One trial including 17 surgical trainees did not contribute to the meta-analysis. We included seven trials (249 surgical trainees belonging to various postgraduate years ranging from year one to four) in which the participants were randomised to supplementary box model training (122 trainees) versus standard training (127 trainees). Only one trial (50 trainees) was at low risk of bias. The box trainers used in all the seven trials were video trainers. Six trials were conducted in USA and one trial in Canada. The surgeries in which the final assessments were made included laparoscopic total extraperitoneal hernia repairs, laparoscopic cholecystectomy, laparoscopic tubal ligation, laparoscopic partial salpingectomy, and laparoscopic bilateral mid-segment salpingectomy. The final assessments were made on a single operative procedure. There were no deaths in three trials (0/82 (0%) supplementary box model training versus 0/86 (0%) standard training; RR not estimable; very low quality evidence). The other trials did not report mortality. The estimated effect on serious adverse events was compatible with benefit and harm (three trials; 168 patients; 0/82 (0%) supplementary box model training versus 1/86 (1.1%) standard training; RR 0.36; 95% CI 0.02 to 8.43; very low quality evidence). None of the trials reported patient quality of life. The operating time was significantly shorter in the supplementary box model training group versus the standard training group (1 trial; 50 patients; MD -6.50 minutes; 95% CI -10.85 to -2.15). The proportion of patients who were discharged as day-surgery was significantly higher in the supplementary box model training group versus the standard training group (1 trial; 50 patients; 24/24 (100%) supplementary box model training versus 15/26 (57.7%) standard training; RR 1.71; 95% CI 1.23 to 2.37). None of the trials reported trainee satisfaction. The operating performance was significantly better in the supplementary box model training group versus the standard training group (seven trials; 249 trainees; SMD 0.84; 95% CI 0.57 to 1.10). None of the trials compared box model training versus animal model training or versus different methods of box model training. There is insufficient evidence to determine whether laparoscopic box model training reduces mortality or morbidity. There is very low quality evidence that it improves technical skills compared with standard surgical training in trainees with limited previous laparoscopic experience. It may also decrease operating time and increase the proportion of patients who were discharged as day-surgery in the first total extraperitoneal hernia repair after box model training. However, the duration of the benefit of box model training is unknown. Further well-designed trials of low risk of bias and random errors are necessary. Such trials should assess the long-term impact of box model training on clinical outcomes and compare box training with other forms of training.

Plain-language summary: We identified and included seven trials in which 249 surgical trainees with limited previous laparoscopic experience received either box model training in addition to their standard apprenticeship training (122 trainees) versus standard apprenticeship training alone (127 trainees). The choice of whether the trainees received supplementary box model training was made in a random method similar to the toss of a coin. Six trials were conducted in USA and one trial in Canada. After supplementary box model training or standard training, the performance of the trainees was evaluated on their first operation after supplementary box model training and during the first operation in humans after an equivalent time after standard training. Different trials assessed the performance in different operations and all these operations were minor to moderate operations. Three trials including 168 trainees reported the complications that the patients developed during or immediately after the operation. There were no deaths in either group in 168 operations performed by 168 trainees and we could not tell whether laparoscopic box model training led to major complications (one major complication in one patient operated by a trainee who underwent standard training out of 86 operations performed by trainees who underwent standard training as compared with no major complications in 82 operations performed by trainees who underwent box model training). None of the trials reported patient quality of life. One trial reported a small reduction in operating time of just over six minutes in the supplementary box model training group. The remaining trials did not report operating time. In one trial, the proportion of patients who were discharged as day-surgery was significantly higher in the supplementary box model training group (24/24 (100%)) compared with the standard training group (15/26 (57.7%)). The remaining trials did not report the proportion of people who stayed overnight. None of the trials reported trainee satisfaction. The operating performance as assessed by surgical experts was significantly better in the supplementary box model training group compared with the standard training group. None of the trials compared box model training compared with animal model training or compared with different methods of box model training. Laparoscopic box model training appears to improve technical skills compared with standard surgical training in trainees with limited previous laparoscopic experience. It may also decrease operating time and decrease the proportion of patients who require overnight stay in the first hernia repair operation that the trainee performed after box model training. However, the duration of the benefit of box model training (ie, whether such benefit continues in subsequent operations) is unknown. Only one trial including 50 trainees was at low risk of bias (no risk of arriving at wrong conclusions because of favouritism by the researchers). Overall, the quality of evidence was very low. Further well-designed trials with less risk of bias because of poor study design or because of chance are necessary. Such trials should assess the long-term impact of box model training on clinical outcomes.