Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 55 7 2017 09 16 459 463 EN Seyed Mohammad Kazem Aghamir Department of Urology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Negar Behtash Department of Urology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Morteza Hamidi Department of Urology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran.AND Department of Urology, AJA University of Medical Sciences, Tehran, Iran. Hasan Farahmand Department of Urology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Alborz Salavati Department of Urology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran. Sara Mortaz Hejri Department of Medical Education, Helath Professions Education Research Center, Tehran University of Medical Sciences, Tehran, Iran. 2016 07 05 2017 04 13 Percutaneous nephrolithotomy (PNL) is a complicated procedure for urology trainees. This study was designed to investigate the effect of trainees’ ages and previous experience, as well as the number of operated cases, on proficiency at PNL by using patient outcomes. A cross sectional observational study was designed during a five-year period. Trainees in PNL fellowship programs were included. At the end of the program, the trainees’ performance in PNL was assessed regarding five competencies and scored 1-5. If the overall score was 4 or above, the trainee was considered as proficient. The trainees’ age at the beginning of the program and the years passed from their residency graduation were asked and recorded. Also, the number of PNL cases operated by each trainee was obtained via their logbooks. The age, years passed from graduation, and number of operated cases were compared between two groups of proficient and non-proficient trainees. Univariate and multivariate binary logistic regression analysis was applied to estimate the effect of aforementioned variables on the occurrence of the proficiency. Forty-two trainees were included in the study. The mean and standard deviation for the overall score were 3.40 (out of 5) and 0.67, respectively. Eleven trainees (26.2%) recognized as proficient in performing PNL. Univariate regression analysis indicated that each of three variables (age, years passed from graduation and number of operated cases) had statistically significant effect on proficiency. However, the multivariate regression analysis revealed that just the number of cases had significant effect on achieving proficiency. Although it might be assumed that trainees’ age negatively correlates with their scores, in fact, it is their amount of practice that makes a difference. A certain number of cases is required to be operated by a trainee in order to reach the desired competency in PNL. https://acta.tums.ac.ir/index.php/acta/article/view/5758 https://acta.tums.ac.ir/index.php/acta/article/download/5758/4964