In July 2003, the US Accreditation Council for Graduate Medical Education (ACGME) initially mandated nationwide

duty hours regulations (DHR) on resident work hours; this lasted until June 2011, when additional rule changes were implemented.1,2 While the aim of these changes was to improve working conditions and patient safety, the medical profession has raised concerns about potential negative effects on graduate medical education (GME).3-5 Most published studies were subjective and single-institution survey-based, with small sample sizes.6-8 Only a few utilised objective measures (such as operative case-loads, standardised in-training examination scores, or the board pass rates at a single or multiple institutions) to examine the impact of the 2003 DHR on the quality of GME and all of them were from surgical specialties.6-8 The literature suggests that the 2003 DHR have an influence on three main groups: trainees, faculty and patients.7,9,10 Generally