Objective To examine the association of consultants’ experience with mortality by day of the week when elective surgery was performed.

Design Retrospective observational study using English hospital administrative data.

Setting All acute and specialist English National Health Service (NHS) hospitals carrying out elective surgery between financial years 2008–2009 and 2010–2011.

Participants Patients undergoing elective surgical procedures.

Main outcome measures Death in or out of hospital within 30 days of the surgical procedure taking place.

Results We examined 3 922 091 (26 409 deaths) elective procedures with valid consultant information between 2008–2009 and 2010–2011 in English hospitals; there were 21 196 consultants in charge of these procedures, which took place in 163 NHS hospitals. Consultant seniority had no significant impact in predicting mortality (p=0.345). Patients undergoing elective surgery under junior consultants had slightly lower odds of 30-day death when compared with patients under more experienced consultants (OR 0.95, 95% CI 0.91 to 0.99). We found significant mortality variation among consultants in charge of elective procedures within hospitals, with only moderate variation between hospitals. The adjusted odds of death remained higher for Friday (OR 1.48, 95% CI 1.42 to 1.54), Saturday (OR 1.97, 95% CI 1.83 to 2.12) and Sunday (OR 1.67, 95% CI 1.50 to 1.85) after adjusting for consultant seniority and patient characteristics. Consultant experience is significantly lower (p<0.0001) on a Friday (median (SD) was 7.9 years (4.4)) than the Monday to Thursday average (median (SD) was 8.5 years (4.3)).

Conclusions Our cohort of patients shows that consultant seniority is not a significant factor in predicting 30-day mortality following elective surgery by day of the week. The end-of-the-week effect remains significant after adjusting for patient, consultant and hospital effects, suggesting that other unobserved factors may be driving the higher mortality towards the end of the week. Consultant's years of experience are lowest on a Friday; however, we do not believe that this small variation has any impact on patient outcomes.