A large Danish study does not confirm the claim in The Lancet that it is less dangerous to undergo surgery in the afternoon.

An article in the acknowledge journal The Lancet caused a stir as a French research group in 2018 claimed that it was less dangerous to undergo surgery in the afternoon than in the morning.

This made researchers at Aarhus University Hospital and Aarhus University in Denmark to conduct a registry-based study on 7,000 patients in the Western Denmark Heart Registry. The French study included almost 600 patients.

- We believe we can refuse this claim. There was no daytime-dependent variation between neither aortic valve replacement nor cardiac bypass surgery concerning mortality or serious complications. Moreover, there were no differences in long-term survival, says Ivy Modrau, Consultant MD.

The Danish researchers reviewed all elective patients undergoing aortic valve replacement or cardiac bypass surgery at Aarhus University Hospital and divided patients into comparable morning and afternoon cohorts.

- In Denmark, we have high-quality and complete databases. Using the unique civil registration number assigned to all Danish citizens, we are able to link data across several databases. In this way we can check facts and give a qualified answer to the questions raised in studies conducted on smaller populations, says Ivy Modrau.

The researchers compared 30-day mortality and major complications (cardiac thrombosis during admission) in the two groups. They also compared the prevalence of atrial fibrillation during admission, peak creatine-kinase MB levels (released when muscle tissue in the heart is destroyed) as well as mortality up to 19 years after surgery; the researchers did not find any differences between the groups.


Behind the research result:

Study type: Propensity-score matched registry study

Collaborators: None

External financing: No

Conflicts of interest: None


Read the scientific article: 

Kenney PS, Nielsen PH, Modrau IS.  Daytime-dependent cardioprotection in cardiac surgery. A large propensity-matched cohort study- The Annals of Thoracic Surgery. Available online 13. April 2020; https://doi.org/10.1016/j.athoracsur.2020.03.030

See also: Montaigne et al. Daytime variation of perioperative myocardial injury in cardiac surgery and its prevention by Rev-Erbαantagonism: a single-centre propensity-matched cohort study and a randomised study. Lancet, The, 2018-01-06, Volume 391, Issue 10115, Pages 59-69; https://doi.org/10.1016/s0140-6736(17)32132-3


Further information: 

Ivy Modrau, Consultant MD, Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital and Associate professor at Department of Clinical Medicine, Aarhus University

Tel.: 7845 3064 (secretary)