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The weekend effect—how strong is the evidence?

BMJ 2016; 353 doi: (Published 19 May 2016) Cite this as: BMJ 2016;353:i2781

Re: The weekend effect—how strong is the evidence?

Unfortunately I have been misquoted in the article. The inability of administrative data (Hospital Episode Statistics) to be used to make meaningful comparisons of outcomes by day of the week is not because "There is nothing in the coding about comorbidity” but due to the absence of any data on the severity of the condition for which the patient was admitted. Comorbidity data present a different shortcoming - they are included but are probably wrong (eg patients at weekends are reported as suffering less comorbidity than those admitted during the week).

Competing interests: No competing interests

20 May 2016
Nick Black
Professor of Health Services Research
15-17 Tavistock Place, London WC1H 9SH