Review finds evidence for weekend effect on mortality in hospitalized patients

Based on 97 studies with more than 51 million patients, researchers calculated that mortality rates were 4.26% for patients admitted on weekends and 3.62% for those admitted on weekdays.

A recent systematic review and meta-analysis found some potential support for the existence of a weekend effect, or a higher mortality rate for patients admitted to the hospital on weekends versus on weekdays.

Researchers searched the PubMed, EMBASE, SCOPUS, and Cochrane databases from January 1966 through April 2013 to find English-language studies that compared discrete mortality data for weekends, including holidays, versus weekdays and included inpatients admitted over the weekend. The primary outcome was all-cause mortality for weekends versus weekdays. Subgroup analyses examined staffing levels, rates and times to procedures, and illness severity. The study results appeared in the September Journal of Hospital Medicine.

Ninety-seven studies involving 51,114,109 patients and published between 2001 and 2012 were included in the review. Seventy-six percent of patients across all studies were classified as weekday patients, while 24% were classified as weekend patients. Weekend and weekday mortality rates were 4.26% and 3.62%, respectively. The researchers found that overall mortality was significantly higher for those admitted on weekends versus weekdays (relative risk, 1.19; 95% CI, 1.14 to 1.23). In subgroup analyses, mortality rates were consistently higher for weekend versus weekday admissions regardless of staffing, rates and delays of procedures, or illness severity.

The researchers noted that they included only English-language studies, that definitions of “weekend” varied by study, and that it is unclear whether the differences in mortality were related to worse weekend care or to other factors, among other limitations. However, they concluded that their results suggested significantly increased mortality rates among patients admitted to the hospital on the weekend versus those admitted on the weekdays. “Further research should be directed to determine the presence of causality between various factors purported to affect mortality,” they wrote, “and it is possible that we ultimately find that the weekend effect may exist for some but not all patients.”