Severity of illness and the weekend effect

Abstract

In their Article (July 1, p 62),1Walker AS Mason A Quan TP et al.Mortality risks associated with emergency admissions during weekends and public holidays: an analysis of electronic health records.Lancet. 2017; 390: 62-72Summary Full Text Full Text PDF PubMed Scopus (87) Google Scholar A Sarah Walker and colleagues reported that part of the so-called weekend effect can be explained using detailed biochemical, haematological, and other tests, which were absent in previous studies based on administrative databases. We believe that the availability of detailed data cannot explain all differences in outcomes between weekends and weekdays. In a report2Kostis WJ Demissie K Marcella SW et al.Weekend versus weekday admission and mortality from myocardial infarction.N Engl J Med. 2007; 356: 1099-1109Crossref PubMed Scopus (491) Google Scholar on admissions for acute myocardial infarction in New Jersey (USA), we suggested that the higher mortality after weekend admissions might be due to the lower rate of invasive procedures on weekends than on weekdays. Higher adjusted mortality and lower use of cardiac procedures on weekends, when considering measures of disease severity, were also observed among 13 988 772 admissions for acute coronary syndromes, using data from the Nationwide Inpatient Sample.3Khoshchehreh M Groves EM Tehrani D Amin A Patel PM Malik S Changes in mortality on weekend versus weekday admissions for Acute Coronary Syndrome in the United States over the past decade.Int J Cardiol. 2016; 210: 164-172Summary Full Text Full Text PDF PubMed Scopus (37) Google Scholar A reduction in the weekend effect was also reported in 2016, concurrent with higher availability of specialised procedures, and with newer guidelines that demand immediate attention to acute myocardial infarction.3Khoshchehreh M Groves EM Tehrani D Amin A Patel PM Malik S Changes in mortality on weekend versus weekday admissions for Acute Coronary Syndrome in the United States over the past decade.Int J Cardiol. 2016; 210: 164-172Summary Full Text Full Text PDF PubMed Scopus (37) Google Scholar The problem might not be the capacity (hospital workload, as measured by the authors) but rather the capability to provide highly specialised care. The hypothesis that lower availability of specialised care could explain the myocardial infarction findings is supported by data that indicate a higher 90-day risk of fatalities following cases of stroke on weekends, but not in those hospitals with on-site availability of specialised personnel and facilities for immediate diagnosis and treatment of stroke.4McKinney JS Deng Y Kasner SE et al.Comprehensive stroke centers overcome the weekend versus weekday gap in stroke treatment and mortality.Stroke. 2011; 42: 2403-2409Crossref PubMed Scopus (96) Google Scholar Differences in severity of illness are unlikely to explain most of the weekend effect, which has lessened over time because of improved availability of specialised care on weekends. We declare no competing interests. Mortality risks associated with emergency admissions during weekends and public holidays: an analysis of electronic health recordsAdjustment for routine test results substantially reduced excess mortality associated with emergency admission at weekends and public holidays. Adjustment for patient-level factors not available in our study might further reduce the residual excess mortality, particularly as this clustered around midday at weekends. Hospital workload was not associated with mortality. Together, these findings suggest that the weekend effect arises from patient-level differences at admission rather than reduced hospital staffing or services. Full-Text PDF Open AccessSeverity of illness and the weekend effect – Authors' replyIn their letter, William J Kostis and Abel E Moreyra suggest that the poor availability of detailed data cannot explain all differences in outcomes between patients admitted at weekends and on weekdays. There is no intrinsic causal mechanism for a named day to lead to higher mortality risk and, therefore, some data clearly must exist that explain how the higher risk arises. Full-Text PDF