Is hospital mortality higher at weekends? If so, why?
Authors: Nick Black
Journal: The Lancet (2016)

In the past few years, politicians, the media, clinicians, and managers have become increasingly interested in the risks involved in being admitted to hospital at weekends. Although higher neonatal mortality has been reported for babies born at weekends than for those born during the week in the USA,1Mangold WD Neonatal mortality by the day of the week in the 1974–75 Arkansas live birth cohort.Am J Public Health. 1981; 71: 601-605Crossref PubMed Scopus (46) Google Scholar the UK,2McFarlane A Variations in number of births and perinatal mortality by the day of week in England and Wales.BMJ. 1978; 2: 1670-1673Crossref PubMed Scopus (92) Google Scholar and Australia3Mathers CD Births and perimatal deaths in Australia: variations by day of week.J Epidemiol Community Health. 1983; 37: 57-62Crossref PubMed Scopus (52) Google Scholar since the 1970s, the first investigation of a weekend effect in other areas of hospital care was not reported until 2001. Bell and Redelmeier4Bell CM Redelmeier DA Mortality among patients admitted to hospitals on weekends as compared with weekdays.N Engl J Med. 2001; 345: 663-668Crossref PubMed Scopus (854) Google Scholar reported higher mortality rates for weekend admissions than for weekday admissions for 23 of the 100 leading causes of death in Canadian hospitals. Since then, studies from around the world have likewise shown differences in mortality between patients admitted at weekends and those admitted during the week. In England, in 2010, Aylin and colleagues5Aylin P Yunus A Bottle A Majeed A Bell D Weekend mortality for emergency admissions. A large, multicentre study.Qual Saf Health Care. 2010; 19: 213-217Crossref PubMed Scopus (187) Google Scholar showed that the odds of death for emergency admissions were 10% higher at weekends than during the week and, in 2012, Freemantle and colleagues6Freemantle N Richardson M Wood J et al.Weekend hospitalization and additional risk of death: an analysis of inpatient data.J R Soc Med. 2012; 105: 74-84Crossref PubMed Scopus (212) Google Scholar reported that mortality for all admissions (emergency and elective) was 11% higher on Saturdays and 16% higher on Sundays than on other days during the week. Widespread interest in England about the possible dangers of being admitted to hospital at weekends has prompted several studies into why this might be, three of which have been published this week. In The Lancet, Cassie Aldridge and colleagues7Aldridge C Bion J Boyal A et al.Weekend specialist intensity and admission mortality in acute hospital Trusts in England: a cross-sectional study.Lancet. 2016; (published online May 10.)http://dx.doi.org/10.1016/S0140-6736(16)30442-1PubMed Google Scholar provide initial results from an ambitious cross-sectional study evaluating the effect of a natural experiment offered by the roll-out of 7 day services in acute hospitals in England. With a focus on the effect of medical specialist (consultant) staffing levels, the investigators surveyed more than 15 000 specialists in 115 acute hospital trusts to obtain data for the time they each spent caring for emergency admissions on a Wednesday and on a Sunday. The estimated weekend effect showed a 10% increase in mortality for weekend admissions (odds ratio 1·10 [95% CI 1·08–1·11]). Patients received only half as much specialist attention at weekends as on weekdays (median 21·90 [IQR 15·07–29·00] total specialist hours per ten emergency admissions on Sunday vs 42·73 h [33·37–55·36]). However, there was no significant association between intensity of specialist staffing and mortality. In view of the response rate to the staff survey (45%), the limitations of basing adjusted mortality on hospital administrative data (which do not provide any biochemical or physiological indication of how sick patients are on admission), and the fact that the study did not consider availability of other staff (eg, junior doctors, nurses), the implications of these results should be interpreted with caution. Although Aldridge and colleagues' findings challenge one of the most widely held views of the cause of higher weekend mortality, establishing whether increasing specialist staffing levels is a beneficial approach must await their secular analyses over the next few years. Meanwhile, also in The Lancet, Benjamin Bray and colleagues'8Bray BD Cloud GC James MA et al.Weekly variation in health-care quality by day and time of admission: a nationwide, registry-based, prospective cohort study of acute stroke care.Lancet. 2016; (published online May 10.)http://dx.doi.org/10.1016/S0140-6736(16)30443-3PubMed Google Scholar interest is in the level of compliance with evidence-based clinical guidelines. With a focus on stroke care, the investigators overcome some of the limitations of administrative data by using a specialist clinical database that allows them to adjust mortality for differences in the severity of admissions (using the US National Institutes of Health Stroke Score or level of consciousness) on weekdays and at weekends. Whereas a study of stroke admissions based on administrative data in 2009–10 reported a 26% higher mortality for weekend admissions than for weekday admissions,9Palmer WL Bottle A Davie C Vincent CA Aylin P Dying for the weekend: a retrospective cohort study on the association between day of hospital presentation and the quality and safety of stroke care.Arch Neurol. 2012; 69: 1296-1302Crossref PubMed Scopus (83) Google Scholar Bray and colleagues' study finds no difference in 30 day mortality in 2013–14; this difference might reflect an improvement in weekend care or could be due to insufficient casemix adjustment in the earlier study. Instead, the investigators suggest we should be more concerned about patients admitted at night, in whom mortality was 10% higher than in those admitted during the day (adjusted odds ratio 0·90 [95% CI 0·82–0·99]). As for adherence to clinical guidelines, such as door-to-needle time and a timely brain scan, patients admitted at night were less likely to receive eight of 12 recommended interventions, which, they suggest, might contribute to heightened mortality. However, before drawing conclusions about the association between adherence to guidelines and outcomes, Bray and colleagues note that although patients admitted at the weekend were also less likely than weekend admissions to receive good quality care, this was not associated with higher mortality. In a third innovative approach to investigating the cause of increased weekend mortality, Meacock and colleagues10Meacock R Anselmi L Kristensen SR Doran T Sutton M Higher mortality rates amongst emergency patients admitted to hospital at weekends reflect a lower probability of admission.J Health Serv Res Policy. 2016; (published online May 6.)DOI:10.1177/1355819616649630PubMed Google Scholar looked beyond the hospital to see the effect of primary care. To do this, the investigators compared the two routes of emergency admissions: direct referrals (mostly from general practitioners) and patients admitted from accident and emergency departments. Whereas the daily number of admissions via accident and emergency departments at weekends was similar to that on weekdays, the number of direct admissions was 61% lower. While mortality for admissions via accident and emergency was only 5% higher at weekends, for direct admissions it was 21% higher. Given that, apart from initial treatment in accident and emergency, both sets of patients receive the same inpatient care, this finding provides circumstantial evidence that mortality differences are more likely to be attributable to how sick patients are on admission, rather than the quality of hospital care. In view of these new, albeit inconsistent, insights into the possible dangers of weekend admissions, what conclusions can be drawn and what further research is needed? First, caution should be taken in estimating the effect on mortality. Previous studies based on routine administrative data did their best to use inventive and sophisticated methods to take casemix difference between weekends and weekdays into account, but had little information about how sick patients were on admission. Studies using specialist clinical databases for specific diseases or clinical departments, which include clinical and physiological data, have found little or no significant difference by day of admission.8Bray BD Cloud GC James MA et al.Weekly variation in health-care quality by day and time of admission: a nationwide, registry-based, prospective cohort study of acute stroke care.Lancet. 2016; (published online May 10.)http://dx.doi.org/10.1016/S0140-6736(16)30443-3PubMed Google Scholar, 11Wunsch H Mapstone J Brady T Hanks R Rowan K Hospital mortality associated with day and time of admission to intensive care units.Intensive Care Med. 2004; 30: 895-901Crossref PubMed Scopus (109) Google Scholar Although more such studies are needed to identify which patients might be at risk of weekend admission, what is really needed is a study in which accurate measures of severity are available on all admissions, so that meaningful comparisons of weekends and weekdays for the whole hospital can be made. The increasingly wide use of electronic national early warning scores provides a means of doing that.12Royal College of PhysiciansNational Early Warning Score (NEWS)Standardising the assessment of acute-illness severity in the NHS.https://www.rcplondon.ac.uk/file/32/download?token=vfwDKQVSDate: July, 2012Google Scholar Second, even if higher mortality at weekends is accounted for by patients being sicker than during the week, there is a widely held view plus anecdotal evidence that the quality of care is poorer at weekends. The reason this might not be manifest when investigators consider mortality is because death is not a particularly sensitive measure of quality given that only about 4% are thought to be avoidable.13Hogan H Zipfel R Neuburger J Hutchings A Darzi A Black N Avoidability of hospital deaths and association with hospital-wide mortality ratios: retrospective case record review and regression analysis.BMJ. 2015; 351: h3239Crossref PubMed Scopus (93) Google Scholar Attention should therefore be turned to other measures, such as health outcomes (morbidity, quality of life), safety (falls, hospital-acquired infections), aspects of patients' experience (delays in diagnosis, not receiving sufficient information), operational efficiency (extended lengths of stay, delayed discharges), and educational quality (training of junior doctors at weekends). Third, perhaps the wrong determinants of poor outcome are being investigated. Maybe nurse staffing levels or the availability of diagnostic staff should be assessed rather than medical staffing.14Bray BD Ayis S Campbell J et al.Associations between stroke mortality and weekend working by stroke specialist physicians and registered nurses: prospective multicentre cohort study.PLoS Med. 2014; 11: e1001705Crossref PubMed Scopus (81) Google Scholar Or perhaps combinations of different professions. But even that approach might not be sufficient because research on inputs, such as staffing levels, risks missing the processes of care, known to be the key determinants of poor quality care.15Taylor N Clay-Williams R Hogden E Braithwaite J Groene O High performing hospitals: a qualitative systematic review of associated factors and practical strategies for improvement.BMC Health Serv Res. 2015; 15: 244Crossref PubMed Scopus (92) Google Scholar For example, avoidable deaths in hospital happen when a patient's deterioration remains undetected, when staff fail to communicate well with one another, and when the underlying culture of the organisation does not encourage and reward attitudes and behaviours that enhance quality.16Sacks GD Shannon EM Dawes AJ et al.Teamwork, communication and safety climate: a systematic review of interventions to improve surgical culture.BMJ Qual Saf. 2015; 24: 458-467Crossref PubMed Scopus (106) Google Scholar The importance of such organisational aspects was recognised in 2013 by National Health Service (NHS) England when they recommended ten national clinical standards for emergency admissions, including factors such as access to diagnostics and timely consultant review.17NHS EnglandSeven day hospital services.https://www.england.nhs.uk/ourwork/qual-clin-lead/7-day-week/Google Scholar Despite many claims about the quality of care at weekends and strong beliefs about the reasons for this, we need to remain open to the true extent and nature of any such deficit and to the possible causes. Jumping to policy conclusions without a clear diagnosis of the problem should be avoided because the wrong decision might be detrimental to patient confidence, staff morale, and outcomes. As Bray and colleagues warn, “Because solutions are likely to come at substantial financial and opportunity cost, policy makers, health-care managers, and funders need to ensure that the reasons for temporal variation in quality are properly understood and that resources are targeted appropriately.”8Bray BD Cloud GC James MA et al.Weekly variation in health-care quality by day and time of admission: a nationwide, registry-based, prospective cohort study of acute stroke care.Lancet. 2016; (published online May 10.)http://dx.doi.org/10.1016/S0140-6736(16)30443-3PubMed Google Scholar I chair NHS England's National Advisory Group for Clinical Audit and Enquiries. Weekend specialist intensity and admission mortality in acute hospital trusts in England: a cross-sectional studyThis cross-sectional analysis did not detect a correlation between weekend staffing of hospital specialists and mortality risk for emergency admissions. Further investigation is needed to evaluate whole-system secular change during the implementation of 7 day services. Policy makers should exercise caution before attributing the weekend effect mainly to differences in specialist staffing. Full-Text PDF Open AccessWeekly variation in health-care quality by day and time of admission: a nationwide, registry-based, prospective cohort study of acute stroke careThe weekend effect is a simplification, and just one of several patterns of weekly variation occurring in the quality of stroke care. Weekly variation should be further investigated in other health-care settings, and quality improvement should focus on reducing temporal variation in quality and not only the weekend effect. 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