In healthcare, the weekend effect is the finding of a difference in mortality rate for patients admitted to hospital for treatment at the weekend compared to those admitted on a weekday. The effects of the weekend on patient outcomes has been a concern since the late 1970s, and a 'weekend effect' is now well documented. Although this is a controversial area, the balance of opinion is that the weekend (and bank holidays) have a deleterious effect on patient care (and specifically increase mortality)—based on the larger studies that have been carried out. Variations in the outcomes for patients treated for many acute and chronic conditions have been studied.
Published research: Non-disease specific (unselected) patients
Medical patients
Schmulewitz et al., in the UK in 2005, studied 3,244 patients with chronic obstructive pulmonary disease, cerebrovascular accidents, pulmonary embolism, pneumonia, collapse and upper gastrointestinal bleed. They found "Weekend admission was not associated with significantly higher in-hospital mortality, readmission rates or increased length of stay compared to the weekday equivalent for any of the six conditions".
However, in 2010, Clarke et al., in a much larger Australian study of 54,625 mixed medical/surgical non-elective admissions showed a significant weekend effect (i.e. worse mortality) for acute myocardial infarction. Marco et al. (2011), in a US study of 429,880 internal medical admissions showed that death within 2 days after admission was significantly higher for a weekend admission, when compared to a weekday one (OR = 1.28; 95% CI = 1.22-1.33). In the same year, in an Irish study of 25,883 medical admissions (Mikulich et al.), patients admitted at the weekend had an approximate 11% increased 30-day in-hospital mortality, compared with a weekday admission; although this was not statistically significant either before or after risk adjustment. Thus the authors pointed out that "admission at the weekend was not independently predictive in a risk model that included Illness Severity (age and biochemical markers) and co-morbidity".
There is some evidence for intervention from physicians, in an attempt to address this issue. Bell et al., in 2013, surveyed 91 acute hospital sites in England to evaluate systems of consultant cover for acute medical admissions. An 'all inclusive' pattern of consultant working, incorporating all guideline recommendations (and which included the minimum consultant presence of 4 hours per day) was associated with reduced excess weekend mortality (p<0.05).
In 2014, it was shown in a huge US study, that the presence of resident trainee doctors (and nurses) may also be of benefit (Ricciardi, 2014). In this study of 48,253,968 medical patients, the relative risk of mortality was 15% higher following weekend admission as compared to weekday admission. This is currently the largest known study in this area. After adjusting for diagnosis, age, sex, race, income level, payer, comorbidity, and weekend admission, the overall odds of mortality was higher for patients in hospitals with fewer nurses and staff physicians. Mortality following a weekend admission for patients admitted to a hospital with resident trainees was significantly higher (17%) than hospitals with no resident trainees (p<0.001).
In the following year, Vest-Hansen et al.—in a whole nation study, in Denmark—studied 174,192 acute medical patients. The age-standardised and sex-standardised 30-day mortality rate was 5.1% (95% CI 5.0-5.3) after admission during weekday office hours, 5.7% (95% CI 5.5-6.0) after admission during weekday (out of hours), 6.4% (95% CI 6.1-6.7) after admission during weekend daytime hours, and 6.3% (95% CI 5.9-6.8) after admission during weekend night-time hours. In 2016, Huang et al., in Taiwan, studied 82,340 patients, admitted to the internal medicine departments of 17 medical centres. Patients admitted at the weekend had higher in-hospital mortality (OR = 1.19; 95% CI 1.09-1.30; p < 0.001).
In a 2016 study of 12 Italian Acute Medical Units, Ambrosi et al. found that elderly patients were six times (95% CI 3.6-10.8) more likely at risk of dying at weekends. They also found that "those with one or more ED admissions in the last 3 months were also at increased risk of dying (RR = 1.360, 95% CI 1.02-1.81) as well as those receiving more care from family carers (RR = 1.017, 95% CI 1.001–1.03). At the nursing care level, those patient receiving less care by Registered Nurses (RNs) at weekends were at increased risk of dying (RR = 2.236, 95% CI 1.27-3.94) while those receiving a higher skill-mix, thus indicating that more nursing care was offered by RNs instead of Nursing Auxiliaries were at less risk of dying (RR = 0.940, 95% CI = 0.91-0.97)."
Conway et al., in 2017, studied of 44,628 Irish medical patients. Weekend admissions had an increased mortality of 5.0%, compared with weekday admissions of 4.5%. Survival curves showed no mortality difference at 28 days (P = 0.21) but a difference at 90 days (P = 0.05).
The effects of the introduction of a 7-day consultant service have been investigated in medical patients. In 2015, Leong et al. studied elderly medical patients in the UK; noting admission numbers increasing from 6,304 (November 2011-July 2012) to 7,382 (November 2012-July 2013), with no change in acuity score. They stated that the "introduction of seven-day consultant working was associated with a reduction in in-hospital mortality from 11.4% to 8.8% (p<0.001)". Weekend discharges increased from general medical wards (from 13.6% to 18.8%, p<0.001) but did not increase from elderly medicine wards.
In December 2016, another study found that reports of higher weekend mortality rates were based on administrative databases with incomplete information about the clinical state of patients on admission, and that studies that used better data found no greater risk.
Surgical patients Non-elective (emergency) Patients There have been many similar studies (with similar conclusions) in surgery. In the US, in a very large study in 2011, 29,991,621 non-elective general surgical hospital admissions were studied (Ricciardi et al.). Inpatient mortality was reported as 2.7% for weekend and 2.3% for weekday admissions (p<0.001). Regression analysis revealed significantly higher mortality during weekends for 15 of the 26 (57.7%) major diagnostic categories. The weekend effect remained, and mortality was noted to be 10.5% higher during weekends compared with weekdays after adjusting for all other variables.
In another huge US study in 2016 (Ricciardi et al., 2016), 28,236,749 non-elective surgical patients were evaluated, with 428,685 (1.5%) experiencing one or more Patient Safety Indicator (PSI) events. The rate of PSI was the same for patients admitted on weekends as compared to weekdays (1.5%). However, the risk of mortality was 7% higher if a PSI event occurred to a patient admitted on a weekend, as compared with a weekday. In addition, compared to patients admitted on weekdays, patients admitted on weekends had a 36% higher risk of postoperative wound dehiscence, 19% greater risk of death in a low-mortality diagnostic-related group, 19% increased risk of postoperative hip fracture, and 8% elevated risk of surgical inpatient death.
Also in 2016, Ozdemir et al. studied 294,602 surgical emergency admissions to 156 NHS Trusts (hospital systems) in the UK, with a 30-day mortality of 4.2%. Trust-level mortality rates for this cohort ranged from 1.6 to 8.0%. The lowest mortality rates were observed in hospitals with higher levels of medical and nursing staffing, and a greater number of operating theatres and critical care beds relative to provider size. Higher mortality rates were seen in patients admitted to hospital at weekends [OR = 1.11; 95% CI 1.06-1.17; p<0.0001], in hospitals with fewer general surgical doctors [OR = 1.07; 95% CI 1.01-1.13; p=0.019] and with lower nursing staff ratios [OR = 1.0; 95% CI 1.01-1.13; p=0.024].
McLean et al., in the UK, also in 2016, studied 105,002 elderly (≥70 years) emergency general surgical admissions. Factors associated with increased 30-day in-hospital mortality were increasing age and Charlson score, admissions directly from clinic, operations undertaken at the weekend, and patients admitted earlier in the study period.
Elective patients The effect is not just seen in non-elective surgical patients. Aylin et al. (2013) in the UK, investigated 27,582 deaths (within 30 days) after 4,133,346 inpatient admissions for elective operating room procedures; overall crude mortality rate was 6.7 per 1000). The adjusted odds of death were 44% and 82% higher, respectively, if the procedures were carried out on a Friday (OR = 1.44, 95% CI 1.39-1.50) or a weekend (OR = 1.82, 95% CI 1.71-1.94) compared with a Monday.
In a Canadian study (McIsaac et al., 2014), 333,344 elective surgical patients were studied, of whom 2826 died within 30 days of surgery; overall crude mortality rate was 8.5 deaths per 1000. Undergoing elective surgery on the weekend was associated with a 1.96 times higher odds of 30-day mortality than weekday surgery (95% CI 1.36-2.84). This significant increase in the odds of postoperative mortality was confirmed using a multivariable logistic regression analysis (OR = 1.51; 95% CI 1.19-1.92).
Both non-elective and elective patients Mohammed et al., in 2012 in the UK, compared elective and non-elective admissions, in terms of day of admission. The mortality for non-elective patients following weekday admission was 0.52% (7,276/1,407,705), compared with 0.77% (986/127,562) following weekend admission. Of the 3,105,249 emergency admissions, 76.3% (2,369,316) were admitted on a weekday and 23.7% (735,933) were admitted at the weekend. The mortality following emergency weekday admission was 6.53% compared to 7.06% following weekend admission. After case-mix adjustment, weekend admissions were associated with an increased risk of death, especially in the elective setting (elective OR = 1.32, 95% CI 1.23- 1.41; vs emergency OR = 1.09, 95% CI 1.05-1.13).
In a 2016 Australian study (Singla et al.), of 7718 elective and non-elective patients, it was shown that unadjusted and adjusted odds of early surgical mortality was higher on the weekend, compared to weekdays (unadjusted and adjusted OR = 1.30 (p<0.001) and 1.19 (p=0.026), respectively). When separated by day of week, there was a trend for higher surgical mortality on Friday, Saturday and Sunday vs all other days, although this did not reach statistical significance.
In the US, also in 2016, Glance et al. conducted a study of 305,853 elective and non-elective surgical patients; undergoing isolated coronary artery bypass graft surgery, colorectal surgery, open repair of abdominal aortic aneurysm, endovascular repair of abdominal aortic aneurysm, and lower extremity revascularisation. After controlling for patient risk and surgery type, weekend elective surgery (OR = 3.18; 95% CI 2.26-4.49; p<0.001) and weekend urgent surgery (OR = 2.11; 95% CI 1.68-2.66; p<0.001) were associated with a higher risk of death compared with weekday surgery. Weekend elective (OR = 1.58; 95% CI 1.29-1.93; p<0.001) and weekend urgent surgery (OR = 1.61; 95% CI 1.42-1.82; p<0.001) were also associated with a higher risk of major complications compared with weekday surgery.
Emergency department (ED) patients
ED admissions have also been well studied. The first major study was published in 2001 by Bell et al. In this Canadian study, 3,789,917 ED admissions were analysed. Weekend admissions were associated with significantly higher in-hospital mortality rates than weekday admissions among patients with ruptured abdominal aortic aneurysms (42% vs 36%, p<0.001), acute epiglottitis (1.7% vs 0.3%, p=0.04), and pulmonary embolism (13% vs 11%, p=0.009).