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What’s New in the Patient Safety World

May 2022

Another Weekend Effect Phenomenon



Add COVID-19 deaths to the list of medical events that are more likely to occur on weekends compared to weekdays,


The average number of global deaths from COVID-19 were 6% higher on weekends compared to weekdays throughout the pandemic (Reuters 2022). According to a study presented at the European Congress of Clinical Microbiology & Infectious Diseases 2022 (Manzoor 2022), there were on average 449 more COVID deaths worldwide on weekends than weekdays (8,532 vs 8,083). The increase was particularly large when specifically comparing Sunday to Monday (8,850 vs. 7,219). The United States had the highest absolute increase in weekend COVID-19 deaths (average 1,483 weekend deaths vs 1,220 weekday deaths).


The data come from the World Health Organization COVID-19 database. All global deaths over a 2-year period from March 7, 2020 to March 7, 2022 were included. Though the authors acknowledge that reporting delays might contribute to those statistics, they feel that hospital staffing levels and system factors are more likely to contribute.


Various studies have demonstrated higher mortality rates for patients admitted on weekends with strokes, atrial fibrillation, diverticulosis surgery, a variety of other surgical procedures, head trauma, COPD, CHF, perinatal events, ICU admissions, ESRD, and other conditions. In fact, in our June 2011 What’s New in the Patient Safety World “Another Study on Dangers of Weekend Admissions” we noted a study (Ricciardi 2011) that found that mortality rates were higher for 15 of 26 major diagnostic categories when patients were admitted on weekends. Even after adjustment for comorbidities and a variety of other clinical and demographic characteristics there remained a significant increase in mortality, on the order of 10% higher for those admitted on weekends.


Though some studies have cast doubt on the weekend effect, our own opinion is that the “weekend effect” and “after-hours effect” are real phenomena and that the causes are multifactorial, including both patient-based and system-based contributing factors. Yes, patients admitted at these times are likely sicker and have a higher severity of illness and therefore are likely to have a higher mortality rate. However, as we’ve pointed out over and over, hospitals do not provide the same levels of service 24 hours a day, seven days a week. Staffing patterns, in terms of volume and even more so in terms of experience, are the most obvious difference but there are many others as well. Many diagnostic tests are not as readily available during these times. On-site physician availability may be different and cross-coverage by physicians who lack detailed knowledge about individual patients is common. You also see more verbal orders, which of course are error-prone, at night and on weekends. But the most significant difference is nurse workload on weekends. We’ve described the tremendous increase in nurse responsibilities on weekends due to lack of other staff (no clerical staff, delayed imaging, physicians not on site) that add additional responsibilities to their jobs. Our December 15, 2009 Patient Safety Tip of the Week “The Weekend Effect” discussed how adding non-clinical administrative tasks to already overburdened nursing staff on weekends may be detrimental to patient care. Just do rounds on one of your med/surg floors or ICU’s on a weekend. You’ll see nurses answering phones all day long, causing interruptions in some attention-critical nursing activities. Calls from radiology and the lab that might go directly to physicians now often go first to the nurse on the floor, who then has to try to track down the physician. They end up filing lab and radiology reports or faxing medication orders down to pharmacy, activities often done by clerical staff during daytime hours. Even in those facilities that have CPOE, nurses off-hours often end up entering those orders into the computer because the physicians are off-site and are phoning in verbal orders. You’ll also see nurses giving directions to the increased numbers of visitors typically seen on weekends. They may even end up doing some housekeeping chores and delivering food trays. All of these interruptions and distractions obviously interfere with nurses’ ability to attend to their clinically important tasks (see our Patient Safety Tips of the Week for August 25, 2009 “Interruptions, Distractions, Inattention…Oops!” and May 4, 2010 “More on the Impact of Interruptions”). That is why we think that simply addressing nurse:patient staffing ratios without addressing nurse workload issues may be short-sighted.


All you have to do is spend some time in your hospital on weekends and you’ll readily see that things are different on weekends.




Some of our previous columns on the “weekend effect:

·       February 26, 2008     Nightmares….The Hospital at Night

·       December 15, 2009   The Weekend Effect

·       July 20, 2010             More on the Weekend Effect/After-Hours Effect

·       October 2008            Hospital at Night Project

·       September 2009        After-Hours Surgery – Is There a Downside?

·       December 21, 2010   More Bad News About Off-Hours Care

·       June 2011                  Another Study on Dangers of Weekend Admissions

·       September 2011        Add COPD to Perilous Weekends

·       August 2012              More on the Weekend Effect

·       June 2013                  Oh No! Not Fridays Too!

·       November 2013        The Weekend Effect: Not One Simple Answer

·       August 2014              The Weekend Effect in Pediatric Surgery

·       October 2014            What Time of Day Do You Want Your Surgery?

·       December 2014         Another Procedure to Avoid Late in the Day or on Weekends

·       January 2015             Emergency Surgery Also Very Costly

·       May 2015                  HAC’s and the Weekend Effect

·       August 2015              More Stats on the Weekend Effect

·       September 2015        Surgery Previous Night Does Not Impact Attending Surgeon Next Day

·       February 23, 2016     Weekend Effect Solutions?

·       June 2016                  Weekend Effect Challenged

·       October 4, 2016        More on After-Hours Surgery

·       July 25, 2017             Can We Influence the “Weekend Effect”?

·       August 15, 2017        Delayed Emergency Surgery and Mortality Risk

·       September 2020        Care Processes and the Weekend Effect

·       October 13, 2020      Night-Time Surgery

·       December 15, 2020   Our Perennial Pre-Holiday Warning: “Be Careful Out There!”






Reuters Staff. COVID-19 Hospital Death Rates Go Up on Weekends. Reuters 2022; April 19, 2022



Manzoor F, Redelmeier DA. COVID-19 Deaths on Weekends. European Congress of Clinical Microbiology & Infectious Diseases 2022. April 5, 2022



Ricciardi R, Roberts PL, Read TE, et al. Mortality Rate After Nonelective Hospital Admission. Arch Surg. 2011; 146(5): 545-551





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