Having a pulmonary embolism? Don't wait for the weekend

Why Patients with PEs Shouldn't Love the Weekend

Hospitals big and small struggle with weekend staffing models.  Mortality has been shown to be higher on the weekend for several common life-threatening illnesses, including CHF exacerbations, acute MI, upper GI bleeds and intracerebral hemorrhage. All these conditions are known to benefit from early intervention; however, whether or not weekend admission changes the mortality of patients admitted with pulmonary embolism is unclear.

What They Did

Rahul Nanchal et al sought to investigate if early interventions for pulmonary embolism, such as inferior vena cava filters (IVC filters) and thrombolytics, were less likely to occur on the weekend and whether resulting mortality was higher on the weekend for patients admitted with PE.

In order to answer this question, the authors (part of the Milwaukee Initiative in Critical Care Outcomes Research or MICCOR, affiliated with the Medical College of Wisconsin) used the Healthcare Cost and Utilization Project Nationwide Inpatient Sample from the years 2000-2008.  This large database, composed of 1,143,707 patients, included 21.7% patients who were admitted on the weekend.  The authors then performed a multivariate analysis of predictors of death, including an analysis of whether mortality was higher on weekends than during the week.  They defined the weekend from 12:01 AM Saturday through 11:59 PM on Sunday; notably, this meant that Friday evenings and Monday early mornings -- times when staffing is likely similar to the weekends -- would be included as weekdays in the analysis.

What They Found 

Baseline characteristics for patients admitted during the week or on the weekend were overall very similar.  One notable difference was that patients admitted on the weekend were slightly more likely to have severe pulmonary embolism (2.8% vs 2.3%, p<0.001), which meant they were more likely to require mechanical ventilation, vasopressors or thrombolytics within the first 2 days of admission.  However, chronic disease scores, which are an important determinant of outcome during PE, were higher in patients admitted during weekdays.  Interestingly, the overall mortality rate decreased from 2000 to 2008 (6% to 3.8%)

Major differences between patients admitted on the weekends with pulmonary embolism in comparison to those admitted on weekdays were:

• Higher mortality: 4.1% vs 4.8%, p<0.05

• More cardiogenic shock, mechanical ventilation and vasopressors

• Lower rate of IVC filter insertion on day 1 of admission (38% vs 29%, p<0.001)           

• Although overall mortality decreased from 2000 to 2008, the magnitude of increased weekend mortality remained constant over time.

What This Means

The key take-home points from this article are:

• Mortality from PE between 2000 to 2008 showed an impressive decrease.  The reasons for this decrease in mortality are unclear, but may include increased use of "PE protocol" CT-angiograms, with increased identification of small PEs since 2000.

• There were a calculated 1,2000 excess deaths in 2008 due to increased mortality on weekend admission for pulmonary embolism.

• This weekend effect persisted in multiple subgroups including regions of the US, teaching hospitals, non-teaching hospitals, and various hospital sizes -- so it appears no staffing model, including tertiary care academic institutions have figured out how to close this hole in staffing.

• This study, along with several other recent studies, suggests that weekend staffing models may create holes in care that put patients at risk for increased mortality.

Clinical Takeaway: This study strongly suggests that like other serious medical conditions, pulmonary embolism carries a higher mortality risk during the weekend, as compared to during weekdays. Physicians should be aware that in most acute care settings, weekend processes of care are nearly always different from those during the week, and should aggressively press for interventions that they deem essential for adequate patient care.  In addition, administrations should understand important holes in weekend staffing models and aim to fill in these holes.  Further research will be required to identify which patient and/or treatment factors account for higher mortality in patients with pulmonary embolism admitted on the weekend.  Only then can the mortality gap between patients admitted during the week and those admitted on the weekend be closed.

Rahul Nanchal et al. Pulmonary Embolism: The Weekend Effect. Chest 2012; 142(3):690-696.