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Association of Intensive Care Unit Patient-to-Intensivist Ratios With Hospital Mortality
Hayley B Gershengorn1, David A Harrison2, Allan Garland3
1Division of Critical Care Medicine, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York.
Insights
The patient-to-intensivist ratio (PIR) in intensive care units (ICUs) varies significantly. An optimal PIR of 7.5 was identified, with higher or lower ratios linked to increased patient mortality.
Area of Science:
- Critical Care Medicine
- Healthcare Management
- Patient Outcomes Research
Background:
- Patient-to-intensivist ratio (PIR) in intensive care units (ICUs) lacks standardization.
- The association between PIR and patient outcomes remains poorly understood, hindering optimal staffing and care quality.
Purpose of the Study:
- To investigate the variability of PIR across UK ICUs.
- To determine the relationship between PIR and hospital mortality for ICU patients.
Main Methods:
- Retrospective cohort analysis of 49,686 adult patients admitted to 94 UK ICUs between 2010-2013.
- Patient-to-intensivist ratio (PIR) calculated as the average number of patients per intensivist daily during a patient's stay.
- Multivariable, mixed-effect, logistic regression used to assess PIR's association with hospital and ICU mortality.
Main Results:
- Significant variation in PIR was observed across ICUs, with a median of 8.5 (IQR, 6.9-10.8).
- A U-shaped association was found between PIR and hospital mortality; the lowest mortality occurred at a PIR of 7.5.
- Mortality rates increased significantly with PIRs above and below 7.5, indicating an optimal ratio.
Conclusions:
- Patient-to-intensivist ratios vary considerably in UK ICUs.
- An optimal PIR of approximately 7.5 was associated with reduced hospital and ICU mortality.
- The number of patients managed by an intensivist significantly impacts patient outcomes, emphasizing the need for standardized staffing ratios.
Importance:
The patient-to-intensivist ratio (PIR) across intensive care units (ICUs) is not standardized and the association of PIR with patient outcome is not well established. Understanding the impact of PIR on outcomes is necessary to optimize senior medical staffing and deliver high-quality care.
Objective:
To test the hypotheses that: (1) there is significant variation in the PIR across ICUs and (2) higher PIRs are associated with higher hospital mortality for ICU patients.
Design, Setting, And Participants:
Retrospective cohort analysis of patients (≥16 years) admitted to ICUs staffed by a single intensivist during daytime hours in the United Kingdom from 2010 to 2013.
Exposures:
Patient-to-intensivist ratios, which we defined for each patient as the number of patients cared for by the intensivist each day averaged over the patient's stay.
Main Outcomes And Measures:
Using standard summary statistics, we evaluated PIR variation across ICUs. We used multivariable, mixed-effect, logistic regression analysis to evaluate the association between PIR and hospital mortality at ultimate discharge from acute hospital (primary outcome) and at ICU discharge.
Finding:
Among 49 686 adults in 94 ICUs, median age was 66 (interquartile range [IQR], 52-76) years, and 45.1% were women. The ultimate hospital mortality was 25.7%. The median PIR for patients was 8.5 (IQR, 6.9-10.8; full range, 1.0-23.5), and varied substantially among individual ICUs. The association between PIR and ultimate hospital mortality was U-shaped; there was a reduction in the odds of mortality associated with an increasing PIR up to 7.5 after which the odds of mortality increased again significantly (average patient mortality for lowest PIR, 22%; PIR of 7.5, 15%; highest PIR, 19%; P = .003). A similar U-shaped association was seen for PIR and mortality in the ICU (nadir of mortality at a PIR of 7.8, P < .001).
Conclusions And Relevance:
PIR varied across UK ICUs. The optimal PIR in this cohort of UK ICU patients was 7.5, with significantly increased ICU and hospital mortality above and below this ratio. The number of patients cared for by 1 intensivist may impact patient outcomes.
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