key: cord-0997922-7tgg7ybg
authors: Quintairos, Amanda; Zampieri, Fernando G.; Souza-Dantas, Vicente Cés; Salluh, Jorge I. F.
title: The Limitations of Standardized Mortality Ratios for Coronavirus Disease 2019 ICU Patients
date: 2021-07-30
journal: Crit Care Med
DOI: 10.1097/ccm.0000000000005245
sha: 3430ea01abeee47af48d54923b28421051e0caa2
doc_id: 997922
cord_uid: 7tgg7ybg

nan

hyperactive deliriums that was not found to be significant and removed from the final model.

Finally, the comment regarding the difference in outcomes between our study and that of van den Boogaard et al (5) raises an interesting point about tools used to assess long-term, patient-centered outcomes. The study cited found that patients with hypoactive delirium had lower mental health scores on the Short Form-36 (SF-36), a self-reported survey that assesses quality of life. Thus, patients with hypoactive delirium subjectively felt their mental health was worse after critical illness than their counterparts with hyperactive or mixed-type delirium. Our study used validated measures of functional status (Katz Activities of Daily Living and the Functional Assessment Questionnaire for Instrumental Activities of Daily Living), depression (Beck Depression Inventory-II), and PTSD (PTSD Checklist-Specific) but did not assess self-reported quality of life. We cannot, however, compare the experience and quality of life of our patients with that in the cohort by van den Boogaard et al (5) . Notably, the differences between the subtypes were only on the mental health component of the SF-36, whereas no difference in physical function scores was found. This discussion further supports the need for investigations into mechanisms driving the different motoric subtypes and the long-term recovery trajectory of patients with differing motoric subtypes of delirium.

To the Editor: W e read with interest the study by Higgins et al (1) published in a recent article of Critical Care Medicine. The authors describe a higher standardized mortality ratio (SMR) and length of stay for coronavirus disease 2019 (COVID-19) than for viral pneumonia patients admitted to ICU. Using the Acute Physiology and Chronic Health Evaluation (APACHE) IV, the authors demonstrate that COVID-19 is associated with worse than expected risk-adjusted outcomes. Although scoring systems have been successfully used for the evaluation of ICU performance (2) for decades, their use to assess outcomes in COVID-19 patients has some important shortcomings.

Recently, Metnitz et al (3) using a national ICU database in Austria, showed that the calibration of Simplified Acute Physiology Score (SAPS) 3 was worse in COVID-19 patients. We believe that several aspects contribute to this finding; first, it is well-known that when evaluating some specific conditions (e.g., transplant, sepsis, trauma), scoring systems tend to do worse (2) . In the case of COVID-19, its presentation, clinical course as well as the rapid changes in its management over the first year of the pandemic may play a role in the outcomes and consequently in risk-adjusted scores. As scoring systems (i.e., APACHE, SAPS) are calculated in the first day of ICU admission, the full severity of COVID-19 may not be present initially. As we learned, a substantial percentage of patients are admitted to the ICU with extensive pneumonia on CT scan and in need of supplementary oxygen. These patients initially have mild extrapulmonary dysfunction; however, with hours-days, a severe and sometimes refractory form of acute respiratory distress syndrome associated with cardiovascular and renal dysfunction may occur. Thus, these high-mortality patients may initially have disproportionately low APACHE points, shifting the SMR to higher than expected. In addition, in the first wave of the pandemic, worries about the safety and effectiveness of noninvasive ventilation (NIV) resulted in early intubation, which may have been associated with increased mortality (4).

As we face all these limitations, should we still use traditional scoring systems to assess COVID-19? SMRs are still the best way to benchmark mortality, and we believe that it is still valid if we cautiously consider its limitations in the context. As we probably had a learning curve, an analysis over a longer period of time would be interesting as it would be able to consider the effect of treatments (i.e., steroids, NIV, high-flow nasal oxygen) that potentially improved ICU outcomes (4, 5) .

In addition, a local (or national) assessment of the discrimination and calibration of the scoring systems for this population should be done to ensure its validity (3). Several factors can explain the divergence in discrimination and calibration in some studies, namely differences in case-mix, process of care, source of data extraction (administrative, software, or manual), and ICU admission and discharge policies. So, if applicable, a customization or a development of a new COVID-19 scoring system should be tested. Finally, comparison of outcomes among COVID-19 patients (serial evaluation of SMR or benchmarking with COVID-19 patients from other ICUs and hospitals) can still be useful to understand performance and outcomes within a more homogeneous group of patients. 

Motoric Subtypes of Delirium: Not Associated With Long-Term Outcomes in Adults After Critical Illness?

Motoric subtypes of delirium and long-term functional and mental health outcomes in adults after critical illness

BRAIN-ICU Study Investigators: Long-term cognitive impairment after critical illness

Delirium and its motoric subtypes: A study of 614 critically ill patients

Delirium in critically ill patients: Impact on long-term health-related quality of life and cognitive functioning

Coronavirus disease 2019 ICU patients have higher-than-expected Acute Physiology and Chronic Health Evaluation-adjusted mortality and length of stay than viral pneumonia ICU patients

ICU severity of illness scores: APACHE, SAPS and MPM

Evaluation and calibration of SAPS 3 in patients with COVID-19 admitted to intensive care units

Clinical course and outcomes of critically ill patients with COVID-19 infection: A systematic review

Dexamethasone in patients hospitalized with COVID-19: Whether, when and to whom