Abstract
Aim: To develop an assessment tool to predict invasive mechanical ventilation (IMV) among influenza-related pneumonia (Flu-p) patients within 14 days of admission.
Methods: In total, 1107 Flu-p patients from five teaching hospitals were retrospectively enrolled from January 2012 - December 2019 and used to develop a predictive model.
Results: Overall, 10.6% (117/1107) of patients underwent IMV within 14 days of admission. Multivariate regression analyses revealed that the following factors were associated with IMV: early neuraminidase inhibitor use (-2 points), lymphocytes < 0.8×109/L (1 points), multi-lobar infiltrates (1 point), age ≥ 65 years old (2 points), systemic corticosteroid use (2 points), PaO2/FiO2 < 300 mmHg (2 points), respiratory rate ≥ 30 breaths/min (3 points), and arterial PH < 7.35 (3 points). A total score of six points was used to identify patients at risk of IMV. This model had a sensitivity of 88.79%, a specificity of 87.55%, and exhibited better predictive performance than the ROX index (AUROC = 0.927 vs 0.688, p< 0.001), modified ROX index (AUROC = 0.927 vs 0.747, p< 0.001), and HACOR scale (AUROC = 0.927 vs 0.524, p< 0.001).
Conclusions: Flu-IV scores can be used to reliably predict 14-day IMV rates in Flu-p patients.
Key words: Influenza; Pneumonia; Invasive mechanical ventilation; Prediction rule
Introduction
Influenza is a common viral respiratory disease that affects between 5% and 10% of the population of the world each year, resulting in 3-5 million severe infections and between 290,000 and 650,000 annual deaths attributable to influenza-related illness [1]. Owing to the significant morbidity and mortality associated with disease, influenza is considered by many researchers to be one of the greatest threats to global public health at present [2].
Influenza-related pneumonia (Flu-p) is a severe form of influenza infection associated with over 50% of influenza-relate hospitalization and mortality [3]. Flu-p can progress from relatively mild disease to more severe cases that can cause ARDS or respiratory failure such that patients must often undergo invasive mechanical ventilation (IMV) within 3-10 days following initial symptom onset [4-5]. The need for IMV is linked to higher rates of patient morbidity and mortality [6], and evaluating a given patient’s odds of requiring IMV is thus a valuable prognostic approach. However, the risk factors associated with the need for IMV have not been fully clarified. Certain assessment tools have been established in an effort to gauge the odds of IMV in individuals suffering from acute hypoxemic respiratory failure, including the ROX index (pulse oximetry/FiO2 to respiratory rate) [7], modified ROX index (PaO2/FiO2 to respiratory rate) [8], and HACOR scale (heart rate, respiratory rate, arterial pH, PaO2/FiO2 and Glasgow Coma Scale) [9]. These tools, however, are not specific to Flu-p patients, nor have any studies specifically examined their predictive power in individuals suffering from Flu-p, and there is thus a clear need for the development of a reliable tool that can predict the requirement for IMV in Flu-p patients at an early time point prior to the onset of potential respiratory failure.
As such, we performed the present retrospective multicenter study with the goal of developing an accurate and easy-to-use assessment tool capable of predicting the odds of a given Flu-p patient undergoing IMV within 14 days of admission.
Materials and methods