Diagnostic Accuracy of Updated HACOR Score to Predict NIV Failure in Patients with Acute Hypoxemic Respiratory Failure

INTRODUCTION: Non-invasive ventilation (NIV) is widely used in patients with acute hypoxemic respiratory failure (AHRF)(1). However, the rate of NIV failure is 30–86% in hypoxemic patients(2) but predicting NIV failure remains a challenge. The HACOR score, a composite score based on respiratory rate, heart rate, consciousness, oxygen saturation, and Acidosis, has shown promise in predicting NIV failure(3). The updated HACOR (HACOR-U) score(4), which also considers SOFA score and other co-morbid illnesses, offers potential for more accurate early prediction, though further validation is needed. OBJECTIVES: The primary objective of this study is to estimate the diagnostic accuracy of the HACOR-U score at 1-2 hours post-initiation of NIV in predicting NIV failure in patients with acute hypoxemic respiratory failure. MATERIALS AND METHODS: This prospective observational study was conducted, involving 50 patients with acute hypoxemic respiratory failure initiated on NIV in a tertiary care hospital.. The HACOR and updated HACOR-U scores were recorded at baseline and 1-2 hours after NIV initiation, and their diagnostic accuracy in predicting NIV failure was assessed. In-hospital mortality and the timing of NIV failure (early vs. late) were also evaluated. HACOR-U was calculated using the formula: HACOR-U score = HACOR score + 0.5 × SOFA + 2.5 if pneumonia is diagnosed – 4 if Cardiogenic Pulmonary Edema is diagnosed + 3 if pulmonary ARDS is present + 1.5 if immunosuppression is present + 2.5 if septic shock is present. RESULTS: The study included patients with a mean age of 49 ± 15 years, of whom 61% were male. At baseline, the mean HACOR score was 9.2 ± 3.2, while the updated HACOR-U score was 13.8 ± 5.7. Following 1-2 hours of non-invasive ventilation (NIV), the HACOR and HACOR-U scores improved, decreasing to 5 ± 3.8 and 9.3 ± 6.3, respectively. The in-hospital mortality rate was 32%, and NIV failure occurred in 38% of patients (19 cases). Of these, 16% experienced early NIV failure (within <12 hours), and 22% experienced late NIV failure (after >12 hours). In the NIV success group, the 28-day mortality rate was 11% (3 patients), whereas it was significantly higher in the NIV failure group, with rates of 88% (7 patients) for early failures and 80% (8 patients) for late failures. The updated HACOR-U score demonstrated good predictive accuracy, with an AUROC of 0.77 at baseline and 0.78 at 1-2 hours post-NIV initiation. DISCUSSIONS/CONCLUSIONS: The updated HACOR (HACOR-U) score can predict NIV failure better compared to original HACOR score. 28-day mortality rate in early NIV failure was higher than those in late NIV failure. If the patients at risk for NIV failure are identified early it may improve patient outcomes by facilitating timely escalation of care.