Early Prediction of Non Invasive Ventilation Failure and Mortality in Chronic Obstructive Pulmonary Disease Patients using HACOR Score: A Cross-sectional Study

Introduction: Non Invasive Ventilation (NIV) is an effective ventilatory measure in the exacerbation of Chronic Obstructive Pulmonary Disease (COPD). However, the response among some patients is not favourable, leading to a requirement for invasive ventilation. This not only increases hospital stays but is also reported to elevate mortality rates. Therefore, there is a need for a scoring system that predicts NIV failures. The Heart rate, Acidosis, Consciousness, Oxygenation and Respiratory rate (HACOR) score is a promising tool that has demonstrated excellent predictive power in detecting early NIV failure. Aim: To predict NIV failure based on the HACOR score at two hours after the initiation of NIV in patients admitted for acute exacerbation of COPD with type 2 respiratory failure. Materials and Methods: The present hospital-based crosssectional study was conducted in the Department of Pulmonary Medicine, Government Hospital for Chest and Communicable Diseases, Andhra Medical College, Visakhapatnam, Andhra Pradesh, India, from November 2023 to April 2024. A total of 70 patients admitted with acute exacerbation of COPD and type 2 respiratory failure were included. All five variables of the HACOR score were measured two hours after the initiation of NIV to predict early NIV failure. These variables include heart rate, arterial blood pH, Glasgow Coma Scale (GCS) score (consciousness), oxygenation and respiratory rate. After the initiation of NIV, the HACOR score was evaluated at various intervals. The diagnostic accuracy of the HACOR score in predicting NIV failure was recorded, which was the main outcome of the study. Receiver Operating Characteristic (ROC) curve and Youden index were applied. The dependent variables were analysed using the Youden index to obtain the best cut-off value of the HACOR score. Results: Out of 70 patients, 66 (94.3%) were males and 4 (5.7%) were females, with a mean±Standard Deviation (SD) age of 68.5±6.1 years. The study reported a 27.1% (19 patients) NIV failure rate based on the HACOR score measured after two hours of NIV. The total study population was divided into two groups based on the measured HACOR score cut-off value of 5. A total of 33 patients had a score ≥5, while 37 patients had a score <5. Among the group with a score ≥5, 17 (51.5%) patients experienced NIV failure. In the group with a score <5, 2 (5.4%) patients had NIV failure. The area under the ROC curve (AUROC) for the entire population was 0.899 for a score ≥5, with a sensitivity of 89.47% and a specificity of 86.27% in determining the outcome of NIV. Conclusion: The HACOR score is a simple bedside test that can effectively predict early NIV failure with good predictive power. A score ≥5 at two hours after the initiation of NIV therapy can be considered a cut-off value for predicting NIV failure.