What Are the Factors Predicting Mortality in Patients Using NIV for COPD?

While prior research has established non-invasive mechanical ventilation (NIV) as an effective way to reduce intubation use, mortality, complications of therapy, and length of hospital and intensive care unit stays for chronic obstructive pulmonary disease (COPD) patients with acute respiratory failure, few studies have offered insight into predictors of mortality among these patients.

Analyzing demographic, biochemical, and clinical characteristics of these patients, researchers have identified advanced age, prolonged NIV use, and unsuccessful response to NIV as independent predictors for long-term mortality.

The findings have important implications as “identification of predictors for poor outcome, will aid clinicians and their patients in (shared) decision making regarding the application and duration of continuation of NIV in severe exacerbations with acute or acute-on-chronic respiratory failure,” explained the researchers.

The single-center study results, published in The Clinical Respiratory Journal, indicated that among the 78 patients included in the study between 2009 and 2011, 14% died during their hospital stay. Within 2 years after the hospital stay, the mortality rate increased to 56%. Most of these deaths were a result of exacerbation of COPD.

Based on univariate analysis, several variables were entered into a multivariate analysis, including advanced age, gender, pH before NIV initiation, respiratory rates >20 minutes, delta paCO2 before NIV initiation versus at NIV termination, duration of NIV, and response to NIV. Of these, older age and NIV use more than 8 days carried a slightly higher risk of mortality (odds ratio [OR] 1.025 and 1.054, respectively), while unsuccessful response to NIV carried a higher risk (OR 2.392).

Throughout the study, the median length of hospital stay was 16.5 days. More than half (55.1%) of patients were successful on NIV treatment. While NIV was successful in 40 of the 67 survivors, the treatment was successful in just 3 of the 11 patients who died during their hospital stay. Unsurprisingly, in-hospital survivors had a significantly higher tolerance to NIV than the non-survivors (80.6% vs 12.5%).

Studying the differences between the patients who survived the hospital stay and those who did not, the researchers observed that significant predictors of short-term mortality included advanced age at admission, smoking status, prednisone maintenance therapy, high Charlson’s Comorbidity Index, low body mass index, blood urea nitrogen ≥8mmol/L, high troponin levels, lower pH before starting NIV, and bicarbonate ≥27.0 mmol/L.

The researchers noted that pH and PaCO2 levels and the changes between 1, 24, and 72 hours were not significantly different between the 2 groups of patients.

Reference

Sprooten R.T.M., Rohde G.G.U., Janssen M.T.H.F., Cobben N.A.M., Wouters E.F.M., Franssen F.M.E. Predictors for long-term mortality in COPD patients requiring non-invasive positive pressure ventilation for the treatment of acute respiratory failure. Clin Respir J. Published online August 6, 2020. doi: 10.1111/crj.13251.