Noninvasive ventilation failure in pneumonia patients ≥65years old: The role of cough strength. 
To explore the association between cough strength and outcomes in elderly patients who received noninvasive ventilation (NIV) due to acute respiratory failure caused by pneumonia.  We enrolled patients ≥65years old with acute respiratory failure caused by pneumonia.  Just before NIV treatment, cough strength was assessed on a cough-strength scale graded from 0 to 5.  Patients graded 0-2 were defined as having no/weak coughs and those graded 3-5 were defined as having moderate/strong coughs.  We enrolled 349 patients in this study.  The prevalence of no/weak cough was 24% (84/349).  Moderate/strong cough patients had lower NIV failure (92/265 [34.7%] vs. 67/84 [79.8%], p<0.01) and lower hospital mortality (85/265 [32.1%] vs. 60/84 [71.4%], p<0.01) than no/weak cough patients.  In multivariate logistic regression analysis, we also found that no/weak cough was an independent risk factor for NIV failure (odds ratio=13.83, 95% confidence interval: 6.01-31.81) and death in hospital (odds ratio=4.41, 95% confidence interval: 2.49-7.81).  In pneumonia patients ≥65years old, no/weak cough is associated with NIV failure and death in hospital.  NIV must be used only with caution in no/weak cough patients.