ACE and susceptibility to pneumonia measurement: PSI = Pneumonia Severity Index; CURB-65 = confusion, uraemia, respiratory rate, blood pressure, age ≥65 years; BB = beta-blockers; ACEi = angiotensin-converting enzyme inhibitors; AP = aspiration pneumonia; EOM = estimate of mean; SEM = standard error of mean; DM = diabetes mellitus; CFS = clinical frailty scale