Represented as OD values, AChE activity was essentially similar in controls (0.034 ± 0.008 OD) and patients on day 10 after stroke onset (0.017 ± 0.003 OD), but was significantly lower in patients with acute ischemic stroke both with and without pneumonia (0.014 ± 0.005 OD and 0.012 ± 0.004 OD; P < 0.01; Additional file 1c). This evidence concerns the gene ACHE and susceptibility to pneumonia measurement.