Identifying asthma and chronic obstructive pulmonary disease in patients with persistent cough. Why was no control group studied?
J M
JM
Rothenberg
D001249:Asthma / Q000175:diagnosis*; D003371:Cough / Q000209:etiology*; D006801:Humans; D008173:Lung Diseases, Obstructive / Q000175:diagnosis*; D012107:Research Design / Q000592:standards