Methods for diagnosing or predicting chronic bronchitis

A method for diagnosing and treating an exacerbation of chronic obstructive pulmonary disease (COPD) in a subject diagnosed with COPD, comprising:

• a) measuring an amount of each of (i) mucin, (ii) mucin 5AC (MUC5AC) and (iii) mucin 5B(MUC5B) in a first sputum sample taken from the subject at a first time point;
• b) calculating a first ratio of the measured amount of MUC5AC to the measured amount of MUC5B from the first sputum sample;
• c) calculating a first KMQuant index for the first sputum sample by multiplying the first ratio by the measured amount of mucin from the first sputum sample to provide a product and dividing the product by 100;
• d) measuring an amount of each of (i) mucin, (ii) MUC5AC and (iii) MUC5B in a second sputum sample taken from the subject at a time point subsequent to the first time point;
• e) calculating a second ratio of the measured amount of MUC5AC to the measured amount of MUC5B from the second sputum sample;
• f) calculating a second KMQuant index for the second sputum sample by multiplying the second ratio by the measured amount of mucin from the second sputum sample to provide a product and dividing the product by 100;
• g) comparing the first KMQuant index calculated for the first sample (c) to the second KMQuant index calculated for the second sputum sample (f), wherein an increase in the KMQuant index calculated for the second sputum sample as compared to the KMQuant index calculated for the first sputum diagnoses an exacerbation of COPD in the subject;
• and
• treating the subject diagnosed as having an exacerbation of COPD, wherein the treating comprises administering a therapeutically effective amount of an osmotic agent for airway surface hydration, an epithelial sodium channel (ENaC) blocker, an inhibitor of mucin secretion, an inhibitor of mucin, production, a cystic fibrosis transmembrane regulator (CFTR) corrector, a CFTR potentiator, or any combination thereof.