Sputum Purulence as a Predictor of Cystic Fibrosis Exacerbations: a Prospective Cohort Trial.

Patients will score their sputum purulence daily using three colour charts. They will also score for respiratory and other symptoms.

Primary analysis will focus on the predicting value of sputum purulence on exacerbations. Secondary analysis will evaluate symptoms on exacerbation prediction. A third subanalysis will focus on correlation of daily pollution fluctuations and sputum purulence or symptoms.