Regression coefficients relating the occurrence of each follow-up severe exacerbations to subsequent severe exacerbations (green circles) or death (black squares).
<p><b>Footnote:</b> Regression coefficients for all variables are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0191243#pone.0191243.s004" target="_blank">S2 Table</a>. For each exacerbation, the reference (baseline) hazard for the reported HR is the period between the immediately previous and the current exacerbation.</p
