FEV % predicted ( rate ratio [ RR ] 1.14 [ 95 % CI , 1.03-1 .27 ] per 10 % lower ) , more previous exacerbations ( RR 1.15 [ 95 % CI , 1.01-1 .31 ] ) , Standard therapy ( RR 1.62 [ 95 % CI , 1.07-2 .47 ] ) , and female sex ( RR 2.18 [ 95 % CI , 1.29-3 .67 ] ) were associated with future severe exacerbations .