Table 2—

Randomised controlled trials comparing an inhaled corticosteroid(ICS; alone) to placebo that include data on the rate ratio of exacerbation and previous use of ICSs prior to randomisation

First author [Ref.]	ICS		Placebo			Rate ratio of exacerbation	p-value
First author [Ref.]	Subjects n	Withdrawal %	Subjects n	Withdrawal %	Prior ICS use %	Rate ratio of exacerbation	p-value
Vestbo 18	145	25	145	35	0	0.96	0.736^#
Burge 19	372	43	370	53	57	0.75	0.026
Szafranski 6	198	31	205	44	26	0.85	0.224
Calverley 20	374	29	361	39	52	0.81	0.003
Calverley 7	257	40	256	41	46	0.89	0.308
Calverley 1	1534	38	1524	44	51	0.82	0.001

^#: not reported in the paper; computed from a comparison of two Poisson counts.