Table 2.

Randomized controlled trials evaluating the effects of phosphodiesterase 4 inhibitors vs. placebo in patients with COPD

Study	n	Duration (weeks)	Mean FEV1 (% predicted)	PDE4 inhibitor	Lung function	Exacerbations	QOL or symptoms
Compton [31]	424	6	47	Cilomilast	PDE4+†	NM	PDE4↔
Rennard [34]	647	24	47	Cilomilast	PDE4+†	PDE4+	PDE4+†
Gamble [32]	59	12	56	Cilomilast	PDE4↔	NM	NM
Rabe [33]	1411	24	51	Roflumilast	PDE4+†	PDE4+	PDE4+†
Bredenbroker [35]*	516	26	35–75 (range)	Roflumilast	PDE4+	PDE4+	NM
Calverley [36, 37, 40]*	1513	52	41	Roflumilast	PDE4+	PDE4+	PDE4↔
Grootendorst [41]*	38	4	61	Roflumilast	PDE4+	NM	NM

^*Denotes that the study is published in abstract form alone and

^†denotes primary endpoint. n, number of randomized individuals; FEV₁, forced expiratory volume in 1 s; QOL, quality of life; PDE4+ denotes significant improvement with phosphodiesterase 4 inhibitor vs. placebo and PDE4↔ denotes nonsignificant difference with phosphodiesterase 4 inhibitor vs. placebo; NM, information not mentioned or not available from paper or abstract; COPD, chronic obstructive pulmonary disease.