Reference	Objective	Design	Evidence
Monsóet al. [84]	To study the risk factors for bacterial exacerbations	PCS	3C+
Lode et al. [466]	To study the risk factors for bacterial aetiology in AECOPD	PCS	3B+
Garcia‐Vidal et al. [467]	To study the risk factors for P. aeruginosa isolation in AECOPD	PCS	3B+
Kahn et al. [468]	To study the entry microbiological criteria in antibiotic trials of AECOPD	RCT	4B+