1. Study characteristics.

Study ID/Setting	Inclusion criteria	AE definition	N participants included/Completing	Mean age, years	% males/ % smokers	Prestudy SCS use, %	SCS ≤ 7 days	SCS > 7 days	Definition of treatment failure
Chen 2005 China/ inpatients	2 years of continuous productive cough, FEV1/FVC post BD < 0.7, FEV1 < 80% predicted. No respiratory failure, diabetes or bronchial asthma	At least 2 of 3 symptoms: increased sputum or dyspnoea or purulent sputum	86/81	71	75/44	Not stated	Prednisolone 30 mg 7 days	Prednisolone 30 mg/d 10 days + 15 mg/d 5 days	Not known
Gomaa 2008 (abstract only)	FEV1 < 50% predicted, no respiratory acidosis	Not stated	42/Not known	Not stated	Not stated	Not stated	Prednisolone 30 mg 7 days	Prednisolone 30 mg 15 days	Outcome not reported
Leuppi 2013 Switzerland/5 sites	Age > 40 years, smoking history ≥ 20 pack‐years	At least 2 of the following: change in baseline dyspnoea, cough or sputum quantity/purulence	314/296	69	60/45	20	5 days: days 1 to 4 methylprednisolone 40 mg, days 2 to 5 oral prednisolone 40 mg	14 days: days 1 to 4 methylprednisolone 40 mg, days 2 to 14 oral 40 mg prednisolone	Received open‐label glucocorticoids during index exacerbation
Rahman 2004 (abstract only) Bangladesh/1 site	Not stated	Not stated	Not stated	Not stated	Not stated	Not stated	Prednisolone 30 mg 7 days	Prednisolone 30 mg 14 days	Outcome not reported
Salam 1998 (abstract only) USA/Unknown sites	Not stated	Not stated	21/Not known	Not stated	Not stated	None in previous month	IV CS 3 days	IV CS 3 days + 7 days OCS	Outcome not reported
Sayiner 2001 Turkey/1 site	FEV1 < 35% predicted, PYH > 20, no respiratory failure requiring ventilation	Not stated, requiring admission	36/34	65	94/Not stated	None in previous month	IV methylprednisone 0.5 mg/kg qds 3 days	IV methylprednisone 0.5 mg/kg qds 3 days, bd 3 days, od 4 days	Required open‐label steroid treatment
Sirichana 2008 (abstract and author data) Thailand/1 site	Age > 40 years, symptoms > 24 hours	Increase in at least 2 of 3 symptoms—dyspnoea, sputum volume, sputum purulence; requiring admission	48/42	73	88/Not stated	None in previous month	Prednisolone 30 mg 5 days	Prednisolone 30 mg 10 days	Outcome not reported
Wood‐Baker 1997 (abstract and author data) Australia & New Zealand/2 sites	Age > 40 years; > 10 pack‐year smoking history; FEV1 < 50% predicted	Not stated, requiring admission	38/28	71	63/Not stated	None for current AEs, no long‐term OS > 5 mg/d	Prednisolone 2.5 mg/kg orally daily for 3 days	Prednisolone 0.6 mg/kg orally daily for 7 days followed by prednisolone 0.3 mg/kg orally daily for 7 days	Lack of progress according to attending physician during treatment