Summary of findings 2. Summary of findings: change from baseline in SGRQ.

Prophylactic antibiotics compared with placebo for COPD
Patients or population: adults with COPD Settings: hospital clinics, multi‐centre Intervention: macrolide, tetracycline, or quinolone Comparison: placebo
Treatment	Anticipated absolute effects (95% CrI)*		No. of participants (studies)
	Absolute change from baseline in SGRQ (95% CrI)	Mean difference in change from baseline in SGRQ score with treatment**
Macrolide (weighted mean 48 weeks' duration)	‐4.00 (‐5.51 to ‐2.68)	2.298 point improvement (3.605 to 0.985 point improvement)	578 (6)
Tetracycline (13 weeks' duration)	‐0.52 (‐3.21 to 2.16)	1.179 point worsening (1.509 point improvement to 3.859 point worsening)	25 (1)
Quinolone (weighted mean 46.5 weeks' duration)	‐3.03 (‐4.69 to ‐1.37)	1.33 point improvement (2.986 point improvement to 0.328 point improvement)	528 (2)
*The basis for the anticipatedrisk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% CrI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CrI). COPD: chronic obstructive pulmonary disease; CrI: credible interval; SGRQ: St George's Respiratory Questionnaire.

*Absolute change from baseline in the placebo arm was ‐1.7 (1.7 point improvement).

**The minimally clinically important difference for SGRQ is 4 points.