Summary of findings 1. Summary of findings.

Biofilm antimicrobial susceptibility testing compared with standard antimicrobial susceptibility testing for guiding antibiotic therapy in cystic fibrosis
Patient or population: adults and children with cystic fibrosis and P aeruginosa Settings: outpatients Intervention: antibiotics chosen on the basis of biofilm antimicrobial susceptibility testing Comparison: antibiotics chosen on the basis of standard antimicrobial susceptibility testing
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No of participants (studies)	Quality of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	Standard antimicrobial susceptibility testing	Biofilm antimicrobial susceptibility testing
FEV1 change from start of treatment (L) Follow‐up: 14 days	The mean change in FEV1 ranged across control groups from 0.12 L to 2.75 L.	The mean change in FEV1 in the intervention groups was 0.04 L higher (0.08 L lower to 0.16 L higher).	NA	68 (2)	⊕⊕⊕⊕ high
FEV1 change from start of treatment (% predicted) Follow‐up: 14 days	The mean (SD) change in FEV1 in the control group was 9.62 (10.12)% predicted.	The mean change in FEV1 in the intervention groups was 2.47% lower (9.29% lower to 4.34% higher).	NA	34 (1)	⊕⊕⊕⊝ moderatea	Data provided by the authors for this outcome.
Time to next exacerbation Follow‐up: 5 years	The median time to subsequent exacerbation was 185 days in the standard testing group and 162 days in the biofilm group. The difference in survival curves was not significant (P = 0.8). The HR for subsequent exacerbation also showed no significant difference between groups, HR 0.54 (95% CI 0.25 to 1.16).		NA	39 (1)	⊕⊕⊕⊝ moderatea
Adverse events: number of moderate adverse events Follow‐up: duration of antibiotic treatment (14 days)	129 per 1000	46 per 1000 (9 to 228)	RR 0.36 (0.07 to 1.77)	73 (2)	⊕⊕⊕⊝ moderateb	There was no significant difference in the number of mild events between standard or biofilm groups. There were no severe adverse events observed in either group.
Sputum density: change in P aeruginosa sputum density (log1₀ CFU/g) Follow‐up: 14 days	The mean change in sputum density ranged across control groups from ‐3.27 to ‐3.83 log1₀ CFU/g.	The mean change in sputum density in the intervention groups was 0.8 log1₀ CFU/g higher (0.59 log1₀ CFU/g lower to 2.18 log1₀ CFU/g higher).	NA	70 (2)	⊕⊕⊕⊕ high
Quality of life: change in CFQ‐R score from start of treatment Follow‐up: 14 days	The mean change in CFQ‐R score in the control group was 26.39 points.	The mean change in CFQ‐R score in the intervention group was 15.04 points lower (15.04 points lower to 1.71 points lower.	NA	38 (1)	⊕⊕⊕⊝ moderatea	There was a significant difference in change in CFQ‐R scores between groups (P = 0.03) favouring the standard susceptibility testing group.
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CFQ‐R: Cystic Fibrosis Questionnaire ‐ Revised; CFU: colony forming units; CI: confidence interval; FEV1: forced expiratory volume in 1 second; HR: hazard ratio; P aeruginosa : Pseudomonas aeruginosa; RR: risk ratio; SD: standard deviation.
GRADE Working Group grades of evidence High quality: further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: we are very uncertain about the estimate.

^a Downgraded once due to small number of participants from 1 trial.
^b Downgraded once due to imprecision: low event rates resulting in wide CIs.