Participants followed-up (studies) | Quality of the evidence (GRADE) | Relative effect^{#} (95% CI) | Anticipated absolute effects | ||

Risk with standard care | Risk difference with procalcitonin-guided protocols | ||||

Treatment failure for the index exacerbation | 834 (5 RCTs) | Low^{¶,+} | RR 0.81 (0.62–1.06) | 206 per 1000 | 39 fewer failures per 1000 (78 fewer to 12 more) |

Length of hospital stay for the index exacerbation | 1062 (8 RCTs) | Moderate^{¶} | MD −0.76 (−1.95–0.43) | Mean length of hospital stay was 8.55 days | MD 0.76 fewer days (1.95 fewer to 0.43 more) |

Proportion of patients who were prescribed antibiotics on admission | 984 (7 RCTs) | Moderate^{¶} | RR 0.56 (0.43–0.73) | 791 per 1000 | 348 fewer prescriptions per 1000 (451 fewer to 214 fewer) |

Duration of the course of antibiotics | 776 (6 RCTs) | Moderate^{+} | MD −3.83 (−4.32–−3.35) | Mean duration of course of antibiotics was 8.27 days | MD 3.83 fewer days (4.32 fewer to 3.35 fewer) |

Exacerbation recurrence rate at longest follow-up | 496 (3 RCTs) | Low^{¶,+} | RR 0.96 (0.69–1.35) | 205 per 1000 | 8 fewer recurrences per 1000 (63 fewer to 72 more) |

Re-hospitalisation rate at longest follow-up | 398 (3 RCTs) | Low^{¶,+} | RR 1.45 (0.92–2.29) | 116 per 1000 | 52 more admissions per 1000 (9 fewer to 150 more) |

Rate of re-hospitalisation due to an exacerbation at longest follow-up | 298 (2 RCTs) | Low^{¶}^{,}^{+} | RR 1.22 (0.71–2.09) | 135 per 1000 | 30 more admissions per 1000 (39 fewer to 147 more) |

Overall mortality at longest follow-up | 1062 (8 RCTs) | Moderate^{+} | RR 0.99 (0.58–1.69) | 41 per 1000 | 0 fewer deaths per 1000 (18 fewer to 29 more) |

Data are presented as n, unless otherwise stated. GRADE (Grading of Recommendations Assessment, Development and Evaluation) working group quality of evidence assessments are as follows. High quality: further research is very unlikely to change the confidence in the estimate of effect; moderate quality: further research is likely to have an important impact on the confidence in the estimate effect and may change the estimate; low quality: further research is very likely to have an important impact on the confidence in the estimate effect and it is likely to change the estimate; very low quality: the estimate effect is very uncertain. RCT: randomised controlled trial; RR: risk ratio; MD: mean difference. ^{#}: The risk in the intervention group (and its 95% CI) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI); ^{¶}: none of the included trials was blinded; ^{+}: did not meet optimal information size criterion.