Stolz 2007

Methods	Randomised clinical trial, single‐centre, University Hospital Basel, Switzerland
Participants	Inclusion criteria: clinical diagnosis of COPD exacerbation Exclusion criteria: patients who were considered to be vulnerable study participants (i.e. those with psychiatric co‐morbidities) were excluded from the study. Other exclusion criteria were immunosuppression, asthma, cystic fibrosis and the presence of infiltrates on chest radiographs on hospital admission Included in this analysis: 208 out of226 randomised patients: 18 post randomisation exclusions due to absence of COPD according to GOLD criteria
Interventions	Guiding antibiotic decisions in COPD patients with repeated measurements Algorithm used in this study: procalcitonin level of 0.1 µg/L was considered to indicate the absence of bacterial infection and the use of ABs was discouraged. A level of 0.1 to 0.25 µg/L indicated possible bacterial infection and the use of ABs was discouraged or encouraged, respectively, based on the stability of the patient’s clinical condition. A procalcitonin level of 0.25 µg/L was considered to suggest the presence of bacterial infection and AB treatment was encouraged
Outcomes	Antibiotic use “Clinical success” defined as improvement of symptoms compared to exacerbation status “Clinical failure” defined as the absence of the attenuation of symptom, the worsening of symptoms, or death Mortality ICU admission Hospital readmission after 30 days and 6 months
Notes	Funding: this study was funded by the Clinic of Pulmonary Medicine; the Clinic of Endocrinology, Diabetes and Clinical Nutrition; and the Emergency Department of the University Hospital Basel. BRAHMS provided procalcitonin assays for this investigator driven study Follow‐up: short‐term follow‐up visit after 14 to 21 days; long‐term follow‐up visit at 6 months Registration: ISRCTN77261143
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Independent statistician created randomisation list
Allocation concealment (selection bias)	High risk	Sealed envelopes, not numbered
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Open‐label trial where physicians knew in which group patients were and where procalcitonin levels were only communicated in the intervention arm
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Blinded personnel
Incomplete outcome data (attrition bias) All outcomes	Low risk	Follow‐up for mortality: 208/208 (100%)
Selective reporting (reporting bias)	Low risk	Outcomes correspond to study protocol
Other bias	Unclear risk	Adherence to procalcitonin protocol not reported/assessed