Baseline characteristics of included studies
| Study | Country | Design | Device (manufacturer) | Patient characteristics | Total sample size (C reactive protein (CRP)/no CRP) |
| 1. Randomised controlled trials | |||||
| (a) Patients presenting with signs of respiratory tract infection | |||||
| Andreeva and Melbye42 | Russia | Cluster | Afinion (Axis Shield) | Adults with lower respiratory tract infection (LRTI)/acute cough for less than 28 days. | 179 (101/78) |
| Cals et al 19 | The Netherlands | Cluster | NycoCard II (Axis Shield) | Adults with suspected LRTI (cough <4 weeks, +1 focal and +1 systemic symptom or sign). | 431 (227/204) |
| Cals et al 20 | The Netherlands | Individual | NycoCard II (Axis Shield) | Adult with LRTI (cough <4 weeks, +1 focal and +1 systemic symptom or sign) or rhinosinusitis <4 weeks, +2 symptoms or signs. | 258 (129/129) |
| Cals et al 43 | The Netherlands | Cluster | NycoCard II (Axis Shield) | Adults with suspected LRTI (cough <4 weeks, +1 focal and +1 systemic symptom or sign). | 379 (203/176) |
| Diederichsen et al 53 | Denmark | Individual | NycoCard II (Axis Shield) | Children and adults with respiratory tract infection. | 812 (414/398) |
| Do et al 54 | Vietnam | Individual | NycoCard II (Axis Shield) | Children and adults with at least one focal and one systemic symptom of acute respiratory tract infection. | 2037 (1017/1019) |
| Little et al 21 | Spain, England, Wales (UK), Poland, Belgium, the Netherlands | Cluster | QuikRead (Orion Diagnostica) | Adults with upper or LRTI less than 28 days. | 4264 (2224/2040) |
| Melbye et al 44 | Norway | Individual | NycoCard II (Axis Shield) | Adults with subjective complaint of pneumonia, bronchitis or asthma or 1 of: cough, shortness of breath, chest pain on deep inspiration or cough. | 239 (108/131) |
| (b) Patients presenting with signs of any acute illness | |||||
| Lemiengre et al 57 (also Verbakel et al 9) | Belgium | Cluster | Afinion (Alere) | Children with an acute illness less than 5 days. | 3147 (1730/1417) |
| Rebnord et al 51 | Norway | Individual | QuikRead Go (Orion Diagnostica) | Children with fever and/or respiratory symptoms. | 397 (138/259) |
| Van den Bruel et al 52 | UK | Individual | Afinion (Alere) | Children with an acute illness less than 5 days. | 54 (26/28) |
| 2. Non-randomised trials | |||||
| (a) Patients presenting with signs of respiratory tract infection | |||||
| Bjerrum55 | Denmark | Cohort | Not specified | Children and adults with acute sinusitis, acute tonsillitis, and acute otitis. | 367 (281/86) |
| Fagan45 | Norway | Cohort | Not specified | Adults treated for acute bronchitis. | 324 (122/202) |
| Hughes46 | Wales (UK) | Before–after | Afinion (Alere) | Adults with symptoms of respiratory tract infection and other. | 94 (not specified) |
| Kavanagh et al 47 | Ireland | Before–after | QuikRead (Orion Diagnostica) | Adults with acute cough and/or sore throat less than 1 month. | 120 (60/60) |
| Llor et al 48 | Spain | Before–after | NycoCard II (Axis Shield) | Adults with acute sinusitis, acute tonsillitis, and acute otitis. | 161 (43/118) |
| Llor et al
49
(also Llor et al 67) | Spain | Before–after | NycoCard II (Axis Shield) | Adults with uncomplicated acute illness (<7 days) with cough as the main symptom and 2+ signs or symptoms of LRTI (increase in sputum volume or purulence, chest pain and/or worsening of dyspnoea). | 836 (208/628) |
| Peters et al 56 | The Netherlands | Case–control | NycoCard II (Axis Shield) | Children and adults with an intellectual disability suspected of LRTI. | 1472 (882/590) |
| (b) Patients presenting with signs of any acute illness | |||||
| Jakobsen et al 50 | Norway, Sweden, Wales (UK) | Cohort | NycoCard II (Axis Shield) and QuikRead (Orion Diagnostica) | Adults with an acute illness episode less than 28 days. | 503 (372/131) |