Characteristics of the included studies
| Author | Publication year | Setting | Study design | Mean age, years | Female sex, (%) | Location of RTI lower RTI (%) | Sample size (CRP testing/no CRP testing) | NOS score for OS |
|---|---|---|---|---|---|---|---|---|
| Bjerrum et al10 | 2004 | Denmark | OS | NA | NA | 0 (0)a | 281/86 | 7 |
| Cals et al20 | 2009 | Netherlands | Cluster RCT | 49.8 | 265 (61.5) | 431 (100) | 227/204 | NA |
| Cals et al13 | 2010 | Netherlands | Parallel-group RCT | 44.3 | 179 (69.4) | 107 (41.5) | 129/129 | NA |
| Cals et al19 | 2011 | Netherlands | Cluster RCT | 48.5 | 135 (58.7) | 230 (100) | 110/120 | NA |
| Cals et al21 | 2013 | Netherlands | Cluster RCT | 49.9 | 235 (62.0) | NA | 203/176 | NA |
| Diederichsen et al25 | 2000 | Denmark | Parallel-group RCT | 37.0 | 465 (57.3) | NA | 414/398 | NA |
| Fagan18 | 2001 | Norway | OS | NA | NA | NA | 122/202 | 6 |
| Gonzales et al11 | 2011 | US | Parallel-group RCT | NA | 86 (65.6) | 88 (67.2) | 69/62 | NA |
| Jakobsen et al22 | 2010 | Norway | OS | NA | 438 (87.1) | NA | 372/131 | 7 |
| Kavanagh et al24 | 2011 | Ireland | OS | NA | NA | NA | 60/60 | 6 |
| Llor et al23 | 2012a | Spain | OS | NA | NA | 5385 (100) | 545/4840 | 6 |
| Llor et al12 | 2012b | Spain | OS | 39.8 | 543 (65.0) | 0 (0)a | 208/628 | 6 |
| Melbye et al26 | 1995 | Norway | Parallel-group RCT | NA | NA | 229 (100) | 108/121 | NA |
↵a All patients had upper respiratory tract infections. CRP = C-reactive protein. NA = not applicable. NOS = Newcastle-Ottawa Scale. OS = observational study. RCT = randomised controlled trial. RTI = respiratory tract infection.