<p>Additional file 1:</p><p>Table S1: Characteristics of samples not-included in meta-analyses</p><p>Table S2: Characteristics of articles additionally included for GCA-specific characteristic analysis</p><p>Table S3: Article quality appraisal scores using the Newcastle-Ottawa Scale (NOS)</p><p>Figure S1: Meta-analysis of time-periods of delay in receiving a diagnosis of GCA (Original SD only)</p><p>Figure S2: Meta-analysis of time-periods of delay in receiving a diagnosis of GCA (Imputed SD only)</p><p>Figure S3: Meta-analysis of time-periods of delay in receiving a diagnosis of GCA (GCA diagnosis through TAB only)</p><p>1 Table S1: Characteristics of samples not-included in meta-analyses Gender Age Reported diagnostic delay Lead author Definition of GCA n % F Mean SD Range Time Mean SD Range Positive TAB for GCA after fever was initial Calamia 15 66.7 67 - 57-75 M 3* - 1-16 symptom Positive TAB for GCA and/or study defined Karanjia 63 - - - - D 52 - - clinical criteria Positive TAB for GCA and/or study defined Kelkel 130 74.6 76 7.5 60-92 M 5* - 0.5-48 clinical criteria Positive TAB for GCA or on clinical Hu 16 6.3 43.1 - 28-60 M 5.5 - 0.25-24.3 grounds (response to steroids) Nuenninghoff GCA defined using 1990 ACR criteria 168 79.2 75.6 - D 40* - 21-89 Loddenkemper Positive TAB for GCA 90 74.4 74.6 7.8 - D 125* 2-2555</p><p>ACR = American College of Rheumatology. Time: D = days, W= weeks & M = months. TAB = Temporal Artery Biopsy. *Reported as median </p><p>Table S2: Characteristics of articles additionally included for GCA-specific characteristic analysis Gender Age Reported diagnostic delay</p><p>2 Defin ition Mean Lead author n % F Mean SD SD Range of (Weeks) GCA Positi ve TAB for GCA 42 54.8 75.1 6.7 9.6 11 - with visual manif estati ons Gonzalez-Gay Positi ve TAB for GCA witho 119 47.1 74.6 6.9 11.5 13 - ut visual manif estati ons Bilate ral blind Schmidt 5 60 81.6 - 7 3* 2-14 ness from GCA Gonzalez-Gay GCA, 29 62.1 74.3 7.5 8 4* 4-20 but negati</p><p>3 ve TAB Positi ve TAB 161 50.9 74.8 6.8 7 1.7* 4-14 for GCA Positi ve TAB 97 - 74.5 6.6 9.7 13 - for GCA – Men Positi ve TAB for 113 53.8 74.7 7.3 11.0 10 - GCA – Femal Gonzalez-Gay e Positi ve TAB 132 46.2 74.0 6.7 9.9 12 - for GCA – Rural Positi ve TAB 78 66.7 75.6 7.3 11.1 11 - for GCA – Urban Gonzalez-Gay Positi 203 53.2 74.7 6.7 9.2 9.9 - ve </p><p>4 TAB for GCA – With heada che Positi ve TAB for GCA – 37 59.5 75.2 6.9 16.6 15 - Witho ut heada che Positi ve TAB for 96 60.4 73.4 6.3 13.4 12 - GCA – With PMR Positi ve TAB for 144 50 75.6 6.9 8.3 10 - GCA – Witho ut PMR Subcli nical 18 66.7 75.6 5.9 16.3 15 - GCA Biops 222 53.2 74.7 6.8 9.9 11 -</p><p>5 y- prove n GCA Positi ve TAB for 46 52.2 13.2 12.8 GCA - <69 years Lopez-Diaz 75.1 6.8 Positi ve TAB for 227 53.7 9.4 10.2 GCA - ≥70 years</p><p>ACR = American College of Rheumatology. ESR = Erythrocyte Sedimentation Rate. PMR = Polymyalgia Rheumatica. Time: D = days, W= weeks & M = months. MRR = Medical Record Review; TAB = Temporal Artery Biopsy. *SD imputed from range </p><p>Table S3: Article quality appraisal scores using the Newcastle-Ottawa Scale (NOS)</p><p>Selection Outcome Article Year 1 3 1 Is exposed cohort How was exposed How was representative? cohort selected? outcome assessed? Calamia 1981 B* A* B* Bella Cueto* 1985 B* A* D Karanjia 1989 B* A* B* Desmet* 1990 B* A* B*</p><p>6 Kelkel 1991 B* A* B* Myklebust* 1996 A* A* B* Brack* 1999 B* A* B* Duhaut* 1999 A* A* B* Nesher* 1999 B* A* A Hu 2002 B* A* D Liozon* 2003 B* A* B* Nuenninghoff 2003 A* A* B* Gonzalez-Gay* 2004 B* A* B* Pease* 2005 B* B* B* Loddenkemper 2007 B* A* B* Mari* 2009 B* A* B* Ezeonyeji* 2011 B* A* B* Mackie* 2011 A* A* B* Czihal* 2012 B* A* B* Prieto-Gonzalez* 2012 B* A* B* Patil* 2015 A* A* B* Singh* 2015 A* A* B* Gonzalez-Gayǂ 2000 A* A* B* Schmidtǂ 2000 C D D Gonzalez-Gay 2001 A* A* B* Gonzalez-Gay 2003 A* A* B* Gonzalez-Gayǂ 2005 A* A* B*</p><p>7 Lopez-Diaz 2008 A* A* B* *Included in delay meta-analyses. ǂIncluded in characteristic-specific delay meta-analysis. A indicates the highest methodological quality whereas D indicates the worst quality; An asterisk (*) denotes that the article has scored highest for that particular criterion. A comma (,) separating two scores denotes that an article i) matched exposed and non-exposed and ii) adjusted for potential confounding factors</p><p>8 % Figure S1: Meta-analysis of time-periods of delay in receiving a diagnosis of GCA (Original SD only)</p><p> author year country n ES (95% CI) Weight</p><p>Desmet 1990 Belgium 21 1.21 (0.53, 1.90) 13.15</p><p>Liozon 2003 France 175 11.29 (9.52, 13.05) 12.81</p><p>Gonzalez-Gay 2004 Spain 199 9.80 (8.30, 11.30) 12.92</p><p>Mackie 2011 England 248 9.14 (7.40, 10.89) 12.82</p><p>Czihal 2012 Germany 110 18.20 (14.13, 22.27) 11.30</p><p>Prieto-Gonzalez 2012 Spain 40 10.60 (6.60, 14.60) 11.36</p><p>Patil 2015 England 46 4.57 (2.95, 6.19) 12.87</p><p>Singh 2015 USA 204 5.90 (4.04, 7.76) 12.76</p><p>Overall (I-squared = 97.5%, p = 0.000) 8.65 (5.05, 12.25) 100.00</p><p> with estimated predictive interval . (-4.51, 21.80)</p><p>NOTE: Weights are from random effects analysis</p><p>0 30 Figure S2: Meta-analysis of time-periods of delay in receiving a diagnosis of GCA (Imputed SD only) %</p><p> author year country n ES (95% CI) Weight</p><p>Bella Cueto 1985 Spain 100 18.00 (7.81, 28.19) 4.62</p><p>Myklebust 1996 Norway 39 6.43 (4.17, 8.69) 15.87</p><p>Brack 1999 USA 74 11.14 (9.44, 12.85) 16.78</p><p>Nesher 1999 Israel 144 6.43 (5.14, 7.72) 17.34</p><p>Duhaut 1999 France 207 6.86 (0.02, 13.70) 7.83</p><p>Pease 2005 England 42 12.86 (5.81, 19.90) 7.56</p><p>Mari 2009 Spain 79 13.14 (10.59, 15.70) 15.32</p><p>Ezeonyeji 2011 England 65 5.00 (2.11, 7.89) 14.69</p><p>Overall (I-squared = 84.6%, p = 0.000) 9.09 (6.56, 11.63) 100.00</p><p> with estimated predictive interval . (1.01, 17.17)</p><p>NOTE: Weights are from random effects analysis</p><p>0 30 Figure S3: Meta-analysis of time-periods of delay in receiving a diagnosis of GCA (GCA diagnosis through TAB only) % author year country n ES (95% CI) Weight</p><p>Bella Cueto 1985 Spain 100 18.00 (7.81, 28.19) 4.49</p><p>Desmet 1990 Belgium 21 1.21 (0.53, 1.90) 9.33</p><p>Myklebust 1996 Norway 39 6.43 (4.17, 8.69) 8.90</p><p>Brack 1999 USA 74 11.14 (9.44, 12.85) 9.10</p><p>Duhaut 1999 France 207 6.86 (0.02, 13.70) 6.30</p><p>Liozon 2003 France 175 11.29 (9.52, 13.05) 9.08</p><p>Gonzalez-Gay 2004 Spain 199 9.80 (8.30, 11.30) 9.16</p><p>Mari 2009 Spain 79 13.14 (10.59, 15.70) 8.78</p><p>Ezeonyeji 2011 England 65 5.00 (2.11, 7.89) 8.62</p><p>Mackie 2011 England 248 9.14 (7.40, 10.89) 9.09</p><p>Prieto-Gonzalez 2012 Spain 40 10.60 (6.60, 14.60) 8.03</p><p>Patil 2015 England 46 4.57 (2.95, 6.19) 9.13</p><p>Overall (I-squared = 96.7%, p = 0.000) 8.55 (5.55, 11.54) 100.00 with estimated predictive interval . (-3.08, 20.17)</p><p>NOTE: Weights are from random effects analysis</p><p>0 30</p>