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Table 3 Subgroup analysis of association between breastfeeding and childhood lymphoma risk for the comparison of breastfeeding versus non/occasional breastfeeding

From: Breastfeeding and the risk of childhood cancer: a systematic review and dose-response meta-analysis

  No. of studies No. of cases OR (95%CI) P value I2 (%) P value for heterogeneity P in meta- regression
Cancer type        0.875
 Hodgkin’s disease (B.1) 9 458 0.86 (0.63 ~ 1.18) 0.341 25.8 0.215  
 Non-Hodgkin’s lymphoma (B.2) 9 686 0.88 (0.67 ~ 1.15) 0.343 26.9 0.205  
Year of publication        0.583
 In and before 2000 (B.3) 4 244 0.75 (0.53 ~ 1.06) 0.103 0.0 0.908  
 After 2000 (B.4) 7 980 0.84 (0.63 ~ 1.12) 0.231 51.5 0.054  
Geographic location        0.041
 Europe (B.5) 6 939 0.98 (0.84 ~ 1.15) 0.826 0.0 0.571  
 Asia (B.6) 4 259 0.53 (0.37 ~ 0.76) 0.001 0.0 0.906  
 North America (B.7) 1 26 0.69 (0.30 ~ 1.58) 0.381 NA NA  
Study quality score        0.436
 < 7 (B.8) 2 85 0.66 (0.31 ~ 1.42) 0.290 39.7 0.198  
 ≥ 7 (B.9) 9 1139 0.86 (0.70 ~ 1.06) 0.152 28.0 0.196  
Sample size        0.578
 ≤ 200 (B.10) 5 368 0.77 (0.44 ~ 1.35) 0.366 45.5 0.119  
 > 200 (B.11) 6 856 0.89 (0.75 ~ 1.06) 0.203 12.7 0.334  
Study design        0.743
 PC-CS (B.12) 8 1068 0.85 (0.68 ~ 1.05) 0.125 34.1 0.156  
 HC-CS (B.13) 3 156 0.78 (0.41 ~ 1.51) 0.461 31.4 0.233  
Definition of reference category        0.044
 Never breastfeeding (B.14) 6 831 0.97 (0.83 ~ 1.14) 0.732 0.0 0.879  
 Occasional breastfeeding (B.15) 5 393 0.66 (0.44 ~ 0.99) 0.042 40.8 0.149 0.170
 ≤ 2 months (B.16) 2 216 1.07 (0.42 ~ 2.72) 0.888 68.3 0.076  
 ≤ 6 months (B.17) 3 177 0.50 (0.34 ~ 0.75) 0.001 0.0 0.937  
  1. Abbreviations: PC-CS population-based case-control study; HC-CS hospital-based case-control study; NA not applicable