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Table 4 Subgroup analysis of smoking effects on pediatric systolic blood pressure

From: Effect of passive exposure to cigarette smoke on blood pressure in children and adolescents: a meta-analysis of epidemiologic studies

Category Model Publication bias Heterogeneitya Beta (95%CI) Pfor effect size
Age group (year)
 0–7 FEM p = 0.55 33.0% (p = 0.11) 0.39 (0.24 to 0.55) < 0.001
 7–13 FEM p = 0.04 0.0% (p = 0.86) 0.14 (− 0.12 to 0.40) 0.31
 12–18 FEM p = 0.68 53.2% (p = 0.12) 0.21 (0.09 to 0.33) 0.001
Type of study
 Cohort FEM p = 0.04 27.2% (p = 0.14) 0.25 (0.16 to 0.34) < 0.001
 Cross-sectional REM p = 0.68 62.5% (p = 0.03) 0.21 (−0.32 to 0.74) 0.44
Smoking definition
 Not reported FEM p = 0.88 28.8% (p = 0.24) 0.16 (−0.38 to 0.70) 0.57
 At least 1 cigarette per month FEM p = 0.47 29.0% (p = 0.21) 0.02 (−0.09 to 0.13) 0.71
 Current daily smoking FEM p = 0.83 45.7% (p = 0.14) 0.25 (0.08 to 0.41) 0.003
 At least 1 cigarette per month REM p = 0.82 55.3% (p = 0.004) 0.30 (0.10 to 0.50) 0.003
Period of exposure
 Pregnancy REM p = 0.02 35.4% (p = 0.08) 0.26 (0.12 to 0.41) < 0.001
 Domestic (postnatal) REM p = 0.07 59.8% (p = 0.03) 0.28 (−0.04 to 0.59) 0.08
Parental smoking habit
 Mother REM p = 0.04 43.2% (p = 0.04) 0.25 (0.09 to 0.41) 0.002
 Father NA NA NA NA NA
 Both REM p = 0.05 56.8% (p = 0.03) 0.34 (0.01 to 0.67) 0.04
Sample size
  < 1000 subjects FEM p = 0.91 27.5% (p = 0.25) 0.61 (−0.41 to 1.63) 0.24
  ≥ 1000 subjects REM p = 0.07 54.6% (p = 0.003) 0.25 (0.11 to 0.39) < 0.001
BP measurement device
 Mercury/aneroid REM 0.576 56.5% (p = 0.011) 0.11 (0.03 to 0.20) 0.007
 Automatic/semiautomatic FEM 0.257 26.7% (p = 0.190) 0.33 (0.17 to 0.48) < 0.001
  1. aHeterogeneity was reported as I-squared and corresponding p value. CI Confidence interval, FEM Fixed effect model, NA Not applicable due to lack of included studies, REM Random effect mode