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Table 3 Subgroup analyses for the effects of periodontal disease on all-cause mortality in people with CKD

From: Association between periodontal disease and mortality in people with CKD: a meta-analysis of cohort studies

Overall and subgroup analysis No. of studies Heterogeneity Model Meta-analysis P value between subgroups
P I2 (%) RR 95% CI P  
Overall 8 0.041 52.2 Random-effect 1.254 1.046–1.503 0.015  
CKD stage         0.79
CKD stage 3–5 3 0.75 0.0% Fix-effect 1.245 1.119–1.385 0.000  
CKD stage 5D (hemodialysis) 4 0.030 66.4% Random-effect 1.315 0.885–1.954 0.176  
Transplant 1 NA NA NA 7.17 1.4–76.4 NA  
Adjustment for confounding factors         
Unadjusted 1 NA NA NA 7.17 1.4–76.4 NA  
Adjusted 7 0.072 48.2% Fixed-effect 1.194 1.091–1.306 0.016 0.77
Adjusted for smoking and other variables 6 0.058 53.3% Random-effect 1.209 1.016–1.438 0.032  
Adjusted for diabetes and other variables 6 0.093 47.1% Fixed-effect 1.175 1.071–1.288 0.001  
Adjusted for diabetes, hypertension and other variables 4 0.664 0.0% Fixed-effect 1.264 1.137–1.404 0.000  
Study duration         0.14
Short (< 5 years) 3 0.029 71.9% Random-effect 1.116 0.855–1.457 0.418  
Long (≥ 5 years) 5 0.448 0.0% Fixed-effect 1.429 1.173–1.742 0.000  
Diagnostic criteria for periodontal disease         0.23
PPD, CALs 5 0.838 0% Fixed-effect 1.422 1.171–1.727 0.000  
CPITN 3 0.009 78.8% Random-effect 1.125 0.812–1.559 0.478  
Regions         0.99
Asian countries 2 0.227 31.6% Fixed-effect 1.257 1.123–1.407 0.000  
European countries and USA 6 0.045 55.8% Random-effect 1.259 0.927–1.710 0.14  
Reference population         0.66
Healthy 4 0.752 0.0% Fixed-effect 1.253 1.128–1.393 0.000  
Healthy to mild periodontal disease 4 0.012 72.4% Random-effect 1.410 0.844–2.356 0.189  
  1. Abbreviations: RR relative risk, CI confidence interval, PPD pocket probing depth, CALs clinical attachment levels, CPITN Community Periodontal Index of Treatment Needs Index, NA data not available