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Table 3 Association between potential confounding variables and second dose BCG in neighbourhood and HU controls.

From: Selection bias: neighbourhood controls and controls selected from those presenting to a Health Unit in a case control study of efficacy of BCG revaccination

  Neighbourhood controls HU controls
Variables Two BCG/One BCG Two BCG/One BCG
  OR 95% CI OR 95% CI
Sex     
   Male 1   1  
   Female 1.17 0.81–1.68 0.82 0.57–1.19
Contact with TB     
   Yes 1.18 0.67–2.08 1.12 0.65–1.91
   No 1   1  
Head of family employed     
   Yes 1.40 0.95–2.06 1.21 0.71–1.89
   No 1   1  
Income of the head of family     
   <1 MW* 1   1  
   1 to <2MW 1.82 0.81–4.10 0.97 0.41–2.28
   2 to <5MW 1.62 0.59–4.56 1.05 0.39–2.82
   ≥ 5MW 0.94 0.25–3.52 0.63 0.22–1.83
   Not reported or not known 1.03 0.50–2.11 1.01 0.46–2.22
Piped water     
   Yes 1.66 0.37–7.50 0.60 0.30–1.22
   No 1   1  
Washing machine     
   Yes 1.02 0.63–1.66 1.24 0.81–1.90
   No 1   1  
Frigidaire     
   Yes 1.57 0.80–3.06 0.76 0.38–1.51
   No 1   1  
Videocassette     
   Yes 1.42 1.01–2.19 0.91 0.63–1.30
   No 1   1  
  1. *MW: the income level of the head of the family was relative to the minimum wage (MW). MW<1 was the baseline. 1–1.9+ = US$100–US$199/month; 2–4.9 = US$200–US$499/month; 5+ = US$>=US$500/month.