Table 2.

Baseline parameters by serum β-carotene quartile (μg/dL)

Q1Q2Q3Q4
(<38)(38–65)(66–104)(≥105)χ2 or ZP
N6736666516540.580.57
n all deaths2882652272024.79<0.001
Mean age at exam (y)57.157.857.658.2135.6<0.001
Mean pack-yearsa14.514.614.711.32.150.14
Mean years since quit smokingb15.815.69.5413.212.3<0.001
Mean insulation years worked31.832.331.731.137.5<0.001
Smoking status76.4<0.001
 Non11612012117771.3<0.001
 Past28226133135222.3<0.001
 Current27528520012671.3<0.001
  • aCurrent and former smokers at baseline.

  • bFormer smokers at baseline.