Table 1.

Age-standardized characteristics of the study populationa

CharacteristicHPFS (n = 171)NHS (n = 252)
Age at blood draw, y, mean (SD)65.2 (7.8)60.2 (6.2)
White, %94.499.4
Height, inches, mean (SD)70.1 (2.9)64.4 (2.4)
Body mass index, kg/m2, mean (SD)26.0 (3.2)25.9 (5.0)
Physical activity, MET-hr/wk, mean (SD)38.0 (35.1)17.7 (20.3)
Season of blood draw, %
 Feb–Apr10.036.2
 May–Jul27.731.4
 Aug–Oct45.915.1
 Nov–Jan16.417.3
Fasting time at blood draw, %
 ≤4 h31.918.5
 5–8 h11.65.0
 9–12 h36.845.7
 ≥13 h19.730.8
Time of day of blood draw, %
 6–8 am29.937.7
 9–10 am37.045.7
 11 am-noon9.97.6
 1–2 pm11.65.2
 3 pm-midnight11.63.8
  • Abbreviations: MET, metabolic equivalent; SD, standard deviation.

  • aAll values (except age at blood draw) are standardized to the age distribution of the study population.