Table 3.

ORs and 95% CIs of breast cancer by quartile of leptin concentration among premenopausal women at blood collection in the Nurses' Health Study II

 Leptin concentrations, ng/mL
≤9.389.39–16.1916.2–26.69≥26.7Ptrenda
Cases/controls86/15987/15995/15662/162
Simple modelb1.00 (reference)0.98 (0.68–1.41)1.07 (0.74–1.54)0.66 (0.44–1.00)0.05
Covariate-adjusted modelc1.00 (reference)0.95 (0.64–1.40)1.09 (0.74–1.60)0.62 (0.40–0.96)0.04
Covariate-adjusted model + BMI at blood drawd1.00 (reference)0.96 (0.64–1.43)1.14 (0.75–1.73)0.69 (0.38–1.23)0.26
Covariate-adjusted model + BMI at age 18 and weight change from age 18 to blood drawe1.00 (reference)0.90 (0.59–1.36)0.98 (0.63–1.54)0.55 (0.31–0.99)0.04

Abbreviation: MET, metabolic equivalent.

  • aDetermined using quartile medians.

  • bConditional logistic regression. Cases and controls were matched on age, menopausal status at blood collection and diagnosis, race/ethnicity, date, time of day, and fasting status at blood collection, and luteal day of blood draw (timed cases only).

  • cConditional logistic regression adjusted for age at menarche (<12, 12, 13, ≥14), parity/age at first birth (nulliparous, age at first firth <25 years/1–4 children, age at first birth 25–29 years/1–4 children, age at first birth ≥30 years/1–4 children, age at first birth <25/≥5 children, age at first birth ≥25/≥5 children), family history of breast cancer (yes/no), history of benign breast disease (yes/no), and physical activity (<3, 3–<9, 9–<18, 18–<27, 27–<42, and ≥42 MET/wk).

  • dConditional logistic regression adjusted for the variables in the covariate-adjusted model plus BMI at blood draw (continuous).

  • eConditional logistic regression adjusted for the variables in the covariate-adjusted model plus BMI at age 18 (continuous) and weight change from age 18 to blood draw (<5, 5–<20, ≥20 kg).