Table 5.

Relationship of SEP index to age at Tanner B2 by site in 1,059 girls ages 6–8 years of age at entry to study with adjustment for BMI% and race/ethnicity, BCERP

San Francisco area n = 427Cincinnati area n = 278New York City (East Harlem) n = 354
TR (95% CI)TR (95% CI)TR (95% CI)
SEP indexa
 Quintile 1 (low)0.93 (0.87–1.00)0.97 (0.90–1.04)1.01 (0.97–1.06)
 Quintile 20.96 (0.91–1.00)1.05 (0.99–1.11)0.99 (0.94–1.03)
 Quintile 30.99 (0.95–1.02)0.96 (0.92–1.00)1.00 (ref)
 Quintile 41.00 (0.97–1.04)0.96 (0.92–1.00)
 Quintile 51.00 (ref)1.00 (ref)
BMI%
 ≥850.95 (0.92–0.98)0.82 (0.79–0.85)0.85 (0.82–0.88)
 50–850.98 (0.95–1.01)0.90 (0.87–0.93)0.93 (0.90–0.97)
 <501.00 (ref)1.00 (ref)1.00 (ref)
Race/ethnicity
 Black0.93 (0.90–0.96)0.94 (0.90–0.98)0.99 (0.96–1.02)
 Hispanic1.02 (0.98–1.05)0.93 (0.84–1.03)1.00 (ref)
 Asian0.99 (0.95–1.03)1.24 (1.09–1.42)
 White1.00 (ref)1.00 (ref)
  • NOTE: Median at referent levels of all variables in the model = 10.21 (95% CI 9.91–10.51). Site–race/ethnicity interaction: P = 0.0002; site–BMI% interaction: P < 0.0001; site–SEP interaction: P = 0.001. SEP trend: San Francisco: P = 0.019; Cincinnati: P = 0.79; New York City: P = 0.39. New York SEP quintile 3 includes 8 girls in quintiles 4 and 5.

  • Abbreviations: B2, breast stage 2; ref, referent;

  • aSEP index – Household income, mother's education, own/rent home.