TABLE 3

Comparing the Proportion with Breast Stage 2+ by Age Between BCERP Puberty Study Cross-Sectional Equivalent Data and PROS9

Age GroupBlackWhite
PROSBCERP Puberty StudyaPROScBCERP Puberty Studya
Total No. of GirlsPercent at Breast Stage 2+Total No. of GirlsPercent at Breast Stage 2+χ SquarebP ValuebTotal No. of GirlsPercent at Breast Stage 2+Total No. of GirlsPercent at Breast Stage 2+χ SquarebP Valueb
6.0–6.91266100187.43.006150637740.24.496
7.0–7.913615257222.28.131112853201011.07.001
8.0–8.914338294380.02.8921334113632129.39<.0001
9.0–9.911563282620.00.9711067323794212.50.000
10.0–10.911280269872.73.0981153623407110.01.002
11.0–11.912696190960.02.999110485244928.15.004
12.0–12.99199133990.07.99992396156981.63.256
  • a Every B visit in the BCERP Puberty Study was treated as if it were a separate girl; missing visits or visits with refused Tanner staging not included.

  • b Fisher’s Exact Test used where cell frequency is ≤5.

  • c PROS did not separate Hispanic and Non-Hispanic white subjects; the BCERP Puberty Study did.