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Table 1 Characteristics of the study population at recruitment, and details of follow-up, by body mass index

From: Hospital admissions in relation to body mass index in UK women: a prospective cohort study

  Body mass index:
  <22.5 22.5-24.9 25.0-29.9 30.0-34.9 35+ All women
Number of women 241,773 337,095 447,971 159,330 65,450 1,251,619
Median (interquartile range) BMI 21.2 (1.6) 23.8 (1.3) 26.9 (2.3) 31.7 (2.3) 37.6 (4.3) 25.4 (5.6)
Mean (SD) age at recruitment 55.8 (4.9) 56.0 (4.9) 56.4 (4.9) 56.3 (4.8) 55.8 (4.6) 56.2 (4.9)
Upper third of socioeconomic group (%) 36.8 36.6 32.7 27.6 22.9 33.4
Mean (SD) number of children 2.0 (1.2) 2.1 (1.2) 2.2 (1.2) 2.3 (1.3) 2.3 (1.4) 2.1 (1.2)
Strenuous physical activity > once a week (%) 26.7 24.1 19.4 14.9 12.2 21.1
Mean (SD) alcohol intake (g/day) 6.7 (8.0) 6.6 (7.7) 5.7 (7.4) 4.6 (6.9) 3.6 (6.3) 5.9 (7.6)
Current smoker (%) 25.3 20.6 19.2 17.0 15.3 20.3
Current HRT user (%) 37.4 35.8 32.9 29.4 24.7 33.7
Hysterectomy (%) 21.1 23.5 26.6 29.0 27.2 25.0
Follow-up       
Woman-years of follow-up (1,000 s) 2,231.4 3,122.7 4,130.1 1,460.7 594.1 11,539.0
Total number incident hospital admissions 485,566 683,385 1,031,052 429,321 204,692 2,834,016
Woman-years of follow-up to first admission (1000 s) 1,484.9 2,047.6 2,577.5 852.9 327.1 7,290.0
Number women with at least one incident admission 138,740 197,724 281,238 107,813 47,160 772,675