Table 2.
Adjusted mean BMD by age group, duration, and dose of current OC use
| Hip BMD a | Spine BMD a | Whole-body BMD a | ||
|---|---|---|---|---|
| Mean (95% CI) | Mean (95% CI) | Mean (95% CI) | ||
| Adolescents, 14–18 years old | ||||
| N b | ||||
| OC duration c | ||||
| Nonuser | 107 | 0.984 (0.960 –1.008) | 1.003 (0.984–1.022) | 1.085 (1.069–1.100) |
| > 0–3 months | 117 | 0.994 (0.977 –1.012) | 1.016 (0.997–1.035) | 1.089 (1.076–1.101) |
| >3–12 months | 46 | 1.012 (0.974–1.051) | 1.016 (0.974–1.057) | 1.101 (1.075–1.128) |
| >12–24 months | 23 | 0.979 (0.941–1.018) | 0.999 (0.960–1.039) | 1.084 (1.055–1.113) |
| >24 months | 8 | 0.971 (0.900–1.043) | 1.010 (0.948–1.073) | 1.094 (1.042–1.145) |
| P for linear trend | 0.77 | 0.86 | 0.75 | |
| OC dose (EE) | ||||
| Nonuser | 107 | 0.983 (0.958–1.007) | 1.002 (0.983–1.021) | 1.084 (1.069–1.100) |
| 30–35 mcg | 121 | 0.994 (0.973–1.016) | 1.012 (0.991–1.033) | 1.092 (1.077–1.107) |
| <30 mcg | 73 | 1.000 (0.974–1.026) | 1.011 (0.990–1.033) | 1.094 (1.076–1.111) |
| P for global test | 0.52 | 0.69 | 0.65 | |
| Young Adults, 19–30 years old | ||||
| OC durationc | ||||
| Nonuser | 110 | 0.983 (0.959–1.006) | 1.040 (1.016–1.065) | 1.107 (1.089–1.125) |
| >0–3 months | 100 | 0.990 (0.950–1.031) | 1.037 (1.004–1.071) | 1.132 (1.109–1.156) |
| >3–12 months | 29 | 1.008 (0.966–1.050) | 1.067 (1.030–1.104) | 1.136 (1.107–1.166) |
| >12–24 months | 34 | 0.965 (0.926–1.005) | 1.037 (0.996–1.078) | 1.109 (1.074–1.143) |
| >24 months | 32 | 0.945 (0.902–0.988) | 0.979 (0.940–1.017) | 1.082 (1.056–1.108) |
| P for linear trend | 0.09 | 0.02 | 0.004 | |
| OC dose (EE) | ||||
| Nonuser | 110 | 0.982 (0.959–1.006) | 1.040 (1.016–1.064) | 1.107 (1.089–1.125) |
| 30–35 mcg | 120 | 0.978 (0.956–1.001) | 1.030 (1.007–1.052) | 1.116 (1.100–1.131) |
| <30 mcg | 75 | 0.952 (0.924–0.980) | 1.004 (0.979–1.029) | 1.095 (1.073–1.117) |
| P for global test | 0.21 | 0.10 | 0.32 | |
a
Adjusted for age, race (White vs. Non-white), BMI, calcium intake, alcohol intake, weight-bearing physical activity, age at menarche, ever smoke (yes/no), and regular periods (yes/no). Mean results are based on OC variable as categorical term in the model.
b
N reflects the number of enrolled study participants by baseline current OC duration and dose. The actual N is slightly lower in some models due to missing data for covariates and/or outcomes.
c
OC duration is months of continuous use of the OC being used at the study visit.