Fracture Risk · Risk Factors
Vessey M et al., 1998 · Contraception
There is good evidence that estrogens and progestogens have an important effect on bone metabolism. This article explores the relationship between oral contraceptive (OC) use and fractures occurring at various sites among the 17,032 participants in the Oxford-Family Planning Association contraceptive study, which now includes information accumulated during 310,000 woman-years of observation between 1968 and 1994. In total, 1308 women suffered at least one fracture during the follow-up period, which was largely confined to premenopausal years. When all fractures were combined, there was a modest, but highly significant trend (p < 0.001) of increasing risk with total duration of oral contraceptive use. In addition, there was statistically significant heterogeneity (p < 0.01) when overall fracture rates were examined in relation to recency of oral contraceptive use during the premenopausal lifespan. The highest relative risk (1.3, 95% CI 1.1-1.5) was for current or recent oral contraceptive users; however, viewed as a whole, no clear pattern of risk was apparent. Examination of the data for individual fracture sites (including the lower end of the radius/ulna) did not provide any evidence of a protective effect of oral contraceptive use. These results are closely similar to those reported from the Royal College of General Practitioners Oral Contraception Study in 1993. Estrogens and progestogens have an important effect on bone metabolism. The present study explored the relationship between oral contraceptive (OC) use and bone fractures in the cohort of 17,032 English and Scottish participants in the Oxford-Family Planning Association contraceptive study (1968-94). The analysis was based on the calculation of woman-years of observation terminated by referral for fracture or release from follow-up due to death, emigration, or short-term pill users reaching age 45 years. A total of 1308 women experienced at least one fracture during 310,000 woman-years of observation and there was a significant (p 0.001) positive relationship between age and fracture risk. Most common were fractures of the radius/ulna, tarsal/metatarsal bones, and ankle. When all fractures were combined, there was a significant (p 0.001) increasing risk with total duration of OC use. Also observed was a significant (p 0.01) heterogeneity when overall fracture rates were examined in relation to recency of OC use during the premenopausal lifespan. The highest relative risk (1.3; 95% confidence interval, 1.1-1.5) was recorded among current or recent OC users. There was about a 20% increase in the overall risk of fracture in women who had used OCs at any time compared with never-users. Overall, however, no clear pattern of risk emerged. These results are similar to those reported in the 1993 Royal College of General Practitioners OC Study. It is assumed that the increased fracture risk in OC users results from life-style characteristics of such women rather than a direct effect of OCs on bone.
Fracture Risk · Risk Factors
Vestergaard P et al., 2006 · Contraception
Prior studies have suggested that oral contraceptives (OCs) may be associated with an increased fracture risk. However, the previous studies have only performed a limited adjustment for other potential risk factors. Subjects and methodsAll women with a fracture (n=64,548) in the year 2000 in Denmark served as cases. For each case, three age-matched controls were randomly drawn from the general population (n=193,641). Exposure was use of OCs between January 1, 1996, and December 31, 2000. Adjustments were made for use of other drugs, pregnancy, prior fracture, other diseases and social variables. In the unadjusted analysis, use of OCs in low dose was associated with a small increase in overall fracture risk. However, upon adjustment, no increase in fracture risk could be demonstrated in any age or dose group. Oral contraceptives are not associated with an increase or a decrease in fracture risk. Any change in fracture risk may be due to confounders.
Hormones and Bone · Contraceptive Effects on Bone
Michaëlsson K et al., 1999 · Lancet
Epidemiological studies indicate a protective effect of postmenopausal oestrogen therapy on the risk of osteoporotic fractures. Whether premenopausal oestrogen exposure in the form of oral contraceptives also reduces the risk of osteoporotic fractures remains uncertain. We did a population-based case control study of hip fracture among Swedish postmenopausal women, 50-81 years of age, through mailed questionnaires and telephone interviews. Of those women who were eligible, 1327 (82.5%) cases and 3312 (81.6%) randomly selected controls responded. Findings: 130 (11.6%) cases and 562 (19.1%) controls reported ever-use of oral contraceptives. Ever-use of oral contraceptives was associated with a 25% reduction in hip fracture risk (odds ratio 0.75 [95% CI 0.59-0.96]). Women who had ever used a high-dose pill (equivalent to > or = 50 microg ethinylestradiol per tablet) had a 44% lower risk for hip fracture than never-users (0.56 [0.42-0.75]). No overall trend was observed with duration of oral-contraceptive use, or time since last use. However, when making comparisons with women who have never used oral contraceptives, the odds ratios for hip-fracture were 0.69 (0.51-0.94) for use after age 40, 0.82 (0.57-1.16) for use at ages 30-39, and 1.26 (0.76-2.09) for use before age 30. Interpretation: Our results imply that in postmenopausal women, oral-contraceptive use late in reproductive life may reduce the risk of hip fracture, although we recognise the limitations of the case-control method.
Fracture Risk · Risk Factors
Barad D et al., 2005 · Fertil Steril
To test for the possible association of past oral contraceptive (OC) use and incident fracture after menopause.
A prospective cohort of 93,725 postmenopausal women.
Forty Women's Health Initiative (WHI) clinical centers across the United States. PATIENT(S): Ethnically diverse 93,725 volunteer postmenopausal women, 50 to 79 years old. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The main outcome was self-reported incident first fracture assessed prospectively by annual questionnaire. RESULT(S): The adjusted relative hazard (HR) for fracture among past OC users was 1.07 (95% CI, 1.01-1.15). Among women without any postmenopausal hormone treatment, past OC use for < or =5 years led to an HR of 1.15 (95% CI, 1.04-1.27) and for past OC use >5 years led to an HR of 1.09 (95% CI, 0.97-1.23) compared with never users. CONCLUSION(S): This study does not support the idea that past OC use protects against later fracture.
