Influence of hormonal and reproductive factors on the risk of vertebral deformity in European women. European Vertebral Osteoporosis Study Group

Bone health and hormonal contraception

INTRODUCTION

Short-term and long-term steroid contraceptive systems are widely employed in adolescents and premenopausal women; they could induce variation in bone metabolism, but whether these changes increase the overall fracture risk is not yet clear.

EVIDENCE ACQUISITION

A systematic search of scientific publications about "hormonal contraceptives" and "bone metabolism" in reproductive age women was conducted.

EVIDENCE SYNTHESIS

In adolescent girl, combined oral contraceptives could have a deleterious effect on bone health when their onset is within three years after menarche and when they contain ethinyl estradiol at the dose of 20 mcg. In perimenopausal women, steroid contraceptives seem not influence bone health nor increase osteoporotic fractures risk in menopause. The oral progestogens intake is not related to negative effects on skeletal health. Depot medroxyprogesterone acetate (DMPA) induce a prolonged hypoestrogenism with secondary detrimental effect on healthy bone; the higher bone loss was observed at the DMPA dose of 150 mg intramuscular such as after long-term DMPA-users. Progestin-based implants and intrauterine devices have not negative effect on bone health.

CONCLUSIONS

Since sex-steroid drugs induce variations in hormonal circulating concentrations, they may negatively affect bone metabolism. Contraceptive choice should be tailored evaluating any possible effect on bone health. Clinicians should always perform a precontraceptive counselling to identify any coexisting condition that may affect bone health. Further randomized studies are needed to confirm these results.

Effect of parity on bone mineral density: A systematic review and meta-analysis

INTRODUCTION

Parity has been suggested as a possible factor affecting bone health in women. However, study results on its association with bone mineral density are conflicting.

METHODS

PubMed, EMBASE, the Cochrane Library, and Korean online databases were searched using the terms "parity" and "bone mineral density", in May 2016. Two independent reviewers extracted the mean and standard deviation of bone mineral density measurements of the femoral neck, spine, and total hip in nulliparous and parous healthy women.

RESULTS

Among the initial 10,146 studies, 10 articles comprising 24,771 women met the inclusion criteria. The overall effect of parity on bone mineral density was positive (mean difference=5.97mg/cm²; 95% CI 2.37 to 9.57; P=0.001). The effect appears site-specific as parity was not significantly associated with the bone mineral density of the femoral neck (P=0.09) and lumbar spine (P=0.17), but parous women had significantly higher bone mineral density of the total hip compared to nulliparous women (mean difference=5.98mg/cm²; 95% CI 1.72 to 10.24; P=0.006). No obvious heterogeneity existed among the included studies (femoral neck I²=0%; spine I²=31%; total hip I²=0%).

CONCLUSION

Parity has a positive effect on bone in healthy, community-dwelling women and its effect appears site-specific.

Osteoporosis: An under-recognized public health problem

Over 200 million people suffer from osteoporosis worldwide, which occurs when bone tissues become structurally deteriorated and bone mass becomes fragile, resulting in an increased risk of fracture. This review aims to describe the underlying risk factors and provide guidance on changes in lifestyle for those at risk of developing osteoporosis. It highlights risk factors such as age, sex, genetic background, and other under lying illnesses (factors that are generally “non-modifiable”). Furthermore, it focuses on factors that are dependent on lifestyle and (local) habits (factors that are “modifiable”), such as diet, sunlight exposure, exercise, and medication. Clearly, osteoporosis is a multifactorial disease and multiple of these risk factors can occur simultaneously. Currently, the data available differ greatly between regions and some areas might be affected more seriously than others. This review suggests that this might be due to differing healthcare training systems and suboptimal awareness of osteoporosis. Importantly, osteoporosis and resulting bone fractures represent a significant economic burden for both individuals and the wider society. Therefore, improved awareness of the disease may influence personal habits, reduce suffering, and alleviate the burden on healthcare expenditure.

Oral contraceptive use and fracture risk around the menopausal transition

OBJECTIVE

The effect of oral contraceptive (OC) use on risk of fracture remains unclear, and use during later reproductive life may be increasing. To determine the association between OC use during later reproductive life and risk of fracture across the menopausal transition, we conducted a population-based case-control study in a Pacific Northwest HMO, Group Health Cooperative.

METHODS

For the January 2008 to March 2013 interval, 1,204 case women aged 45 to 59 years with incident fractures, and 2,275 control women were enrolled. Potential cases with fracture codes in automated data were adjudicated by electronic health record review. Potential control women without fracture codes were selected concurrently, sampling based on age. Participants received a structured study interview. Using logistic regression, associations between OC use and fracture risk were calculated as odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Participation was 69% for cases and 64% for controls. The study sample was 82% white; mean age was 54 years. The most common fracture site for cases was the wrist/forearm (32%). Adjusted fracture risk did not differ between cases versus controls for OC use in the 10 years before menopause (OR 0.90, 95% CI 0.74, 1.11); for OC use after age 38 (OR 0.94, 95% CI 0.78, 1.14); for duration of use, or for other OC exposures.

CONCLUSIONS

The current study does not show an association between fractures near the menopausal transition and OC use in the decade before menopause or after age 38. For women considering OC use at these times, fracture risk does not seem to be either reduced or-reassuringly-increased.

Steroidal contraceptives and bone fractures in women: evidence from observational studies

BACKGROUND

Age-related decline in bone mass increases the risk of skeletal fractures, especially those of the hip, spine, and wrist. Steroidal contraceptives have been associated with changes in bone mineral density in women. Whether such changes affect the risk of fractures later in life is unclear. Hormonal contraceptives are among the most effective and most widely-used contraceptives. Concern about fractures may limit the use of these effective contraceptives. Observational studies can collect data on premenopausal contraceptive use as well as fracture incidence later in life.

OBJECTIVES

We systematically reviewed the evidence from observational studies of hormonal contraceptive use for contraception and the risk of fracture in women.

SEARCH METHODS

Through June 2015, we searched for observational studies. The databases included PubMed, POPLINE, Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, EMBASE, CINAHL, and Web of Science. We also searched for recent clinical trials through ClinicalTrials.gov and the ICTRP. For other studies, we examined reference lists of relevant articles and wrote to investigators for additional reports.

SELECTION CRITERIA

We included cohort and case-control studies of hormonal contraceptive use. Interventions included comparisons of a hormonal contraceptive with a non-hormonal contraceptive, no contraceptive, or another hormonal contraceptive. The primary outcome was the risk of fracture.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data. One author entered the data into RevMan, and a second author verified accuracy. We examined the quality of evidence using the Newcastle-Ottawa Quality Assessment Scale (NOS), developed for case-control and cohort studies. Sensitivity analysis included studies of moderate or high quality based on our assessment with the NOS.Given the need to control for confounding factors in observational studies, we used adjusted estimates from the models as reported by the authors. Where we did not have adjusted analyses, we calculated the odds ratio (OR) with 95% confidence interval (CI). Due to varied study designs, we did not conduct meta-analysis.

MAIN RESULTS

We included 14 studies (7 case-control and 7 cohort studies). These examined oral contraceptives (OCs), depot medroxyprogesterone acetate (DMPA), and the hormonal intrauterine device (IUD). This section focuses on the sensitivity analysis with six studies that provided moderate or high quality evidence.All six studies examined oral contraceptive use. We noted few associations with fracture risk. One cohort study reported OC ever-users had increased risk for all fractures (RR 1.20, 95% CI 1.08 to 1.34). However, a case-control study with later data from a subset reported no association except for those with 10 years or more since use (OR 1.55, 95% CI 1.03 to 2.33). Another case-control study reported increased risk only for those who had 10 or more prescriptions (OR 1.09, 95% CI 1.03 to 1.16). A cohort study of postmenopausal women found no increased fracture risk for OC use after excluding women with prior fracture. Two other studies found little evidence of association between OC use and fracture risk. A cohort study noted increased risk for subgroups, such as those with longer use or specific intervals since use. A case-control study reported increased risk for any fracture only among young women with less than average use.Two case-control studies also examined progestin-only contraceptives. One reported increased fracture risk for DMPA ever-use (OR 1.44, 95% CI 1.01 to 2.06), more than four years of use (OR 2.16, 95% CI 1.32 to 3.53), and women over 50 years old. The other reported increased risk for any past use, including one or two prescriptions (OR 1.17, 95% CI 1.07 to 1.29) and for current use of 3 to 9 prescriptions (OR 1.36, 95% CI 1.15 to 1.60) or 10 or more (OR 1.54, 95% CI 1.33 to 1.78). For the levonorgestrel-releasing IUD, one study reported reduced fracture risk for ever-use (OR 0.75, 95% CI 0.64 to 0.87) and for longer use.

AUTHORS' CONCLUSIONS

Observational studies do not indicate an overall association between oral contraceptive use and fracture risk. Some reported increased risk for specific user subgroups. DMPA users may have an increased fracture risk. One study indicated hormonal IUD use may be associated with decreased risk. Observational studies need adjusted analysis because the comparison groups usually differ. Investigators should be clear about the variables examined in multivariate analysis.

Parity, lactation, bone strength, and 16-year fracture risk in adult women: findings from the Study of Women's Health Across the Nation (SWAN)

Our objective was to examine the associations of lifetime parity and accumulated length of lactation with bone strength in women prior to the menopause transition and fracture risk during and after the transition. Participants were 2239 pre- or early peri-menopausal women from the Study of Women's Health Across the Nation (SWAN), ages 42-53 years at baseline, who had no childbirths after age 42. Bone mineral density (BMD) was measured in the femoral neck and the lumbar spine at the baseline SWAN visit using dual-energy x-ray absorptiometry, and the composite indices of femoral neck strength relative to load (in three failure modes: compression, bending, and impact) were calculated from femoral neck BMD, femoral neck size, and body size. Data on fractures after age 42 were collected for a median follow-up of 15.7 years (interquartile range, 11.4-18.5 years). In multiple linear regressions adjusted for covariates, lifetime parity was associated positively with femoral neck strength relative to load (0.024 standard deviation (SD) increment in impact strength index per childbirth, p=0.049), but accumulated length of lactation was associated negatively with lumbar spine BMD (0.018 SD decrement per every additional 6 months of lactation, p=0.040). In Cox proportional hazards regressions adjusted for covariates, neither parity nor lactation was associated with fracture hazard after age 42. In conclusion, parity and lactation have little impact on peak bone strength prior to menopause, and do not affect fracture risk after age 42 over 16-year follow-up.

Duration of breastfeeding as a risk factor for vertebral fractures

PURPOSE

Among the risk factors for osteoporosis and fractures, gynecological history (fertile period, parity and breastfeeding) play an important part. Changes in calcium metabolism to enable an adequate mineral transfer to the milk have a prominent role in bone loss during breastfeeding. Data on the influence of breastfeeding in postmenopausal osteoporosis are inconsistent. The aim of the present study was to identify any association between duration of breastfeeding and vertebral fractures in postmenopausal women.

METHODS

All patients underwent the following tests: bone mineral density measurements of the lumbar spine (L1-L4) and the total and femoral neck using dual-energy X-ray absorptiometry and antero-posterior and lateral radiography of the thoracic and lumbar spine to identify vertebral fractures.

RESULTS

The study involved 752 women with a mean age of 64.5±9.3; 23% of them reported vertebral osteoporotic fractures. The women with vertebral fractures had breastfed for longer periods (11.8±12.9 vs. 9.3±11.2months, p=0.03) and had more pregnancies (2.6±2.2 vs. 2.2±1.3, p=0.002). Breastfeeding for more than 18months was associated with a two-fold risk of developing vertebral fractures (OR 2.12, 95% CI 1.14-5.38, p=0.04), particularly in those without current or past use of drugs positively affecting bone.

CONCLUSIONS

Our study showed an association between long periods of breastfeeding and vertebral fractures, supporting a role for lengthy lactation as a risk factor for osteoporotic fractures after menopause. Bearing in mind all the benefits of breastfeeding, this finding suggests the importance of an adequate calcium and vitamin D intake during pregnancy and breastfeeding, with the aid of dietary supplements if necessary.

Steroidal contraceptives and bone fractures in women: evidence from observational studies

BACKGROUND

Age-related decline in bone mass increases the risk of skeletal fractures, especially those of the hip, spine, and wrist. Steroidal contraceptives have been associated with changes in bone mineral density in women. Whether such changes affect the risk of fractures later in life is unclear. Hormonal contraceptives are among the most effective and most widely-used contraceptives. Concern about fractures may limit the use of these effective contraceptives. Observational studies can collect data on premenopausal contraceptive use as well as fracture incidence later in life.

OBJECTIVES

We systematically reviewed the evidence from observational studies of hormonal contraceptive use for contraception and the risk of fracture in women.

SEARCH METHODS

In May 2012, we searched for observational studies. The databases included MEDLINE, POPLINE, Cochrane Central Register of Controlled Trials (CENTRAL), LILACS, EMBASE, CINAHL, and Web of Science. We also searched for recent clinical trials through ClinicalTrials.gov and the ICTRP. For other studies, we examined reference lists of relevant articles and wrote to investigators for additional reports.

SELECTION CRITERIA

We included cohort and case-control studies of hormonal contraceptive use. Interventions included comparisons of a hormonal contraceptive with a nonhormonal contraceptive, no contraceptive, or another hormonal contraceptive. The primary outcome was the risk of fracture.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data. One author entered the data into RevMan, and a second author verified accuracy. We examined the quality of evidence using the Newcastle-Ottawa Quality Assessment Scale (NOS), developed for case-control and cohort studies. Sensitivity analysis included studies of moderate or high quality based on our assessment with the NOS.Given the need to control for confounding factors in observational studies, we used adjusted estimates from the models as reported by the authors. Where we did not have adjusted analyses, we calculated the odds ratio (OR) with 95% confidence interval (CI). Due to varied study designs, we did not conduct meta-analysis.

MAIN RESULTS

We included 14 studies (7 case-control and 7 cohort studies). These examined oral contraceptives (OCs) (N=12), depot medroxyprogesterone acetate (DMPA) (N=4), and the hormonal intrauterine device (IUD) (N=1). This section focuses on evidence from the six studies with moderate or high quality evidence that we included in the sensitivity analysis.All six studies examined oral contraceptive use. We noted few associations with fracture risk. One cohort study found OC ever-users had increased risk for all fractures (reported RR 1.20; 95% CI 1.08 to 1.34). However, a case-control study with later data from a subset reported no association except for those with 10 years or more since use (reported OR 1.55; 95% CI 1.03 to 2.33). Another case-control study reported increased risk only for those who had 10 or more prescriptions (reported OR 1.09; 95% CI 1.03 to 1.16). A cohort study of postmenopausal women found no increased fracture risk for OC use after excluding women with prior fracture. Two other studies found little evidence of association between OC use and fracture risk. A cohort study noted increased risk for subgroups, such as those with longer use or specific intervals since use. A case-control study reported increased risk for any fracture only among young women with less than average use.Two case-control studies in the sensitivity analysis also examined progestin-only contraceptives. One reported increased fracture risk for DMPA ever-use (reported OR 1.44 (95% CI 1.01 to 2.06), more than four years of use (reported OR 2.16; 95% CI 1.32 to 3.53), and women over 50 years old. The other noted increased risk for any past use, including one or two prescriptions (reported OR 1.17; 95% CI 1.07 to 1.29), and for current use of 3 to 9 or 10 or more prescriptions. In addition, one study reported reduced fracture risk for ever-use of the hormonal IUD (reported OR 0.75; 95% CI 0.64 to 0.87) and longer use of that IUD.

AUTHORS' CONCLUSIONS

Observational studies do not indicate an overall association between OC use and fracture risk. Some reported increased risk for specific user subgroups. DMPA users may have an increased fracture risk. One study indicated hormonal IUD use may be associated with decreased risk. Observational studies need adjusted analysis because the comparison groups usually differ. Researchers should be clear about the variables examined in multivariate analysis.

Hip geometry variation is associated with bone mineralization pathway gene variants: The Framingham Study

Mineralization of bone matrix is an important process in bone formation; thus defects in mineralization have been implicated in bone mineral density (BMD) and bone structure alterations. Three central regulators of phosphate balance, ALPL, ANKH, and ENPP1, are central in the matrix mineralization process; therefore, the genes encoding them are considered important candidates genes for BMD and bone geometry. To test for an association between these three candidate genes and BMD and bone geometry traits, 124 informative singlenucleotide polymorphisms (SNPs) were selected and genotyped in 1513 unrelated subjects from the Framingham offspring cohort. Initial results showed that SNP rs1974201 in the gene ENPP1 was a susceptibility variant associated with several hip geometric indices, with the strongest p value of 3.8 × 10(7) being observed for femoral neck width. A few modest associations were observed between SNPs in or near ALPL and several bone traits, but no association was observed with ANKH. The association signals observed for SNPs around rs1974201 were attenuated after conditional analysis on rs1974201. Transcription factor binding-site prediction revealed that the HOXA7 binding site was present in the reference sequence with the major allele, whereas this potential binding site is lost in the sequence with the minor allele of rs1974201. In conclusion, we found evidence for association of bone geometry variation with an SNP in ENPP1, a gene in the mineralization pathway. The alteration of a binding site of the deregulator of extracellular matrix HOXA7 warrants further investigation.

The effects of hormonal contraceptives on bone turnover markers and bone health

Sex hormones are important regulators of bone metabolism. As hormonal contraceptives contain either oestrogens or progestins, or a combination thereof, it is conceivable that these widely used agents have an effect on bone metabolism and bone health. The main users of hormonal contraceptives, adolescent girls and young women, are still building bone and accruing bone mass and may therefore be particularly susceptible to the effects of hormonal contraceptives on bone. Despite these concerns, the effects of hormonal contraceptives on bone health are still poorly understood. As biochemical markers of bone turnover have been proven useful tools in the assessment and monitoring of bone metabolism, we reviewed the effects of combined and gestagen-only hormonal contraceptives on bone turnover markers and related effects on bone mineral density and fracture risk in premenopausal women, as documented in the literature until January 2009.

The use of depot-medroxyprogesterone acetate in contraception and its potential impact on skeletal health

BACKGROUND

In the fall of 2007, the controversy about the contraceptive use of depot-medroxyprogesterone acetate (DMPA) and its potential impact on skeletal health reached the media in the province of Quebec, Canada, thereby becoming a matter of concern for the lay public and physicians. In order to discuss this subject openly, the National Institute of Public Health of Quebec (INSPQ) organized a scientific meeting on February 15, 2008, with targeted physicians delegated by their medical associations in the fields of general practice, obstetrics and gynaecology, rheumatology, orthopaedic surgery, physiatry and endocrinology.

STUDY DESIGN

Participants reviewed the scientific literature using the study classification method according to the level of evidence, reviewed published guidelines of medical societies and organizations on the subject and reached a consensus position. This manuscript presents a review of the literature and describes the consensus position of the targeted medical associations.

RESULTS

The consensus position adopted by all the targeted medical associations determined that DMPA was a cost-effective contraceptive option that must be considered in the light of the clinical situation and preference of each woman. Candidates for injectable contraception should be informed that the use of DMPA is associated with a slight decrease in bone mineral density (BMD), which is largely, if not completely, reversible. There should not be an absolute limit to the length of time that the DMPA contraceptive is used, regardless of the woman's age. Monitoring BMD is not recommended among users of DMPA for contraceptive purposes. Finally, the consensus statement declared that, although supplements of calcium and vitamin D are beneficial for skeletal health for women in general, such supplementation should not be recommended solely based on a woman's use of DMPA.

CONCLUSION

Given the scientific evidences, DMPA use remains a valid contraceptive option for women. Its potential impact on BMD must be balanced against the significant individual, familial and social consequences of unintended pregnancy.

Influence of parity on bone mineral density and peripheral fracture risk in Moroccan postmenopausal women

The aims of the study were to determine: (1) the relationship between parity and bone mineral density (BMD); (2) the relationship between parity and osteoporotic peripheral fractures.

MATERIAL AND METHODS

The group studied included 730 postmenopausal women. Patients were separated into four groups according to the number of fullterm pregnancies, group 1: nulliparae, group 2: one to three pregnancies, group 3: four to five pregnancies, and group 4: six and more pregnancies. Additionally, patients were separated into three groups according to their ages, as <50 years, 50-59 years and >or=60 years.

RESULTS

The median parity was 4 [0-20]. All the patients with parity greater than six had spine and hip BMD values significantly lower than values in the other groups (p<0.001). After adjustment for age and body mass index (BMI), decreased lumbar and total hip BMD were still associated to increased parity (analysis of covariance (ANCOVA), p=0.04 and 0.023, respectively). The relation between parity and lumbar BMD was highly significant among women aged <50 years (age-adjusted p=0.022), while there was no parity-spine BMD association in the other age groups. The relation between parity and hip BMD was seen only in the group 50-59 years (age-adjusted p=0.042). A positive history for peripheral fractures was present in 170 (23%) patients. There was relationship between parity and peripheral fractures neither in the whole population nor in the sub-groups according to age.

DISCUSSION

The present study suggests that the BMD of the spine and hip decreases with an increasing number of pregnancies, and this situation shows variations in different age groups. However, there was no correlation between parity level and peripheral fractures.

Cortical bone remodeling rates in a sample of African American and European American descent groups from the American Midwest: comparisons of age and sex in ribs

This study employs regression analysis to explore population and sex differences in the pattern of age-associated bone loss, as reflected by histomorphometric variables that are measures of intracortical and endocortical bone remodeling. A comparison of an African American sample from the Washington Park Cemetery in St. Louis, Missouri, and a European American rib sample composed of cadavers, autopsies, and forensic cases from Missouri reveals the existence of complex age-associated patterns for differences in measures of intracortical remodeling and cortical area. Females from the two samples express similar bone dimensions and dynamics. The African American females appear to lose more bone than their male counterparts, but this difference is absent in the European American sample. When age-associated patterns are considered, it is in the younger cohorts that African Americans exhibit greater relative cortical area than European Americans, but this is reversed in the older ages, when the latter group manifests greater bone mass. The European American males consistently differ in the slopes and intercepts for the variables compared to the other groups, and differences are highly significant with African American females, with the former group maintaining bone mass while the latter exhibit a more rapid bone loss. Achieving larger relative cortical area due to smaller endosteal area, coupled with better bone quality due to lower intracortical porosity early in life, may be a mechanism by which African Americans, especially females, maintain adequate bone mass in older ages, which buffers them from bone loss and related fragility fractures despite higher rates of intracortical remodeling and endosteal expansion later in life. These results suggest that both genetic and environmental factors are responsible for the differences in bone remodeling and bone mass observed between these samples.

Combined hormonal contraception and bone health: a systematic review

This systematic review examined whether women who use combined hormonal contraception experience changes in risk of fracture or bone mineral density (BMD) that differ from nonusers. We identified 86 articles from PubMed and EMBASE (published 1966 to August 2005) that reported on fracture or BMD outcomes by use of combined hormonal contraceptives. The evidence relating to combined oral contraceptives (COCs) and fracture is inconclusive, as results from the available studies conflict. Studies of adolescent and young adult women generally found lower BMD among COC users than nonusers. Evidence for premenopausal adult women suggested no differences in BMD between COC users and nonusers. COC use in perimenopausal and postmenopausal women preserved bone mass, while nonusers lost BMD, but BMD among former COC users in this age group was the same as for never-users. Evidence for other combined hormonal methods was very limited, with one study indicating no effect of combined hormonal injectable use among premenopausal women on BMD and one study suggesting lower BMD among premenopausal users of the NuvaRing than in nonusers.

Determinants of incidence of osteoporotic fractures in the female Spanish population older than 50

It is well known that the adoption of preventive measures for osteoporosis may contribute to minimizing its impact as a result of bone fractures. However, there are well-recognized risk factors involved in the onset of osteoporosis that are not possible to modify. Better knowledge of these non-modifiable factors could aid prevention in subjects at high risk of fractures. The aim of this study was to evaluate the likely association between gynecological, reproductive and family history of hip fracture with the incidence of vertebral and nonvertebral osteoporotic fractures in women older than 50. We studied 255 women aged 50 and over, randomly selected from a Spanish population that had participated in a study of prevalence of vertebral fractures (EVOS study). This cohort was prospectively followed for 8 years by means of four postal questionnaires, in order to find out the incidence of nonvertebral fractures. Concerning the incidence of vertebral fractures, participants were invited to repeat the lumbar spine X-rays 4 years after the initial study. A total of 31 women had incident osteoporotic fractures. The analysis of gynecological variables showed that an increase in the age at menarche was a risk factor for all incident osteoporotic fractures [OR=1.57 (1.04-2.37)]. The presence of amenorrhea at any age during the fertile period was associated with higher incidence of all osteoporotic fractures [OR=6.30 (1.61-24.70)]. Among all the reproductive variables analyzed (pregnancy, number of live births and breast-feeding) only pregnancy was an important protective factor in preventing incident Colles fracture [OR=0.15 (0.03-0.62)]. A family history of hip fracture was associated with a higher incidence of all osteoporotic fractures [OR=3.59 (1.01-12.79)]. In summary, a late age at menarche, the presence of amenorrhea and having close relatives with hip fracture were all risk factors which, independently of bone mineral density (BMD) and age, were associated with higher incidence of all osteoporotic fractures. Pregnancy was an important protective factor for the incidence of Colles fractures.

Menstrual and Reproductive Factors and Fracture Risk: The Leisure World Cohort Study

BACKGROUND

Because menopausal estrogen is related to the development of osteoporosis, we investigated the potential associations of the estrogen-related events of menarche, pregnancy, and menopause with fracture risk in a population-based, prospective study of older women.

METHODS

The Leisure World Cohort was established in the early 1980s when residents of a California retirement community, including 8877 women, completed a health survey. Incident fractures of the hip (n = 1220), wrist (n = 463), and spine (n = 613) incurred over two decades were identified from four follow-up questionnaires, hospital discharge records, and (for hip fracture) death certificates. Hazard ratios (HR) adjusted for age and other potential confounders were calculated using proportional hazards regression.

RESULTS

Late age at menarche was associated with decreased hip fracture risk (HR = 0.84, 95% CI 0.72-0.98, for age > or = 14 vs. < or = 12 years) but was unrelated to fractures at other sites. Hip fracture risk was also reduced in women who had been pregnant (HR = 0.83, 95% CI 0.72- 0.95). Women who reported menopause at age 45+ had a lower risk of wrist fracture compared with those with menopause at age < or = 44 (HR = 0.74, 95% CI 0.58-0.95 for ages 45-54; HR = 0.71, 95% CI 0.49-1.04 for ages 55+). Although fracture risks did not differ between ever and never users of menopausal estrogen, recency since last use was related to wrist fractures (HR = 1.09, 95% CI 1.03-1.16 for each 5 years since last years).

CONCLUSIONS

The estrogen-related events of menarche, pregnancy, and menopause were not associated with osteoporotic fracture risk in a consistent manner. Other factors related to these events may be influencing development of osteoporosis and the likelihood of sustaining a fracture in older women.

Effects of oral contraceptives on bone mineral density

Osteoporosis is a major health problem that leads to a high incidence of spine, radial, and hip fractures. It is now well recognized that a chronically hypoestrogenic state increases bone turnover that, in turn, causes a critical decrease in bone mineral density (BMD), an important determinant of fracture risk. During the premenopausal period, hypogonadism can have deleterious effects on skeletal health by reducing peak bone mass or inducing precocious bone loss. In young women, hypothalamic amenorrhea, caused by gonadotropin-releasing hormone pulsatility dysregulation, is often associated with bone loss. Although the relationship between hypothalamic amenorrhea and bone density is not completely understood, the most plausible intervention for this disorder at the moment seems to be the use of hormone replacement. Oral contraceptives are associated with an improvement in BMD if assumed upon the onset of anovulatory cycles and, therefore, estrogen deficiency, but confer no benefit in healthy women with normal ovarian function. In perimenopausal oligomenorrheic women, the use of oral contraceptives seems to have bone-sparing effects. In conclusion, the protective role of oral contraceptives on bone density is biologically plausible, since this treatment represents a replacement therapy with continuous exposure to exogenous estrogens.

Impact de la contraception estroprogestative et progestative sur la densité minérale osseuse

Oral contraceptives are used by numerous women very often throughout a prolonged period of time and more and more frequently early in life, within the first reproductive years. The close relationship between oestrogen metabolism and bone turnover raises the question of the potential bone impact of oral contraceptives containing low dose of ethinyl-oestradiol and especially in adolescent girls. During adulthood, most studies have reported that oral contraceptive pills, even those containing a low dose of ethinyl-oestradiol (20 mug), had neutral, or possibly beneficial, effect on bone health. Use of oral contraceptives within the perimenopausal years also would allow to preventing bone loss, given that all vascular and metabolic contra-indications are respected. However, the skeletal effects of oral contraceptives are a greater concern for adolescent girls. Some data suggest that the use of 20 mug pills may impede the development of peak bone mass, particularly when started within the teen years. The bone impact of other hormonal contraceptive methods appears correlated with the degree of suppression of oestrogen levels. There is no effect of low dose progestagen-only pills or progestagen implants on bone health. On the other hand, administration of depot medroxyprogesterone acetate is associated with significant bone loss at all skeletal sites. However, the loss of bone mass might be reversed after discontinuation of use, especially in younger women. The bone impact of progestin only pills that have a strong antigonadotrophinic activity is not currently evaluated although there is some concern about increased bone loss in case of oestrogen deficiency period of long duration.

Maternity and bone mineral density

During pregnancy and lactation, changes occur in a variety of factors which have great potential to influence bone mineral density (BMD). Smoking habits, the level of alcohol consumption, the level of physical activity, body weight, soft tissue composition and hormone levels are all factors that change during the course of these conditions. Some of these factors are capable of increasing BMD, and some can reduce it. Due to these various changes, it is virtually impossible to predict the development in BMD that will occur during a pregnancy and lactation. However, longitudinal studies have suggested that both pregnancy and lactation are associated with a BMD loss of up to 5%, albeit that the BMD recovers after weaning. Cross-sectional studies have indicated that women with many children and a long total period of lactation have similar or higher BMD and similar or lower fracture risk than their peers who have not given birth. As the studies showing this trend have been observational and cross sectional case-control studies, the conclusions can only be regarded as being suggestive, and no causality can be proven.

Associations between baseline risk factors and vertebral fracture risk in the Multiple Outcomes of Raloxifene Evaluation (MORE) Study

Different risk factors may influence the effectiveness of osteoporosis therapies. The interaction of 30 baseline risk factors and the effectiveness of raloxifene in the MORE study were assessed. The efficacy of raloxifene in reducing vertebral fractures is largely independent of the presence of clinical risk factors for osteoporotic fractures.

INTRODUCTION

The aim of this analysis was to determine the effect of different risk factors on the effectiveness of raloxifene to reduce vertebral fractures in the Multiple Outcomes of Raloxifene Evaluation (MORE) study using logistic regression models.

MATERIALS AND METHODS

The association was assessed using univariate analyses and a multivariate model between 30 potential risk factors at baseline and the risk of vertebral fractures after 3 years in the placebo group, as well as the interaction of risk factors with raloxifene therapy (at a dose of 60 or 120 mg/day).

RESULTS AND CONCLUSIONS

In the univariate analysis of the placebo group, after adjusting for baseline lumbar spine BMD (LS BMD), short stature (odds ratio [OR] = 1.18), age (OR = 1.38), years since menopause (OR = 1.38), impaired cognitive function, visuospatial capabilities (OR = 1.19), impaired musculoskeletal strength (OR = 1.23), low femoral neck BMD (OR = 1.21), and prior vertebral fracture (OR = 4.95) were significantly associated with the incidence of new vertebral fractures. In the univariate analysis, significant interactions were observed between raloxifene treatment and age (p = 0.04), serum triglycerides (p = 0.03), LS BMD (p = 0.08), and diabetes mellitus (p = 0.04). In the multivariate analysis, the effectiveness of raloxifene was independent of almost all risk factors, with the exception of baseline serum triglyceride level and LS BMD, suggesting an increased efficacy of raloxifene in patients with increased triglyceride levels (p = 0.006) and lower LS BMD values (p = 0.008) at baseline. These data suggest that the efficacy of raloxifene in reducing vertebral fractures is largely independent of the presence of clinical risk factors for osteoporotic fractures.

Determinants of the size of incident vertebral deformities in European men and women in the sixth to ninth decades of age: the European Prospective Osteoporosis Study (EPOS)

More severe vertebral fractures have more personal impact. In the European Prospective Osteoporosis Study, more severe vertebral collapse was predictable from prior fracture characteristics. Subjects with bi-concave or crush fractures at baseline had a 2-fold increase in incident fracture size and thus increased risk of a disabling future fracture.

INTRODUCTION

According to Euler's buckling theory, loss of horizontal trabeculae in vertebrae increases the risk of fracture and suggests that the extent of vertebral collapse will be increased in proportion. We tested the hypothesis that the characteristics of a baseline deformity would influence the size of a subsequent deformity.

METHODS

In 207 subjects participating in the European Prospective Osteoporosis Study who suffered an incident spine fracture in a previously normal vertebra, we estimated loss of volume (fracture size) from plane film images of all vertebral bodies that were classified as having a new fracture. The sum of the three vertebral heights (anterior, mid-body, and posterior) obtained at follow-up was subtracted from the sum of the same measures at baseline. Each of the summed height loss for vertebrae with a McCloskey-Kanis deformity on the second film was expressed as a percentage.

RESULTS AND CONCLUSIONS

In univariate models, the numbers of baseline deformities and the clinical category of the most severe baseline deformity were each significantly associated with the size of the most severe incident fracture and with the cumulated sum of all vertebral height losses. In multivariate modeling, age and the clinical category of the baseline deformity (crush > bi-concave > uni-concave > wedge) were the strongest determinants of both more severe and cumulative height loss. Baseline biconcave and crush fractures were associated at follow-up with new fractures that were approximately twice as large as those seen with other types of deformity or who previously had undeformed spines. In conclusion, the characteristics of a baseline vertebral deformity determines statistically the magnitude of vertebral body volume lost when a subsequent fracture occurs. Because severity of fracture and number of fractures are determinants of impact, the results should improve prediction of the future personal impact of osteoporosis once a baseline prevalent deformity has been identified.

Effect of parity on bone mineral density in female rhesus macaques from Cayo Santiago

This cross-sectional study investigates the relationship between parity, bone mineral density, and spontaneous osteopenia/osteoporosis in a large skeletal population of female rhesus macaques (Macaca mulatta) from the free-ranging colony of Cayo Santiago, Puerto Rico. The sample consists of 119 mature female monkeys aged 4.0-22.2 years at time of death. The data consist of measurements of bone mineral content (BMC) and bone mineral density (BMD), obtained from dual-energy X-ray absorptiometry (DEXA) of the last lumbar vertebra. After controlling for age, there is a significant increase in BMD of the spine with increasing parity (P = 0.0006), up to a parity of 7 offspring. Thus, high parity initially has a positive effect on BMD in female rhesus monkeys, but this positive effect disappears with parities that are greater than 7 offspring. After controlling for parity, however, age has a negative (P = 0.015) effect on BMD, beginning several years after the attainment of peak BMD (age 9.5 years). Thus, it appears that parity initially mitigates the effects of aging, but the positive effect of parity on BMD is eventually overwhelmed by the aging process. Mean BMC and BMD values are higher in parous females compared to nulliparous females in the same age range. Similarly, females with low parity have significantly lower mean BMD values than do age-matched high-parity controls, and the frequency of osteopenia and osteoporosis is greater in low-parity females. Forty-three percent (43%) of the osteopenic/osteoporotic females in the sample are members of the low-parity group, even though it composes only 13% (16/119) of the entire sample. This study demonstrates that the free-ranging female rhesus monkeys from Cayo Santiago are a good nonhuman primate model for the study of bone mineral density, parity, osteopenia, and osteoporosis.

Risk factors for Colles' fracture in men and women: results from the European Prospective Osteoporosis Study

The aim of this study was to determine the contribution of constitutional and lifestyle variables on the subsequent risk of distal forearm (Colles') fracture in a multinational, multicenter, population-prospective study. A total of 15,745 subjects from the European Vertebral Osteoporosis Study, who had completed a baseline questionnaire on lifestyle and constitutional factors, were followed up annually using a validated questionnaire to ascertain the occurrence of new fractures. Risks are expressed as hazard ratios (with 95% confidence intervals) derived from a Cox proportional hazards regression model. The incidence of Colles' fracture was 1.7 and 7.3 per 1000 person years in men and women, respectively. In women delayed menarche, over the age of 15 years, was associated with a modest increased risk [HR 1.5 (range 1.1-2.0)]. Regular walking in that group also increased the risk [HR 1.6 (1.2-2.2)] perhaps reflecting the increased exposure to risk of falling. None of the other factors examined revealed any important influences. The results are broadly in line with the few other published prospective studies suggesting only a modest role for these factors in influencing susceptibility to fracture.

Epidemiology of osteoporosis

Osteoporosis is a major public health problem through its association with fracture. The problem may be alleviated substantially by appropriate early intervention before fracture occurs. This chapter discusses the epidemiology of osteoporosis and addresses the following questions: How should osteoporosis be defined? What is the incidence and prevalence of osteoporosis and fracture? Is there geographical variation in the occurrence of osteoporosis? What are the risk factors for osteoporosis and do they explain the occurrence of osteoporosis and osteoporotic fracture?

Is the predictive power of previous fractures for new spine and non-spine fractures associated with biochemical evidence of altered bone remodelling? The EPOS study. European Prospective Osteoporosis Study

BACKGROUND

In the European Prospective Osteoporosis Study (EPOS), a past spine fracture increased risk of an incident fracture 3.6 - 12-fold even after adjusting for BMD. We examined the possibility that biochemical marker levels were associated with this unexplained BMD-independent element of fracture risk.

METHODS

Each of 182 cases in EPOS of spine or non-spine fracture that occurred in 3.8 years of follow-up was matched by age, sex and study centre with two randomly assigned never-fractured controls and one case of past fracture. Analytes measured blind were: osteocalcin, bone-specific alkaline phosphatase, total alkaline phosphatase, serum creatinine, calcium, phosphate and albumin, together with the collagen cross-links degradation products serum CTS and urine CTX. Most subjects also had bone density measured by DXA.

RESULTS

Cases who had recent fractures did not differ in marker levels from cases who had their last fracture more than 3 years previously. No statistically significant effect of recent fracture was found for any marker except osteocalcin, which was 17.6% lower in recent peripheral cases compared to unfractured controls (p<0.05) and this was independent of BMD.

CONCLUSION

Past fracture as a risk indicator for future fracture is not strongly mediated through increased bone turnover.

Epidemiology and outcomes of osteoporotic fractures

Bone mass declines and the risk of fractures increases as people age, especially as women pass through the menopause. Hip fractures, the most serious outcome of osteoporosis, are becoming more frequent than before because the world's population is ageing and because the frequency of hip fractures is increasing by 1-3% per year in most areas of the world. Rates of hip fracture vary more widely from region to region than does the prevalence of vertebral fractures. Low bone density and previous fractures are risk factors for almost all types of fracture, but each type of fracture also has its own unique risk factors. Prevention of fractures with drugs could potentially be as expensive as medical treatment of fractures. Therefore, epidemiological research should be done and used to identify individuals at high-risk of disabling fractures, thereby allowing careful allocation of expensive treatments to individuals most in need.

Calcium in pregnancy and lactation

Pregnancy and lactation are periods of high calcium requirement. This review highlights recent advances in our understanding of calcium and bone metabolism during human pregnancy and lactation and discusses the findings in relation to the calcium nutrition of the mother. The evidence indicates that pregnancy and lactation are characterized by physiological adaptive processes that are independent of maternal calcium intake and that provide the calcium necessary for fetal growth and breast-milk production without requiring an increase in maternal calcium intake. There are firm data that demonstrate that a low calcium intake during lactation does not lead to impaired lactational performance or to exaggerated bone loss. However, more research is required to define whether a low calcium intake prior to or during pregnancy can have deleterious effects on reproductive and lactational performance, and on the long-term health of the mother and child.

Bone turnover markers and estradiol level in postmenopausal women

It has been found recently that women with estradiol (E) levels < 5 pg/ml were more likely to suffer osteoporotic fractures. We evaluated the relationships between biomarkers of bone turnover and changes in hormone levels in early or late postmenopausal women without any replacement therapy. Follicle stimulating hormone (FSH), luteinizing hormones (LH), estradiol and serum resorption (crosslaps) and formation (osteocalcin) markers were assayed. Bone densities in the spine and femoral neck were also measured. Elevated FSH, LH and decreased estradiol in postmenopausal women were accompanied by higher osteocalcin (9.1-9.7 ng/ml) and crosslaps level (3305-3458 pmol/l) compared to premenopausal women (6.8 ng/ml and 2087 pmol/l). Bone density was lower in elderly women. A significant inverse correlation was found between estradiol and crosslaps level; FSH and LH were also correlated with bone markers. Estradiol levels < 9 pg/ml were associated with increased bone resorption, decreased hip bone density and higher frequency of osteopenia and osteoporosis. Over 57% of women with an estradiol < 9 pg/ml could be identified as having "a high turnover" compared with 30% with estradiol above 9 pg/ml. Our results indicate that changes in bone density may not be very clear but an increase in bone turnover is distinctly apparent in women with severe estradiol deficiency.

The role of bone turnover markers and risk factors in the assessment of osteoporosis and fracture risk

The clinical evaluation of osteoporosis in individual patients involves confirmation of the diagnosis, the investigation of secondary causes of osteoporosis and the evaluation of subsequent fracture risk. Optimum clinical assessment involves bone mineral densitometry with the treatment thresholds modified by clinical risk factors for individual patients. Bone turnover markers and clinical risk factors can be used to identify patients at risk of osteoporotic fracture and those who have secondary osteoporosis. Risk assessment should involve the evaluation of absolute rather than relative risk. Further work is required to improve the integration of clinical risk factors, bone turnover markers and bone densitometry into appropriate models to enable the assessment of the absolute risk of fracture for individual patients.

Reproductive history in relation to plasma hormone levels in healthy post-menopausal women

OBJECTIVES

We sought to examine the relationship between reproductive history and measures of selected gonadotrophins and steroid hormones among post-menopausal women. Previous studies have suggested that there is a negative correlation between parity and post-menopausal serum estrogens, which may be a mechanism by which pregnancies protect women from the development of breast cancer.

METHODS

We analyzed women who experienced a natural menopause within the Healthy Women Study cohort both 1 and 8 years after menopause. Lifetime reproductive history was obtained and blood was assayed for estrone, estradiol, androstenedione, testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) at 1 year post-menopause and for many of these steroid hormones at 8 years post-menopause. Also at 8 years post-menopause, a hip bone mineral density measure was obtained.

RESULTS

Age at menopause related to a modest increase in estrone at 1 year but a decrease in estrone and estradiol at eight years. Adjustment for body mass index (BMI), oral contraceptive use, alcohol use, cigarette smoking, and education had little impact on these findings. There were no other internally consistent relationships between reproductive variables and steroid hormones or hip-bone mineral density.

CONCLUSIONS

These observations do not support the hypothesis that parity acts to diminish endogenous levels of post-menopausal estrogens.

Risk factors for vertebral deformities in men: relationship to number of vertebral deformities. European Vertebral Osteoporosis Study Group

Recent epidemiological studies suggest a similar overall prevalence of vertebral deformity in men to that in women, though the influence of increasing age on the prevalence of vertebral deformity is less marked in men. However, most affected men have only a single or two vertebral deformities, which may be unrelated to osteoporosis. The aim of this study was to examine the role of risk factors, previously demonstrated to be associated with vertebral osteoporosis in females, in men with single/dual deformities compared to those with multiple deformities. Age stratified random samples of men aged 50 years and over were recruited from population registers in 30 European centers as part of the European Vertebral Osteoporosis Study (EVOS). Subjects had a lateral spinal radiograph and the presence of vertebral deformity was determined using the McCloskey algorithm. Lifestyle and other risk factor data were obtained from an interviewer-administered questionnaire. In all 6937 men with a mean age of 64.4 (SD = 8.5) years were studied of whom 738 (10.6%) subjects had one or two deformities, and 109 (1.6%) subjects had three or more deformities. There was a marked increase in the prevalence of multiple vertebral deformities with increasing age, but only a modest effect of age on the prevalence of single deformities. Associations between various risk factors for osteoporosis and vertebral deformity were analyzed separately in men with single/dual vertebral deformity from those with three or more deformities using logistic regression. After adjustment for age, there were statistically significant associations between the following risk factors and multiple deformities: previous hip fracture (odds ratio [OR] 10.5), lack of regular physical activity (OR 2.9), low body mass (OR 2.5), and previous steroid use (OR 2.3). By contrast, there were only weak associations with these same variables in males with single/dual deformities and, apart from poor self-reported general health, all of the 95% confidence intervals spanned unity. There was no difference in the reporting of very heavy levels of physical activity under the age of 50 years between men with single/dual deformities and those with multiple deformities. In conclusion, men with multiple deformities showed a similar pattern of risk factor association to those seen in women with vertebral deformity, in contrast to men with single/dual deformities.

Oral-contraceptive use and risk of hip fracture: a case-control study

BACKGROUND

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.

METHOD

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.

Secondary osteoporosis and the risk of vertebral deformities in women

Among an age-stratified sample of 942 Rochester, MN women, the overall prevalence of any vertebral deformity, as assessed by radiographic morphometry, was 21.3 per 100. The prevalence increased with age and, after adjusting for age, vertebral deformities were independently associated with height, weight, a history of distal forearm or hip fractures, and anticoagulant use. Altogether, 73% of the women with a vertebral deformity and 66% of controls had one or more of the conditions that have been linked with secondary osteoporosis, which in aggregate were associated with an age-adjusted 1.2-fold (95% CI 0.8-1.7) increase in risk that was not statistically significant. The prevalence of severe vertebral deformities was 11.7 per 100 women and the prevalence of very severe deformities was 5.7 per 100. There was a stronger relationship of age and most other risk factors with severe vertebral deformities than with isolated mild deformities, suggesting that a subset of mild deformities may not represent actual vertebral fractures. The metabolic disorders linked with secondary osteoporosis were associated with little increase in the risk of severe vertebral deformities, taken together, or of mild deformities. However, in aggregate these conditions were associated with a 2.3-fold increase (95% 1.1-4.8) in very severe vertebral deformities, which points to a role for rapid cancellous bone loss among women with the worst spinal osteoporosis.

Epidemiology of spinal osteoporosis

Approximately 30% of postmenopausal white women in the United States have osteoporosis, and 16% have osteoporosis of the lumbar spine in particular. Bone density of the spine is positively associated with greater height and weight, older age at menopause, a history of arthritis, more physical activity, moderate use of alcoholic beverages, diuretic treatment, and current estrogen replacement therapy, whereas later age at menarche and a maternal history of fracture are associated with lower levels of density. Low bone density leads to an increased risk of osteoporotic fractures. Fracture risk also increase with age. Vertebral fractures affect approximately 25% of postmenopausal women, although the exact figure depends on the definition used. Recent data show that vertebral fracture rates are as great in men as in women but, because women live longer, the lifetime risk of a vertebral fracture from age 50 onward is 16% in white women and only 5% in white men. Fracture rates are less in most nonwhite populations, but vertebral fractures are as common in Asian women as in those of European heritage. Other risk factors for vertebral fractures are less clear but include hypogonadism and secondary osteoporosis; obesity is protective of fractures as it is of bone loss. Compared with hip fractures, vertebral fractures are less disabling and less expensive, costing approximately $746 million in the United States in 1995. However, they have a substantial negative impact on the patient's function and quality of life. The adverse effects of osteoporotic fractures are likely to increase in the future with the growing number of elderly people.