A prospective study of uric acid by glucose tolerance status and survival: the Rancho Bernardo Study

OBJECTIVES

Little is known about uric acid (UA) levels and mortality in the context of glycaemia. We examined whether serum UA levels predict all-cause and cardiovascular disease (CVD) mortality differentially in older adults by glucose tolerance status.

DESIGN AND METHODS

Between 1984 and 1987, 2342 community-dwelling men and women had an oral glucose tolerance test, UA measurement, and assessment of traditional CVD risk factors. We defined glucose tolerance status as normoglycaemia (NG), pre-diabetes (pre-DM), and type 2 diabetes mellitus (T2DM). Ninety per cent were followed for vital status up to 23 years. Death certificates were coded using the Ninth International Classification of Diseases.

RESULTS

Baseline age was 69.5 years; 44.4% were men. At baseline 939 had NG, 957 pre-DM, and 446 T2DM. The mean UA by glucose tolerance status was 327.1, 362.8, and 374.7 micromol L(-1). During follow-up, there were 1318 deaths 46.8% attributed to CVD. In Cox-regression analysis, each 119 micromol L(-1) (2 mg dL(-1)) increment in UA levels predicted an increased hazard ratio (HR) for all-cause deaths independent of age, smoking, body mass index, alcohol, physical activity, diuretic use and estimated glomerular filtration rate in all groups (NG: HR 1.25 95% CI 1.06-1.47, P =0.005; pre-DM: HR 1.20 95% CI 1.06-1.37, P = 0.04; T2DM: HR 1.20 95% CI 1.01-1.47, P = 0.04). After adjusting for CVD risk factors, the UA association with CVD mortality was significant only in the pre-DM and T2DM groups.

CONCLUSION

All-cause mortality was independently associated with UA in all groups, but UA predicted CVD mortality only in those with abnormal glucose tolerance.

Peripheral arterial disease and osteoporosis in older adults: the Rancho Bernardo Study

SUMMARY

We examined the association between peripheral arterial disease (PAD) and bone health in 1,332 adults. We found a weak association between PAD and osteoporosis and bone loss only in women, but the association was not independent of age. PAD was not associated with fractures in this community-based population.

INTRODUCTION

Increased rates of osteoporosis have been reported in patients with cardiovascular disease, suggesting a link between osteoporosis and atherosclerosis.

METHODS

We examined the association between PAD and bone health in 1,332 adults who attended a research visit in 1992-1996, when the ankle-brachial index (ABI), bone mineral density (BMD), and spine X-rays were obtained. A total of 837 participants attended a follow-up visit in 1997-2000.

RESULTS

PAD defined by an ABI < or = 0.90 was present in 15.4% of the women and 13.3% of the men. Prevalence of osteoporosis was significantly higher in women with PAD compared to women without PAD (p < 0.05). During an average 4-year follow-up, women with PAD had a significantly higher rate of bone loss than women without PAD (p = 0.05). The associations were no longer significant after age adjustment. In men, PAD was not associated with osteoporosis, but men with PAD had lower BMD at the femoral neck than men without PAD (p = 0.03). PAD was not associated with osteoporotic fractures in either sex.

CONCLUSION

We found a weak and age-dependent association between PAD and osteoporosis in women but not men. PAD was not associated with fractures in this community-based population.

Adipocytokines, sex hormones, and cardiovascular risk factors in postmenopausal women: factor analysis of the Rancho Bernardo study

Steroid sex hormones modulate the expression of adipocytokines implicated in the pathogenesis of athero-thrombotic cardiovascular disease. We used exploratory factor analysis to search for latent associations between circulating sex steroid hormones, adipocytokines, and cardiovascular risk factors in a well-characterized cohort of postmenopausal women. Among participants in the Rancho Bernardo community study we identified 515 Caucasian women with a mean age of 74+/-8 years and mean body mass index of 24.2+/-3.7 kg/m(2). All had intact ovaries and none was using estrogen therapy. We constructed models aiming for structural clarity and high loading of variables on individual factors. Total adiponectin loaded with major lipid subfractions (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and fasting triglycerides) and with sex hormone-binding globulin. Leptin loaded with central obesity (waist circumference) and fasting insulin levels. Neither adipocytokine loaded with total or bioavailable testosterone or with estradiol or dehydroepiandrosterone sulfate. Sex hormones consistently loaded together on a separate factor; this co-segregation was not influenced by body mass index. Exclusion of women with diabetes did not alter these observations. In conclusion, we identified evidence of latent associations between adipocytokines and a range of cardiovascular risk factors in postmenopausal women. Our results suggest that cardiovascular risk in older women may be modulated through a hitherto unrecognized association between adiponectin, lipid subfractions, and sex hormone bioavailability.

Sex-specific association of serum vitamin D levels with physical function in older adults

In women, but not men, lower 25-hydroxyvitamin D [25(OH)D] levels were associated with impaired performance on two lower extremity function tests in both cross-sectional and prospective analyses.

INTRODUCTION

Preserved physical function may explain how 25(OH)D supplementation reduces falls and fractures.

METHODS

A total of 1,065 community-dwelling men and women (mean age 74.6 years) with 25(OH)D levels and performance on timed up and go (TUG) and timed chair stand (TCS) were seen in 1997-1999; 769 (72%) participants returned for follow-up. Associations were examined using generalized linear models.

RESULTS

25(OH)D levels were higher in men than women, but the prevalence of vitamin D insufficiency defined as 25(OH)D <75 nmol/L was 14%. There were no baseline sex differences in TUG or TCS. However, after 2.5 years, decline in TCS and TUG was greater in women than men (11% vs. 3%; p < 0.001). Women in the lowest 25(OH)D quartile (<80 nmol/L) compared to the highest quartile had an accelerated rate of functional decline on the TUG and TCS independent of covariates. No significant associations were seen in men.

CONCLUSION

In women, but not men, lower 25(OH)D levels were associated with impaired performance on two lower extremity function tests in both cross-sectional and prospective analyses. These results provide additional evidence that 25(OH)D is associated with physical function, which may explain how vitamin D supplementation reduces falls and fractures.

Effect of dehydroepiandrosterone supplementation on bone mineral density, bone markers, and body composition in older adults: the DAWN trial

We present results of a randomized, placebo-controlled trial to examine the effect of 50 mg daily oral DHEA supplementation for one year on bone mineral density (BMD), bone metabolism and body composition in 225 healthy adults aged 55 to 85 years.

INTRODUCTION

Dehydroepiandrosterone (DHEA) levels decline dramatically with age, concurrent with the onset of osteoporosis, suggesting a role for DHEA supplementation in preventing age-related bone loss.

METHODS

We conducted a randomized, placebo-controlled trial to examine the effect of 50 mg daily oral DHEA supplementation for one year on bone mineral density (BMD), bone metabolism and body composition in 225 healthy adults aged 55 to 85 years.

RESULTS

DHEA treatment increased serum DHEA and DHEA sulfate levels to concentrations seen in young adults. Testosterone, estradiol and insulin-like growth factor (IGF-1) levels increased in women (all p < 0.001), but not men, receiving DHEA. Serum C-terminal telopeptide of type-1 collagen levels decreased in women (p = 0.03), but not men, whereas bone-specific alkaline phosphatase levels were not significantly altered in either sex. After 12 months, there was a positive effect of DHEA on lumbar spine BMD in women (p = 0.03), but no effect was observed for hip, femoral neck or total body BMD, and no significant changes were observed at any site among men. Body composition was not affected by DHEA treatment in either sex.

CONCLUSION

Among older healthy adults, daily administration of 50 mg of DHEA has a modest and selective beneficial effect on BMD and bone resorption in women, but provides no bone benefit for men.

Serum 25-hydroxyvitamin D, parathyroid hormone, and bone mineral density in men: the Rancho Bernardo study

INTRODUCTION

This study examined the distribution and determinants of serum 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) and their associations with bone mineral density (BMD) at the hip and spine in 414 older men (mean age 74 years) living in southern California.

METHODS

At a clinic visit (1997-2000), demographic and lifestyle information, fracture history, and medication use were recorded; venous blood for serum 25OHD and PTH was obtained; and BMD was measured at the hip and spine.

RESULTS

Only one man had vitamin D deficiency (25OHD <20 nmol/l), but 15.5% of the men had high parathyroid levels (PTH >or=65 pg/ml). The mean 25OHD and PTH levels were 109.0 nmol/l and 50.3 pg/ml, respectively. Overall, 21.5% used calcium and 9.7% used vitamin D supplements. Serum 25OHD decreased with age and was lowest in the winter; levels were higher in supplement users (vitamin D and/or calcium; p<0.01). Serum PTH did not vary by age or season, and it was lower in supplement users (p<0.01). After excluding 12 men who were outliers for serum 25OHD and PTH, there was no significant correlation between serum 25OHD and PTH (r=-0.05, p=0.3). In multiple adjusted models, serum 25OHD was positively associated with BMD at the hip (p=0.01) and spine (p=0.001). Serum PTH was moderately and inversely associated with BMD at the hip (p=0.04) but not at the spine (p=0.77).

CONCLUSION

We conclude that serum 25OHD is associated with bone health in older, community-dwelling men.

Low testosterone levels are associated with carotid atherosclerosis in men

OBJECTIVE

To study the relationship between endogenous sex hormone levels and intima-media thickness (IMT) of the carotid artery measured by ultrasonography.

DESIGN

Population-based cross-sectional study.

METHODS

Sex hormone levels measured by immunoassay, anthropometric measurements and IMT was studied in 1482 men aged 25-84 years participating in the 1994-1995 Tromsø study. The data were analysed with partial correlation, multiple linear regression and logistic regression analysis.

RESULTS

Linear regression models showed that total testosterone and sex hormone-binding globulin levels, but not calculated free testosterone, serum oestradiol or dehydroepiandrosterone sulphate levels were inversely associated with the age-adjusted IMT (P = 0.008 and P < 0.001 respectively). These associations were independent of smoking, physical activity, blood pressure and lipid levels, but were not independent of body mass index (BMI). Excluding men with cardiovascular disease (CVD) did not materially change these results. In a logistic regression model adjusted for the confounding effect of CVD risk factors, men with testosterone levels in the lowest quintile (<9.0 nmol L(-1)) had an independent OR = 1.51 (P = 0.015) of being in the highest IMT quintile.

CONCLUSIONS

We found an inverse association between total testosterone levels and IMT of the carotid artery in men that was present also after excluding men with CVD, but was not independent of BMI. The clinical relevance of this, however, is uncertain and needs to be investigated in a clinical setting.

A comparison between peripheral BMD and central BMD measurements in the prediction of spine fractures in men

INTRODUCTION

Most of the research on osteoporosis has been conducted on women. Few studies have compared central and peripheral densitometry and their association with vertebral fractures in men. The present study was designed to compare peripheral bone mineral density (BMD) measurements with central BMD measurements, and to examine their association with radiographic spine fracture in men.

METHODS

We studied 402 community-dwelling men aged 45-92 years (mean: 70 years) from the Rancho Bernardo Study cohort who attended a clinic visit between 1988 and 1992 when BMD measurements of the midshaft radius, ultradistal wrist, lumbar spine, and total hip were obtained, and who returned for lateral X-rays of the thoracic and lumbar spine an average of 4 years later. Logistic regression, T-scores, and quintiles were used to analyze BMD and its association with vertebral fractures.

RESULTS

The prevalence of osteoporosis defined by the National Osteoporosis Foundation criteria (for women) was 14.2% at the spine and 13% at the hip. Because there are no validated definitions of osteoporosis based on the ability to predict fracture risk for peripheral densitometry, the frequency of overlap by bone site was calculated among men in the lowest quintile of each site. Of the 402 men, 82 men (20.3%) had at least two sites with BMD measurements in the lowest quintile. After an average of 4 years, 33 (8.2%) men had at least one radiographic vertebral fracture, and ten (2.5%) men had at least two vertebral fractures. Low BMD at the spine (with and without covariate adjustment) was associated with having one or more vertebral fractures, whether using NOF T-score-defined osteoporosis [Odds ratio (OR): 3.81; confidence interval (CI): 1.52, 9.57] or the lowest quintile versus all others (OR: 2.53; CI: 1.03, 6.19). After age and/or other covariate adjustments, neither BMD at the total hip nor at the peripheral sites was associated with spine fractures using either NOF women-based criteria or male quintiles from this cohort.

CONCLUSION

Although different men had osteoporosis defined by quintiles at different sites, only low BMD at the spine was associated with vertebral fracture.

Hysterectomy, oophorectomy, and endogenous sex hormone levels in older women: the Rancho Bernardo Study

This study examines the cross-sectional association of hysterectomy and oophorectomy status, chronological age, and years since menopause with plasma levels of total and bioavailable testosterone and estradiol, androstenedione, estrone, and sex hormone-binding globulin (SHBG) in community-dwelling postmenopausal women who were not using estrogen replacement therapy. Six hundred and eighty-four women, aged 50-89 yr, were surveyed for hysterectomy and oophorectomy status and had plasma obtained between 1984-1987. Of these, 438 (67%) had not undergone hysterectomy or oophorectomy (intact), 123 (18%) reported hysterectomy with bilateral oophorectomy, and 123 (18%) reported hysterectomy with conservation of 1 or both ovaries. After adjustment for age and body mass index, both total and bioavailable testosterone levels were reduced by more than 40% (P < 0.001) in hysterectomized women with bilateral oophorectomy compared to those in intact women, with intermediate levels observed in hysterectomized women with ovarian conservation. Androstenedione levels were about 10% lower in hysterectomized women with or without ovarian conservation compared to those in intact women (P = 0.039). Total estradiol levels tended to be lower (P = 0.095) in bilaterally oophorectomized women. Levels of bioavailable estradiol, estrone, and SHBG did not differ by hysterectomy and oophorectomy status. Among intact women, total, but not bioavailable, testosterone levels increased with age (P = 0.015), reaching premenopausal levels for the 70-79 decade with relatively stable levels thereafter. Among oophorectomized women, total and bioavailable testosterone levels did not vary with age and were 40-50% lower than those in intact women throughout the 50-89 yr age range. Androstenedione levels decreased 27% and SHBG levels increased 30% (P < 0.001) with age in intact, but not oophorectomized, women. Levels of other hormones did not vary with age. Stratification by years since menopause or surgery yielded similar results. These results demonstrate that the postmenopausal ovary remains a critical source of androgen throughout the lifespan of older women. The clinical consequences of lower testosterone levels years after oophorectomy are unknown. Reconsideration of prophylactic oophorectomy and clinical trials to evaluate the effects of androgen replacement after oophorectomy are needed.

Endogenous levels of dehydroepiandrosterone sulfate, but not other sex hormones, are associated with depressed mood in older women: the Rancho Bernardo Study

OBJECTIVE

The purpose of this study was to determine whether endogenous steroid hormone levels are associated with depressed mood in community-dwelling older women.

DESIGN

A cross-sectional population-based study.

SETTING

Rancho Bernardo, California

PARTICIPANTS

A total of 699 non-estrogen using, community-dwelling, postmenopausal women (aged 50 to 90 years) from the Rancho Bernardo cohort who were screened for depressed mood and had plasma obtained for steroid hormone assays in 1984-1987.

MEASUREMENTS

Plasma levels of total and bioavailable (non-SHBG-bound) estradiol and testosterone, estrone, androstenedione, cortisol, dehydroepiandrosterone, and (DHEA) and its sulfate (DHEAS) were measured by radioimmunoassay. Mood and depression were assessed using the Beck Depression Inventory.

RESULTS

Only DHEAS levels were significantly and inversely associated with depressed mood, and the association was independent of age, physical activity, and weight change (P = .0002). Age, sedentary lifestyle, and weight loss were positively associated with depressed mood. Alcohol intake, cigarette smoking, marital status, type of menopause, and season of testing were unassociated with depressed mood. A subset of 31 women with categorically defined depression had lower DHEAS levels compared with 93 age-matched nondepressed women (1.17 +/- 1.08 vs 1.57 +/- .98 micromol/L; P = .01).

CONCLUSIONS

These results add to the evidence that DHEA/S is a neuroactive steroid and point to the need for careful long-term clinical trials of DHEA therapy in older women with depressed mood.