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Low Serum Testosterone and Mortality in Male Veterans
Molly M. Shores, MD;
Alvin M. Matsumoto, MD;
Kevin L. Sloan, MD;
Daniel R. Kivlahan, PhD
Arch Intern Med. 2006;166:1660-1665.
ABSTRACT
Background Low serum testosterone is a common condition in aging associated with decreased muscle mass and insulin resistance. This study evaluated whether low testosterone levels are a risk factor for mortality in male veterans.
Methods We used a clinical database to identify men older than 40 years with repeated testosterone levels obtained from October 1, 1994, to December 31, 1999, and without diagnosed prostate cancer. A low testosterone level was a total testosterone level of less than 250 ng/dL (<8.7 nmol/L) or a free testosterone level of less than 0.75 ng/dL (<0.03 nmol/L). Men were classified as having a low testosterone level (166 [19.3%]), an equivocal testosterone level (equal number of low and normal levels) (240 [28.0%]), or a normal testosterone level (452 [52.7%]). The risk for all-cause mortality was estimated using Cox proportional hazards regression models, adjusting for demographic and clinical covariates over a follow-up of up to 8 years.
Results Mortality in men with normal testosterone levels was 20.1% (95% confidence interval [CI], 16.2%-24.1%) vs 24.6% (95% CI, 19.2%-30.0%) in men with equivocal testosterone levels and 34.9% (95% CI, 28.5%-41.4%) in men with low testosterone levels. After adjusting for age, medical morbidity, and other clinical covariates, low testosterone levels continued to be associated with increased mortality (hazard ratio, 1.88; 95% CI, 1.34-2.63; P<.001) while equivocal testosterone levels were not significantly different from normal testosterone levels (hazard ratio, 1.38; 95% CI, 0.99%-1.92%; P=.06). In a sensitivity analysis, men who died within the first year (50 [5.8%]) were excluded to minimize the effect of acute illness, and low testosterone levels continued to be associated with elevated mortality.
Conclusions Low testosterone levels were associated with increased mortality in male veterans. Further prospective studies are needed to examine the association between low testosterone levels and mortality.
INTRODUCTION
Testosterone levels decline with aging, with an average decrease in total serum testosterone levels of approximately 1.5% per year.1 The prevalence of low serum total testosterone levels is approximately 20% by the age of 50 years and 50% by the age of 80 years. Manifestations of low testosterone include decreased muscle mass and bone mineral density, increased fat mass, central obesity, insulin resistance, decreased libido and energy, irritability, and dysphoria.2 In contrast to menopause, in which all women undergo a nearly complete cessation of gonadal estrogen secretion, in men, gonadal androgen secretion decreases gradually and progressively after the age of 30 years, but does not generally cease, and androgen levels remain highly variable in older men. The prevalence of clinical androgen deficiency (symptoms plus low testosterone levels) was recently reported to be about 6% to 12% in middle-aged and elderly men.3 Testosterone levels also decrease with acute and chronic illnesses and with medications such as glucocorticoids and opiates.2 Because of the aging of our society, many older men are affected by age-associated low testosterone levels.2 In addition, the use of testosterone has increased significantly, with a tripling in prescriptions for testosterone over a 3-year period.4 However, despite the marked increase in testosterone use, the overall risks and benefits remain unclear.4-5
In a recent small study6 in a geriatric rehabilitation unit, we found that men with a low testosterone level had an increased 6-month mortality compared with men with a normal testosterone level who were of a comparable age and had comparable medical morbidity. Given these unforeseen preliminary findings, we conducted the present retrospective cohort study to examine if repeatedly low serum testosterone levels were associated with increased mortality in a larger sample of middle-aged and elderly men with a longer follow-up, of up to 8 years.
METHODS
DATA SOURCE
We used the Consumer Health Information and Performance Set computerized clinical database at the VA (Veterans Affairs) Puget Sound Health Care System to assess the relationship between low serum testosterone levels and all-cause mortality. The University of Washington Human Subjects Division approved access to the clinical database and to a national VA death registry, the Beneficiary Identification and Records Locator System (BIRLS)–Death File,7 through December 31, 2002. The database contained demographic information, dates of clinic visits and blood draws, laboratory results, pharmacy data, and International Classification of Diseases, Ninth Revision (ICD-9) diagnostic codes8 for inpatient and outpatient visits that occurred from October 1, 1994, through December 31, 1999.
SAMPLE
The inclusion criteria were as follows: (1) 40 years or older at the initial testosterone test and (2) at least 2 testosterone levels obtained at least 1 week apart but less than 2 years apart before January 1, 2000. We required a minimum of 2 testosterone levels because a prior study9 found that in about 33% of cases, low testosterone levels may be normal in a subsequent test. In some cases, because multiple levels were obtained on the same day (ie, free and total testosterone levels), subjects had more than 2 testosterone level results when they enrolled into the study. The exclusion criteria were as follows: (1) female sex, (2) antiandrogen treatment at baseline (ie, leuprolide, goserelin, flutamide, bicalutamide, or cyproterone acetate), and (3) documented history of prostate or testicular cancer before study enrollment.
GONADAL STATUS
Indication for Obtaining Testosterone Levels
The indications for obtaining testosterone levels were not available in the computerized database. However, in a prior manual review of nearly 300 medical records,10 the clinical indications for obtaining testosterone levels were as follows: evaluation of sexual dysfunction (31.6%), osteoporosis (21.6%), follow-up of a prior low testosterone level (15.4%), geriatric rehabilitation (10.4%), genitourinary conditions (9.0%), cancer (3.2%), endocrine conditions (3.0%), and other or unknown reasons (5.6%) (percentages do not total 100 because of rounding).
Assays
Serum total and free testosterone levels were measured using automated platform immunoassays in the clinical laboratory of the VA Puget Sound Health Care System. The phlebotomy times for testosterone samples were not standardized. Testosterone has a diurnal variation, with peak plasma testosterone levels in the morning. However, this variation is most marked in younger men, and markedly diminished or absent in older men,11 suggesting that the potential effect of variable phlebotomy times was minimal.
Testosterone Classification
The lower limit of normal was defined as a total testosterone level of less than 250 ng/dL (<8.7 nmol/L) or a free testosterone level of less than 0.75 ng/dL (<0.03 nmol/L). These levels were used as threshold levels because they have been identified as clearly low and generally associated with symptoms of hypogonadism, even in older men.4, 12 Men were classified as having low testosterone levels if they had 2 low testosterone levels or if more than 2 levels were measured; most of the levels were low. Men were classified as having equivocal testosterone levels if they had at least 1 low and 1 normal level and if more than 2 levels were obtained, they had an equal number of low and normal testosterone levels. Men were classified as having normal testosterone levels if they had at least 2 normal testosterone levels and if more than 2 levels were obtained, most were normal.
COVARIATES
Body mass index (BMI) was calculated as weight in kilograms divided by the square of height in meters. The BMI data were missing in 124 cases (14.5%). Overall medical morbidity was estimated using an algorithm shown to be valid and reliable in VA computerized clinical databases. A VA-adapted pharmacy-based case-mix instrument (RxRisk-V)13 algorithm estimates medical morbidity from the VA clinical database using pharmacy data. This method of determining medical morbidity is considered more accurate than using diagnostic codes because it reflects actively treated illnesses. The medical morbidity score is determined from the number of specified medical conditions treated in the prior 12 months (range of potential conditions, 0-45). We also obtained data on specific medical conditions that may be related to testosterone level and mortality and that had good reliability and validity using the VA-adapted pharmacy-based case-mix instrument (RxRisk-V) ( > 0.6). These conditions were diabetes mellitus, chronic obstructive pulmonary disease, human immunodeficiency virus, hyperlipidemia, and coronary artery disease (CAD).13 In addition, we obtained data on glucocorticoid and opiate prescriptions because these may lower testosterone levels. Treatment data for intramuscular testosterone levels were available only in paper medical records and not in the computerized clinical record system included in the database.
OUTCOMES
The primary outcomes were all-cause mortality and survival from the date of the second testosterone level obtained through December 31, 2002. Subjects were followed up from the time of enrollment into the study (the date when the second testosterone level was obtained) through the end of 2002. Mortality data were obtained through 2002 from the BIRLS–Death File, which contains approximately 10.7 million records and has an estimated 94.5% to 96.5% sensitivity.14-15 A review of major US mortality databases found that the BIRLS–Death File had a high accuracy rate16 that compares favorably with other national mortality databases. However, a more recent study17 found lower accuracy rates of 80% to 92% for the BIRLS–Death File, compared with the National Death Index or state death certificates. For more comprehensive mortality data, we also obtained mortality data from the regional VA database. In addition, we confirmed that men who were identified as survivors received care at the VA facility after 2002. Men were censored from the survival analysis as of their last clinic visit if they did not receive care after 2002. Thus, all men in the study had a death recorded in either the BIRLS–Death File or regional records, had a clinic visit documented after 2002, or were censored.
STATISTICAL ANALYSIS
We determined baseline differences between men with low, equivocal, and normal testosterone levels with  2 tests and analysis of variance. Kaplan-Meier survival curves were used to illustrate the association between testosterone status and all-cause mortality. Cox proportional hazards regression models were used to compare differences in survival between men with low, equivocal, and normal testosterone levels. Initially, each covariate was added to the model individually to examine the influence of the covariate on our primary outcome. Then, we conducted a partially adjusted analysis that included the covariates of age, medical morbidity, BMI, and glucocorticoid and opiate treatment, followed by a fully adjusted model in which we included all covariates. Because of missing BMI data, the sample size was decreased in the Cox proportional hazards regression analyses. To estimate if this affected our analyses, we repeated the analyses, first excluding subjects with a missing BMI and then using the mean BMI to replace missing BMI data. We found similar results in both analyses, so we used the mean BMI in the Cox proportional hazards regression analyses. We added interaction terms to test for potential interactions of each covariate with low testosterone level. Regression diagnostics were done to examine for colinearity among the covariates. Finally, because acute illness may cause a transient decrease in testosterone levels, we conducted a sensitivity analysis by excluding men who died within the first year. We had greater than 80% power to detect a 10% difference and greater than 95% power to detect a 15% difference in absolute mortality rates. All analyses were performed using a commercially available software program (SPSS, version 11.5.2.1; SPSS Inc, Chicago, Ill).
RESULTS
From the clinical database, we identified 858 men, 40 years or older, who had repeated testosterone levels obtained and had no history of prostate or testicular cancer or antiandrogen treatment. There were 452 men (52.7%) with normal testosterone levels, 240 (28.0%) with equivocal levels, and 166 (19.3%) with low levels. Testosterone levels differed significantly between the 3 groups (Table 1). Men with low testosterone levels were older, had a greater BMI, and had a greater prevalence of diabetes mellitus compared with men with normal testosterone levels. Men with equivocal testosterone levels had a greater BMI than men with normal testosterone levels. Men with low and normal testosterone levels had more testosterone levels obtained than men with equivocal testosterone levels. There were no significant differences between the groups in marital status; medical morbidity; prevalence of chronic obstructive pulmonary disease, human immunodeficiency virus, CAD, or hyperlipidemia; and treatment with opiates and glucocorticoids (Table 1).
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Table 1. Baseline Characteristics of Men With Low, Equivocal, and Normal Testosterone Levels*
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The mean (SD) follow-up was 4.30 (1.78) years. Fifty-six men (6.5%) had an unconfirmed vital status and were censored as of the date of their last visit. All-cause mortality was 20.1% (95% confidence interval, 16.2%-24.1%) in men with normal testosterone levels, 24.6% (95% confidence interval, 19.2%-30.0%) in men with equivocal testosterone levels, and 34.9% (95% confidence interval, 28.5%-41.4%) in men with low testosterone levels. Men with low and equivocal testosterone levels had shorter survival times than men with normal testosterone levels, as illustrated by the Kaplan-Meier survival analysis (log-rank test; 22 = 14.4, P=.001) (Figure). The proportional hazards assumption was confirmed through visual inspection of the survival curves. In an unadjusted Cox proportional hazards regression model, men with equivocal testosterone levels did not differ from men with normal testosterone levels in mortality risk. Men with low testosterone levels had a significantly greater mortality risk than men with normal testosterone levels. After adjustment for age, medical morbidity, BMI, and glucocorticoid and opiate treatment, the adjusted hazard ratios for equivocal and low testosterone levels were elevated. In a fully adjusted model, men with low testosterone levels continued to have a greater mortality risk, although men with equivocal testosterone levels did not differ significantly from men with normal testosterone levels (Table 2). Tests for interaction did not reveal any effect modification on the hazard ratio for low testosterone level. In a sensitivity analysis, we excluded subjects with 1-year mortality (50 [5.8%]). Men with low testosterone levels continued to have an increased mortality risk in an adjusted model (Table 2).
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Figure. Unadjusted Kaplan-Meier survival curves for the 3 testosterone level groups. Men with low and equivocal testosterone levels had a significantly shorter survival than men with normal testosterone levels (log-rank test; 22 = 14.4, P = .001).
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Table 2. Crude and Multivariate-Adjusted Data for Mortality Associated With Testosterone Levels
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COMMENT
In this study of male veterans 40 years and older, without prostate cancer, followed up for a mean of 4.3 years, men with low and equivocal serum testosterone levels had increased all-cause mortality and shorter survival times compared with men with normal testosterone levels. In an unadjusted model, low testosterone levels were associated with an increased mortality risk of 88% greater than that for men with normal testosterone levels. In the fully adjusted model, which included the covariates of age, medical morbidity, BMI, race, and other clinical factors, low testosterone level continued to be associated with an increased mortality risk of 88% greater than in men with normal testosterone levels. However, a retrospective cohort study cannot establish a causal relationship between testosterone status and mortality, and it is possible that the association is because of the mediation of some other factor that is linked to low testosterone level and mortality. Prior studies may be relevant in examining this association further.
STUDIES OF TESTOSTERONE LEVELS AND ACUTE ILLNESS
The serum testosterone level decreases approximately 90% within 24 to 48 hours after the onset of critical illness, such as surgery, major burns, multiple trauma, and critical medical illness involving ventilator dependence.18-21 In patients with acute stroke, a low serum total testosterone level correlated with stroke severity and size22 and predicted 6-month mortality. Another study21 found that a low testosterone level correlated with acute illness on admission to an intensive care unit and that survivors had an increase in testosterone levels at discharge in contrast to persistently low levels among nonsurvivors of a comparable age and with a comparable illness severity. In the sensitivity analysis, we excluded early deaths that may have been related to acute illness and continued to find persistent elevated mortality in men with low testosterone levels. Further prospective studies are needed to clarify factors other than acute illness in the association between low testosterone level and increased mortality.
STUDIES OF TESTOSTERONE LEVELS AND CHRONIC ILLNESSES
Several studies23-26 have found that low testosterone levels are associated with the metabolic syndrome, hyperinsulinemia, and diabetes mellitus. Several studies27-29 noted that low testosterone levels are associated with multiple risk factors for CAD, including hypertension, central obesity, thrombosis, and C-reactive protein, and variable effects on lipids. In several recent studies,30-32 testosterone treatment improved the angina threshold, increasing exercise time to ischemia in men with CAD. Low testosterone levels are also associated with sarcopenia, decreased bone mineral density, osteoporosis, anorexia, and fatigue. These are components of the frailty syndrome that is associated with significant morbidity, institutionalization, and mortality in elderly persons.33 Thus, low testosterone levels are associated with chronic illnesses that are themselves associated with mortality. In our study, we attempted to control for the effect of chronic illness and medications that may suppress testosterone levels by controlling for age, BMI, diabetes mellitus, CAD, chronic obstructive pulmonary disease, human immunodeficiency virus, hyperlipidemia, and treatment with opiates and glucocorticoids. In addition, we excluded men who had prostate or testicular cancer before study enrollment. After controlling for overall medical morbidity and these other clinical covariates, we continued to find an association between low testosterone levels and mortality. However, it is possible that there are other chronic medical illnesses or conditions not assessed in this study that explain the association between testosterone level and mortality.
STUDIES OF MORTALITY IN MEN WITH LOW TESTOSTERONE LEVELS
Men with hypopituitarism and untreated gonadotropin deficiency had increased cardiovascular mortality34 and increased overall mortality35 compared with treated subjects. Another study36 of hypopituitarism found increased mortality in men with an unknown gonadal status compared with men who were treated with testosterone. In another study,37 men with Klinefelter syndrome, which is characterized by hypogonadism, had increased mortality compared with that of age-matched control subjects. There have been conflicting results from studies examining the association of castration and mortality. One study38 of legally castrated men found increased all-cause mortality but a decrease in cardiovascular mortality. A study39 of castrated, institutionalized, mentally retarded men found decreased mortality while a study40 of castrated male singers found no mortality differences compared with intact men. Finally, 2 longitudinal studies of older men found no association between testosterone levels and all-cause mortality41 or cardiovascular mortality.42 However, there have been few large prospective studies to examine the association between low testosterone levels and mortality in community-dwelling older men. Recent preliminary findings from a large prospective study43 found increased cancer-related mortality in community-dwelling men with a total testosterone level of less than 200 ng/dL (<6.9 nmol/L). These results of increased mortality in a cohort of men who are healthier than the VA cohort suggest that the association between low testosterone level and mortality may be more generalizable.
Among several limitations to our study, the most significant is the retrospective study design with a lack of systematic assessment of a prospective cohort. This precludes establishing a causal relationship or ruling out the possibility that residual confounding may have occurred because of some other unmeasured factors that may explain the association between low testosterone levels and mortality. Another limitation is that testosterone treatment data were not available. However, we hypothesize that testosterone treatment would bias the results toward the null because it would minimize the differences between the men with low and normal testosterone levels. Another limitation is the use of platform testosterone assays. These assays are similar to those used by most clinical laboratories, but they may be affected by alterations in sex hormone–binding globulin concentrations.44 However, the criteria used to define low testosterone were sufficiently stringent to exclude most men with low testosterone levels because of a low sex hormone–binding globulin concentrations. Subsequent studies need to be performed using assays (eg, free testosterone by equilibrium dialysis) that are not subject to these alterations.44 Finally, our population is not representative of community-dwelling men because it was a VA clinic–based population. This limits the generalizability of these conclusions given that VA patients have greater medical morbidity and a lower socioeconomic class.45 Also, our cohort had a high overall mortality of 24.2% over a mean follow-up of 4.3 years. However, a recent study46 of veterans followed up at 9 VA medical centers found a similarly high mortality (18%) over a 2-year period. Another study,47 of more than 400 000 VA patients, found a crude mortality of 25.7% over 4 years. Thus, although the mortality rate in our study is high, it is comparable to that of other VA studies.
In conclusion, compared with men with normal testosterone levels, the covariate-adjusted mortality risk was nonsignificantly increased by 38% in men with equivocal testosterone levels and significantly increased by 88% in men with low testosterone levels. After removing first-year deaths, low testosterone levels continued to be associated with increased mortality, with a 68% greater mortality risk compared with men with normal testosterone levels. The persistence of elevated mortality risk after excluding early deaths suggests that the association between low testosterone and mortality is not simply due to acute illness. Large prospective studies are needed to clarify the association between low testosterone levels and mortality.
AUTHOR INFORMATION
Correspondence: Molly Shores, MD, Department of Psychiatry and Behaviorial Sciences, University of Washington/VA Puget Sound Health Care System, 1660 S Columbian Way, Mailstop S-182GRECC, Seattle, WA 98108 (mxs{at}u.washington.edu).
Accepted for Publication: April 7, 2006.
Financial Disclosure: Dr Shores was the recipient of a prior grant from Solvay Pharmaceuticals Inc and has been a consultant to Solvay Pharmaceuticals Inc; and Dr Matsumoto was the recipient of grant support from and performed research for GlaxoSmithKline, Solvay Pharmaceuticals Inc, and Ascend Therapeutics, and has been a consultant to GlaxoSmithKline, Solvay Pharmaceuticals Inc, and GTx Inc.
Funding/Support: This study was supported by the Geriatric Research, Education, and Clinical Center, VA Puget Sound Health Care System; the Royalty Research Fund of the University of Washington (Dr Shores); and a VA merit review grant (Dr Matsumoto).
Role of the Sponsor: The funding bodies had no role in data extraction and analyses, in the writing of the manuscript, or in the decision to submit the manuscript for publication.
Author Affiliations: Geriatric Research, Education, and Clinical Center (Drs Shores and Matsumoto) and Center of Excellence in Substance Abuse Treatment and Education (Drs Sloan and Kivlahan), VA Puget Sound Health Care System, Seattle, Wash, and Departments of Psychiatry and Behavioral Sciences (Drs Shores, Sloan, and Kivlahan) and Medicine (Dr Matsumoto), University of Washington, Seattle.
REFERENCES
1. Feldman HA, Longcope C, Derby CA, et al. Age trends in the level of serum testosterone and other hormones in middle-aged men: longitudinal results from the Massachusetts Male Aging Study. J Clin Endocrinol Metab. 2002;87:589-598.
FREE FULL TEXT
2. Matsumoto AM. Andropause: clinical implications of the decline in serum testosterone levels with aging in men. J Gerontol A Biol Sci Med Sci. 2002;57:M76-M99.
FREE FULL TEXT
3. Araujo AB, O’Donnell AB, Brambilla DJ, et al. Prevalence and incidence of androgen deficiency in middle-aged and older men: estimates from the Massachusetts Male Aging Study. J Clin Endocrinol Metab. 2004;89:5920-5926.
FREE FULL TEXT
4. Institute of Medicine. Testosterone and health outcomes. In: Liverman CT, Blazer DG, eds. Testosterone and Aging: Clinical Research Directions. Washington, DC: National Academy Press; 2004:24-27.5. Rhoden EL, Morgentaler A. Risks of testosterone replacement therapy and recommendations for monitoring. N Engl J Med. 2004;350:482-492.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
6. Shores MM, Moceri VM, Gruenewald DA, Brodkin KI, Matsumoto AM, Kivlahan DR. Low testosterone is associated with decreased function and increased mortality risk: a preliminary study of men in a geriatric rehabilitation unit. J Am Geriatr Soc. 2004;52:2077-2081.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
7. Cowper DC, Kubal JD, Maynard C, Hynes DM. A primer and comparative review of major US mortality databases. Ann Epidemiol. 2002;12:462-468.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
8. International Classification of Diseases, Ninth Revision, Clinical Modification Washington, DC: Public Health Service, US Dept of Health and Human Services; 1988.9. Swerdloff RS, Wang C, Cunningham G, et al. Long-term pharmacokinetics of transdermal testosterone gel in hypogonadal men. J Clin Endocrinol Metab. 2000;85:4500-4510.
FREE FULL TEXT
10. Shores MM, Sloan KL, Matsumoto AM, Moceri VM, Felker B, Kivlahan DR. Increased incidence of diagnosed depressive illness in hypogonadal older men. Arch Gen Psychiatry. 2004;61:162-167.
FREE FULL TEXT
11. Bremner WJ, Vitiello MV, Prinz PN. Loss of circadian rhythmicity in blood testosterone levels with aging in normal men. J Clin Endocrinol Metab. 1983;56:1278-1281.
FREE FULL TEXT
12. National Institute on Aging Advisory Panel. Report of National Institute on Aging Advisory Panel on testosterone replacement in men. J Clin Endocrinol Metab. 2001;86:4611-4614.
FREE FULL TEXT
13. Sloan KL, Sales AE, Liu C, et al. Construction and characteristics of the RxRisk-V: a VA-adapted pharmacy-based case-mix instrument. Med Care. 2003;41:761-774.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
14. Fisher SG, Weber L, Goldberg J. Mortality ascertainment in the veteran population: alternatives to the National Death Index. Am J Epidemiol. 1995;141:242-250. Davis F.
FREE FULL TEXT
15. Page WF, Barun MM, Caporaso NE. Ascertainment of mortality in the US veteran population: World War II veteran twins. Mil Med. 1995;160:351-355.
WEB OF SCIENCE
| PUBMED
16. Dominitz JA, Maynard C, Boyko EJ. Assessment of vital status in Department of Veterans Affairs national databases: comparison with state death certificates. Ann Epidemiol. 2001;11:286-291.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
17. Lorenz KA, Asch SM, Yano EM, Wang M, Rubenstein LV. Comparing strategies for United States veterans' mortality ascertainment. http://www.pophealthmetrics.com/content/3/1/2. Accessed March 30, 2006.18. Woolf PD, Hamill RW, McDonald JV, Lee LA, Kelly M. Transient hypogonadotropic hypogonadism caused by critical illness. J Clin Endocrinol Metab. 1985;60:444-450.
FREE FULL TEXT
19. Nierman DM, Mechanick JI. Hypotestosteronemia in chronically critically ill men. Crit Care Med. 1999;27:2418-2421.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
20. Spratt DI, Cox P, Orav J, Moloney J, Bigos T. Reproductive axis suppression in acute illness is related to disease severity. J Clin Endocrinol Metab. 1993;76:1548-1554.
ABSTRACT
21. Dong Q, Hawker F, McWilliam D, Bangah M, Burger H, Handelsman DJ. Circulating immunoreactive inhibin and testosterone levels in men with critical illness. Clin Endocrinol (Oxf). 1992;36:399-404.
PUBMED
22. Jeppesen LL, Jorgensen HS, Nakayama H, Raaschou HO, Olsen TS, Winther K. Decreased serum testosterone in men with acute ischemic stroke. Arterioscler Thromb Vasc Biol. 1996;16:749-754.
FREE FULL TEXT
23. Tibblin G, Adlerberth A, Lindstedt G, Bjorntorp P. The pituitary-gonadal axis and health in elderly men: a study of men born in 1913. Diabetes. 1996;45:1605-1609.
ABSTRACT
24. Stellato RK, Feldman HA, Hamdy O, Horton ES, McKinlay JB. Testosterone, sex hormone–binding globulin, and the development of type 2 diabetes in middle-aged men: prospective results from the Massachusetts Male Aging Study. Diabetes Care. 2000;23:490-494.
ABSTRACT
25. Laaksonen DE, Leo N, Punnonen K, et al. Testosterone and sex hormone–binding globulin predict the metabolic syndrome and diabetes in middle-aged men. Diabetes Care. 2004;27:1036-1041.
FREE FULL TEXT
26. Tsai EC, Matsumoto AM, Fujimoto WY, Boyko EJ. Association of bioavailable, free, and total testosterone with insulin resistance: influence of sex hormone–binding globulin and body fat. Diabetes Care. 2004;27:861-868.
FREE FULL TEXT
27. English KM, Steeds R, Jones TH, Channer KS. Testosterone and coronary heart disease: is there a link? QJM. 1997;90:787-791.
FREE FULL TEXT
28. Alexandersen P, Haarbo J, Christianson C, et al. The relationship of natural androgens to coronary heart disease in males: a review. Atherosclerosis. 1996;125:1-13.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
29. Wu FC, von Eckardstein A. Androgens and coronary artery disease. Endocr Rev. 2003;24:183-217.
FREE FULL TEXT
30. English KM, Steeds RP, Jones TH, Diver MJ, Chaner KS. Low-dose transdermal testosterone therapy improves angina threshold in men with chronic stable angina: a randomized, double-blind, placebo-controlled study. Circulation. 2000;102:1906-1911.
FREE FULL TEXT
31. Webb CM, Adamson DL, de Zeigler D, Collins P. Effect of acute testosterone on myocardial ischemia in men with coronary artery disease. Am J Cardiol. 1999;83:437-439.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
32. Rosano GM, Leonardo F, Pagnotta D, et al. Acute anti-ischemic effect of testosterone in men with coronary artery disease. Circulation. 1999;99:1666-1670.
FREE FULL TEXT
33. Morley JE, Kaiser FE, Sih R, Hajjar R, Perry HM III. Testosterone and frailty. Clin Geriatr Med. 1997;13:685-695.
WEB OF SCIENCE
| PUBMED
34. Rosen T, Bengtsson B-A. Premature mortality due to cardiovascular disease in hypopituitarism. Lancet. 1990;336:285-288.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
35. Tomlinson JW, Holden N, Hills RK, et al. Association between premature mortality and hypopituitarism. Lancet. 2001;357:425-431.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
36. Bates AS, Van't Hoff W, Jones PJ, Clayton RN. The effect of hypopituitarism on life expectancy. J Clin Endocrinol Metab. 1996;81:1169-1172.
ABSTRACT
37. Bojesen A, Juul S, Birkebaek N, Gravholt CH. Increased mortality in Klinefelter syndrome. J Clin Endocrinol Metab. 2004;89:3830-3834.
FREE FULL TEXT
38. Eyben FE, Graugaard C, Vaeth M. All-cause mortality and mortality of myocardial infarction for 989 legally castrated men. Eur J Epidemiol. 2005;20:863-869.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
39. Hamilton JB, Mestler GE. Mortality and survival: comparison of eunuchs with intact men and women in a mentally retarded population. J Gerontol. 1969;24:395-411.
FREE FULL TEXT
40. Nieschlag E, Nieschlag S, Behre HM. Lifespan and testosterone. Nature. doi:10.1038/366215a0. 1993;366:215.
PUBMED
41. Morley JE, Kaiser FE, Perry HM III, et al. Longitudinal changes in testosterone, luteinizing hormone, and follicle-stimulating hormone in healthy older men. Metabolism. 1997;46:410-413.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
42. Barrett-Connor E, Khaw KT. Endogenous sex hormones and cardiovascular disease in men: a prospective population-based study. Circulation. 1988;78:539-545.
FREE FULL TEXT
43. Araujo AB, Handelsman DJ, McKinlay JB. Total testosterone as a predictor of mortality in men: results from the Massachusetts Male Aging Study. In: Proceedings of the Endocrine Society's 87th Annual Meeting; June 4-7, 2005; San Diego, Calif. Abstract P1-561.44. Matsumoto AM, Bremner WJ. Serum testosterone assays: accuracy matters [editorial]. J Clin Endocrinol Metab. 2004;89:520-524.
FREE FULL TEXT
45. Agha Z, Lofgren RP, VanRuiswyk JV, Layde PM. Are patients at Veterans Affairs medical centers sicker? a comparative analysis of health status and medical resource use. Arch Intern Med. 2000;160:3252-3257.
FREE FULL TEXT
46. Lavretsky H, Bastani R, Gould R, et al. Predictors of two-year mortality in a prospective "UPBEAT" study of elderly veterans with comorbid medical and psychiatric symptoms. Am J Geriatr Psychiatry. 2002;10:458-468.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
47. Selim AJ, Kazis LE, Rogers W, et al. Risk-adjusted mortality as an indicator of outcomes: comparison of the Medicare Advantage Program with the Veterans' Health Administration. Med Care. 2006;44:359-365.
FULL TEXT
|
WEB OF SCIENCE
| PUBMED
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ABSTRACT
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Hypogonadism as a risk factor for cardiovascular mortality in men: a meta-analytic study
Corona et al.
Eur J Endocrinol 2011;165:687-701.
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Sex hormones and cause-specific mortality in the male veterans: the Vietnam Experience Study
Phillips et al.
QJM 2011;0:hcr204v1-hcr204.
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Endogenous Testosterone and Mortality in Men: A Systematic Review and Meta-Analysis
Araujo et al.
J. Clin. Endocrinol. Metab. 2011;96:3007-3019.
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Update: Hypogonadotropic Hypogonadism in Type 2 Diabetes and Obesity
Dandona and Dhindsa
J. Clin. Endocrinol. Metab. 2011;96:2643-2651.
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Low serum testosterone, arterial stiffness and mortality in male haemodialysis patients
Kyriazis et al.
Nephrol Dial Transplant 2011;26:2971-2977.
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Low Testosterone Associated With Obesity and the Metabolic Syndrome Contributes to Sexual Dysfunction and Cardiovascular Disease Risk in Men With Type 2 Diabetes
Wang et al.
Diabetes Care 2011;34:1669-1675.
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Endogenous testosterone and cardiovascular disease in healthy men: a meta-analysis
Ruige et al.
Heart 2011;97:870-875.
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Low free testosterone is associated with heart failure mortality in older men referred for coronary angiography
Wehr et al.
Eur J Heart Fail 2011;13:482-488.
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Androgen stimulates endothelial cell proliferation via an androgen receptor/VEGF/cyclin A-mediated mechanism
Cai et al.
Am. J. Physiol. Heart Circ. Physiol. 2011;300:H1210-H1221.
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Association Between Serum Testosterone and Sex Hormone-Binding Globulin and Exercise Capacity in Men: Results of the Study of Health in Pomerania (SHIP)
Koch et al.
J Androl 2011;32:135-143.
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Review: Testosterone and the metabolic syndrome
Muraleedharan and Jones
Therapeutic Advances in Endocrinology and Metabolism 2010;1:207-223.
ABSTRACT
Low serum testosterone and increased mortality in men with coronary heart disease
Malkin et al.
Heart 2010;96:1821-1825.
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Testosterone levels and cardiovascular disease
Ma and Tong
Heart 2010;96:1787-1788.
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Testosterone deficiency syndrome (TDS) and the heart
Jackson
Eur Heart J 2010;31:1436-1437.
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Testosterone for 'late-onset hypogonadism' in men?
DTB 2010;48:69-72.
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Testosterone Therapy in Men with Androgen Deficiency Syndromes: An Endocrine Society Clinical Practice Guideline
Bhasin et al.
J. Clin. Endocrinol. Metab. 2010;95:2536-2559.
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Certainly More Guidelines than Rules
McLachlan
J. Clin. Endocrinol. Metab. 2010;95:2610-2613.
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Rapid loss of appendicular skeletal muscle mass is associated with higher all-cause mortality in older men: the prospective MINOS study
Szulc et al.
Am J Clin Nutr 2010;91:1227-1236.
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Low circulating androgens and mortality risk in heart failure
Guder et al.
Heart 2010;96:504-509.
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Androgen Receptor-dependent Transactivation of Growth Arrest-specific Gene 6 Mediates Inhibitory Effects of Testosterone on Vascular Calcification
Son et al.
J. Biol. Chem. 2010;285:7537-7544.
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Associations of Total Testosterone, Sex Hormone-Binding Globulin, Calculated Free Testosterone, and Luteinizing Hormone with Prevalence of Abdominal Aortic Aneurysm in Older Men
Yeap et al.
J. Clin. Endocrinol. Metab. 2010;95:1123-1130.
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Sex Steroid Hormone Concentrations and Risk of Death in US Men
Menke et al.
Am J Epidemiol 2010;171:583-592.
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Salivary Sex Hormone Measurement in a National, Population-Based Study of Older Adults
Gavrilova and Lindau
J Gerontol B Psychol Sci Soc Sci 2009;64B:i94-i105.
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Review: Androgens, erectile dysfunction and cardiovascular risk in type 2 diabetes
Hackett
British Journal of Diabetes & Vascular Disease 2009;9:214-217.
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Endogenous sex hormones and the prospective association with cardiovascular disease and mortality in men: the Tromso Study
Vikan et al.
Eur J Endocrinol 2009;161:435-442.
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Long-term benefits of testosterone replacement therapy on angina threshold and atheroma in men
Mathur et al.
Eur J Endocrinol 2009;161:443-449.
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The Dark Side of Testosterone Deficiency: III. Cardiovascular Disease
Traish et al.
J Androl 2009;30:477-494.
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Good Semen Quality and Life Expectancy: A Cohort Study of 43,277 Men
Jensen et al.
Am J Epidemiol 2009;170:559-565.
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Lower Testosterone Levels Predict Incident Stroke and Transient Ischemic Attack in Older Men
Yeap et al.
J. Clin. Endocrinol. Metab. 2009;94:2353-2359.
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Low Serum Testosterone and Estradiol Predict Mortality in Elderly Men
Tivesten et al.
J. Clin. Endocrinol. Metab. 2009;94:2482-2488.
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Testosterone therapy in men
Theodoraki and Bouloux
Menopause Int 2009;15:87-92.
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Low Serum Testosterone Increases Mortality Risk among Male Dialysis Patients
Carrero et al.
J. Am. Soc. Nephrol. 2009;20:613-620.
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The Dark Side of Testosterone Deficiency: II. Type 2 Diabetes and Insulin Resistance
Traish et al.
J Androl 2009;30:23-32.
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Testosterone deficiency--the male menopause?
Simon
InnovAiT 2008;1:625-630.
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Variation in Estrogen-Related Genes Associated with Cardiovascular Phenotypes and Circulating Estradiol, Testosterone, and Dehydroepiandrosterone Sulfate Levels
Peter et al.
J. Clin. Endocrinol. Metab. 2008;93:2779-2785.
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Low Serum Testosterone and Mortality in Older Men
Laughlin et al.
J. Clin. Endocrinol. Metab. 2008;93:68-75.
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Testosterone Making an Entry Into the Cardiometabolic World
Basaria and Dobs
Circulation 2007;116:2658-2661.
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Relationship Between Low Levels of Anabolic Hormones and 6-Year Mortality in Older Men: The Aging in the Chianti Area (InCHIANTI) Study
Maggio et al.
Arch Intern Med 2007;167:2249-2254.
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Androgen Receptor Gene CAG Repeat Length and Body Mass Index Modulate the Safety of Long-Term Intramuscular Testosterone Undecanoate Therapy in Hypogonadal Men
Zitzmann and Nieschlag
J. Clin. Endocrinol. Metab. 2007;92:3844-3853.
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Prevalence and Consequences of Androgen Deficiency in Young Male Cancer Survivors in a Controlled Cross-Sectional Study
Greenfield et al.
J. Clin. Endocrinol. Metab. 2007;92:3476-3482.
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Sex Steroids and All-Cause and Cause-Specific Mortality in Men
Araujo et al.
Arch Intern Med 2007;167:1252-1260.
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In men older than 70 years, total testosterone remains stable while free testosterone declines with age. The Health in Men Study
Yeap et al.
Eur J Endocrinol 2007;156:585-594.
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Medical Implications of the Male Biological Clock.
Lewis et al.
JAMA 2006;296:2369-2371.
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Endocrinology & Metabolism News, October 2006
J. Clin. Endocrinol. Metab. 2006;91:17a-17a.
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