Sexual Function in Men Older Than 50 Years of Age: Results from the Health Professionals Follow-up Study

  1. Constance G. Bacon, ScD;
  2. Murray A. Mittleman, MD, ScD;
  3. Ichiro Kawachi, MD, PhD;
  4. Edward Giovannucci, MD, ScD;
  5. Dale B. Glasser, PhD; and
  6. Eric B. Rimm, ScD
  1. From Harvard School of Public Health, Brigham and Woman's Hospital, Harvard Medical School, and Beth Israel Deaconess Medical Center, Boston, Massachusetts; and Pfizer, Inc., New York, New York.
     
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    Abstract

    Background: Although many studies have provided data on erectile dysfunction in specific settings, few studies have been large enough to precisely examine age-specific prevalence and correlates.

    Objective: To describe the association between age and several aspects of sexual functioning in men older than 50 years of age.

    Design: Cross-sectional analysis of data from a prospective cohort study.

    Setting: U.S. health professionals.

    Participants: 31 742 men, age 53 to 90 years.

    Measurements: Questionnaires mailed in 2000 asked about sexual function, physical activity, body weight, smoking, marital status, medical conditions, and medications. Previous biennial questionnaires since 1986 asked about date of birth, alcohol intake, and other health information.

    Results: When men with prostate cancer were excluded, the age-standardized prevalence of erectile dysfunction in the previous 3 months was 33%. Many aspects of sexual function (including overall function, desire, orgasm, and overall ability) decreased sharply by decade after 50 years of age. Physical activity was associated with lower risk for erectile dysfunction (multivariable relative risk, 0.7 [95% CI, 0.6 to 0.7] for >32.6 metabolic equivalent hours of exercise per week vs. 0 to 2.7 metabolic equivalent hours of exercise per week), and obesity was associated with higher risk (relative risk, 1.3 [CI, 1.2 to 1.4] for body mass index >28.7 kg/m2 vs. <23.2 kg/m2). Smoking, alcohol consumption, and television viewing time were also associated with increased prevalence of erectile dysfunction. Men who had no chronic medical conditions and engaged in healthy behaviors had the lowest prevalence.

    Conclusions: Several modifiable health behaviors were associated with maintenance of good erectile function, even after comorbid conditions were considered. Lifestyle factors most strongly associated with erectile dysfunction were physical activity and leanness.

    Editors' Notes

    Context

    • We know little about age-specific prevalence and correlates of sexual function among U.S. men.

    Contribution

    • Among 31 742 male health care professionals, 74% younger than 59 years of age and 10% older than 80 years of age rated sexual function as good or very good. Moderate or big problems were identified by 12%, 22%, and 30% of those younger than 59 years of age, 60 to 69 years of age, and older than 69 years of age, respectively. Increasing age after age 50 years, inactive lifestyle, obesity, and multiple medical conditions and medications were associated with worse function.

    Implications

    • These cross-sectional analyses show that sexual dysfunction is common, particularly among older men.

    –The Editors

    For decades, diminished sexual function has been taken for granted as a natural part of the aging process. The strong relationship between erectile dysfunction and aging has been demonstrated in observational studies dating back to 1948 (1). For many men, decreases in sexual function are also associated with decrements in quality of life (2-4). With recent advances in treatment and with the growing body of epidemiologic research on the cause of the problem, many cases of erectile dysfunction can be treated and some possibly prevented. The aim of our study was to describe the prevalence and correlates of male sexual function in the four decades of life after 50 years of age. We also estimated the effect of previous erectile function, comorbid conditions, and modifiable risk factors in an effort to examine the causes of age-related erectile dysfunction.

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    Methods

    Participants

    The Health Professionals Follow-up Study (HPFS) is a cohort of male dentists, optometrists, osteopaths, podiatrists, pharmacists, and veterinarians in the United States who responded to a mailed questionnaire in 1986. The response rate for the original survey was 32%. Follow-up questionnaires are mailed every 2 years (5). At the time of the 2000 questionnaire, 43 235 men, age 53 to 90 years, were alive and actively participating in the study. We mailed the questionnaire up to four times to nonrespondents and received 34 282 responses (response rate, 79%).

    Erectile dysfunction among patients with prostate cancer is commonly associated with therapy rather than with the systemic causes thought to account for most other cases of the disorder. Therefore, we excluded from the primary analyses men who reported a prostate cancer diagnosis, which was later confirmed through medical record review, at any date before the assessment of erectile function (n = 2540). Men with missing responses to the primary outcome variable were also excluded from the relative risk analysis (n = 2514). These men tended to be older and have higher prevalence of chronic disease than participants in the present study.

    Outcome Measures

    Sexual Function and Dysfunction

    In 2000, participants were asked to rate their ability in the previous 3 months, without treatment, to have and maintain an erection adequate for intercourse. Response options included very poor, poor, fair, good, and very good. Men with poor or very poor ability were considered to have erectile dysfunction, the primary outcome in these analyses. Additional measures of sexual function, such as desire, ability to reach orgasm, and usual quality of erections, are items modified from the University of California, Los Angeles (UCLA), Prostate Cancer Index (6, 7). In 2000, participants were not queried about the frequency of or opportunities for intercourse; psychosocial function; partner discord; or heterosexual, homosexual, or bisexual preferences.

    Age and Other Independent Variables

    Age during the month when the 2000 questionnaire was returned was calculated from the date of birth ascertained on the 1986 baseline questionnaire. In age-adjusted analyses, 5-year age categories were used. Every 2 years, participants were asked to report their smoking status and the average number of cigarettes smoked per day in the previous year. Men who did not smoke before 1986 and did not report smoking during follow-up were considered never-smokers. Men who reported smoking in the past but were not smoking at the time of the 2000 questionnaire were considered past smokers. Men who reported smoking on the 2000 questionnaire were considered current smokers.

    Because alcohol intake is assessed every 4 years (8), our most recent measure was taken from the 1998 questionnaire. Men reported average consumption of beer, wine, and spirits in the previous year. Response categories ranged from never to six or more servings per day. One serving was equivalent to one glass, can, or bottle of beer; one 4-oz glass of wine; or one measure of spirits. Alcohol content per serving was estimated as 12.8 g for beer, 11.0 g for wine, and 14.0 g for spirits. We calculated intake for each beverage type and summed all values to determine the average total daily alcohol consumption.

    We assessed physical activity on the 2000 questionnaire using a previously validated questionnaire (9). This instrument consists of 10 questions about the average time per week that participants spent doing the following activities in the previous year: walking to work or for exercise; jogging; running; bicycling; lap swimming; tennis; squash or racquetball; calisthenics or rowing, stair, or ski machine; weightlifting or weight machine; and heavy outdoor work. Response options included 13 categories ranging from none to 40 or more hours per week. We also asked the number of stair flights climbed daily and usual walking pace. Metabolic equivalents (METs) were assigned for each type of exercise, and MET hours per week were calculated on the basis of the amount of time participants spent doing each activity. Television viewing time was measured in a similar format. With the same 13 response options, participants were asked to report the amount of time they spent sitting or lying down while watching television. Body size was assessed by using self-reported height and weight (10). Body mass index was calculated as kg/m2.

    On each HPFS questionnaire, participants are asked to report health conditions diagnosed by a physician in the previous 2 years, as well as current medications. Self-reported hypertension and hypercholesterolemia were not further verified, but reports of diabetes, heart disease, stroke, prostate cancer, and other cancer were verified through supplemental questionnaires, medical records, or both. Current medications were measured by using drug class categories, such as β-blockers and tricyclic antidepressants. In each category, the two most popular drugs were listed as examples. We also asked about supplemental use of dehydroepiandrosterone and St. John's wort. As mentioned earlier, we asked participants to rate their ability to have and maintain erections without treatment. Therefore, we did not control for erectile dysfunction treatments in these analyses.

    Statistical Analysis

    We conducted a cross-sectional analysis of erectile dysfunction. Age-stratified frequencies of demographic characteristics, health behaviors, chronic conditions, and many aspects of sexual function are presented. We also present prevalence rates of erectile dysfunction in 5-year age strata.

    Using the Mantel–Haenszel statistic to estimate adjusted relative risks (11), we examined the association of erectile dysfunction with age, health behaviors, and comorbid conditions. Unlike logistic regression, the Mantel–Haenszel procedure estimates the relative risk directly and does not require the rare-disease assumption for the odds ratio to estimate the relative risk. Compatible tests for trend of ordered categorical variables were conducted by using the median values of each variable category.

    Role of the Funding Sources

    The National Institutes of Health provided funding for HPFS general follow-up. Pfizer, Inc., provided funding for the examination of causes of sexual function. One of the coauthors, Dr. Glasser, is employed by Pfizer, Inc. The first and last authors made all final decisions regarding the design, conduct, and reporting of the study and the decision to submit the manuscript for publication.

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    Results

    This group of 31 742 health professionals with no known history of prostate cancer ranged in age from 53 to 90 years at the time of the 2000 questionnaire. As shown in Table 1, men in the oldest age group were less likely to be married, smoke, or engage in physical activity and were more likely than younger men to have comorbid conditions. Table 2 provides unadjusted frequencies and mean ratings for many aspects of sexual function. There is a clear, linear, age-related decline for nearly all of the variables assessed. For instance, mean overall sexual function was equivalent to “good” (mean overall score, 4.1) in the youngest men and declined steadily to “poor” (mean overall score, 1.8) in the oldest group. When men with prostate cancer were excluded, the age-standardized prevalence of erectile dysfunction in the previous 3 months was 33%.

    View this table:
    Table 1. Demographic Characteristics, Health Behaviors, and Comorbid Conditions for 31 742 Health Professionals without Prostate Cancer by Age Group
    View this table:
    Table 2. Sexual Function in 31 742 Health Professionals without Prostate Cancer by Age Group

    Fewer than 2% of men who reported erection problems said that their first difficulty occurred before age 40 years, and only 4% said that it occurred between age 40 to 49 years. After age 50 years, the percentage of men who had experienced their first problems with erection increased sharply—26% in men age 50 to 59 years and 40% in men age 60 to 69 years. The prevalence of erectile dysfunction increased with increasing age. Participants with prostate cancer (2109 for whom data on erectile dysfunction were available) were excluded from all other analyses; however, prevalence of erectile dysfunction in these participants is presented in the Figure because of the stark contrast to the prevalence in other men. Men who remained free of comorbid conditions had the lowest prevalence of erectile dysfunction at all ages. For men younger than 60 years of age who had one or more comorbid condition, the prevalence of erectile dysfunction was double that of healthy men, even when participants with prostate cancer were excluded. Men with a healthy lifestyle and no chronic disease had the lowest risk for erectile dysfunction; the greatest difference was seen for men 65 to 79 years of age.

    Figure. *Chronic disease includes other cancer, heart disease, hypertension, diabetes, or stroke. †Risk factors include antidepressant use, consumption of more than two alcoholic drinks per day, smoking, body mass index ≥ 25 kg/m , exercise <21.5 metabolic equivalents per week, or television viewing >8.5 h/wk.
    View larger version:
    Figure. *Chronic disease includes other cancer, heart disease, hypertension, diabetes, or stroke. †Risk factors include antidepressant use, consumption of more than two alcoholic drinks per day, smoking, body mass index ≥ 25 kg/m , exercise <21.5 metabolic equivalents per week, or television viewing >8.5 h/wk. Reported prevalence of erectile dysfunction in the previous 3 months according to disease status and lifestyle risk factors.2

    To further understand the effects of aging and health on erectile dysfunction, we modeled the relative risk for erectile dysfunction by age for three groups of men: 1) HPFS participants without prostate cancer; 2) a subset of group 1 who reported good or very good erectile function before the study's inception in 1986 and were also free of comorbid conditions before 1986; and 3) a subset of group 2 who remained healthy throughout the study period. The relative increase in the prevalence of erectile dysfunction with age was remarkably similar for all HPFS participants up to age 80 years, regardless of comorbid conditions (Table 3). For example, compared with 55- to 59-year-old men, the relative risk for erectile dysfunction was 5.7 (95% CI, 5.2 to 6.3) among 75- to 79-year-old men in the whole cohort, 5.9 (CI, 5.2 to 6.7) in the subset of men who were healthy at baseline, and 6.1 (CI, 5.0 to 7.4) among men who remained healthy throughout the entire study period.

    View this table:
    Table 3. Relative Risk for Erectile Dysfunction in the Previous 3 Months by Age for Men without Prostate Cancer

    The relative risks for erectile dysfunction associated with modifiable health behaviors are shown in Table 4. We found an inverse association between physical activity and erectile dysfunction (P < 0.001 for trend). Frequent vigorous exercise (>32.6 MET hours per week, the equivalent of running at least 3 hours per week or playing singles tennis 5 hours per week) was associated with a 30% lower risk for erectile dysfunction than was very little or no exercise (<2.7 MET hours per week). Body mass index and television viewing were positively associated with erectile dysfunction. Moderate alcohol consumption and being a nonsmoker were inversely associated with risk for erectile dysfunction. Comorbid conditions most strongly associated with erectile dysfunction, excluding prostate cancer, were diabetes (relative risk, 1.5 [CI, 1.2 to 1.9]), nonprostate cancer (relative risk, 1.4 [CI, 1.1 to 1.6]), and stroke (relative risk, 1.4 [CI, 1.0 to 1.9]). Use of antidepressant medication (relative risk, 1.7 [CI, 1.2 to 2.2]) and β-blockers (relative risk, 1.2 [CI, 1.1 to 1.5]) was also significantly associated with erectile dysfunction.

    View this table:
    Table 4. Cross-Sectional Relative Risks for Erectile Dysfunction in the Previous 3 Months according to Demographic Characteristics, Health Behaviors, and Comorbid Conditions among Men without Prostate Cancer (n= 29 228)

    We conducted an additional analysis of the relationship between physical activity and erectile dysfunction, stratified by 10-year age groups. We found that younger men (<60 years of age) benefit more from exercise than older men (≥ 80 years of age) (age-adjusted relative risk, 0.5 [CI, 0.4 to 0.6] and 0.9 [CI, 0.8 to 1.0], respectively, for >32.6 MET hours per week vs. <2.7 MET hours per week). Negative health behaviors, such as being overweight, watching more than 20 hours of television per week, and smoking, were also more strongly associated with increased risk for erectile dysfunction in younger men.

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    Discussion

    This U.S. study of prevalence and risk factors for erectile dysfunction (the largest to date, to our knowledge) found a 10-fold difference in relative risk for erectile dysfunction associated with older age, regardless of health status or previous erectile function. Comorbid conditions, such as diabetes, cancer, stroke, and hypertension, were also associated with increased risk for erectile dysfunction, whereas physical activity, leanness, moderate alcohol consumption, and not smoking were associated with decreased risk.

    Previous smaller studies have documented the associations of age, disease, and health behaviors with erectile function, but our data on 31 742 men from a wide age range (53 to 90 years) provided the opportunity to estimate more precisely the age-specific prevalence of erectile dysfunction and associated independent risk factors. Our data on erectile function were collected in 2000, after public awareness may have begun to reduce the social stigma associated with this condition. Because the men in HPFS are all health professionals, they may respond more accurately to questions about sexual function and health than the general population.

    Despite these advantages, our study also has some important limitations. As is the case for all cross-sectional studies, it was not possible to establish causality or directionality of the relationship between erectile dysfunction and other variables. In a pilot study conducted in 1998 among a subset of 2072 HPFS participants with no chronic disease, we found that scores on the UCLA Prostate Cancer Index sexual function scale (6, 7) were highly correlated with the single question from that scale assessing erectile function (Pearson and Spearman correlation coefficients, 0.90). As a result, we used only one self-reported question to assess erectile dysfunction in the previous 3 months. We were able to compare the prevalence of various aspects of sexual function across age groups, but these results may not precisely reflect changes in sexual function over time. Cohort effects in men of different ages may be related to cultural norms and attitudes about sex associated with generational influences. It would be valuable to question the same men at different time points after age 50 years to uncover further effects of aging on sexual function.

    A cohort of health professionals has strong advantages for internal validity, but our results may not be generalizable to the entire population of older U.S. men. Men included in this study had lower rates of obesity and less diabetes than same-age men in the general population (12). In addition, participants in our study were more likely to be white, have higher educational attainment, have higher incomes, and have better health care access than similar-age men in the general population. Therefore, our findings probably reflect a more favorable profile for sexual function across the life course compared with the general population (4, 13). Given that caveat, when our results were age-standardized, including prostate cancer cases, to the 2000 census, the expected prevalence of erectile dysfunction among U.S. men older than 50 years of age was 32%.

    In 1987, 1290 men from the Boston area, age 40 to 70 years, responded to a community-based survey as part of the Massachusetts Male Aging Study (14). A subset of these men was surveyed again in 1995. The prevalence of moderate to complete erectile dysfunction ranged from 22% among 40-year-old men to nearly 50% in 70-year-old men. In cross-sectional analyses, smokers had a twofold increased risk for complete erectile dysfunction, but unlike in our study, the researchers found no association between obesity and erectile dysfunction. Heavy alcohol use was minimally associated with increased risk for the disorder.

    Derby and colleagues (15) examined the association between lifestyle behavior changes and erectile dysfunction, also in the Massachusetts Male Aging Study. Although increased physical activity reduced risk, smoking cessation, decreased alcohol consumption, and weight loss were not associated with erectile dysfunction. The nonsignificant findings may be due to the small sample sizes, since only 593 men were included in the prospective analyses. Other researchers have found smoking (16, 17) and lack of physical activity (18) to be associated with higher rates of erectile dysfunction, but the evidence is sparse.

    Definitions of erectile dysfunction vary widely, ranging from dissatisfaction with sexual performance to physical impossibility of intercourse. Additional studies have observed prevalence rates of erectile dysfunction ranging from 2% to 26% among men 50 to 60 years of age (19-27), compared with 10% in our study. Much higher prevalence rates with even more variability have been observed among men older than 70 years of age: 18% to 93% (19, 21-27) compared with 61% in our study. We considered erectile dysfunction to be present only in men reporting poor or very poor function. Other researchers might have included men with fair function, but we chose the more conservative definition. In addition to true risk differences, some of the reported differences observed may be attributed to varying definitions of erectile dysfunction and sampling of participants with prostate cancer. Rates of erectile dysfunction are 10- to 15-fold higher among men with prostate cancer (Figure), especially among younger age groups.

    The relative effect of age remained strong in each of the three groups we compared in Table 3. The slopes of erectile dysfunction by age (Figure) are nearly parallel for men with and without comorbid conditions. The absolute risk for erectile dysfunction was approximately 10% higher at all ages for men with comorbid conditions compared with healthy men. In contrast, nearly all health behaviors had a stronger relative effect on erectile dysfunction among younger men than among older men.

    As shown in Table 4, time spent watching television was significantly associated with erectile dysfunction after we controlled for physical activity and other health behaviors. This result is consistent with studies finding that physical activity and television viewing time have independent effects on adult health outcomes (5, 28-31). We found no association between total sitting time, which included working, traveling, reading, performing at-home tasks, and watching television, and increased risk for erectile dysfunction. This suggests that lengthy television viewing may be a marker of extreme sedentary lifestyle rather than physical damage associated with sitting.

    In general, we found that many risk factors associated with heart disease were also associated with increased risk for erectile dysfunction. A recent review of the vascular mechanisms underlying erectile dysfunction (32) concluded that erectile dysfunction and cardiovascular disease may have some shared pathways based on animal and human models. High cholesterol has also been associated with increased risk for erectile dysfunction (33). Nitric oxide synthesis is inhibited through many age-, disease-, and behavior-related pathways necessary to stimulate smooth-muscle relaxation and increase blood flow necessary for erection.

    Despite general clinical knowledge that conditions such as hypertension and diabetes affect sexual function, we found that much of the erectile dysfunction among older men occurred in those who were healthy. Although the prevalence of erectile dysfunction strongly increased with age, modifiable health behaviors, especially physical activity and leanness, were associated with a reduced risk for erectile dysfunction among men without prostate cancer. If further research can establish causality, preventive heath messages might focus on behavioral steps to maintain erectile function, including avoidance of obesity, smoking, and physical inactivity.

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    Article and Author Information

    • Grant Support: By the National Institutes of Health (grants CA55075 and HL35464) and Pfizer, Inc.

    • Potential Financial Conflicts of Interest:Employment: D.B. Glasser (Pfizer, Inc.); Consultancies: M.A. Mittleman (Pfizer, Inc., and Lily-ICOS); Honoraria: M.A. Mittleman (Pfizer, Inc., and Lily-ICOS); Stock ownership or options (other than mutual funds): D.B. Glasser (Pfizer, Inc.); Grants received: M.A. Mittleman (Pfizer, Inc.), E.B. Rimm (Pfizer, Inc.).

    • Requests for Single Reprints: Constance G. Bacon, ScD, c/o Eric B. Rimm, ScD, Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115.

    • Current Author Addresses: Drs. Bacon, Giovannucci, and Rimm: Department of Nutrition, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA 02115.

    • Dr. Mittleman: Beth Israel Deaconess Medical Center, 1 Autumn Street, Floor 5, Boston, MA 02115.

    • Dr. Kawachi: Department of Health and Social Behavior, Harvard School of Public Health, 677 Huntington Avenue, Boston, MA 02115.

    • Dr. Glasser: Pfizer, Inc., Sexual Health Team, 235 East 42nd Street, New York, NY 10017.

    • Author Contributions: Conception and design: C.G. Bacon, M.A. Mittleman, I. Kawachi, D.B. Glasser, E.B. Rimm.

    • Analysis and interpretation of the data: C.G. Bacon, I. Kawachi, E. Giovannucci, D.B. Glasser, E.B. Rimm.

    • Drafting of the article: C.G. Bacon, I. Kawachi, E. Giovannucci.

    • Critical revision of the article for important intellectual content: C.G. Bacon, M.A. Mittleman, I. Kawachi, E. Giovannucci, D.B. Glasser, E.B. Rimm.

    • Final approval of the article: C.G. Bacon, M.A. Mittleman, I. Kawachi, E. Giovannucci, E.B. Rimm.

    • Provision of study materials or patients: E.B. Rimm.

    • Statistical expertise: C.G. Bacon, M.A. Mittleman, E. Giovannucci.

    • Obtaining of funding: E. Giovannucci, D.B. Glasser, E.B. Rimm.

    • Collection and assembly of data: C.G. Bacon, E.B. Rimm.

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