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

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. 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 -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 MantelHaenszel 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 MantelHaenszel 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. 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%. Table 1. Demographic Characteristics, Health Behaviors, and Comorbid Conditions for 31 742 Health Professionals without Prostate Cancer by Age Group 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 sharply26% 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