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Profile of Men Randomized to the Prostate Cancer Prevention Trial: Baseline Health-Related Quality of Life, Urinary and Sexual Functioning, and Health Behaviors

From the Southwest Oncology Group Statistical Center, Division of Public Health Sciences, and Clinical Division, Fred Hutchinson Cancer Research Center, Seattle, WA; Department of Surgery, Brooke Army Medical Center, and Southwest Oncology Group, Operations Office, San Antonio, TX; QualityMetric, Lincoln, RI; New England Medical Center, Boston, MA; Schools of Medicine and Public Health and Jonsson Comprehensive Cancer Center, University of California at Los Angeles, Los Angeles, CA; Department of Health Services, University of Washington, Seattle, WA; and Department of Public Health Sciences, Wake Forest University School of Medicine, Winston-Salem, NC.

Address correspondence to Carol M. Moinpour, PhD, Southwest Oncology Group Statistical Center/MP557, 1100 Fairview Ave North, Box 19024, Seattle, WA 98109-1024; email carolm{at}swog.fhcrc.org

	ABSTRACT

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION REFERENCES

 
PURPOSE: To describe men who agreed to be randomized to the Prostate Cancer Prevention Trial (PCPT), a 7-year, double-blind placebo-controlled study of the efficacy of finasteride in preventing prostate cancer.

METHODS: Comprehensive health-related quality-of-life data are presented for 18,882 randomized PCPT participants.

RESULTS: PCPT participants are highly educated, middle to upper income, and primarily white (92%). Participants reported healthy lifestyles. The mean American Urological Association Symptom Index score was well below the maximum entry score of less than 19; existing urinary symptoms were generally not bothersome. The scores for two sexual functioning scales could range from 0 to 100, with higher scores reflecting worse sexual functioning. The mean score for the Sexual Problem Scale was 19.2 out of 100, and the mean Sexual Activities Scale was 44.1 out of 100. Scores for seven of the eight Medical Outcomes Study 36-item Short-Form Health Survey scales (higher scores are better) were 10 to 20 points higher than those reported by a general population sample and differed minimally by race but not by age. Previously reported associations between sexual dysfunction and hypertension, diabetes, and depression were also observed. Men who never smoked reported less sexual dysfunction than did those who either had quit or still smoked.

CONCLUSION: Individuals who are likely to enroll in primary prevention trials have a high socioeconomic status, healthy lifestyle behaviors, and better health than the general population. These data help oncologists design chemoprevention trials with respect to the selection of health-related quality-of-life assessments and recruitment strategies.

	INTRODUCTION

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THE PROSTATE CANCER Prevention Trial (PCPT) is a randomized, double-blind, placebo-controlled study of the efficacy of finasteride in preventing prostate cancer. The Southwest Oncology Group is coordinating this intergroup chemoprevention trial, supported by the Eastern Cooperative Oncology Group and the Cancer and Leukemia Group B. The study was funded by the National Cancer Institute, Division of Cancer Prevention and Control, now part of the newly established Early Detection and Community Oncology Program in the Division of Cancer Prevention. The use of a 5-alpha-reductase inhibitor (finasteride) as a chemopreventive agent represents a shift from secondary prevention efforts, such as early detection and treatment of prostate cancer, to primary prevention. The scientific rationale for the selection of finasteride as a chemopreventive agent has been documented elsewhere.^1-4

Health-related quality of life (HRQL) reflects dimensions of functioning that may be affected by medical conditions and their treatment.^5,6 Dimensions measured by most HRQL questionnaires are based on the World Health Organization’s definition of health: "Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity."⁷ HRQL outcomes are of interest in clinical trials that examine both treatment and prevention. Cardiovascular treatment trials were among the first to include measures of HRQL outcomes.^8-14 Assessment of HRQL in cancer treatment gained momentum in the late 1980s and early 1990s.^15-18 Because participants are healthy and long intervention periods are usually required in a primary prevention research setting, it is important to monitor effects on HRQL. Monitoring side effects becomes particularly important when chemopreventive agents are administered. By collecting HRQL data, researchers convey their concern with monitoring functioning and well-being of participants on the trial,¹⁹ and recent trials have included comprehensive HRQL assessments.^20-26 A comprehensive HRQL assessment should also address relevant positive and negative health behaviors (eg, consumption of fruits and vegetables, smoking status); these data can serve as important covariates in both observational and randomized studies. For example, data support a protective effect for physical activity on the incidence of prostate cancer.²⁷

The purpose of this article is to report baseline characteristics of PCPT participants for demographic status, health behaviors, HRQL (urinary and sexual function and general quality of life) and to examine relationships between comorbid medical conditions (diabetes, hypertension, and depression) and smoking status, and baseline measures of physical and mental health and sexual functioning. After completion of the trial in 2004, investigators will report HRQL and symptom data by treatment arm. One aim of this article is to reinforce the inclusion of comprehensive HRQL measures in large samples of males in the United States (US) and to emphasize their value for public health policy decisions about chemopreventive interventions.

	METHODS

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Trial Design
The PCPT is a randomized, double-blind, placebo-controlled trial designed to evaluate whether finasteride can reduce the incidence of prostate cancer over a 7-year period.⁴ The multicenter study includes 219 participating centers from the Southwest Oncology Group (107 centers), the Eastern Cooperative Oncology Group (77 centers), and the Cancer and Leukemia Group B (35 centers) in the United States and Canada. Approximately 25,000 men were required for enrollment in order to randomize 18,000. This sample size is necessary for 90% power to detect a 25% treatment arm difference in the proportion of positive biopsies after 7 years of study treatment. Enrollment began in October 1993 and ended in December 1996. A 3-month placebo run-in period was included to assess participant adherence to the drug schedule. At the end of this period, participants who had adherence rates of 80% to 120% and met other trial eligibility requirements (see below) were randomized to receive finasteride or placebo daily for 7 years. Randomizations occurred between January 1994 and May 1997. Two clinic visits are required per year interspersed with two telephone calls to monitor safety and adherence to trial requirements and to collect outcome data. Every year participants complete a battery of questionnaires addressing demographic status, health behaviors, and HRQL (urinary and sexual function and general quality of life). Figure 1 and Table 1 contain information about the specific questionnaires and the timing of the assessments.

View larger version (18K): [in this window] [in a new window]   Fig 1. PCPT schema. Abbreviations: DRE, digital rectal examination; PSA, prostate-specific antigen.

Analytic Approach
A total score for a patient-completed scale was considered missing if more than 20% of the items were left blank. If fewer than 20% of the items in a scale had no responses, the mean of the remaining items was substituted for any missing items. Internal consistency reliability was determined for each patient-reported scale score using Cronbach’s coefficient alpha.⁴³ Questionnaire submission rates are presented for the first 3 years of the trial only.

Data are presented descriptively in this article for (a) age (above and below median age of 63 years); (b) African-American participants; (c) enrolled but not randomized (eg, ineligible, lost interest, moved, and so on); and (d) total randomized sample. Nearly half of the randomizations occurred during the first 6 months of randomization (January 1994 through June 1994). Data presented in this article were also examined to see whether there were any differences in this initial bolus of randomizations versus those randomized during the remainder of the recruitment period after June 1994. Given no substantial differences for this group, these data are not presented in this article.

Correlations were calculated for the two Medical Outcomes Study (MOS) 36-item Short-Form Health Survey (SF-36) summary indices, the Physical Component Scale (PCS) and the Mental Component Scale (MCS), and the Sexual Activity and Sexual Problems total scores. MOS data for the Sexual Problems Scale and the SF-36 were provided for comparisons with our sample by John E. Ware, Jr, for a PCPT HRQL advisory meeting (August 1994). The MOS data included only patients who were 55 years of age or older from the US general population as well as those who were visiting a physician for either minor or serious medical conditions. (PCS and MCS scores below 50 reflect physical functioning or mental health below that of the general US population. PCS and MCS scores above 50 are better than those reported by members of the general population. Each difference of one point for a summary score represents one tenth of an SD.²⁸ ) We also calculated effect sizes⁴⁴ (the differences between means divided by the SD of the MOS reference group measure) to compare SF-36 individual and summary scale scores for PCPT participants and the MOS normative samples. Effect sizes of 0.5 to 0.8 are considered moderate to large.⁴⁴

A priori hypotheses based on the literature predicted that sexual dysfunction would be greater for participants who had hypertension, diabetes, or depression or who were current smokers. These hypotheses were examined in two ways: (a) descriptive statistics for participants with or without the comorbidity and (b) tests of association (²) between dichotomized versions of each scale (above and below the median total score) and each comorbidity. We used ² tests to examine the association between the dichotomous sexual functioning scales and three smoking categories (never smoked at least 100 cigarettes in lifetime v did smoke at least 100 cigarettes in lifetime but quit v current smoker). The effect of length of quit time on sexual function was also examined using a generalized linear model. All statistical analyses were carried out using the Statistical Analysis System.⁴⁵

	RESULTS

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Questionnaire Submission Rates
Submission rates for the urinary and sexual functioning questionnaire during the first 2 years of the trial were as follows: enrollment, 100%; randomization, 99.9%; 6 months, 93.6%; 1 year, 92.3%; 2 years, 89.3%; and 3 years, 89.5%. Submission rates for the SF-36 were as follows: enrollment, 100%; 6 months, 92.8%; 1 year, 92.5%; 2 years, 89.3%; and 3 years, 89.5%.

Demographic Status
Table 3 lists demographic data for two groups of men: the total randomized sample of 18,882 and the 708 African-American randomized participants, the largest single minority group in the PCPT. Eight percent of the randomized participants are members of a racial or ethnic group; 4% are African American. For the total randomized sample, participants range from 55 to 86 years of age, with a median age of 63. The age of African-American participants is similar to that of the total randomized sample, with a median of 61 and a range of 55 to 84 years. PCPT participants are highly educated. Education is similarly distributed for African-American participants; the largest discrepancy is for the postgraduate education category. Demographic distributions for the total randomized sample and African-American participants are most dissimilar for income categories, with the African-American group having considerably more participants in the lower income category. Only the age distribution differed for participants enrolled but not randomized versus those randomized, with 50% of the nonrandomized group 60 to 64 years of age. Most PCPT participants are currently married; there are fewer African-American participants in the currently married category. Finally, 85% of the men in the PCPT do not have first-degree relatives with prostate cancer.

Diet
Table 4 also lists the percentage of participants reporting frequent consumption of the following high-fat foods: three types of red meat, whole milk (excluding milk on cereal), cheese (excluding cottage cheese), and sweet diet items (pastries, doughnuts, cookies, cake). For the relatively healthy PCPT sample, there was little consumption of these sources of fat on such a frequent basis (eg, < 1% red meat consumed five times a week or more). At baseline, 12% of the total randomized participants drank whole milk regularly and close to 20% of participants consumed desserts and sweet food items almost daily. African-American participants reported eating less cheese and sweet diet items on a regular basis.

Physical Activity
Table 4 lists responses to one of the six PCPT physical activity items. Eighty percent of PCPT participants reported being at least "fairly active" in the past 4 weeks. In fact, almost 50% reported walking daily or as much as three or more times a day; 30% reported walking for longer than 30 minutes; 31% reported walking "fast" or "very fast" (data not shown). A "social desirability" question (data not shown) about levels of general activity (eg, hobbies, social activities) showed even higher percentages of respondents reporting "very active" (33%) and "extremely active" (11%) than the physical activity item listed in Table 4. The distributions of physical activity response categories are relatively similar for the different groups of participants.

Lipid Levels
Table 4 also lists descriptive data for total cholesterol and high-density lipoprotein cholesterol. Total cholesterol values are slightly lower for participants 63 years of age or older. Total cholesterol values for African-American participants mirror those of men younger than 63 and are slightly higher for high-density lipoprotein cholesterol regardless of the comparison group.

HRQL
Urinary functioning. Table 5 lists data for two urinary functioning and two sexual functioning measures. The mean American Urological Association (AUA) Symptom Index Score was 6.7 for the total randomized sample. A mean score of 6.7 reflects minimal problems with urinary functioning and is expected because participants for the trial were required to have AUA Symptom Index scores of less than 20 in order to be randomized. Impact of urinary symptoms on functioning was assessed with the Benign Prostatic Hyperplasia Impact Index (BII). The mean BII score was 1.0, indicating that reported urinary functioning symptoms were not particularly bothersome. Adequate internal consistency reliability was demonstrated for the AUA Symptom Index (coefficient alpha = 0.74) and the BII (coefficient alpha = 0.78). Men 63 years of age and older reported more urinary functioning problems and more bother associated with these problems than did men younger than 63. Men enrolled but not randomized had higher mean AUA Symptom Index and BII scores than randomized men.

SF-36 Health Survey. Table 7 lists SF-36 data (eight SF-36 scales and two SF-36 summary scales, PCS and MCS) for the following variables: two age categories, African Americans, PCPT participants enrolled but not randomized, PCPT randomized sample, and MOS normative data. PCPT participants reported better physical functioning, better role functioning associated with physical status, less pain, and better perceived health than the MOS general population sample. These differences in HRQL between PCPT participants and the MOS normative sample represent moderate to large effect sizes as defined by Cohen.⁴⁴ The effect sizes for the two measures of emotional functioning, the Mental Health Index dimension score and the MCS, are smaller but worthy of notice. The difference by age observed for urinary and sexual functioning and health behaviors is not evident for the HRQL measures, although there are slightly higher mean scores for the younger group for the Physical and Role-Physical scales. The SF-36 mean scores for African-American participants are slightly lower than those for the PCPT population but higher than those for men in the MOS normative sample. SF-36 mean scores for randomized versus nonrandomized men were similar. Internal consistency reliability was acceptable for six of the SF-36 scales (coefficient alphas ranged from 0.73 to 0.90). Internal inconsistency reliabilities for the social function (r = .67) and role function associated with physical status scales (r = .69) were lower than the generally held standard of 0.70 for coefficient alpha.⁴⁶

Correlations between each of the sexual functioning and SF-36 measures were small: MCS and the Sexual Activity Scale, -.13; MCS and the Sexual Problems Scale, -.14. The correlation was -.21 between the PCS and each sexual functioning scale. The direction was as predicted (more sexual dysfunction associated with lower HRQL scores). The two measures of sexual dysfunction were highly positively correlated (r = .72). As expected, the PCS and MCS were not highly correlated (-.11).

Comorbidity and HRQL
Table 8 lists descriptive statistics for the two sexual functioning measures by three comorbid medical conditions and smoking status. As hypothesized, mean Sexual Activity and Sexual Problems scores were higher (indicating worse sexual function) if the participant had any of the three comorbid conditions. Participants who had never smoked had the best scores for the two sexual functioning scales, "quitters" had intermediate scores, and current smokers had the worst scores. ² tests of the association between each of the two sexual function measures and hypertension, diabetes, depression, and smoking status were all statistically significant (P < .001 in all cases). The longer the quit period, the better the sexual functioning score, even after adjustment for age, PCS, MCS, hypertension, and diabetes.

	DISCUSSION

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HRQL assessments are useful in primary prevention trials to document that participation does not compromise the status of healthy enrollees over the course of the trial. HRQL assessments also help characterize those who volunteer for prevention trials. Clearly, the men who volunteered for the PCPT represent primarily a white group, who are healthier than average and have higher HRQL or health status scores than do men of similar age in the general population. These men have adopted behaviors designed to improve their health. Witness (a) the small percentage of randomized participants who are still smoking, (b) the modest alcohol consumption, (c) the consumption of low-fat foods, and (d) the high levels of physical activity. This characterization is consistent with data reported for other prevention trials, such as the Breast Cancer Prevention Trial²³ and the Postmenopausal Estrogen/Progestin Interventions trial.²² Participants report middle to upper-middle socioeconomic status based on census data estimates of income and are relatively well educated. We might expect PCPT participants to have more positive HRQL scores than those reported by the MOS normative sample, for example, given that trial eligibility criteria screened out men with significant comorbidities.⁴⁰

We also demonstrated that men enrolled but not randomized were similar to those randomized for most of the variables considered in this report. The observed differences for urinary symptoms and their degree of bothersomeness are likely due to some of the nonrandomized men having AUA Symptom Index scores above the cutoff for participation (ie, scores of 20).

Average lipid levels were similar to the total serum cholesterol mean value of 209 (SD, 49) reported for the Massachusetts Male Aging Study survey for men who ranged in age from 40 to 70 years⁴⁷ and less for three of four age groups studied in the Lipid Research Center Prevalence Study–North America.⁴⁸ These comparisons must be qualified because we do not know the extent to which PCPT participants were taking cholesterol-lowering drugs. However, about 40 million individuals in the US who have total cholesterol values of greater than 240 mg/dL. Of these, only about 2.5% are taking such medications. An estimated 14% of individuals who have symptoms of myocardial ischemia are taking lipid-lowering medications.⁴⁹ Although PCPT participants seem healthier than the general population (MOS normative sample) on most HRQL measures, their serum cholesterol levels at enrollment were similar to averages reported for one of the two large population studies cited earlier.

In the PCPT, urinary and sexual functioning symptoms were of particular interest. Urinary functioning can be compromised in older men for a variety of reasons, particularly for enlarged prostate conditions such as benign prostatic hyperplasia (BPH).^50,51 Finasteride was first developed to treat BPH.^52,53 The impact of finasteride on BPH is a secondary trial end point. Sexual functioning is of interest because up to 5% of men have reported dysfunction in libido, potency, and ejaculate volume while taking finasteride in trials conducted with this agent.^52,53 We know that sexual dysfunction varies with age⁴⁷ and with unhealthy behaviors (eg, smoking)⁴⁷ and comorbid conditions and their treatment.^47,54 Sexual dysfunction (impotence, loss of libido, and reduced ejaculatory volume) increased over a 2-year period for PCPT participants on the placebo arm.⁵⁵ Our analysis of PCPT participants also showed that sexual dysfunction was substantially greater for men with three such medical conditions (hypertension, diabetes, and depression) and one unhealthy behavior (smoking). Sexual dysfunction was positively associated with cigarette smoking (mechanism believed to be through the action of nicotine on the vascular system⁴⁷) and negatively associated with quit time for PCPT participants. Our data suggest that hypertension, diabetes, and depression have a greater impact on sexual functioning than on more general areas of functioning as measured by the SF-36 PCS and MCS, consistent with other data reported for American men.^56,57 In the Wagner et al⁵⁶ study, preliminary data suggested an effect of comorbid conditions on general HRQL for men in the United Kingdom. We did not collect duration of sexual dysfunction, an important variable in the Wagner et al study.

The PCPT is the single largest study of prostate cancer prevention currently being conducted in the US and Canada, with almost 25,000 men enrolled on the PCPT and nearly 19,000 men randomized to a trial lasting 7 years. It is important to document for future prevention research efforts that HRQL assessment is feasible in trials of this size. One feasibility measure is participant willingness to complete HRQL questionnaires. PCPT questionnaire submission rates indicate that the men were, and continue to be, willing to complete required questionnaires. Another feasibility measure is documentation that selected HRQL questionnaires were appropriate for prevention trial participants. Measurement properties for PCPT participant–completed questionnaires were adequate for group-level comparisons; that is, in general, the internal consistency reliabilities of these scales were 0.70.⁴⁶ Two of the eight SF-36 scales (Social Functioning and Role Functioning–Emotional) did not meet this criterion. One reason could be a suggestion of a ceiling effect for these two areas of functioning in our healthy sample, a factor that can contribute to lower internal consistency reliability.⁴⁶ Internal consistency reliability was also lower than desired for the Sexual Activity Scale (developed in-house). However, PCPT data did support the sensitivity to group differences (discriminant validity with respect to presence or absence of comorbid medical conditions) of both sexual functioning scales, an important measurement property for HRQL scales in clinical trials.

Four percent of PCPT participants are African American; overall, minority participants make up 8% of the PCPT randomized sample. Substantial effort was expended to recruit the 8% of minorities represented in the PCPT.⁵⁸ Recruitment of African-American men was emphasized because this minority group is particularly at risk for prostate cancer. Data presented in this article indicate that the profile of African-American participants is similar to that of the overall randomized sample for the trial regarding HRQL, urinary and sexual function, and health behaviors. The PCPT has attracted African-American men who are also interested in their health and who are on average healthier than men of their age in the general population.

We conclude from an examination of these data that the men who made a 7-year commitment to the PCPT already were concerned about their health and were practicing healthy behaviors. They reported better HRQL than men in the MOS normative sample. The challenge for the PCPT is to maintain participants’ interest in their health and to communicate the importance of the trial’s research information for improving the health of both current participants and future generations of men. At the outset of this trial, we selected finasteride as a preventive agent for its safety profile as well as the scientific rationale for its potential as a cancer prevention agent. Should finasteride prove to be an efficacious means of preventing prostate cancer, we would want to know long-term effects of its use on participant functioning and well-being. Given data that support chemopreventive efficacy, comprehensive HRQL data can inform the public health debate about tradeoffs associated with widespread use of chemopreventive agents such as finasteride. PCPT baseline data can inform oncologists who are designing cancer prevention trials about the type of participants likely to be recruited to such trials and the feasibility of including HRQL assessments with healthy populations.

	ACKNOWLEDGMENTS

 
Supported by Public Health Service grants no. 5 U10 CA37429 and 2 U10 CA37429-09 from the National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, MD.

We thank Anita Stewart, PhD, for her guidance in the assessment of physical activity, Ellen R Gritz, PhD, for her assistance in the assessment of smoking status, Alan R. Kristal, Dr PH, for his assistance in interpreting food consumption as measured in the Health Behaviors Questionnaire, Susan G. Nayfield, MD, for her review and suggestions regarding the patient-completed measures, Jeffrey Probstfield, MD, for consultation regarding the lipid data, Huguette Redinger for her assistance in preparing the manuscript, and PCPT Clinical Research Associates and nurses who administered the HRQL questionnaires.

	NOTES

 
Funding for active drug and placebo and small grants for recruitment and adherence activities provided by Merck & Company.

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Submitted March 4, 1999; accepted January 5, 2000.

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