Journal of Gerontology: MEDICAL SCIENCES
1998, Vol. 53A, No. 3, M195-M200
Copyright 1998 by The Cerontological Society ofAmerica
Preferences of Elderly Men for Prostate-Specific
Antigen Screening and the Impact of Informed Consent
Andrew M.D. Wolf, and John B. Schorling
Department of Medicine, University of Virginia School of Medicine, Charlottesville.
Background. Use of the prostate-specific antigen (PSA) as a screening test remains highly controversial, particularly in older men. This study was undertaken to assess the impact of information on the preferences of older men for
such screening.
Methods. The elderly cohort (age >65 years) of a larger randomized trial was studied to determine the effect of a 3minute scripted informational intervention on primary care patients' interest in PSA screening and on potential predictors of screening interest.
Results. Informed patients were significantly less interested in screening than were uninformed patients {p - .006).
Informed patients considered PSA screening to be significantly less efficacious than did uninformed patients (p =
.004), but among both uninformed and informed patients, perceived efficacy correlated with interest in screening (multivariate OR 2.3, 95% CI 1.5-3.8 for uninformed patients; OR 2.2, 95% CI 1.3-3.9 for informed patients). Perceived
seriousness of prostate cancer predicted interest in screening among uninformed patients (OR 1.8, 95% CI 1.3-2.6),
but not among informed patients. Informed patients who were married were less interested in screening than those who
were single, divorced, or widowed (OR 0.3, 95% CI .08-0.9). Marital status did not predict screening interest among
uninformed patients.
Conclusions. Involving elderly patients in the decision whether to screen with the PSA by providing them with
information leads to a significant reduction in interest in such screening. Factors that appear to influence the screening
preferences of informed elderly patients include perceived efficacy of screening and marital status, whereas uninformed patients are more likely to weigh the perceived seriousness of prostate cancer in their screening decision.
QCREENING for prostate cancer with the prostatev 3 specific antigen (PSA) is one of the most controversial
issues in the area of cancer detection. On the one hand, the
burden of suffering from prostate cancer remains tremendous: It is the most frequently diagnosed cancer among men,
accounting for 41% of new cancer diagnoses, and is the second leading cause of cancer death (1). Moreover, the operating characteristics (sensitivity and specificity) of the PSA
compare favorably to other commonly used cancer screening
tests (2), and the PSA has been found to detect cancer at an
earlier stage than with digital rectal exam alone (3). On the
other hand, it has not yet been convincingly demonstrated
that screening with the PSA leads to improved patient-oriented outcomes, including decreased all-cause mortality and
cancer-specific mortality, or improved quality of life, and
randomized trials to address these concerns are at least a
decade from completion. Nowhere is the controversy surrounding PSA screening more acute than in its use with
elderly men. Clearly, prostate cancer incidence increases
with age (4), so the opportunity for early detection is potentially greater in elders. Yet, the risk of complications of early
intervention is higher in the elderly population (5), and
greater comorbidity, together with the long latency period of
many prostate cancers, raises the likelihood that early intervention may not lead to improved patient-oriented outcomes.
Indeed, while some authorities do not recommend routine
PSA screening for patients of any age (6,7), even proponents
of screening do not recommend it for patients with life
expectancies under 10 years (8). Recent evidence based on
risk-benefit modeling suggests mat potential harms may outweigh benefits even by age 70 (9).
Despite the great uncertainty, it appears that elderly men
are the most likely to undergo PSA testing. In a recent
analysis of PSA test utilization in Olmsted County, Minnesota, utilization rates were highest for men age 70 to 84
years; even men age 85 years and older were more likely to
undergo PSA testing than men under the age of 65 years
(10). While it is not known how much of this PSA testing
was for evaluation of symptoms rather than for screening, it
is likely that screening accounted for a large proportion of
the test ordering.
Given that the uncertainty regarding PSA screening will
not diminish until well after the millennium, and that
screening elderly men will remain particularly problematic,
physicians who offer such screening are obligated to
involve their patients in the screening decision. Accordingly, it behooves clinicians to better understand their
elderly patients' preferences for PSA screening. This analysis was undertaken to assess the preferences of elderly men
for PSA screening and to examine the impact of an
informed consent discussion on these preferences. To help
clinicians better understand which factors elderly patients
consider important to their screening decision, potential
predictors of PSA screening interest were sought. This
analysis is derived from a larger randomized trial that
examined the preferences of primary care patients age 50
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WOLF AND SCHORLING
years and over (11); however, as PSA screening is particularly controversial in elderly men, specific attention to this
segment of the population is clearly warranted.
METHODS
This analysis focuses on the elderly cohort (age 65 years
and older) of a randomized controlled trial that examined
the impact of an informational intervention on patient interest in PSA screening. The study involved 205 men, 104 of
whom were elderly, who had no history of prostate cancer
and had never been screened with the PSA. They visited one
of four university-affiliated primary care practices between
June 1994 and March 1995 for routine appointments. The
men randomly received either a scripted overview of PSA
screening or a brief control message, both read aloud by a
trained research assistant. The methodology of the randomized trial and the content of the informational intervention
have been reported previously (11). Key elements of the
information included the lifetime probability of developing
and dying from prostate cancer, known risk factors for
prostate cancer, likelihood and implications of an abnormal
PSA result, usual evaluation of an abnormal result, and the
uncertain benefits and common complications of early
prostate cancer treatment.
Baseline sociodemographic information, including age,
race, education, income, and marital status, was collected
from both intervention and control patients prior to randomization. Family history of prostate cancer and self-perceived health status were also elicited. Following randomization and delivery of the intervention or control message,
patient interest in undergoing PSA screening was determined using a 5-point Likert scale (from definitely not
interested to definitely interested). In addition, patients
were queried regarding potential predictors of interest derived from the Health Belief Model (12). These factors—
including perceived seriousness of the underlying disease,
perceived susceptibility to the disease, perceived efficacy of
screening in terms of improved health outcome, and perceived barriers to screening—have been shown previously
to predict other types of cancer screening behavior (13,14).
Finally, both intervention and control patients were administered the following risk-benefit tradeoff question: "How
willing would you be to undergo treatment for prostate cancer if the doctor thought you could be cured but wasn't
sure, and the treatment had a 25% (1 in 4) chance of causing impotence (inability to have an erection) and a 5% (1 in
20) chance of incontinence (leakage of urine)?" The complication rates used in the question were based on published
studies available at the time of the survey, and responses
were measured on a 5-point Likert scale from very willing
to very unwilling.
Baseline patient characteristics in the informed and uninformed elderly cohorts were compared using the two-tailed
/-test for continuous variables and chi-square test for categorical variables. To determine the impact of the informational intervention on PSA screening interest, differences in
mean interest between uninformed and informed elderly
patients were analyzed using the two-tailed f-test. Differences in screening interest between elderly and nonelderly
patients were examined using the two-tailed /-test and two-
way analysis of variance (for differences by age group and
intervention group). Potential predictors of interest in PSA
screening in the entire elderly cohort were examined with
chi-square testing using the Mantel-Haenszel test for linear
association. Factors found to be significantly associated
with screening interest from these bivariate analyses were
included in a multivariate model using stepwise ordinal
logistic regression, because interest in PSA (the outcome
variable) was measured on a 5-point scale and was not normally distributed. Multivariate associations are reported as
odds ratios (OR); ordinal logistic regression assumes a constant OR for each outcome category, in this case interest
level in PSA screening.
To explore how the information affected patient preferences for screening, potential predictors of interest were
sought by separately analyzing patient characteristics in the
informed and uninformed cohorts, using the Mantel-Haenszel test for linear association. Results are presented for the
bivariate analyses that yielded significant associations for
either or both of the informed and uninformed groups.
These factors were then used to develop two multivariate
predictive models (one for each of the study arms) with
interest in PSA as the outcome variable. Ordinal logistic
regression was used to create the prediction models, and
results are expressed as odds ratios with 95% confidence
intervals (CI). All significance testing was two-tailed.
RESULTS
Baseline characteristics of the elderly primary care patients in this trial are shown in Table 1. There were no statistically significant differences between the informed and
uninformed patients. The majority of patients did not graduate from high school, had family incomes of under $15,000,
were married, and had Medicare as their only medical insurance. There was also no difference in self-perceived health
status between informed and uninformed patients.
Interest in PSA screening was significantly lower among
elderly patients who received the informed consent intervention than in control (uninformed) patients. As depicted
in Figure 1, mean interest in screening was 2.8 on the 5point scale among informed patients and 3.6 among uninformed patients (p = .006); this translates into a 20%
diminution in interest in informed compared with uninformed patients.
Table 1. Baseline Characteristics:
Uninformed Versus Informed Elderly Patients*
Age, yr (SD)
Percent
Minority
Non-high school graduates
Family income < $15,000
Married
Medicare only insurance
Family history prostate cancer
Uninformed
Patients
(n = 56)
Informed
Patients
(n = 48)
71.5(4.9)
73.2 (6.7)
35.7
64.3
72.2
69.6
76.8
31.3
66.7
73.9
58.3
83.3
10.4
9.1
*No differences were significant at p-value < .05.
PSA SCREENING IN ELDERLY MEN
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I informed
Mean Interest
Uninformed 3.6
Informed
2.8
P = 0.006
D uninformed
High
Low
50-64
2
3
4
Interest in PSA Screening
Figure 1. Elderly patients' interest in prostate-specific antigen screening.
There were no significant differences in screening interest between younger (age 50-64 years, n = 101) and older
(age 65 years and older, n = 104) patients. Mean interest
among younger patients was 3.6 on the 5-point scale, as
compared with 3.2 for older patients (p = 0.1). As shown in
Figure 2, the effect of the informational intervention was
similar for younger and older patients, lowering interest
significantly in both groups. Two-way analysis of variance
confirmed no significant interaction between age and intervention group for screening interest (p = 0.9).
Potential predictors of interest in PSA screening in the
entire elderly cohort are presented in Table 2. Informed
patients, older patients, and patients who considered themselves healthier were significantly less interested in screening in the bivariate analyses. However, when these three
factors were entered in a multivariate model, only the informational intervention remained a significant predictor of
screening interest. To understand why better health was
associated with lower screening interest, potential relationships between self-perceived health status and other patient
factors were explored. There was a weak negative correlation between health and perceived susceptibility to prostate
cancer (r = -.17, p = .09) and between health and willingness to accept treatment risks (r = -. 16, p = . 10).
Informed patients considered PSA screening to be significantly less efficacious than did uninformed patients (p =
.004 for difference). There were no significant differences
between uninformed and informed patients in perceived
seriousness of prostate cancer, perceived susceptibility to
prostate cancer, barriers to screening, and willingness to
accept treatment risks.
Predictors of interest in PSA screening among uninformed
(control) and informed elderly patients are shown in Table 3.
Among uninformed patients, perceived seriousness of prostate
cancer, willingness to accept prostate cancer treatment risks
for potential cure, and perceived efficacy of screening all predicted interest in screening. Among informed patients, as with
uninformed patients, perceived efficacy of screening predicted
interest. In addition, perceived susceptibility to prostate cancer
was positively correlated with screening interest and being
married was negatively correlated. Age was not associated
65 & over
Age Group (years)
Figure 2. Comparison of younger and older patients' interest in
prostate-specific antigen screening by intervention group (informed vs
uninformed). While information lowered interest significantly in both age
groups, there was no significant interaction between age and intervention
group for interest in screening (p = 0.9 by two-way analysis of variance).
Table 2. Predictors of Interest in PSA Screening:
Entire Elderly Cohort (N = 104)
Bivariate
p- value*
Adjusted
Odds Ratio
95% Clf
Significant in multivariate analysis
Informational Intervention
.007
0.4
0.2-0.8
Significant in bivariate analysis only
Age
Perceived health status
.05
Not significant (p > .05)
Education
Race
Household income
Marital status
Family history of prostate cancer
n.s.
n.s.
n.s.
n.s.
n.s.
Predictor
.04
*Mantel-Haenszel test for linear association.
fCI = confidence interval; adjusted for age and perceived health status.
Table 3. Bivariate Predictors of Interest in PSA Screening:
Uninformed Versus Informed Patients
Bivariate p- value*
Predictor
Perceived seriousness
Willingness to accept treatment risks
Perceived efficacy of screening
Perceived susceptibility to prostate cancer
Marital status
Uninformed
Patients
(« = 56)
Informed
Patients
(n = 48)
.005
.04
.008
n.s.
n.s.
n.s.
.0002
.002
n.s.t
.02
*Mantel-Haenszel test for linear association,
fn.s. = not significant (p > .05).
with screening interest in either uninformed or informed
cohorts. However, in patients age 75 years and older, there
was a strong trend toward decreased interest among informed
patients (p for difference in mean interest .06).
Table 4 presents the results of the multivariate analyses for
the uninformed and informed cohorts. Perceived efficacy
WOLF AND SCHORLING
M198
remained a significant predictor of screening interest among
both uninformed and informed patients. Perceived seriousness remained a predictor among uninformed patients,
whereas willingness to accept treatment risks was no longer
predictive. Marital status remained predictive of screening
interest in the informed cohort, with the OR of 0.3 indicating
that married patients were less likely to desire PSA screening. Perceived susceptibility to prostate cancer no longer
predicted screening interest among informed patients.
DISCUSSION
Given the great uncertainty about whether prostate cancer screening benefits elderly patients, providing these
patients with information about the benefits and burdens of
screening is critical. The principal finding of this study was
that the provision of such information resulted in a significant decrease in interest in PSA screening. In the elderly
cohort as a whole, two other factors—age and self-perceived health status—also predicted interest in screening.
Advancing age was associated with a dropoff in interest,
which is not surprising in that the informational intervention specifically mentioned that many physicians do not
recommend screening beyond 75 years. Somewhat surprisingly, patients with better self-perceived health were less
interested in screening. This may be partly explained by the
finding that healthier patients perceived themselves to be
slightly less susceptible to prostate cancer and were somewhat less willing to chance impotence or incontinence—the
principal risks of early prostate cancer treatment—than
were patients who perceived their health to be poorer. In the
multivariate model, however, only the informational intervention predicted interest in screening.
Comparing the elderly and nonelderly cohorts, there was
no significant difference in PSA screening interest. Moreover, the informational intervention had a similar impact on
both younger and older patients, significantly diminishing
interest in screening. It appears that receiving information
had a greater impact than age on patients' screening interest.
Are there any characteristics of elderly patients that predict interest in PSA screening? Based on our analysis of the
uninformed (control) patients, the perception that screening
is efficacious, the perception that prostate cancer is serious,
and greater willingness to accept treatment risks for potential cure all predicted interest, though the latter factor was
not significant in the multivariate analysis. No sociodemographic variables such as age, race, education, income, or
marital status helped to predict interest.
How did the provision of information about prostate
cancer and PSA screening alter these predictors? First,
informed patients considered PSA screening to be significantly less efficacious than did their uninformed counterparts. This is not an unexpected finding in that the informational intervention included a discussion of the uncertainty
as to whether early intervention in prostate cancer improves
survival or quality of life, and discussed the risks of early
prostate cancer treatment. Second, although the informed
cohort, on the whole, perceived PSA screening to be less
efficacious, efficacy still correlated with interest in being
screened; that is, among informed patients, the more efficacious they considered the test, the more interested they
were in having it. Third, the perception that prostate cancer
is serious and willingness to accept treatment risks did not
factor into informed patients' interest in screening. This is
likely due to the elements of the informational intervention
that emphasized the highly variable natural history of
prostate cancer and the risks of impotence and incontinence
with treatment of early-stage disease. Fourth, informed
patients who were married were less likely to be interested
in screening than their single, divorced, and widowed counterparts. This may be due to concern over impotence, as one
survey relating to treatment of early-stage prostate cancer
found that a majority of men were willing to sacrifice
extension of life expectancy for maintenance of sexual
potency (15). Fifth, among informed patients, in contrast to
uninformed patients, perceived susceptibility to prostate
cancer was associated with interest in screening, although
this relationship did not persist in the multivariate analysis.
By informing patients that advancing age, family history,
and Black race increase risk of prostate cancer, the intervention did provide patients with sufficient information to
gauge their personal susceptibility, which may explain the
association. Finally, there was a strong but statistically nonsignificant trend toward diminished interest in screening
among informed patients 75 years and older. In that the
informational script specifically stated that many physicians
do not recommend screening with the PSA beyond age 75,
this finding is not unexpected.
Most physicians have not traditionally involved their
patients in decisions whether to screen for asymptomatic
disease. The concept of implied consent—that patients who
voluntarily present for medical care consent a priori to the
care provided by their physicians—has led to a practice
standard whereby screening decisions are determined
almost exclusively by the physician. This concept makes
sense for screening practices where the benefits have been
convincingly demonstrated, such as with mammographic
screening in women 50-65 years, and where the burdens of
screening are known to be negligible. Such is clearly not the
Table 4. Predictors of Interest in PSA Screening in Uninformed Versus Informed Patients: Multivariate Model*
Uninformed Patients
Predictor
Perceived efficacy of screening
Perceived seriousness of prostate cancer
"Ordinal logistic regression.
Odds
Ratio
95%
Confidence
Interval
2.3
1.8
1.5-3.8
1.3-2.6
Informed Patients
Predictor
Perceived efficacy
Marital status
Odds
Ratio
95%
Confidence
Interval
2.2
0.3
1.3 -3.9
0.08-0.9
PSA SCREENING IN ELDERLY MEN
case with prostate cancer screening in the elderly. There is
no evidence to suggest that screening for early stage
prostate cancer confers a mortality, morbidity, or quality of
life benefit on elderly men, while there is evidence, albeit
controversial, to suggest that "watchful waiting" (i.e., treating only symptomatic disease) can have a favorable outcome (16). The potential burdens of screening with the PSA
are substantial, including the evaluation of a large number
of false-positive results (two-thirds of abnormal PSA results
are false-positives [17]), the excessive worry created by
both false- and true-positive results, and the significant risk
of complications caused by treatment of prostate cancer
detected by PSA screening. In a survey of Medicare patients
who had undergone radical prostatectomy between 1988
and 1990, over 30% reported incontinence to the point of
requiring pads and 60% reported complete impotence (5);
these complication rates are significantly higher than published rates for younger patients.
The potential benefits of screening elderly men for asymptomatic prostate cancer are also tempered by the effects of
competing risks. Because the elderly generally have many
competing risks for death compared to younger patients,
the actual impact of a new diagnosis of prostate cancer on
life expectancy may be very small, even discounting the
risks of treatment (18). When these risks are factored in,
there is a strong possibility that the survival benefit of treatment could be negligible, and that survival may, in fact, be
shortened.
The current literature on elderly patients' preferences for
prostate cancer treatment is limited and offers conflicting
information. One survey, which included both older and
younger men, found that 68% of men were willing to trade
off a 10% or greater advantage in 5-year survival to maintain sexual potency (15), while another survey of outpatient
veterans found that 62% were willing to accept incontinence and 83% were willing to accept impotence for better
long-term survival, although older patients were less willing to accept impotence than younger patients (19). Among
elderly patients who had actually undergone radical prostatectomy for prostate cancer, fully 89% would choose
surgery again, although there was significant variability in
quality-of-life responses; those who developed incontinence and/or impotence had a significantly reduced quality
of life compared to other respondents (20). The discrepancies between these survey results and the variability of
responses accentuate the importance of involving elderly
patients in the decision whether to embark on prostate cancer screening.
There are several limitations to this study. First, the study
cohort was of relatively low educational and income status,
limiting the generalizability of the findings. Second, the
main outcome measure, patient interest in PSA, was a surrogate marker for actual screening. Third, the size of the
elderly cohort analyzed in this study was small enough to
raise the possibility of a type II (or p) error; that is, there
may have been significant differences between informed
and uninformed patients that this study was too small to
detect. Fourth, as our understanding of prostate cancer and
prostate cancer screening evolves, the content of the informational intervention will inevitably become outdated.
M199
Even so, it will be approximately a decade before the
results of randomized trials of early intervention in prostate
cancer become available (21,22); hence, uncertainty regarding efficacy of screening will persist for the foreseeable
future. Moreover, the greater significance of this study is
that older patients can understand information about a controversial screening test, and can utilize that information to
formulate screening preferences. Finally, one might criticize the content of the control script as being too favorable
and that of the intervention script as being too cautionary,
hence skewing the results of the study. Indeed, there was
nothing in the control script to dissuade patients from
screening, while the intervention script did mention some
of the potential burdens, controversies, and recommendations related to screening. However, we would argue that
the control message is a reasonable surrogate for what currently happens in the majority of practice settings: either no
involvement of the patient in the screening decision, or the
patient offered screening without discussion. The intervention script was designed to simulate an informed consent
discussion, which inherently raises both potential benefits
and burdens of screening. Moreover, the intervention was
reviewed and revised by a panel of primary care physicians
and urologists, who felt that it represented a reasonable facsimile of an informed consent discussion.
There is sufficient concern over the appropriateness of
screening with the PSA that it would be reasonable to not
offer such screening to elderly men with life expectancies
of under 10 years or with significant coexisting illness.
However, physicians who do offer screening should explicitly involve their patients in the screening decision by providing them with sufficient information to enable them to
weigh the benefits and burdens of screening. Based on the
findings of this study, such informed decision making will
result in fewer elderly patients seeking PSA screening, but
will target those individuals for whom screening is commensurate with their values and preferences.
ACKNOWLEDGMENTS
This study was supported in part by Grant IRG-72256 from the American Cancer Society. Dr. Wolf is the recipient of an American Cancer Society Cancer Control Development Award for primary care physicians. The
authors thank Dr. John T. Philbrick for his assistance with data analysis.
The full text of the intervention and control scripts is available in Reference 11.
Address correspondence to Dr. Andrew M. D. Wolf, Box 494, University of Virginia Health Sciences Center, Charlottesville, VA 22908.
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Received April 14, 1997
Accepted November 5, 1997