Education predicts quality of life among men with prostate cancer cared for in the department of Veterans affairs
A longitudinal quality of life analysis from CaPSURE†‡
The contents of this work are solely the responsibility of the authors and do not necessarily represent the official views of the Department of Veterans Affairs.
From the Mental Health and Urology Services and the Interdisciplinary Research Program to Improve Care for Older Veterans, a Research Enhancement Award Program of the Health Services Research & Development, Department of Veteran Affairs, San Francisco Veterans Affairs Medical Center, and the Department of Psychiatry and Urology, University of California at San Francisco, San Francisco, California
Previous findings have suggested that patient educational attainment is related to cancer stage at presentation and treatment for localized prostate cancer, but there is little information on education and quality of life outcomes. Patient education level and quality of life were examined among men diagnosed with prostate cancer and cared for within an equal-access health care system, the Department of Veterans Affairs Veterans Health Administration (VA).
Participants were 248 men with prostate cancer cared for in the VA and enrolled in CaPSURE. Repeated-measures analysis of variance was used to examine quality of life over time according to education level, controlling for age, ethnicity, income, site of clinical care, and year of diagnosis.
Patients with lower levels of education tended to be younger, nonwhite, and have lower incomes. Controlling for age, ethnicity, income, year of diagnosis, and site, men with less formal education, compared with those with more, had worse functioning in the physical (P = .0248), role physical (P = .0048), role emotional (P = .0089), vitality (P = .0034), mental health (P = .0054), social function (P = .0056), and general health (P = .0002) domains and worse urinary (P = .003) and sexual (P = .0467) side effects.
Men with less education experienced worse health-related quality of life across a wide range of domains and greater urinary and sexual symptoms than their peers who had more education. Clinicians should be aware that, even within an equal access to health care system, men with less education are vulnerable, having greater difficulty functioning in their daily lives after their prostate cancer treatment. Cancer 2007. © 2007 American Cancer Society.
Educational attainment and health literacy have been related to stage of prostate cancer at diagnosis and patterns of care.1, 2 For example, Kane et al.2 found that men with lower levels of education, at older ages, were less likely to have received definitive treatments such as radical prostatectomy and external beam radiation therapy than were older men with higher levels of education. Whereas it is not clear that education level is related to prostate cancer outcomes, such as health-related quality of life (HRQOL), apart from its impact on the treatment choice, previous work has found that men with less education have less knowledge of prostate cancer before diagnosis3, 4 and have poor understanding of prostate cancer and its treatments after diagnosis even after participation in an educational program on prostate cancer.5 Because poor understanding of prostate cancer and its treatment potentially could contribute to poor management of symptoms and greater disruption to lifestyle, it is important to understand the influence of education on HRQOL and on the specific symptoms associated with prostate cancer and its treatments.
In this study we examined the relation between education level and early prostate cancer outcomes. We focused on HRQOL and prostate cancer-specific symptoms among men diagnosed with prostate cancer and cared for in the Department of Veterans Affairs Veterans Health Administration (VA). We examined the symptoms and HRQOL of men in the VA for several reasons. First, because the VA cares for veterans of the lowest socioeconomic strata, we would be able to obtain a sample where a large proportion of the men would have lower education levels. Second, the VA is an equal access to a health care system that reduces financial and geographic barriers to medical care.6, 7 This provides an excellent opportunity to examine the impact of patient factors, such as educational attainment, that may influence posttreatment symptom burden and recovery, even when financial and other structural barriers to care are reduced.
MATERIALS AND METHODS
Study participants were men diagnosed with prostate cancer between 1989 and 2002 and participating in the CaPSURE study database registry. The CaPSURE study is a longitudinal observational study of men with prostate cancer diagnosed by biopsy and recruited consecutively from participating urology clinics and centers. All men recruited to the study were informed of the research methods and consented to participation according to a protocol approved by the Committee on Human Research at the University of California, San Francisco, and the individual sites, where applicable. Detailed descriptions of the sample characteristics and methods have been published previously.8–10
The analytic population for this study consisted of those patients cared for in the 3 VA CaPSURE sites (Richmond, Va; San Francisco, Calif; Seattle, Wash) who were in the database as of July 2003 and had completed a baseline questionnaire (n = 259). Of these, the 248 patients who had completed both a baseline questionnaire and at least 1 posttreatment questionnaire (6 or 12 months) were included in the analyses. Of these, 112 were recruited from Richmond, 38 from San Francisco, and 98 from Seattle.
Data Collection and Instruments
We asked patients to complete self-report forms that included questions about age, marital status, ethnic background, education level, and annual household income. Clinical data including year of diagnosis, PSA at diagnosis, Gleason score, stage, number of comorbid conditions, treatment choice, and body mass index were obtained by experienced medical record abstractors.
Outcome variables included generic HRQOL and disease-specific HRQOL (ie, urinary, sexual, and bowel symptoms). Measures included the Medical Outcomes Study Short Form-36 (SF-36) v 1.0 and the UCLA Prostate Cancer Index (PCI). Both instruments are widely used and substantial evidence has been accumulated to support their validity. The SF-36 is a measure of generic HRQOL that assesses physical, functional, emotional, and social domains of function and provides summary scores for physical and mental health. The PCI is a disease-specific measure that assesses urinary, sexual, bowel function, and bother. Each instrument was administered and scored according to standard instructions with subscale scores ranging from 0 to 100 where higher scores indicated better function. Physical Component Summary and Mental Component Summary scores of the SF-36 were derived from the subscale scores using a norm-based algorithm and where higher scores indicate better function.11 Questionnaires were administered at baseline, immediately after study enrollment, and at 6 and 12 months posttreatment. Baseline questionnaires collected before 1995 were administered after the commencement of treatment.
The association between education level and clinical and sociodemographic variables including age at diagnosis, ethnicity, annual household income, relation status, site of clinical care, prostate-specific antigen level, Gleason total, T stage, number of comorbid conditions, and body mass index were explored using chi-square analysis. In the analyses, educational attainment was treated as a categorical variable with 4 levels, including 1) less than a high school diploma, 2) high school diploma, 3) some college, and 4) college graduate or higher education. These categories were selected based on the reasoning that these are clearly defined groups that differ in recognizable educational accomplishments and would be comparable to the categories used in similar studies. Repeated measures analyses were conducted to determine the association between education level and HRQOL and prostate cancer-specific function and bother over time. This approach to the analysis was used because it takes into account the correlation of the recurring outcomes within patients. In addition, it handles missing values and truncation in an optimal way, by taking into account the time patterns of the available data. The repeated-measure model included education level and adjusted for age, ethnicity, annual household income, site of clinical care, timing of HRQOL assessment, and the interaction between education and the timing of the HRQOL assessment. We included the interaction term in the model to determine whether patterns of HRQOL differed by education level over the course of disease. We considered including treatment type in the final model because of a trend toward association of treatment type with education and conducted a multinomial logit analysis to assist with this decision. Because the outcome of this analysis (primary treatment) has 5 possible categories, we fit a multinomial logistic regression model to predict primary treatment. In multinomial regression, 1 outcome category serves as the referent for the others. In this analysis, radical prostatectomy is the referent category because it was the most common primary treatment and would provide the most statistical power. Independent variables were selected after preliminary analysis of bivariate relations and included age at diagnosis used as a categorical variable (ie, less than 55, 55-64, 65-74, 75 and older), number of comorbid conditions (0, 1-2, 3-5), ethnicity, annual household income, and year of diagnosis. Education level was forced into the model. Only year of diagnosis was significantly associated with type of treatment received in the final model (P = .0025). For this reason, subsequent analyses were not adjusted according to treatment type.
Men in the CaPSURE VA sample are predominantly of lower education and income levels (Table 1). Approximately one-third of the sample (32%) had less than a high school education and over half of the men (53%) reported annual household incomes of less then $20,000. Most of the men were 65 years of age or older (63%) at the time of diagnosis, three-quarters (75%) were married or in a relation, and approximately one-third (32%) of the sample were African American. Most of the men (90%) reported at least 1 illness or disability in addition to prostate cancer and just under half (45%) had 3 or more comorbid conditions. About a third of the men (37%) had received radical prostatectomy as the primary treatment for prostate cancer. Of the rest, 7% had received external beam radiation therapy, 17% hormonal therapy, and 12% brachytherapy, and 15% were managed with observation.
Table 1. Demographic and Clinical Characteristics According to Education Level*
|Age||<55||2 (3)||0 (0)||5 (9)||5 (11)||<.01|
|55–64||12 (16)||27 (47)||17 (31)||19 (40)|
|65–74||45 (58)||19 (33)||23 (42)||14 (30)|
|75+||18 (23)||12 (21)||10 (18)||9 (19)|
|Relationship†||Relationship||57 (78)||46 (81)||36 (72)||30 (65)||.27|
|Single||16 (22)||11 (19)||14 (28)||16 (35)|
|Ethnicity||Asian||2 (3)||1 (2)||1 (2)||0 (0)||<.01|
|Hispanic||1 (1)||0 (0)||0 (0)||2 (4)|
|Black||37 (48)||16 (28)||12 (22)||7 (15)|
|White||35 (45)||38 (66)||37 (67)||37 (79)|
|Annual household income||<$20,000||54 (83)||27 (52)||22 (45)||9 (20)||<.01|
|$20–30||6 (9)||14 (27)||11 (22)||14 (31)|
|$31–50||3 (5)||8 (15)||10 (20)||11 (24)|
|$51–75||1 (2)||3 (6)||4 (8)||6 (13)|
|>$75,000||1 (2)||0 (0)||2 (4)||5 (11)|
|Year of Diagnosis||1989–1994||15 (20)||9 (17)||7 (15)||3 (8)||<.01|
|1995–1997||30 (41)||14 (27)||9 (19)||7 (18)|
|1998–2002||29 (39)||29 (56)||32 (67)||30 (75)|
|Number of comorbid conditions||None||8 (10)||3 (5)||4 (8)||2 (4)||.27|
|1–2||42 (55)||22 (40)||23 (44)||19 (40)|
|3–5||27 (35)||30 (55)||25 (48)||26 (55)|
|PSA||<4||2 (4)||6 (13)||6 (13)||5 (13)||.45|
|4.1–10||23 (41)||22 (49)||22 (49)||19 (49)|
|10.1–20||16 (29)||10 (22)||12 (27)||7 (18)|
|>20||15 (27)||7 (16)||5 (11)||8 (21)|
|Gleason grade||2–4||9 (13)||4 (8)||4 (9)||5 (12)||.16|
|5–6||20 (30)||24 (48)||26 (57)||19 (45)|
|7||22 (33)||8 (16)||11 (24)||10 (24)|
|8–10||16 (24)||14 (28)||5 (11)||8 (19)|
|Stage||T1||21 (31)||14 (27)||17 (35)||24 (57)||.16|
|T2||40 (60)||33 (65)||29 (60)||17 (40)|
|T3||5 (7)||4 (8)||2 (4)||1 (2)|
|BMI||0||3 (4)||1 (2)||0 (0)||1 (2)||.59|
|Normal (<25)||22 (30)||17 (30)||12 (24)||10 (21)|
|Over (25–29.9)||30 (41)||24 (42)||24 (47)||28 (60)|
|Obese (30–34.9)||19 (26)||15 (26)||15 (29)||8 (17)|
|Treatment||RP||28 (36)||23 (40)||23 (42)||13 (28)||<.06|
|Brachytherapy||6 (8)||6 (10)||7 (13)||10 (21)|
|EBR||9 (12)||3 (5)||3 (5)||0|
|HT||16 (21)||8 (14)||4 (7)||11 (23)|
|Surveillance||13 (17)||11 (19)||7 (13)||6 (13)|
|Unknown||5 (6)||7 (12)||11 (20)||7 (15)|
Men with lower education levels were more likely to be poor and older at the time of diagnosis (see Table 1). There were few differences in other demographic and clinical characteristics by education level, with the exception that men with less education were significantly more likely to be diagnosed at an earlier date (P < .001). A trend was observed toward differences in primary treatment choice by education level (P < .06) where men with higher education tended to receive brachytherapy or hormonal therapy (P = .06).
Analysis of variance was used to examine differences in generic HRQOL and disease-specific HRQOL at baseline and at 6 and 12 months posttreatment. With the exception of urinary function at baseline and role emotional function at 12 months, there were no differences in baseline and 12-month generic HRQOL and disease-specific HRQOL according to education. At 6 months, however, generic HRQOL differed by education on the SF-36 measures of physical functioning, role physical, role emotional, mental health, social function, and general health (Table 2). Similar differences were seen on the physical and mental component scores. In each domain, men with less education reported worse functioning. There was a trend for men with less education, compared with those with more, to report more difficulty with sexual function (P = .05; see Table 3). Other than this, no significant differences were found for the disease-specific HRQOL in sexual and urinary function and bother.
Table 2. Health-Related Quality of Life Mean Scores at 6 Months Posttreatment by Education Controlling for Patient Sociodemographic Characteristics*
|Physical functioning||46.22 (29.24)||62.50 (26.83)||60.44 (30.03)||73.65 (25.82)||<.01|
|Role physical||20.95 (30.34)||45.24 (45.28)||31.45 (42.80)||58.65 (42.98)||<.01|
|Role emotional||46.49 (46.85)||70.63 (41.78)||70.00 (40.45)||85.90 (34.22)||<.01|
|Vitality||45.68 (23.33)||53.05 (23.29)||50.94 (21.38)||58.75 (25.41)||.15|
|Mental health||67.08 (17.59)||75.05 (14.76)||73.35 (24.02)||79.71 (17.86)||.05|
|Social function||60.00 (26.43)||72.50 (27.03)||66.53 (30.51)||78.50 (27.13)||.05|
|Bodily pain||54.56 (27.17)||64.11 (28.39)||58.47 (28.48)||63.75 (24.59)||.38|
|General health||43.75 (19.61)||63.36 (20.93)||63.96 (27.46)||62.99 (21.22)||<.01|
|Physical component summary score||32.88 (9.32)||39.75 (11.64)||38.83 (12.53)||41.44 (10.64)||0.02|
|Mental component summary score||46.51 (11.00)||50.5 (9.89)||50.01 (11.76)||55.30 (10.32)||.03|
Table 3. UCLA Prostate Cancer Symptom Index Mean Scores at 6 Months Posttreatment by Education*
|Urinary function||71.01 (28.68)||61.94 (29.85)||66.45 (31.74)||78.01 (22.40)||.13|
|Urinary bother||48.75 (34.88)||58.75 (34.23)||62.88 (35.97)||65.18 (32.16)||.19|
|Bowel function||75.43 (23.41)||80.13 (16.22)||77.23 (21.22)||77.64 (21.35)||.78|
|Bowel bother||71.05 (31.04)||76.79 (28.90)||73.48 (33.62)||73.21 (30.37)||.87|
|Sexual function||22.87 (20.19)||20.66 (20.79)||35.10 (29.11)||30.56 (29.64)||.05|
|Sexual bother||34.21 (40.03)||34.15 (39.43)||33.87 (35.68)||53.70 (43.14)||.15|
A mixed model repeated measures analysis was used to examine the association between disease-specific HRQOL and HRQOL over time (ie, baseline, 6 months, 12 months) and level of education, controlling for age, ethnicity, annual household income, site of clinical care, and the interaction between education and time of HRQOL assessments. Men with less education, compared with those with more, experienced greater decline and less recovery over the first year after diagnosis in physical function, role physical function, role emotional function, vitality, mental health, social function, and general health domains of generic HRQOL and on physical and mental health summary scores. Also, they reported greater decline and less recovery on urinary function and bother from urinary symptoms and on sexual function than did men with more education. Table 4 shows the P-values from mixed model analysis of HRQOL over time by education level and means adjusted for time of HRQOL assessment age, ethnicity, annual household income, site of clinical care, and the interaction between education and time of HRQOL assessment. After including patients with at least 2 years of follow-up, the effect of education remained significant for the majority of the general health domains of generic HRQOL, and for the disease-specific dimensions of urinary function and bother and sexual bother. Post-hoc analysis for differences in adjusted means between levels of education revealed that the effects were due to differences between the group with less than a high school education and the groups with higher levels of educational attainment.
Table 4. Adjusted Means for Health-Related Quality of Life and Symptoms According to Education Over Time*
Additional analyses were conducted to examine the interactions between education and income, age, and ethnicity, and between time and income, age, and ethnicity. These models revealed significant interactions between education and income across many of the domains of HRQOL, including role physical, role emotional, vitality, social function, bodily pain, general health, sexual function, and sexual bother (data not shown, P < .05). Interactions with race were significant for bodily pain, urinary function, and sexual bother, and interactions with age were significant for role emotional, mental health, social function, and urinary bother (data not shown, P < .05). The interactions between time and age, ethnicity, and income were not significant.
The results of our study contribute to knowledge of social disparities in prostate cancer outcomes, pointing to educational attainment as an important patient factor influencing both specific symptoms and broad areas of physical, social, and emotional function. Whereas men with less education cared for in the VA Health Care System received similar treatments as men with more education, they experienced worse outcomes 6 months after treatment and had less recovery of quality of life over 2 years postdiagnosis. Those with a high school education or less experienced significantly worse urinary and sexual symptoms, worse bother from urinary symptoms, and poorer function, physically, emotionally, and socially, less energy, and worse mental and physical health, overall.
In context, it is especially important to note that the magnitude of difference between those with less than a high school education and those with college or more education was greater than 1 standard deviation for several domains—differences that are meaningful clinically as well as being statistically significant.12, 13 At 6 months, the generic HRQOL of men with less than a high school education was worse than that of those with the most education by almost 40 points for the role physical domain, a measure of problems with work and other daily activities due to physical health. HRQOL was worse by over 20 points for role emotional, indicating problems with work and other daily activities due to emotional health, for physical functioning, indicating limitations in performing physical activities, and for social functioning, indicating interruption of normal family, work, community, and other social activities. Thus, for men with a high school degree or less education, prostate cancer and its treatment had a clear, pervasive, and persistent impact on lifestyle as well as contributing to specific urinary and sexual side effects.
The VA Health Care System cares for patients of the lowest socioeconomic strata, regardless of ability to pay for care.14 Previous studies of patients cared for in the VA have found them to have greater concurrent medical and psychiatric illnesses than those who receive care in the private setting.6 Consistent with this, studies using the CaPSURE prostate cancer registry have found that men diagnosed with prostate cancer cared for in the VA have less education and income, a greater number of comorbid conditions, and are more often diagnosed with prostate cancer with higher risk factors than those who pay for their care with private health insurance.15 In this study, we found that, within the Department of Veterans Affairs Veterans Health Administration, men who have less educational attainment and who are diagnosed with prostate cancer are an especially vulnerable group. These men have poorer HRQOL outcomes than those with higher education, and experience greater urologic symptom burden during the first year after diagnosis of prostate cancer. Those with more education in the VA sample have HRQOL outcomes and urologic symptoms similar to outcomes found in previous samples of men seen across a wide variety of urologic clinical settings.16 In contrast, men with low education in the VA CaPSURE sample had worse HRQOL outcomes than those of general samples, and were similar to those men seen outside the VA, but cared for in clinical settings that provide care to patients of lower socioeconomic status.17–19
Previous work on social disparities in health outcomes has found that those of lower socioeconomic status experience poor HRQOL outcomes and greater symptom burden.10 However, few prostate cancer investigations have focused on the relation between education and HRQOL outcomes. There are several exceptions. Eton et al.20 found that men with low educational attainment reported worse mental functioning after diagnosis of prostate cancer compared with those with higher education. Brar et al.21 found that men with less than a high school education, compared with those with more, had greater improvement in SF-6 mental health scores at 6 months follow-up. Whereas the Brar et al finding appears to conflict with our data, the improvement in mental health among these men of low education may be the result of their participation in a state-funded prostate cancer treatment and counseling program. Our study adds to this literature suggesting that those with less education experience pervasive and persistent posttreatment disruption to their daily lives, regardless of access to care. In addition, level of educational attainment is easy to ascertain in the clinical setting, and could facilitate the rapid identification of vulnerable individuals in need of additional assessment and support.
Whereas our study suggests that men with low educational attainment are a vulnerable group even within an equal access to health care setting, it is not clear why this would be the case. Several explanations are possible. One interpretation is that men with less education, even in an equal access to health care system, may experience greater difficulty understanding educational material on the disease, its treatments, and posttreatment care.5 Poor understanding of the self-care instructions provided in the urology clinical setting or poor understanding of information on the kinds of posttreatment support available to manage symptoms may contribute to difficulties with the management of symptoms, worry about disease burden and recurrence, and difficulty in adjusting one's lifestyle to treatment schedules and symptoms. Interventional studies provide evidence consistent with this, suggesting that men with low education levels have a deficit of information that can be improved upon.22, 23
An alternate explanation is that men with less education have lives that are more adversely impacted by prostate cancer and its treatments than men with more education. This might be the case where men with less education have greater work and family responsibilities or fewer material resources for managing symptoms than those with more education. Several recent reviews of social disparities and cancer suggest that low education is associated with a cluster of other factors (eg, minority ethnicity, low income) that contribute to social disadvantages, and consequently to disparities in cancer outcomes.24, 25 For example, men who are diagnosed with prostate cancer who have low education levels, low income, and few resources may need to continue employment, making time off work for treatments and managing side effects more difficult. Further research is needed to understand the role of education as a factor influencing social status and outcomes.
Strengths of our study include our use of psychometrically strong measures of sociodemographic characteristics and generic and disease-specific HRQOL. However, it is important to note that our findings are based on 3 VA medical centers. For this reason, additional study will be needed to determine whether these results will generalize to a broader VA sample or to the general population. Also, although education contributed independently to HRQOL, controlling for age, ethnicity, and income our data reveal that these variables may interact in complex ways to influence well-being after prostate cancer treatment. Additional research will be important to fully understand the contributions of these overlapping variables to HRQOL.
In conclusion, men with lower education levels, especially those with less than high school education, are a vulnerable group even within an equal access to health care setting. Compared with those who have attained more formal education, they experience greater symptom burden and greater disruption in their ability to function in their daily lives due to prostate cancer and its treatments. Because of the close relations among education, income, and ethnicity, further study of educational attainment is critical to understanding social disparities in prostate cancer outcomes. In patient care settings, clinicians should identify the informational needs of men of lower education levels and ensure that they are adequately informed about the management of prostate-specific symptoms and receive support to mitigate the impact of treatment on their lives.