The Memorial Anxiety Scale for Prostate Cancer
Validation of a new scale to measure anxiety in men with prostate cancer
The psychological difficulties facing men with prostate cancer are acknowledged widely, yet identifying men who may benefit from mental health treatment has proven to be a challenging task. The authors developed the Memorial Anxiety Scale for Prostate Cancer (MAX-PC) to facilitate the identification and assessment of men with prostate cancer-related anxiety. This scale consists of three subscales that measure general prostate cancer anxiety, anxiety related to prostate specific antigen (PSA) levels in particular, and fear of recurrence.
Ambulatory men with prostate cancer (n = 385 patients) were recruited from clinics throughout the United States. Prior to routine PSA tests, participants completed a baseline assessment packet that included the Hospital Anxiety and Depression Scale; the Distress Thermometer; the Functional Assessment of Cancer Therapy Scale, Prostate Module; and measures of role functioning, sleep, and urinary functioning. PSA values from the last three tests also were collected. Follow-up evaluation was completed within 2 weeks after patients learned of their PSA test result using a subset of these scales.
Analysis of the MAX-PC revealed a high degree of internal consistency and test-retest reliability for the total score and for the three subscales, although reliability was somewhat weaker for the PSA Anxiety Scale. Concurrent validity was demonstrated by correlations between the MAX-PC and measures of anxiety. Overall changes in PSA levels were correlated only modestly with changes in MAX-PC scores (correlation coefficient, 0.13; P = 0.02).
The MAX-PC appears to be a valid and reliable measure of anxiety in men with prostate cancer receiving ambulatory care. Cancer 2003;97:2910–8. © 2003 American Cancer Society.
The prostate is the most common site of cancer in older males in the U.S. An estimated 198,100 new cases of prostate cancer are diagnosed annually, 80% of which occur in men older than 65 years.1 Not only does a diagnosis of prostate cancer entail uncertainties regarding the possibility of functional disabilities or even death, but these older men also are experiencing the losses related to the later phase of the life cycle. Although the psychological toll is high, reactions to a diagnosis of prostate cancer vary widely, from a healthy acceptance of both the diagnosis and the treatment to reactions of marked anxiety, depression, hopelessness, and general distress. In one study, nearly one-third of men with prostate cancer in a genitourinary medical clinic had levels of psychological distress that met criteria for a diagnosis of anxiety disorder.2
Several factors influence reactions to a prostate cancer diagnosis, including prior psychological adjustment, social support, economic resources, and other life changes or events (e.g., loss of spouse, recent or impending retirement).3–5 However, despite the high prevalence rate, there has been remarkably little systematic research concerning the nature of psychological distress and the prevalence of psychiatric disorders in this population.6–8 Sources of distress commonly noted include sexual dysfunction, urinary incontinence, bowel dysfunction, weakness, fatigue, hot flashes, and pain.9–11 In addition, many individuals experience profound changes in their mood, irritability, and anxiety due to either the disease or its treatment.3, 5, 12–16
Although the psychological needs and psychiatric symptoms of men with prostate cancer are important, securing mental health evaluation and treatment for this population has presented difficulties.2 Compared with patient assessments, urologists underestimate patient symptoms that cause impairment of quality of life.17 Oncologists and oncology nurses often are reluctant to ask patients about psychological problems and frequently fail to recognize symptoms of depression, even when they are severe.4, 18, 19 Many elderly men with cancer are reluctant to acknowledge their emotional distress and/or seek treatment because of both embarrassment and stigma. Doctors often learn of their patients' distress from spouses, who also have high levels of distress.3, 20 Distress also may manifest as complaints of physical symptoms rather than acknowledging the psychological origin of these complaints. Perhaps most commonly, men with prostate cancer express their anxiety through concerns about their prostate specific antigen (PSA) levels. Concern about PSA levels is common and troubling, because the levels herald disease progression. Weeks before their actual tests, men are anxious and sometimes delay testing or request repeated PSA testing to assure that the results are correct.21
To improve the recognition and assessment of anxiety related to prostate cancer and PSA levels, we developed a self-report measure, the Memorial Anxiety Scale for Prostate Cancer (MAX-PC). A 24-item scale was designed to tap 3 aspects of prostate-cancer related anxiety: general anxiety related to prostate cancer and treatment, fear of recurrence, and anxiety specifically related to PSA testing. This scale incorporated items from the Fear of Recurrence Scale developed by Kornblith and colleagues22, 23 and modified items from the Breast Cancer Anxiety Questionnaire developed by Kash and Jacobsen24 as well as new items generated by clinical experts.
The MAX-PC was administered initially to a sample of 66 men with prostate cancer to assess item clarity, ease of completion, and psychological reactions to the content. New items were then generated from patient feedback on the initial versions of the scale. These items were intended to form three distinct subscales: a Prostate Cancer Anxiety Subscale, a PSA Anxiety Subscale, and a Fear of Recurrence Subscale. Although the reactions to this pilot sample were quite positive, six items were deleted, two items were added, and the wording of two items was modified based on patients' comments concerning lack of clarity of the item.
The current study was designed to provide initial validation for a 24-item measure in a large sample of ambulatory men with prostate cancer. Specifically, we administered the MAX-PC along with several measures to test reliability and validity (concurrent and discriminant). In addition, we assessed patients both before and shortly after learning the results of a PSA test to assess the consistency of the MAX-PC over time and its sensitivity to changing PSA levels.
MATERIALS AND METHODS
Patients were recruited from genitourinary clinics throughout the U.S. These sites all were institutions and group practices that participate in clinical trial research for AstraZeneca Pharmaceuticals (the AstraZeneca Pharmaceutical Research Consortium of Oncology Investigators). No financial support was provided by AstraZeneca to any of the participating investigators for the conduct of this study. All patients were eligible to participate in this study if they were being monitored with regular PSA tests, were older than 18 years, and were English-speaking. All patients were informed of the nature of the study, including relevant risks and benefits, and provided written informed consent. The study was approved by the institutional review boards of Memorial Sloan-Kettering Cancer Center and the AstraZeneca Pharmaceutical Research Consortium.
After patients provided informed consent (usually during the patient's clinic visit just prior to having blood drawn for PSA testing), study participants were given a packet of seven questionnaires and were asked to complete these questionnaires while they waited to see their physician. In addition to the MAX-PC, the measures administered at study entry included the Hospital Anxiety and Depression Scale (HADS), a 14-item self-rated questionnaire that has been tested extensively in cancer populations, with Depression and Anxiety Subscales of 7 items each;25–29 the Distress Thermometer, a recently developed visual analogue scale4 on which scores range from 0 (no distress) to 10 (extreme distress); the Functional Assessment of Cancer Therapy Scale, Prostate Module (FACT-P), developed by Cella and colleagues,30–32 which is a quality-of-life questionnaire that includes a 27-item core quality-of-life measure (the FACT Quality-of-Life Scale [FACT-G]) grouped into four subscales (Physical Well-Being, Social/Family Well-Being, Emotional Well-Being, and Functional Well-Being), and 12 items specific to prostate cancer (FACT-P); the Role Functioning and Sleep Subscales of another quality-of-life measure, the Medical Outcomes Survey (MOS) Short Form 36;33 the Urinary Function Subscale of the Quality-of-Life in Prostate Cancer measure developed by Litwin and colleagues;9 and a brief sociodemographic34 and medical questionnaire (including PSA values from the last 3 tests drawn). After completing the baseline assessment, participants were given another set of questionnaires (the MAX-PC, the HADS, and the Distress Thermometer) with instructions to complete these measures within 1 week after they were informed of their PSA test result (the follow-up assessment). Completed questionnaires were mailed to the data coordinator at each of the participating sites.
Descriptive statistics were used to characterize the sample with regard to demographic and clinical characteristics. Scale properties for the MAX-PC scale were evaluated using several methods, including the coefficient α and the item-total correlation (r) to assess internal consistency, an analysis of individual items to assess the validity and specificity of each item, and test-retest reliability coefficients. Exploratory factor analysis (using a principal components extraction method and varimax rotation) was used to assess the extent to which the scale fit the initially intended three-factor model. Concurrent and discriminant validity was assessed by correlational analyses (i.e., correlation of the MAX-PC with measures of psychological distress and physical functioning). Longitudinal data also were analyzed to ascertain whether changes in MAX-PC scores corresponded to changes in other measures of psychosocial functioning or actual changes in PSA levels.
Three hundred eighty-five men completed the assessment at study entry. The average age of participants was 71.05 years (standard deviation, 9.3 years; range, 40–93 years). The majority of participants were Caucasian (n = 319 patients; 86.2%) and were married at the time of participation (n = 306 patients; 82.7%) (Table 1). Roughly half of the men in the sample were classified with organ-confined disease (n = 188 patients; 54.6%; T1 or T2, N0, and M0), whereas 92 patients (26.7%) had locally advanced disease (T3 or T4, N0, and M0), and 64 patients (18.6%) had metastatic prostate carcinoma (T3 or T4, N1–N3, and Ma–Mc; these data were missing for 41 patients). The average Karnofsky performance rating for the sample was 96.5, with only 2 patients (0.6%) who had a rating < 70 and 7 patients (2%) who had a rating < 80.
Table 1. Demographic and Medical Characteristics
|Race|| || |
| African American||35||9.5|
|Marital status|| || |
| Divorced, separated, widowed||53||14.3|
|Education|| || |
| Less than high school||46||12.5|
| High school graduate||84||2.9|
| Partial college||82||22.3|
| College or graduate degree||155||42.2|
|Disease stage|| || |
| Organ-confined disease||188||54.6|
| Locally advanced disease||92||26.7|
| Metastatic disease||64||18.6|
|Baseline PSA level|| || |
| None detectable||22||6.2|
| < 2 ng/ml||244||68.9|
| 2–10 ng/ml||56||15.8|
| > 10 ng/ml||32||9.0|
|Medical history|| || |
| Radiation therapy||251||70.5|
| Seed implants||315||89.5|
| Hormonal therapy||215||61.1|
| Other chemotherapy||337||95.7|
Follow-up data were available for 348 participants, representing 90% of the original sample. The average time between baseline and follow-up assessments was 13.7 days (standard deviation, 10.0 days; median, 12 days; time between assessments was not available for 52 participants). A small (but unknown) percentage of patients returned the Time 2 questionnaire before they learned of their PSA results, which likely attenuated the correlation between changes in PSA levels and changes in MAX-PC scores; however, these questionnaires could not be identified reliably and, thus, were included in the data analysis. Even among questionnaires that were returned after patients learned of their follow-up PSA results, the vast majority of study participants had little change in PSA levels between baseline and follow-up assessments. For the purpose of data analysis, participants were classified with no change in their PSA levels if the magnitude of change in PSA levels was < 2 ng/ml in either direction. Of the 385 patients available for this analysis, 278 patients (72.2%) were classified with no change in their PSA level. Only 24 patients (6.2%) had increases ≥ 2 ng/ml in their PSA levels, whereas 83 patients (21.6%) had decreases ≥ 2 ng/ml. The median change in PSA levels was 0, with a range of + 100 to − 107. Because of the presence of extreme scores, these data were converted to ranks for correlational analyses (i.e., Spearman correlation coefficients [rs]).
Analysis of the Original 24-Item MAX-PC
A reliability analysis of the original 24-item MAX-PC revealed a number of problematic items that led to subsequent modification and shortening of the scale (Table 2). The coefficient α for the total score (24 items) was 0.89, with a median item-total correlation of 0.57 (range, 0.13–0.67). The coefficient α values for the three subscales were 0.90 for the Prostate Cancer Anxiety Subscale, 0.56 for the PSA Anxiety Subscale, and 0.76 for the Fear of Recurrence Subscale. The median item-total correlations for the three subscales were 0.61 (range, 0.38–0.72), 0.44 (range, 0.26–0.45), and 0.54 (range, − 0.08–0.69), respectively.
Table 2. Internal Consistency of Total Score and Subscales
|Prostate Cancer Anxiety (Subscale 1)||0.90||0.38–0.72||0.90||0.58–0.71|
|PSA Anxiety (Subscale 2)||0.56||0.26–0.45||Not modified||—|
|Fear of Recurrence (Subscale 3)||0.76||−0.08–0.69||0.82||0.59–0.72|
Results of the initial factor analysis of the 24-item scale generated a somewhat confusing set of results. An analysis of the scree plot suggested both a three-factor model and a five-factor model, yet six factors had Eigen values > 1.0. However, an inspection of the five-factor and six-factor solutions revealed several single-item factors with seemingly little interpretive significance. Given these findings, coupled with our a priori design of the questionnaire to fit a three-factor model, we chose to analyze the three-factor solution (Table 3).
Table 3. Rotated Factor Loadings
Analysis of the initial three-factor solution demonstrated considerable consistency with the three subscales that were supposed to comprise the MAX-PC but with several items that did not load significantly on any factor. Of the 14 items that were supposed to comprise the Prostate Cancer Anxiety Subscale, 13 items had loadings ≥ 0.5 on the first factor, and no items had higher loading on a different factor. Likewise, two of the three PSA Anxiety Subscale items had loadings > 0.5 on the second factor (and the third item loading was 0.49), and five of the seven Fear of Recurrence Subscale items had loadings > 0.5 on the third factor (one item from this subscale had a higher loading on the second factor).
Analysis of the Modified 18-item MAX-PC
After reviewing the initial reliability data and factor analysis results as well as the correlations between individual items and measures used to assess concurrent validity (not reported here), a modified and abbreviated version of the original scale was derived (Table 4). This revised scale omitted 3 of the 14 items from the Prostate Cancer Anxiety Subscale and 3 of 7 items from the Fear of Recurrence Subscale. The three-item PSA Anxiety Subscale was retained in its entirety.
Table 4. The Modified 18-Item Memorial Anxiety Scale for Prostate Cancer
|YOUR FEELINGS ABOUT PROSTATE CANCER AND PROSTATE SPECIFIC ANTIGEN TESTS|
|We would like to better understand how patients cope with aspects of their treatment for prostate cancer and the medical tests frequently involved in their care.|
|I. Below is a list of comments made by men about prostate cancer. Please indicate by circling the number next to each item how frequently these comments were true for you during the past week; not at all, rarely, sometimes, often.|
| ||Not at all||Rarely||Sometimes||Often|
|1. Any reference to prostate cancer brought up strong feelings in me.||0||1||2||3|
|2. Even though it's a good idea, I found that getting a PSA test scared me.||0||1||2||3|
|3. Whenever I heard about a friend or public figure with prostate cancer, I got more anxious about my having prostate cancer.||0||1||2||3|
|4. When I thought about having a PSA test, I got more anxious about my having prostate cancer.||0||1||2||3|
|5. Other things kept making me think about prostate cancer.||0||1||2||3|
|6. I felt kind of numb when I thought about prostate cancer.||0||1||2||3|
|7. I thought about prostate cancer even though I didn't mean to.||0||1||2||3|
|8. I had a lot of feelings about prostate cancer, but I didn't want to deal with them.||0||1||2||3|
|9. I had more trouble falling asleep because I couldn't get thoughts of prostate cancer out of my mind.||0||1||2||3|
|10. I was afraid that the results from my PSA test would show that my disease was getting worse.||0||1||2||3|
|11. Just hearing the words “prostate cancer” scared me.||0||1||2||3|
|II. For the next three questions, please indicate how frequently these situations have EVER been true for you.|
| ||Not at all||Rarely||Sometimes||Often|
|12. I have been so anxious about my PSA test that I have thought about delaying it.||0||1||2||3|
|13. I have been so worried about my PSA test result that I have thought about asking my doctor to repeat it.||0||1||2||3|
|14. I have been so concerned about my PSA test result that I have thought about having the test repeated at another lab to make sure they were accurate.||0||1||2||3|
|III. Listed below are a number of statements concerning a person's beliefs about their own health. In thinking about the past week, please indicate how much you agree or disagree with each statement: strongly agree, agree, disagree, or strongly disagree. Please circle the number of your answer.|
| ||Strongly agree||Agree||Disagree||Strongly disagree|
|15. Because cancer is unpredictable, I feel I cannot plan for the future.||0||1||2||3|
|16. My fear of having my cancer getting worse gets in the way of my enjoying life.||0||1||2||3|
|17. I am afraid of my cancer getting worse.||0||1||2||3|
|18. I am more nervous since I was diagnosed with prostate cancer||0||1||2||3|
Reliability data for the modified version of the MAX-PC were slightly better compared with reliability data for the original scale. The coefficient α for the revised 18-item scale was 0.89, with a median item-total correlation of 0.59 (range, 0.26–0.68; see Table 2). The coefficient α for the two modified subscales (Prostate Cancer Anxiety and Fear of Recurrence) were 0.90 (median item-total correlation, 0.65; range, 0.58–0.71) and 0.82 (range, 0.59–0.72), respectively.
Test-retest reliability (for the 18-item scale) was established by comparing MAX-PC scores at the baseline and follow-up assessments (an average of 10 days). Test-retest reliability was 0.89 (95%CI, 0.87–0.91) for the total score, 0.83 (95%CI, 0.79–0.86) for the Prostate Cancer Anxiety Subscale, 0.74 (95%CI, 0.67–0.79) for the PSA Anxiety Subscale, and 0.98 (95%CI, 0.97–0.98) for the Fear of Recurrence Subscale.
Principal components factor analysis of the revised 18-item scale clearly supported the 3-factor model, because the scree plot, Eigen values, and factor loadings all supported the expected 3-factor solution. This solution was highly consistent with the original questionnaire design (Table 3). All 11 items from the Prostate Cancer Anxiety Subscale had factor loadings ≥ 0.5 on factor 1, and 10 items had loadings ≥ 0.60; whereas all 3 items from the PSA Anxiety Subscale loaded onto factor 2 with loadings ≥ 0.60, and the 4 Fear of Recurrence items loaded on factor 3 with loadings > 0.7.
Concurrent and Discriminant Validity
Total scores on the MAX-PC (revised 18-item version) were correlated significantly with several measures of anxiety that were administered concurrently (Table 5). Specifically, MAX-PC total scores were correlated highly with HADS total scores (r = 0.52; P < 0.0001), scores on the Anxiety Subscale of the HADS (r = 0.57; P < 0.0001), and the Distress Thermometer (r = 0.45; P < 0.0001). The correlation between MAX-PC total scores and the HADS Depression Subscale, as expected, was lower compared with the correlation observed for the Anxiety Subscale, although this correlation remained significant (r = 0.31; P < 0.0001). Significant, albeit modest, negative associations also were observed between MAX-PC scores and scores on a measure of sleep quality (r = − 0.20; P = 0.0002) and overall quality of life (r = − 0.28; P < 0.0001).
Table 5. Correlations with the Prostate Specific Antigen Anxiety Scale (Modified 18-item version)
|HADS total score||0.52||0.43||0.20||0.53|
|Quality of life total||−0.28||−0.24||−0.15||−0.40|
There was no correlation between MAX-PC scores and absolute PSA levels at baseline (rs = 0.02; P = 0.69). In addition, anxiety levels did not differ among participants who did or did not undergo prior prostatectomy (r = − 0.06; P = 0.29). Likewise, there was no association between MAX-PC total scores and scores on measures of overall physical functioning (i.e., Karnofsky performance score: r = − 0.01; P = 0.83; MOS Role Functioning Subscale: r = 0.06; P = 0.25), or urinary functioning (r = − 0.06; P = 0.23). There was no difference in MAX-PC scores depending on stage of disease (F[2,338] = 0.58; P = 0.56). However, there were small but statistically significant associations between MAX-PC scores and age (r = − 0.13; P = 0.01) as well as education (r = − 0.13; P = 0.01).
Analysis of the MAX-PC subscales indicated that the Prostate Cancer Anxiety Subscale appeared to tap anxiety much more specifically than the other subscales, whereas the Fear of Recurrence Subscale was more sensitive to psychological distress broadly defined (Table 5). Both the Prostate Cancer Anxiety Subscale and the Fear of Recurrence Subscale were highly (and comparably) associated with the HADS Anxiety Subscale (r = 0.51 and r = 0.50, respectively; P < 0.0001 respectively) and the distress thermometer (r = 0.43 and r = 0.37, respectively; P < 0.0001). However, the Fear of Recurrence Subscale was correlated highly with the HADS total score (r = 0.53; P < 0.0001), the Depression Subscale of the HADS (r = 0.43; P < 0.0001), overall quality of life (r = − 0.40; P < 0.0001), and scores on the measure of sleep disturbance (r = − 0.25; P < 0.0001). Conversely, the Prostate Cancer Anxiety Subscale was not correlated as highly (although all correlations were statistically significant) with any of these measures (HADS Depression Subscale: r = 0.20; P = 0.0002; quality-of-life measure: r = − 0.28; P < 0.0001; sleep disturbance: r = − 0.15; P = 0.004). The PSA Anxiety Subscale was associated less clearly with any of the measures administered, although the strongest and only significant associations were with the HADS total score and the HADS subscales.
Although we anticipated that patients with rising PSA levels would display more PSA-related anxiety when they were retested, this hypothesis received only limited support (Table 6). Overall changes in PSA levels (calculated as the difference between PSA levels before and after the baseline assessment) were correlated modestly with changes in MAX-PC scores (the follow-up score minus the baseline score: rs = 0.13; P = 0.02). An analysis of the three MAX-PC subscales indicated that the Prostate Cancer Anxiety Subscale was much more sensitive to changes in PSA levels compared with the other two subscales. There was a significant correlation between changes in scores for the Prostate Cancer Anxiety Subscale and PSA changes (rs = 0.18; P = 0.002), but there was no correlation between PSA changes and scores for the other two subscales (PSA Anxiety Subscale: rs = 0.02; P = 0.67; Fear of Recurrence Subscale: rs = − 0.02; P = 0.72).
Table 6. Correlations with Prostate Specific Antigen Anxiety Based on Longitudinal Analyses (Modified 18-item version)
|HADS total score||0.30||0.28||0.00||0.12|
Significant associations also were found between changes in the MAX-PC score and the other measures of anxiety and psychological distress. Changes in the MAX-PC total score were associated significantly with changes in the HADS total score (r = 0.30; P < 0.0001) and with changes in the HADS Anxiety Subscale (r = 0.39; P < 0.0001). However, there was no significant correlation between changes in the HADS Depression Subscale and MAX-PC total scores (r = 0.09; P = 0.09). The Prostate Cancer Anxiety Subscale of the MAX-PC also appeared to be more sensitive to changes over time compared with the other two subscales, with significant correlations between this subscale and the HADS total score (r = 0.28; P < 0.0001) and the HADS Anxiety Subscale (r = 0.37; P < 0.0001), but not the HADS Depression Subscale (r = 0.07; P = 0.20). The correlations between changes in the HADS total scores and subscales and the other two MAX-PC subscales were considerably smaller and were largely nonsignificant (Table 6).
The MAX-PC was designed to provide a brief, effective method for detecting anxiety in men with prostate cancer. This study, which represents a first attempt at providing validation for the MAX-PC, demonstrated considerable support for the utility of this measure, albeit in a modified and somewhat abbreviated form. Based on data from a large, representative sample drawn from across the U.S., we observed a high degree of reliability for the MAX-PC (i.e., internal consistency and test-retest reliability) as well as concurrent and discriminant validity. We observed substantial correlations between the MAX-PC and measures of other anxiety and distress, lower (but still significant) correlations with measures of depression and sleep disturbance, and no correlation with measures of urinary functioning, physical functioning, or other medical variables that should not necessarily correlate with anxiety (e.g., PSA level and disease stage).
The MAX-PC was designed to assess three different aspects of prostate-related anxiety, including anxiety related to prostate cancer in general (the Prostate Cancer Anxiety Subscale), anxiety specifically focused on PSA testing (the PSA Anxiety Subscale), and fears of cancer recurrence (the Fear of Recurrence Subscale). Factor analysis clearly supported the anticipated 3-factor model, with all items (in the modified 18-item scale) loading on the intended factors. Associations with measures of concurrent and discriminant validity revealed an interesting pattern of differences across the three subscales. The Prostate Cancer Anxiety Subscale appeared to tap anxiety much more specifically than the other factors (higher correlations with measures of anxiety and lower correlations with measures of depression, sleep disturbance, quality of life, etc.). The Fear of Recurrence Subscale, conversely, appeared to tap psychological distress more generally, because correlations with depression and quality of life were considerably higher, almost as high as the correlations with measures of anxiety. Empirical support for the PSA Anxiety Subscale, however, was somewhat weaker, leading us to revise the wording of these questions for future applications of the scale (described further below).
Results from the longitudinal component of the study were somewhat more difficult to interpret. Patients completed the study instruments shortly before they had blood drawn for their PSA test and again after they learned the results of that test (typically about 2 weeks later). We observed a significant (although quite modest) correlation between changes in PSA levels and changes in MAX-PC scores, as expected, particularly on the Prostate Cancer Anxiety Subscale (changes in PSA Anxiety Subscale and Fear of Recurrence Subscale scores were not associated with changes in PSA levels). However, as noted above, a small percentage of patients returned the Time 2 questionnaire before they learned of their PSA results, which likely decreased our ability to find significant changes over time (i.e., attenuating the correlation between changes in PSA levels and changes in MAX-PC scores). These correlations also may have been more modest than anticipated, because the patients demonstrated little change in PSA levels (75% of patients had no substantial change in PSA level). Thus, although we anticipated that anxiety levels would change substantially over time because of changing medical status, this group of patients may be described more accurately as medically stable, supporting our use of longitudinal data for establishing test-retest reliability.
Although the results based on our original 24-item scale certainly were encouraging, several items were eliminated after preliminary analyses indicated that they were either unnecessary or ineffective at capturing the intended construct. The resulting 18-item scale appears to have even stronger empirical support compared with our original scale, particularly given the importance of brevity in clinical research. We also chose, on the basis of these analyses, to change the wording of the three items that comprise the PSA Anxiety Subscale. These items, which originally were conceived in a behavioral framework (e.g., Have you ever delayed going for your next PSA test because you were too anxious about it?), rarely were endorsed by our sample (hence the low reliability and validity data for this subscale). In light of this observation, we elected to reword these items to reflect (as noted in Table 4) an attitudinal framework (e.g., Have you ever considered delaying a PSA test because you were too anxious about it?) in hopes of increasing the applicability for most patients. Although the impact of this change in wording is unknown, we anticipate improved reliability and validity data for this subscale.
Despite the strong initial support for the overall MAX-PC in terms of both reliability and validity, the current results are tempered by several methodological limitations. First, although we attempted to stratify recruitment to include equal proportions of patients with early disease and advanced disease, the majority of patients had organ-confined or locally advanced disease and stable PSA levels. Hence, it is unclear how the scale properties may differ in a population with more advanced disease. Certainly, the possibility of observing changes in anxiety as disease status changes is more likely in a population in which the disease status actually is changing. Perhaps more importantly, we anticipate that the MAX-PC (and the Fear of Recurrence Subscale in particular) may be more useful in differentiating general anxiety from anxiety specific to prostate cancer in a population of acutely ill patients. Nevertheless, further research using the MAX-PC will be needed to understand the utility of this scale more fully.
A second significant issue in terms of our validation data concerns the lack of any psychiatric assessment of the patients studied. Without a clinical diagnosis, it is not possible to determine which patients may meet the criteria for a diagnosis of an anxiety disorder. Thus, we are unable to establish cut-off scores to identify patients who may benefit from a referral for psychiatric consultation and/or antianxiety medications. Again, further research will be needed to assess the sensitivity and specificity of the MAX-PC using various cut-off scores.
Despite these limitations, we believe the MAC-PC represents a useful mechanism for identifying and quantifying anxiety in men with prostate cancer. This growing population has long been difficult to engage in psychiatric/psychosocial interventions, although these patients are subject to much psychological distress as a result of both diagnosis and treatment of their disease. The ability to rapidly screen and identify patients who may be experiencing significant anxiety certainly is needed and may facilitate clinical research efforts aimed at treating these troubling symptoms and minimizing the impact of anxiety on overall quality of life for men with prostate cancer.
The authors thank AstraZeneca and its participating institutions, particularly Dr. G. Kolvenbag and Dr. Lisa Porter and her staff. They also thank Enid Zuckerman for her administrative guidance and Dr. Harry Herr; Dr. Michele Donat; Mary Ellen O'Sullivan, R.N.; and Dr. Lou Primavera for their clinical insights and assistance in developing this study.