Objective Evidence-based quality of life (QL) questionnaires require the identification of issues of importance to patients. The primary aim of this study was to inform providers on patient-expressed issues while enhancing the content validity of instruments assessing QL and patient-reported outcomes (PROs) in prostate cancer. The study provided additional psychometric properties for the new PRO and QL instrument, the Prostate Cancer Symptom Scale (PCSS).
Methods An anonymous web-based survey of 2128 patients with prostate cancer was conducted with patients rating 18 QL items on a five-point scale.
Results Most respondents (74%) were aged 55–74 years, had early stage disease at diagnosis (81%) and were diagnosed within 2 years of the survey (81%). The top five-rated issues were: overall QL, ability to perform normal activities, maintaining independence, ability to sleep and not being a burden. These items were ranked as either ‘very important’ or ‘important’ by at least 88% of patients. None of the most highly ranked issues were symptoms. Instead, the highest ranked items were global issues reflecting the impact of symptoms on patients. In addition to the enhanced content validity findings, good reliability results and initial support for construct validity are reported for the PCSS.
Conclusions This is the largest survey providing patient-expressed background for content validity for QL and PRO measures. The findings of this study should aid development of newer practical questionnaires, such as the PCSS, which can be adapted to electronic platforms enhancing rapid and accurate PRO and QL evaluation.
- Quality of life evaluation
- patient reported outcomes
- prostate cancer
- psychometric properties
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Key concerns affecting patients with prostate cancer are essential when evaluating the impact of therapeutic and supportive care interventions. Major end points requiring evaluation include quality of life (QL) and patient-reported outcomes (PROs). While a large number of QL and PRO questionnaires have been developed,1 few are used in clinical trials and even fewer are used in daily patient evaluation. Issues that limit the assessment of PROs include the practicality of incorporating this evaluation into trials and patient care, and the method of choosing items for inclusion in these measures. Concerns have been expressed about the limited participation of patients themselves during the development of these questionnaires. Appropriately, the Food and Drug Administration 2009 guidance for industry document stated that “…without adequate documentation of patient input, a PRO instrument's content validity is likely to be questioned”.2 The current study was initiated to gain, for the first time, the input of a large number of patients with prostate cancer to provide evidence for PRO measures in general and for the new quality of life and PRO instrument, the prostate cancer symptom scale (PCSS), in particular. In addition to PCSS, a number of other QL and PRO measures, comprehensively described in a previous systematic review,3 have been developed for patients with prostate cancer. Although the present analysis was initiated to support the content validity of the PCSS, the results reported herein can be of value for other prostate cancer PRO instruments.
Somatic symptoms reflect physical well-being and are a component of overall quality of life.4 ,5 However, QL and broad affective responses are multidimensional constructs influenced by the interaction of physical, psychological, social and spiritual well-being,6 and therefore should be distinguished from physical symptom reporting. Previous work by our group has shown that patients with lung or breast cancer more highly value PRO aspects that evaluate global issues such as quality of life, maintaining independence and performing normal activities, as opposed to specific symptoms.7 ,8 The current project also assessed whether patients with prostate cancer similarly prioritise more global issues of concern compared with somatic symptoms.
PRO evaluation is gaining recognition in clinical oncology9 and more cancer-specific instruments are being developed.10 The PCSS is designed to emulate the theoretical model11 of the Lung Cancer Symptom Scale (LCSS) which is a widely used measure with well-validated psychometric properties in patients with lung cancer.7 ,11–13 The LCSS is a brief and practical questionnaire concentrating on the issues of greatest importance to patients. As such, the LCSS has been successfully migrated to an electronic platform (called the ‘eLCSS-QL’).14 This electronic platform can be used on tablets or other devices. The electronic methodology improves accuracy and reduces the burden on patients and staff in conducting PRO evaluation, while providing immediately available results for comparison over time. Using the electronic platform, the questionnaire requires only about 2 min to administer and overall can save time in a busy clinic setting.14 Currently, few QL/PRO measures are used commonly either in research or in practice in patients with prostate cancer. The findings of this study can add to the evidence-based foundation for enhancing existing instruments, and in developing newer measures, such as the PCSS. By providing a brief and practical measure, the PCSS may encourage a more frequent QL assessment to aid in personalising patient care and assessing interventions in clinical investigations.
Participants and data collection
A cross-sectional, online electronic survey of patients with prostate cancer was conducted over a 3-day period. Patients were surveyed using the established patient base of the online NexCura patient information resource. Patients who had previously registered in the NexCura website (http://www.nexcura.com) were routinely asked if it would be permissible to be contacted in the future. Those with prostate cancer and agreeing to be contacted received invitation emails outlining the purpose of the survey and that it would be performed anonymously. These patients who agreed to be included in the study then received the electronic survey related to prostate cancer. Participation was elective, responses were fully anonymous and no patient identifier was used at any time during the study.
Patients with either active disease or a history of prostate cancer were invited to be included in the survey. Caregivers were excluded from the survey. Participants' consent was indicated by each individual's willingness to complete and return the questionnaire. The ownership and mission of NexCura has evolved since the completion of this survey and at the time of this writing, the NexCura website was no longer active online.
Patients were asked first to complete a demographic form consisting of 10 questions concerned with the sociodemographic profile and health-related information of patients. This included self-reporting of age group, time since prostate cancer diagnosis, stage at diagnosis, cancer recurrence and types of treatment received. To determine disease stage, patients were asked to choose among the following four options: “My prostate cancer was confined to my prostate (localised disease; no cancer outside the prostate capsule),” “My prostate cancer was spread outside of my prostate, but not to other organs in my body (the cancer may have spread to the nearby seminal vesicles, or other nearby tissues within the pelvic area),” “My prostate cancer was spread outside of my prostate to areas far from my prostate, such as lymph nodes or bone,” or “I do not know”. On the basis of these responses, patients were classified as having early stage (stages I and II), locally advanced (stage III) or metastatic (stage IV) disease.
To determine the list of QL and PRO items to be evaluated and ranked by patients, a panel of 17 oncology professionals who focus on prostate cancer (medical oncologists, urologists and oncology nurses) reviewed the literature and existing PRO/QL instruments.15–18 The panel selected 18 items felt to be of the greatest importance based on the literature review and their experiences. These issues encompassed the physical, functional, psychological, social and spiritual domains of QL. Patients were also encouraged to submit items that they felt might supplement the survey. The 18 QL/PRO items were rated by patients on a five-point categorical scale ranging from ‘not important at all’ to ‘very important’. Categorical variables were compared using Fisher's exact tests. A p value of <0.05 was considered statistically significant. All statistical analyses were performed using the statistical program R (Foundation for Statistical Computing, Vienna, Austria) (R: A language and environment for statistical computing [program]. Vienna, Austria: R Foundation for Statistical Computing, 2012).
The demographic characteristics of this study's cohort were compared to those of the Surveillance, Epidemiology and End Results (SEER) program of the National Cancer Institute. SEER includes data from ∼28% of the US population.19 Using the SEER 1973–2010 database (April 2013 release), men with primary prostate cancer diagnosed from 2000 to 2010 were identified. The information retrieved included age and stage at diagnosis.
Continued assessment of psychometric properties of the PCSS
The primary focus of this study was to analyse items of importance in prostate cancer to enhance evidence-based content validity for the PCSS using a large-scale online survey methodology. The Prostate Cancer Symptom Scale (PCSS) is an 18-item self-report instrument for measuring QL, major symptoms and PROs of prostate cancer. It is a modification of the well-tested LCSS.7 ,11–13 As seen in the items tested, the PCSS measures major symptoms and global issues of concern to patients with prostate cancer. Additionally, it uses three of the global items as a prognostic 3-Item Global Index (related to total symptom distress, activity status and overall QL).20
The PCSS focuses on the physical and functional domains of QL, and captures the psychological, social and spiritual domains in less depth. The patient is asked to focus on describing prostate cancer symptoms to limit comorbidity aspects as much as possible. The time frame is the past day (past 24 hours), based on the rationale that the scale items represent states or conditions that may fluctuate, not enduring traits. The reading level required for the patient scale is second grade level. The PCSS uses an interval level visual analogue scale to determine the intensity of patient responses. Each item is given an individual score equal to the length of the line, with zero=lowest rating (best status) and 100=highest rating (worst status).7 ,8 ,11–13 Scores are then reversed for two electronic summary reports to discuss with patients (scores for today's visit and scores over time).
Initial psychometric testing in addition to determination of large-scale content validity for the PCSS is reported. Support for content validity was initially obtained using the literature and then a panel of healthcare experts in prostate cancer prior to asking the patients to rate all items. Initial reliability testing (for internal consistency) for the PCSS was calculated from the results of 45 men with prostate cancer who completed the PCSS (using Cronbach's α test). Construct validity was assessed using classic validity testing guidelines,21 whereby the PCSS score is compared between two groups of patients known to have either very good or very poor health status. If the PCSS is sensitive to differences in disease status using the contrasted groups approach, then there should be a significant difference in the PCSS score between these two patient groups.
The respondents' demographic profile and prostate cancer characteristics in comparison to the SEER cohort (627 464 individuals) are presented in table 1. A total of 2128 patients completed the survey; the majority of patients (74%) were aged 55–74 years. Most patients (81%) had early stage disease at initial diagnosis and were diagnosed within 2 years of the survey. The staging and demographics of the 2128 patients in this survey were similar to that of the SEER cohort, although the patients in this study were on average somewhat younger. The proportion of patients older than 75 years was significantly lower in this study compared with the SEER cohort (p<0.001). Nearly half of the patients (48%) in the survey were treated with radical prostatectomy, and only 10% had not received any anticancer treatment. Even though most patients (81%) had early stage disease, this large survey still enlisted nearly 120 patients with metastatic cancer, providing a reasonably large sample of patients with this extent of disease.
QL and PRO questions assessed for content validity
The QL and PRO survey results for the 2128 patients with prostate cancer are presented from the large online survey (table 2). These results were ranked by the percentage rating of each item in either the top two categories (‘very important’ plus ‘important’) or by only the top category (‘very important’). Of the 18 items surveyed, 12 were symptoms and 6 were global issues. The five most highly ranked issues are global items rather than specific symptoms, whether one looks at the ratings by either the top two categories or by only the ‘very important’ category (with the one exception that ‘urinary incontinence’ as a symptom was ranked number 4 in the ‘very important’ category). The global issues, such as maintaining quality of life (rated in the top two categories by 96% of patients), the ability to perform normal activities (95%) and maintaining independence (95%), received the highest ratings by patients. The highest rated symptoms were fatigue (87% of patients), urinary incontinence (87%), depression (80%), difficulties with urination (79%) and erectile dysfunction (77%). Patients were invited to suggest additional items. However, only a very small number of patients volunteered additional items and none of these were indicated with sufficient frequency to add as additional items to the PCSS.
QL and PRO findings are presented for subgroups of patients of interest (tables 3 and 4, and the text). Four subgroups were included: (1) patients who had or had not received radical prostatectomy, (2) patients with metastatic (stage IV) disease, (3) patients without disease recurrence and (4) patients who received hormone therapy following disease recurrence. No matter which subgroup is examined, the top five-rated issues were ranked very similarly; they were all global impact items and were rated by the patients as being of greater importance than any of the specific symptoms.
Comparison of subgroups revealed that the importance of PRO issues was fairly congruent across all subgroups. There are some issues, however, differing by patient subgroup and merit attention, as seen in tables 3 and 4. Some variations by subgroup are seen in the ratings of specific symptoms. While hot flashes was the lowest ranked item by all groups, predictably a large difference was reported by those who received hormonal therapy (46% rated this item in the ‘very important’ plus ‘important’ categories) when compared with the whole group (34%), with those treated with radical prostatectomy (32%, p=0.004), or with those patients who are free of cancer (32%, p=0.002). When contrasted with the whole group, the 128 patients receiving hormonal therapy after disease recurrence reported less erectile dysfunction (77% for the whole group, and 48% in the hormone treated subset) or sexual difficulties (76% vs 48%). Urinary difficulties (69%) and incontinence (77%) were less often reported (10% lower ratings) by the hormone treated group than for any other subset (p<0.05 in each instance). For all other issues, patients receiving hormone therapy rated each item similarly (within 5%) to the whole group. As previously reported,22 ,23 patients with stage IV extent (typically with bone metastases) ranked pain considerably higher than other groups. All urinary and sexual issues were rated more highly by patients reportedly free of disease when compared with those with metastatic prostate cancer.
As seen in table 4, the more than 1000 patients undergoing radical prostatectomy generally ranked most issues similarly to those not having this procedure. Three items differed by 4% or greater between these two groups. Patients experiencing radical prostatectomy expressed greater concerns regarding both sexual issues surveyed (9% differences with p<0.001 in each instance). The surgically treated patients also expressed slightly greater concern with urinary incontinence (4% difference, p=0.004).
Additional assessment of psychometric properties of the PCSS including reliability and construct validity testing
In addition to determining patient generated content validity for the PCSS, support for reliability (internal consistency) and initial construct validity were good for this 18-item self-report instrument which measures QL, major symptoms and PROs of prostate cancer. For reliability testing, the early content findings derived from the literature and reviewed by a panel of experts were then taken to a patient sample as part of a larger prospective evaluation.24 This sample included 45 patients with advanced prostate cancer who completed the PCSS. Internal consistency, using Cronbach's α, was 0.86, exceeding the acceptable reliability guideline of 0.70 for new measures.21
Initial support for construct validity, using the contrasted groups approach, also was good for the PCSS. In a sample of 35 men with advanced castration-resistant prostate cancer with similar demographic characteristics (median age 73): 74% Caucasian and 26% African-American, a median of 16 years of education and 37% with incomes of <$40 000 per year), two groups were divided into early and late disease trajectory groups using common standards of disease status. The results indicated that the PCSS is measuring what it purports to measure and it is sensitive to group differences21 in that the 16 men with less advanced cancer (the earlier trajectory group) reported better QL (mean, 67.9) than the 19 men with more advanced disease (the later trajectory group) who reported a lower QL (mean, 57.9), using the electronic version.
The present survey is the largest study designed to assess patient input for issues of importance in prostate cancer. As such, it provides patient-generated evidence for content validity of PRO and QL measures in this malignancy. The web-based method enhanced the ability to collect responses from a large number of patients, and to do so rapidly. Cancer symptoms were less highly ranked compared with more global issues such as QL, maintaining independence and performing normal activities. Of interest, in recent similar assessments in lung cancer and breast cancer, patients also rated these global issues more highly than symptoms.7 ,8 While the number, magnitude and type of specific symptoms may vary among individuals, all respondents ranked these three global issues as their main concerns. Symptoms remain important to patients (as demonstrated by 87% of patients ranking urinary incontinence highly); however, it must be recognised that it is the impact and distress of symptoms on overall QL and functioning that patients express at the top of the list. This is true for the whole group of over 2000 patients and for the various subsets, including those with metastatic disease.
The five-point categorical scale used in this survey allowed a strong separation in the ranking of issues, from 96% of patients to 34% when combining the top two categories and from 74% to 10% when considering only the top category (‘very important’). Among common specific symptoms, fatigue and urinary problems were the highest ranked by patients, whereas hot flashes, diarrhoea, constipation and appetite were consistently reported to be lower. Each of the 18 items ranked by the patients is worthy of attention. Even hot flashes, which was the lowest ranked item, was deemed to be either important or very important by about one-third of patients. Not surprisingly, patients with advanced prostate cancer who often receive hormonal therapy were more likely than others to consider hot flashes as important. Documentation of this impact on such individuals is needed for dependable PRO evaluation, rather than relying on expert opinion, which is not always accurate. Of note, the expert panel members did not anticipate that global issues would be so clearly ranked at the top of the survey. Additional evaluation of the psychometric properties of the PCSS performed in the subgroup of patients with advanced prostate cancer showed good reliability and support for construct validity pointing towards the strong psychometric underpinning of the instrument. These assessments were intentionally performed in one specific patient subgroup (i.e., patients with advanced prostate cancer) to minimise measured or unmeasured differences between patients when assessing construct validity using the contrasted groups approach.
As with all surveys, this study has limitations and strengths. All collected data, including demographic information, were self-reported. It is an advantage that the web-based technology allows participation of a large number of patients, but, on the other hand, it is only available to those with internet access, some degree of computer literacy and the desire to learn more about their cancer. It may be that patients with higher disease severity are less likely to access the web and complete the survey. Patients using the NexCura website had to be able to communicate in English, and this website attracted a predominantly North American audience (88–91% of respondents), as determined in prior studies using the Nexcura platform.25 ,26 The major strengths of the present survey include the large sample size and that all ratings are patient reported. In addition, the generalisability of the results is further supported by the demographic and disease characteristics of the surveyed patients which are similar to the overall population of patients with prostate cancer in the USA, as seen in the SEER data displayed in table 1.27 One notable exception is that patients participating in the present survey were younger than what would be expected based on the SEER data. Younger patients are more likely to have higher computer literacy and thus access the survey. It is unknown if older patients would share the same views.
The present survey provides evidence of the importance of specific PRO and QL issues as reported by over 2000 patients with prostate cancer. These results elucidate data for such evaluation from the patients' point of view that has not previously been available. Additionally, this large sample allows examination of the views of patients in a variety of subgroups including those currently free of disease as opposed to those with stage IV extent, as well as the opinions of those who had undergone radical prostatectomy. Review of the findings can be helpful for both the PCSS and other PRO and QL measures used in patients with prostate cancer.3 In particular, this study demonstrates that an exclusive focus on symptom measures is incongruent with patient-expressed needs.
The study's findings contribute to the content validity of PRO measures for patients with prostate cancer. It provides enhanced psychometric properties for the new PCSS questionnaire: support of content validity by patients is indeed strong, based on findings of this large survey. In addition to reflecting the views of patients, the PCSS can provide a PRO and QL measure that is succinct and practical for use in patient care and clinical trial settings. This format lends itself to patient use on such electronic platforms as a modern tablet14 or via an application. These results add to the evidence in major cancers indicating that measures focusing solely on symptoms, without including items related to the impact of such symptoms on overall QL, fail to address PRO issues that are clearly deemed to be crucial by patients.7 ,8
Contributors PM, RJG and PJH planned the study. RJG and PJH managed and implemented the study. PM and RAJ conducted data analysis. PM, RJG and PJH wrote the first draft of the paper and are guarantors of the study; all authors contributed to further redrafting of the final manuscript. All authors had full access to all the data in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Funding This study was supported in part by grants from the US National Cancer Institute (grant number 1R21CA131754-01) and from the Robert Wood Johnson Foundation Nurse Faculty Scholars Programme (grant number 66517). PM is supported by the US National Institutes of Health T32 CA009666 grant.
Competing interests None declared.
Ethics approval Ethical approval was not sought at the time the survey was conducted as responses were fully anonymous, participation was elective and the study did not contain questions on sensitive topics. Participants' informed consent was indicated by each individual's willingness to complete the questionnaire.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement All primary data used for this study are available on request via email to the corresponding author.