| | Development of a symptom assessment instrument for chronic hemodialysis patients: the dialysis symptom indexAccepted 14 July 2003. Abstract Little is known about the prevalence, severity, or impact of symptoms in hemodialysis patients because of the lack of a validated symptom assessment instrument. We systematically developed an index to assess physical and emotional symptom burden in this patient population. We employed four steps in the generation of this index: a review of dialysis quality-of-life instruments, three focus groups, experts' content validity assessment, and test–retest reliability measurement. Seventy-five symptoms were identified. Of these, 46 appeared in ≥ 4 of the instruments/focus groups and were considered for inclusion. Twelve were grouped into other symptom constructs and experts judged four of the remaining items not to be pertinent, leaving 30 items in the new index. Overall kappa statistic was 0.48±0.22. These steps allowed the systematic development of a 30-item symptom assessment index for hemodialysis patients. Additional reliability and validity testing is needed prior to its widespread use.
1. Introduction  The rapid growth in patients over 65 with end-stage renal disease (ESRD) has led to an increased interest in the palliative care of dialysis patients.1., 2., 3. The annual mortality rate of this population, 24%, is higher than many common cancers.4., 5. Moreover, the health-related quality of life (HRQOL) of dialysis patients is much lower than the general population.6., 7., 8. Previous studies suggest this is a result of multiple co-morbid illnesses, treatment-related side effects, lifestyle alteration, and the psychosocial impact of living with ESRD.9., 10., 11., 12. Less is known about the prevalence, severity, and overall impact of physical and psychological symptoms in this population.6., 8., 13. Chronic dialysis patients can suffer from a number of physical and emotional symptoms.14., 15., 16., 17., 18. For example, fatigue, which commonly results from the anemia of renal failure, affects as many as 80% of patients on dialysis.14 Human recombinant erythropoietin decreases this fatigue, and has been shown to have a beneficial effect on HRQOL.19 Nonetheless, patients often report other symptoms including anorexia, pain, nausea, pruritis, shortness of breath, muscle cramps, paresthesias, feeling depressed, sexual difficulty, and sleep disturbance.14., 15., 18., 20., 21. These symptoms may play an important role in the observed decrement in HRQOL of this patient population. In other areas, such as oncology and the acquired immune deficiency syndrome (AIDS), investigators have found a relationship between symptom burden and HRQOL.22., 23., 24. Unfortunately, the prevalence, severity, and impact on HRQOL of symptoms in dialysis patients have not been well studied. Many instruments currently used to evaluate the HRQOL of dialysis patients have items pertaining to symptoms. However, a comprehensive and psychometrically tested questionnaire designed specifically for the assessment of physical and emotional symptoms in this population is lacking.25., 26., 27. Such an instrument would be helpful both for research purposes and as a tool to improve care of patients dependent on dialysis. For example, symptom assessment instruments used in other fields have shown that providers frequently under-recognize and under-treat symptoms, that family members are moderately accurate surrogates in reporting patient symptoms, and that routine questioning about symptoms can result in improved treatment.22., 24., 28., 29., 30., 31., 32., 33., 34., 35., 36. In a recent study conducted by our group on the potential value of palliative care to a highly ill segment of the hemodialysis population, we employed the Memorial Symptom Assessment Scale-Short Form (MSAS-SF) to assess symptom burden.1 The MSAS-SF was developed to assess the presence, severity, and frequency of 32 symptoms in patients with cancer, and it has since been used in patients with AIDS.23., 37. Using the MSAS-SF, we found several physical and emotional symptoms to be prevalent and severe in our study population, and to be associated with impairments in HRQOL. Moreover, we observed that nephrologists commonly failed to document in the medical record many of the symptoms reported by patients, raising the possibility that symptoms are under-recognized in patients on hemodialysis. However, because it was designed for cancer patients, the MSAS-SF contains many items of less relevance to those on dialysis and lacks certain items of potential importance to patients with ESRD dependent on this therapy. We believe that understanding physical and emotional symptom burden in patients on dialysis is essential if efforts to improve the HRQOL of this patient population are to be successful. For this reason, we sought to revise the MSAS-SF to generate an instrument that would allow for reliable and valid assessment of symptom prevalence and severity in patients on hemodialysis, the most common form of renal replacement therapy in this country. This report describes the preliminary steps taken to formulate this index. 2. Methods 2.1. Overview The institutional review boards at our institution and at the Dialysis Clinic Incorporated approved all study procedures. The Dialysis Symptom Index (DSI) was created in four phases using qualitative and quantitative research methods. First, we reviewed a convenience sample of four HRQOL questionnaires used in dialysis patients containing items on physical and emotional symptoms and one symptom assessment survey used in patients with chronic renal failure not yet dependent on dialysis. Second, we conducted three focus groups, two in dialysis patients and one in renal providers, to identify a wide range of symptoms experienced by the hemodialysis population. Using the information obtained from these two steps, we systematically selected items for potential inclusion on the new index. Third, to improve our content validity, we asked four experts in the field of HRQOL and ESRD, and four full-time clinical nephrologists to judge the clinical relevance and wording of each of the items. The data obtained from these three steps were used to modify the MSAS-SF and to formulate the new index. We emulated the format of the MSAS-SF to configure our new instrument for three main reasons. The instrument is bi-dimensional; it assesses both the presence and severity/frequency of physical and emotional symptoms. This format has been successfully used in other patient populations, particularly those with cancer. Lastly, in our previous study of dialysis patients, the MSAS-SF was easy to administer and patients had no trouble completing it. As a final step, we administered the index twice, 4–7 days apart, in 20 hemodialysis patients to obtain test–retest reliability data. Detailed descriptions of these four steps are discussed below and are outlined in Figure 1. 2.2. Health-related quality-of-life questionnaire review We selected a convenience sample of four of the most widely recognized HRQOL questionnaires that have been developed for, and used in, patients with ESRD over the past five years as well as a symptom index designed for pre-dialysis patients. From this review, we identified any item that asked either directly or indirectly about a physical or emotional symptom. Items that did not precisely match a symptom construct were recorded as the symptom they most closely matched as determined by one investigator (SDW). We added each new item to the symptoms noted in the MSAS-SF. 2.3. Focus groups Because of the unique experience of living on dialysis and of caring for those afflicted with ESRD, we chose to elicit the input of hemodialysis patients and renal care providers in the formulation of this index and to use a focus group format for this purpose. First, we conducted a group with renal providers including physicians, social workers, and dieticians to identify the symptoms seen by these individuals in chronic hemodialysis patients. We distributed a copy of the original MSAS-SF to each provider one week in advance of the meeting and asked him or her to review the scale. During the group, we asked the providers to discuss their experiences with symptoms, to comment on the items appearing on the MSAS-SF, and to identify items not present on the MSAS-SF that they believed should be included on a hemodialysis-directed symptom assessment instrument. The discussion was audiotaped and transcribed, and field notes were taken by the principal investigator (SDW). We then held two focus groups with hemodialysis patients. Patients participating in these groups were from two non-profit Dialysis Clinic Incorporated (DCI) clinics in the Pittsburgh area and were selected by nurse coordinators and nephrologists at these clinics based solely on willingness to participate. The first group was made up entirely of African American patients receiving their care at a clinic that treats a primarily urban, lower-middle class population. The second group was made up of Caucasian hemodialysis patients receiving dialysis at a clinic that cares for a middle class, suburban population. We opted to enroll patients from these two units because prior studies suggest that African Americans and Caucasian dialysis patients may experience different symptoms, and we wished to ensure that our sample would be demographically representative of the general dialysis population.44 Discussions were aimed at the physical and emotional symptoms these patients had experienced since starting dialysis. Symptoms that were mentioned at least once in the focus groups were considered as potential items for the new index. These meetings were audiotaped and transcribed, and the principal investigator took field notes. One Caucasian moderator with prior experience in conducting focus groups ran all three sessions. One investigator reviewed the field notes and transcripts from all three focus groups. 2.5. Content validity Four experts in the field of ESRD and quality-of-life assessment and four full-time clinical nephrologists were identified and asked to rate the relevance of each item (4-point Likert scale, 1 =not relevant to 4=highly relevant) and the wording of each item (4-point Likert scale, 1=completely inappropriate wording to 4=completely appropriate wording). The experts, who were from four different medical centers, were chosen based on previous research and publication in the area of HRQOL and ESRD, while the four clinicians were a convenience sample based on their affiliation, direct or indirect, with our institution. Relevance was defined as the “importance of the symptom to hemodialysis patients and renal providers.” Appropriateness of wording was defined as “how well the wording of the item captured the symptom it was intended to assess.” Items that 6 or more of the 8 reviewers judged to be “highly relevant” (score of 4) were included on the new index, while items that 5 or fewer reviewers judged to be “highly relevant” were eliminated. We then reviewed the included items for appropriateness of wording. Items for which two or more of the 8 reviewers judged the wording to be less than completely appropriate (scores <4), were reviewed further for potential modification. The principal and senior investigator (GES), an expert in scale development and survey psychometrics, discussed these items, and wording was modified if both investigators agreed to a specific change. 2.6. Test–retest reliability assessment As part of a larger study of symptoms in ESRD, we selected twenty hemodialysis patients and asked them to participate in test–retest reliability assessment. This group of patients, all from the VA Pittsburgh Healthcare System dialysis unit, comprised 19 men and 1 woman and was 70% African American and 30% Caucasian. After providing informed consent, these patients were administered the new index by a trained interviewer during a routine dialysis session. Four to seven days later, the index was re-administered by the same interviewer, also during a routine dialysis treatment. We chose to use a 4–7 day time frame in place of the standard one to two weeks for test–retest reliability assessment because of the potentially transient nature of many of the symptoms experienced by this population. Kappa statistics were determined for each of the symptoms appearing in the index. Additionally, we identified the symptoms most commonly reported by these twenty patients on the first administration to begin to confirm the applicability of the new index. 3. Results 3.1. Health-related quality-of-life questionnaire review We reviewed four HRQOL instruments. Two of the instruments, the Kidney Disease Quality of Life Questionnaire Short Form (KDQOL-SF) and the CHOICE Health Experience Questionnaire (CHEQ) are dialysis-specific instruments that have been used in large studies of the dialysis population.27., 38., 39. The KDQOL-SF was developed by the RAND Corporation, uses the SF-36 as its core, and incorporates additional kidney disease targeted items.7., 25., 38., 39. Its internal consistency reliability and content and construct validity have been well established, and the development of the instrument involved the input of dialysis patients and renal providers.7., 25., 38., 39. The CHEQ, an instrument designed to assess HRQOL in both hemodialysis and peritoneal dialysis patients, contains 21 domains and several items pertaining to physical and emotional symptoms.27 It too has good psychometric properties and was developed with the input of dialysis patients.27 In addition to these questionnaires, we reviewed the HEMO study quality-of-life questionnaire and the Dartmouth COOP charts for ESRD, which have been developed for and used in dialysis patients. The HEMO Study Quality-of-Life Assessment questionnaire has as its core the KDQOL long form, an extended version of the KDQOL-SF.40 It is supplemented with additional items, some of which deal with dialysis-related symptomatology. Although the KDQOL-LF, which makes up much of the HEMO study questionnaire, has good psychometric properties, reliability and validity data on the additional items are unknown.40., 41., 42. The Dartmouth COOP charts questionnaire is a 36-item scale which contains several questions on symptoms.26 Although, there are limited data on the psychometric properties of the Dartmouth COOP charts questionnaire for dialysis patients, it is a recently developed measure for quality-of-life assessment for this patient population and is known to the study investigators. It was selected for review in this study for these reasons. Also included in this review was the Patient Symptom Form used in the Modification of Diet in Renal Disease Study, a large study of patients with chronic renal failure not yet dependent on dialysis.43 Because of the significant overlap of symptoms between these two populations, this instrument was included in our analysis. Symptoms appearing on these questionnaires and the MSAS-SF, and their frequency of appearance, are shown in Table 1. | | |  | Number of Questionnaires Containing Symptom | Symptoms | |
|---|
| 6 | Feeling sad, nausea, itching, feeling irritable, lack of energy, pain | |
| 5 | Feeling nervous, weakness, lightheaded, difficulty sleeping, lack of appetite, numbness/tingling | |
| 4 | Bodily pain, back pain, feeling bloated, difficulty concentrating, shortness of breath, dry skin, can't fall asleep, can't stay asleep, feeling anxious, dizziness, muscle cramps, problems with sex, changes in skin, “don't look like myself” | |
| 3 | Constipation, cough, feeling drowsy, vomiting, loss of libido/decreased interest in sex, impotence, low exercise tolerance, worrying, chest pain, stomach cramps | |
| 2 | Diarrhea, restless legs, dry mouth, swelling of arms or legs, muscle soreness, lack of strength, easy bruising, washed out/drained, blurred vision, joint stiffness | |
| 1 | Cramps during dialysis, bone/joint pain, changes in skin color, cramps after dialysis, excessive thirst, headache, heartburn, pain in dialysis access, sweats, increased thirst, easy bleeding, change in taste, loss of taste, bad taste in mouth, weight gain, cold intolerance, chills, difficulty swallowing, hiccoughs, mouth sores, trouble seeing, foot problems, hives/rash, hot/cold spells, trouble hearing, trouble with memory, hair loss | | | | |
3.2. Focus groups 3.2.1. Provider focus group Participants in the renal care provider group included two nephrologists, one renal social worker, and one dietician. The participating nephrologists, both of whom practiced in an academic setting, had a combined 41 years of experience treating patients receiving hemodialysis. The social worker had 16 years of experience caring for patients receiving chronic dialysis. The renal dietician had been working with this patient population for 16 years. From this group discussion, 27 symptoms that appear in hemodialysis patients were identified. Four items on the MSAS-SF were thought to be uncommon and not generally of significance in dialysis patients. These included sweats, hair loss, mouth sores, and dizziness. Two items present on the MSAS-SF were believed to be relevant, yet too general. Participants subdivided these two items, “difficulty sleeping” and “problems with sexual interest or activity” into two separate questions each. Results from this focus group are presented in Table 2. 3.2.2. Patient focus groups The second focus group was made up of 10 African American hemodialysis patients, 5 men and 5 women, with an average age of 52 (range 40–67). The mean number of years on dialysis for this group was 4.5 (range 1–13). Two patients had a history of a previous failed kidney transplant and seven suffered from diabetes mellitus. This group identified 36 symptoms. The third focus group was made up of three white hemodialysis patients, two women and one man, who had been on dialysis for a mean of 6 years (range 4–9). The average age of these patients was 51 (range 44–58), all three had a failed prior kidney transplant and none were diabetic. These three participants identified 41 individual symptoms. Results from these patient focus groups are also presented in Table 2. 3.3. Item selection From the questionnaire review and focus groups, a total of 75 separate symptoms were identified. Forty-seven symptoms appeared in 4 or more of these questionnaires/focus groups. Of these 47, 12 items were judged to overlap significantly with other symptoms and were compressed into these symptom constructs. For example, lack of strength, weakness, and low exercise tolerance were combined into “fatigue or lack of energy.” This process is detailed in Figure 2. One item, “don't look like myself,” was felt to represent a sign and not a symptom construct and was eliminated. This left 34 symptoms to be included in the analysis of relevance and wording in the next step of development. 3.4. Content validity Content validity surveys were received from all eight reviewers. Three or more reviewers judged four items to be less than highly relevant. These symptoms, which included blurred vision, back pain, feeling drowsy, and feeling bloated, were eliminated from consideration for inclusion in the index. Seven of the remaining 30 symptoms were identified by two or more reviewers as being less than completely appropriately worded. These included “lack of appetite,” “swelling of arms or legs,” “restless legs,” “lack of energy,” “bone/joint pain,” “difficulty concentrating,” and “difficulty becoming sexually aroused.” Consensus was reached to change the wording on four items. Lack of appetite was changed to “decreased appetite;” swelling of arms or legs was modified to read “swelling in legs;” lack of energy was changed to “feeling tired or lack of energy;” and restless legs was changed to “restless legs or difficulty keeping legs still.” These steps led to the formulation of a 30-item index, which, similar to the MSAS-SF, inquires about the presence of the symptom and the severity of that symptom based on a 5-point Likert scale. The final instrument is shown in the Appendix. 3.5. Test–retest reliability assessment Twenty patients completed the index on two separate occasions. The percent total agreement was high (mean 0.80±0.09). Kappa statistics range from 0.06 to 0.90 (mean 0.48±0.22). Three values were below 0.2: diarrhea, lightheadedness/dizziness, and difficulty concentrating. Ten items demonstrated kappa values of ≥0.60. An additional eight symptoms had kappa statistics ≥0.40. Complete results of the test–retest process are displayed in Table 3. The mean number of symptoms reported by the 20 patients was 9.8 with a range of 2–19. Four symptoms: feeling tired/lack of energy, dry mouth, dry skin, and itching were reported by more that 50% of these twenty patients; and an additional eleven symptoms were described by more than 33% of subjects. 4. Discussion Past and current research has focused on ways to improve the substantial impairments in the HRQOL of chronic hemodialysis patients.45., 46., 47. In the oncology and HIV-literature, there is a clear inverse relationship between symptoms and quality of life, leading investigators to focus on decreasing symptom burden as a way to improve patient well-being.23., 30., 48., 49., 50. Similar work in nephrology is limited by the lack of a freestanding, comprehensive, and validated instrument for symptom assessment in dialysis patients. Nonetheless, it is well recognized that the rigors of the thrice weekly hemodialysis procedure, near universal cardiovascular and infectious comorbidity, metabolic derangements associated with ESRD, and psychological impact of living on dialysis contribute to the many symptoms that can plague this population. We believe that the accurate assessment and treatment of bothersome symptoms in dialysis patients is essential if efforts to improve the care of this patient population are to be successful. This belief, along with our recognition that dialysis patients can suffer from a constellation of symptoms unique to ESRD, served as the driving force behind the effort to develop the Dialysis Symptom Index. Most prior studies that have assessed dialysis patients' symptoms have used ad hoc instruments. Parfrey and colleagues conducted a series of studies nearly 15 years ago to generate a symptom assessment index.15., 16., 17. Although several steps including the incorporation of data pertaining to physical and emotional symptoms and preliminary evaluation of the scale's psychometric properties were completed, widespread testing and advanced scale development did not take place because of competing research interests of the investigators.51 Moreover, over the past decade, the aging of the ESRD population and widespread use of erythropoietin have likely altered the symptom profile of patients on dialysis.19., 52. These factors also led us to pursue development of the DSI. The development of a valid scale is a complex process requiring several well-planned and well-executed steps. Issues that need to be considered include the survey construct, the target population, generation and formatting of questions, mode of administration, potential measurement error, and psychometric testing of the instrument. We carefully considered these factors during development of the DSI. First, we used a patient and provider centered approach to develop our new index.53., 54., 55. Patients were chosen to ensure both ethnic and geographic diversity. Patients are likely to explore different symptoms with different health care providers, leading us to include a range of renal providers in our first focus group. Second, we employed both qualitative and quantitative research techniques to ensure both completeness and appropriateness of our data. Third, we asked experts in clinical care and research to review our first draft and provide feedback on the scale to collect preliminary validity data. Finally, we pilot tested the instrument in a group of patients to ensure that test–retest reliability was acceptable. These methods and the final product, the Dialysis Symptom Index, highlight important points about symptom burden and symptom assessment in dialysis patients and the potential utility of this new index. First, there was great variability in the symptoms reported both in the literature and among our focus group respondents. The five questionnaires we reviewed contained different symptoms, variation which also existed in the responses of our focus group participants. Although the differences in responses from the two patient focus groups may be partially explained by differences in the experiences and demographic characteristics of the participants, the explanation for the variability in responses between the patient groups and the provider group is less clear. We believe that this points out that patients and providers may have very different perspectives on the symptoms that patients on hemodialysis experience, and that providers may under-appreciate the importance attached to specific symptoms by their patients. If so, this underscores the significance of finding ways to improve the dialysis patient–renal provider interaction. The use of a symptom instrument such as the DSI may allow for the improved exchange of information between patients and providers. Second, there are a multitude of symptoms that can affect the dialysis population and could be considered for inclusion in an instrument to assess symptom burden. We identified a total of 75 unique symptoms from our instrument review and focus groups. This finding underscores the challenge of formulating an index that is comprehensive, yet concise and easy for patients to complete. Symptoms in these patients likely result from several processes. These include the physical demands of thrice weekly treatment, multiple comorbid conditions, metabolic derangements such as anemia, hyperphosphatemia, and hyperparathyroidism, and the psychological and social impact of being dependent on renal replacement therapy. Our aim was to configure a scale that would capture the most common and most bothersome symptoms and be viewed as useful from the perspective of a patient, a clinician, and the research community. Certain symptoms such as blurred vision that passed our preliminary criteria for inclusion and could be viewed as highly important by some, may not appear in our index. It is our belief that the symptoms that do appear are the physical and emotional symptoms that are most likely to afflict this patient group, and the brevity and potential ease of use of the index will increase its reliability, validity, responsiveness, and clinical utility. We did provide an open-ended question at the end of the index for patients to report on the presence of other symptoms not included on the scale. Future studies will determine if patients commonly report other symptoms. Certain methodological issues require further study. First, while our preliminary estimation of the index's reliability using test–retest procedures was good, three items had very low kappa values (<0.20). These included diarrhea, lightheadedness, and difficulty concentrating. We believe that both diarrhea and lightheadedness/dizziness are transient symptoms, which is the likely explanation for this finding. The DSI was administered while the subjects were receiving dialysis and the variability of dialysis treatment hypotension might have accounted for the differences in lightheadedness/dizziness. We are unsure why the reliability of difficulty concentrating was low. This finding, along with our preliminary results relating to “diarrhea” and “lightheadedness/dizziness,” need to be evaluated in greater detail. Second, this preliminary study did not include the administration of other instruments to test the construct validity of the DSI. We plan to replicate our results with a larger population of dialysis patients and assess the relationship between the DSI and validated measures of depression and HRQOL. Nonetheless, our results to date provide preliminary evidence that at this early stage of development, the Dialysis Symptom Index demonstrates good reliability characteristics when measured by test–retest procedures. There are several limitations to the current study. First, we used investigator-defined criteria to eliminate items from the DSI rather than asking a larger cohort of patients to judge all the symptoms we identified from the questionnaires and focus groups. It is possible that this process resulted in the elimination of symptoms of importance to this patient population. However, we believe that the relative brevity of the scale will help to limit measurement error. Second, the smaller sizes of the provider and second patient focus group could have limited the breadth of data obtained in these two meetings. Moreover, sicker patients who may have had large symptom burdens may not have participated in the patient focus groups limiting the number of symptoms reported. We attempted to account for this by asking health care providers about the symptoms they commonly see. Third, we used a one-week time frame to conduct re-testing of the Dialysis Symptom Index. Although symptoms may be quite transient in dialysis patients as a result of the rigors of each dialysis session and the intermittent metabolic derangements of ESRD, the use of a shorter time frame would have raised the issue of recall bias, and the utility of a longer time frame would have been affected by the short-lived nature of certain symptoms. Further test–retest and internal consistency testing are clearly needed to delineate the reliability of this scale. In summary, we have described the preliminary development of a freestanding, patient-centered instrument for the assessment of physical and emotional symptom burden in patients receiving hemodialysis. The specific steps we employed have allowed us to generate a concise, yet comprehensive and clinically relevant scale. Although additional psychometric testing is required, future studies on the morbidity associated with ESRD and the factors affecting the HRQOL of hemodialysis patients will be able to employ the DSI to further characterize the burden and impact of symptoms. This index also will help to improve communication between renal providers and dialysis patients. Furthermore, studies employing clinical interventions to improve the quality of life of patients with ESRD will now be better able to gauge the effect of such interventions on physical and emotional symptom burden. The Dialysis Symptom Index has the potential to become a highly useful tool to increase our understanding of the issues faced by patients dependent on hemodialysis. Acknowledgements Drs. Weisbord and Fried were supported by a grant from the Center for Health Equity Research and Promotion at the Pittsburgh and Philadelphia VA Healthcare Systems. Dr. Weisbord was also supported by NIH grant T32HL07820-05. Dr. Arnold was supported by the Project on Death in America Faculty Scholars Program, the Greenwall Foundation, Ladies Hospital Aid Society of Western Pennsylvania, the International Union Against Cancer (UICC) Yamagiwa-Yoshida Memorial International Cancer Study Grant, and the LAS Trust Foundation.
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PII: S0885-3924(03)00517-7 doi:10.1016/j.jpainsymman.2003.07.004 © 2004 U.S. Cancer Pain Relief Committee. Published by Elsevier Inc. All rights reserved. | |
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