Outcome Measures for Fatigue in Patients on Hemodialysis

Sixty percent to 97% of patients on maintenance hemodialysis therapy experience fatigue, which is associated with an increased risk for cardiovascular events, mortality, and decreased quality of life. Patients describe hemodialysis-related fatigue as debilitating, preventing them from being able to work and limiting their participation in social and recreational activities. Patients have rated fatigue as of higher importance than death and other components of quality of life. Despite the development of pharmacological and lifestyle interventions, fatigue is under-recognized in patients on maintenance hemodialysis.

In the context of chronic illness, there is no commonly accepted definition of fatigue, and previous qualitative studies in patients on hemodialysis have illustrated the complexity and multidimensionality of fatigue in that patient population. At present, measures of fatigue developed for other patient populations are being used for patients on hemodialysis. However, according to Angela Ju, BSc (Hons), and colleagues, those measures may not be appropriate for hemodialysis patients.

The researchers conducted a systematic review of outcome measures for fatigue as part of the SONG-HD initiative. The review was designed to “identify the content, general characteristics, and psychometric properties of outcome measures used to assess fatigue in patients receiving hemodialysis in order to inform the selection of a robust and feasible measure suitable for use in randomized trials conducted in this setting.” Results of the review were reported in the American Journal of Kidney Diseases [2018;71(3):327-343].

Searches were conducted in MEDLINE, Embase, PsycINFO, and CINAHAL from inception to April 12, 2017. Google Scholar and reference lists of relevant studies were also searched. A total of 3110 references were identified. Of those, 140 eligible studies involving >24,800 participants receiving hemodialysis across 31 countries were included. (Two studies did not report the number of participants). Of the 140 studies, 13% (n=18) were randomized controlled trials, 17% (n=24) were nonrandomized controlled trials, and 70% (n=90) were observational studies.

There were 45 different measures across the 140 studies. Of those, 53% (n=24) were developed for patients receiving maintenance hemodialysis, 40% (n=17) for nonhemodialysis patients, and 4% (n=2) for patients with chronic kidney disease. Of the 24 measures specific to hemodialysis patients, 79% (n=19) were designed by the authors for use in their study only, without validation. Thirty-two measures were developed specifically for fatigue and 11 examined broader outcomes such as quality of life and symptoms. The most frequently used measure was the 36-Item Short Form Health Survey; 19 measures were used in two or more studies. The number of items in each measure varied from one to 80; time for completion ranged from 1 to 30 minutes.

Items related to fatigue were classified into 11 content dimensions: tiredness, level of energy, life participation, postdialysis fatigue, limb/muscle weakness, ability to concentrate, ability to think clearly, motivation, memory, verbal abilities, and negative emotions; and four measurement dimensions: severity, frequency, duration, and change. The most frequently measured content dimensions were level of energy (20 measures, 44%), tiredness (15 measures, 35%), and life participation (15 measures, 33%). Dimensions such as memory, verbal abilities, and ability to think clearly were included in only a few measures. Seven of the 11 content dimensions assess the impact of fatigue on various aspects of an individual’s functioning; four assess aspects of fatigue. The most frequently assessed measurement dimension was severity; only one measure included an assessment of change in fatigue.

Psychometric Properties

For most measures, none of the recommended psychometric properties were evaluated in the hemodialysis population. Of the fatigue-specific measures developed for another patient population, only the Chalder Fatigue Scale (CHS) and Hemodialysis Fatigue Scale have been studied in the hemodialysis population. Good internal consistency was seen with the CFS, as was construct validity. The CFS also demonstrated reasonable discriminant validity. There was also evidence for good structural validity, internal consistency, and criterion validity for the Hemodialysis Fatigue Scale; however, the full measure is not available for use in English.

The researchers cited some limitations to the study, including the inability to identify all studies that report relevant validation data and the limited available data for psychometric properties of the measures in the hemodialysis population. The researchers also drew conclusions based on the interpretation made by the authors of the initial development studies, with no separate critical review of data analyses.

In conclusion, the researchers said, “Our review demonstrates that there is some promising work being conducted to address this debilitating symptom of fatigue in the hemodialysis population. The development of a standardized, valid, and reliable patient-reported outcome measure for fatigue in this population is likely to improve the consistency and accuracy in measuring fatigue. Recently, the SONG-HD initiative was established and identified fatigue as a core outcome domain based on consensus among patients, caregivers, and health professionals, and efforts are now underway to develop a core outcome measure for fatigue; this systematic review reflects part of the preparatory work for that development process. Such a measure will help ensure that important and relevant aspects of fatigue in hemodialysis are measured, reduce reporting bias, and allow for a direct comparison of the effect of interventions across studies. It could also be useful in practice to monitor and inform the management of fatigue in patients receiving hemodialysis. Establishing and implementing a core outcome measure for fatigue in hemodialysis is critical for the development and evaluation of interventions, which may lead to overall improvement in treatment satisfaction, patient well-being, and health outcomes among patients undergoing hemodialysis.”

Takeaway Points

  1. Researchers conducted a systematic review of outcome measures for fatigue to identify and evaluate the characteristics of patient-reported outcome measures for fatigue in patients receiving hemodialysis.
  2. From 140 studies, the researchers identified 45 different measures used to measure fatigue. Of those, 24 were developed for patients receiving hemodialysis.
  3. The measures addressed 11 content dimensions of fatigue and four measurement dimensions of fatigue.