Fatigue is among the most common and debilitating symptoms of multiple sclerosis (MS), affecting approximately 80% of persons who have the disease. Recently, as part of the National Institutes of Health Patient Reported Outcome Measurement Information System (PROMIS), a bank of items was developed for measuring self-reported fatigue. This article has two purposes. (1) To assess, from the perspective of individuals living with MS, the relevance of a subset of items from the PROMIS fatigue item bank. (2) To identify additional aspects of fatigue that individuals with MS believe are important for clinicians when asking about their fatigue experience.
Key points
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Fatigue substantially affects the quality of life of persons with multiple sclerosis (MS).
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A sample of individuals living with MS ranked a subset of self-report items with respect to their relevance in measuring fatigue in MS. The most highly ranked items were, “How often did you feel tired even when you haven’t done anything,” and “How often did you have to push yourself to get things done because of your fatigue?”
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No self-report measure can gather the detailed and personally relevant information that can be elicited by a skilled clinician. It is possible, however, that standardized measures may pave the way for such communication.
Introduction
Fatigue is among the most common and debilitating symptoms of multiple sclerosis (MS), affecting approximately 80% of persons who have the disease. In one study, 69% considered fatigue their worst symptom. Fatigue in MS may directly affect participation in important roles such as employment, and can profoundly magnify other MS symptoms.
Because fatigue is a subjective experience for which currently there is no laboratory measurement test, the assessment of fatigue typically is accomplished through self-report. In recent years standardized self-report measures have been developed using an item-banking approach. Recently, as part of the National Institutes of Health Patient Reported Outcome Measurement Information System (PROMIS), a bank of items was developed for measuring self-reported fatigue. In the PROMIS domain framework fatigue is defined as “an overwhelming, debilitating, and sustained sense of exhaustion that decreases one’s ability to carry out daily activities, including the ability to work effectively and to function at one’s usual level in family or social roles.” (p1318)
This study described herein had two purposes. The first was to assess, from the perspective of individuals living with MS, the relevance of a subset of items from the PROMIS fatigue item bank. The second was to identify additional aspects of fatigue that individuals with MS believed were important for clinicians when asking about their fatigue experience.
Introduction
Fatigue is among the most common and debilitating symptoms of multiple sclerosis (MS), affecting approximately 80% of persons who have the disease. In one study, 69% considered fatigue their worst symptom. Fatigue in MS may directly affect participation in important roles such as employment, and can profoundly magnify other MS symptoms.
Because fatigue is a subjective experience for which currently there is no laboratory measurement test, the assessment of fatigue typically is accomplished through self-report. In recent years standardized self-report measures have been developed using an item-banking approach. Recently, as part of the National Institutes of Health Patient Reported Outcome Measurement Information System (PROMIS), a bank of items was developed for measuring self-reported fatigue. In the PROMIS domain framework fatigue is defined as “an overwhelming, debilitating, and sustained sense of exhaustion that decreases one’s ability to carry out daily activities, including the ability to work effectively and to function at one’s usual level in family or social roles.” (p1318)
This study described herein had two purposes. The first was to assess, from the perspective of individuals living with MS, the relevance of a subset of items from the PROMIS fatigue item bank. The second was to identify additional aspects of fatigue that individuals with MS believed were important for clinicians when asking about their fatigue experience.
Methods
Participants
Approval was obtained from the institutional review board of the appropriate institutions for the study, and all rights of human subjects were protected in this research. Participants were recruited through a Web site and print advertisements as well as from a disability registry maintained at the University of Washington, Seattle (UW). Individuals in the registry who had MS were sent an invitation letter followed by a phone call to assess their interest in participation.
Procedures
To evaluate the level of fatigue in the sample, the survey began with the item, “To what degree have you experienced fatigue?” The item was scored on a numerical rating scale of 0 to 10, where 0 = “not at all” and 10 = “a great deal”.
Item rankings
A sorting and ranking procedure was designed to quantify, from the perspective of persons with MS, the relevance of items in the PROMIS fatigue bank. The full item bank consists of 95 items, which was judged to be too many for individuals to meaningfully rank. Study investigators reduced the items to 20 in a series of successive steps described in detail elsewhere. To summarize, the item pool was reduced to 44 items by eliminating items with duplicate content. These 44 items were ranked by 27 physical therapists, 7 medical doctors, and 3 occupational therapists. Based on their ratings and on cumulative coverage of content, the item pool was further reduced to the 20 items ultimately presented to participants.
The selected items were printed onto 20 2 × 3.5-inch paper note cards and mailed to participants along with written instructions for the ranking procedure. Participants first responded to the question, “To what degree have you experienced fatigue?” Responses ranged from 0 (not at all) to 10 (a great deal). Next, participants identified and recorded the 3 items of the 20 that they considered the most relevant to their fatigue. Instructions stated: “If your doctor were to ask you 3 (only 3) questions about your fatigue, what 3 questions would give your doctor the best description of your fatigue?” Next, participants selected the item from those remaining that they would want to be asked if they could add just one more question. This procedure was repeated until participants had chosen a total of 10 items. The 3 items selected as giving “the best description” were assigned a ranking of 8. The fourth item selected was assigned a ranking of 7, and so on through the tenth item that was assigned a ranking of 1. Thus, higher values indicated stronger preference.
Open-ended responses
After identifying and ranking their top 10 items, participants were asked, “Are there other questions (ones not printed on the cards) that you think are needed for a good summary of your fatigue?” Space was provided for participants to write responses.
Analysis
Item rankings
The item rankings provided by participants were ordinal-level, not interval-level, data; therefore, the appropriate average of these ranks is the median. However, because only 10 items per person received a rank (all others were scored as 0), the median rankings for most items was 0. To better discriminate among item ranks, the arithmetical mean rank across raters was calculated, which is referred to hereafter as the relevance index (RI). The authors note that this index provides relative (not equal-interval level) information about the strength of participant preferences for one item over another.
Open-ended responses
Responses to the open-ended questions were categorized according to recurring themes. Two of the study investigators (K.F.C. and A.M.B.) independently reviewed participant responses and developed categories that they thought adequately summarized the content of responses. The investigators then met and came to agreement on names and number of organizing categories. Each investigator again reviewed responses and categorized them into the agreed-upon categories. After making classifications independently, they met and compared results, resolving discrepancies by consensus.
Results
Participants
Of 31 invited individuals with MS from the UW registry, 21 (68%) agreed to participate and completed the sorting procedure. Forty-one additional subjects saw a study advertisement or heard about the study from someone else and contacted the researchers directly. Of these 41, 25 (61%) subsequently completed the sorting procedure, for a grand total of 46 participants with MS. Characteristics of the participants are reported in Table 1 .
| Demographics | |
| Age (y) | Mean = 54.1, SD = 9.3 |
| Disease duration (y) | Mean = 14.1, SD = 8.2 |
| Female | n = 37 (80.4%) |
| Fatigue (0–10 scale) | |
| None (0) | n = 2 (4.3%) |
| Mild (1) | n = 0 (0%) |
| Moderate (2–4) | n = 5 (10.8%) |
| Severe (5–10) | n = 39 (84.8%) |
Item Rankings
RI values were calculated for each of the 20 items reviewed by participants and are listed in Table 2 . As the table reports, the 2 items with the highest rankings were, “How often did you feel tired even when you hadn’t done anything?” and “How often did you have to push yourself to get things done because of your fatigue?” Other highly ranked items had to do with feeling tired and fatigue’s impact on “finishing things,” “physical function,” and “thinking clearly.”
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