SEARCH

SEARCH BY CITATION

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

Objective

Current patient-reported outcome measures of fatigue in rheumatoid arthritis (RA) have limitations, providing only a global perspective. This study constructed a questionnaire (the Bristol RA Fatigue Multi-Dimensional Questionnaire [BRAF-MDQ]) from 45 preliminary questions derived from analysis of patient interviews and surveys and explored its structure for fatigue dimensions. The BRAF-MDQ and short BRAF numerical rating scales (NRS) and visual analog scales (VAS) for severity, effect, and ability to cope with fatigue were evaluated for validity.

Methods

Two hundred twenty-nine RA patients with fatigue (VAS score ≥5 of 10) completed preliminary BRAF and comparator fatigue scales. Iterative analyses informed item removal or retention in the BRAF-MDQ and identification of subscales (using Cronbach's alpha for internal consistency and factor analysis to identify dimensions). The BRAF-MDQ and short scales were tested in relation to potentially associated variables for criterion and construct validity (Spearman's correlation).

Results

The 20-item BRAF-MDQ had good internal consistency (Cronbach's α = 0.932), criterion validity (correlation with other fatigue scales: r = 0.643–0.813), and construct validity (correlations with disability, mood, helplessness, and pain: r = 0.340–0.627). Factor analysis showed 4 distinct dimensions (physical fatigue, living with fatigue, cognition fatigue, and emotional fatigue), which correlated well with the RA Multidimensional Assessment of Fatigue scale (r = 0.548–0.834). The BRAF VAS and NRS showed similar criterion and construct validity.

Conclusion

The BRAF instruments include standardized NRS and VAS for fatigue severity, effect, and coping, are RA specific, and have evidence to support validity. The BRAF-MDQ uniquely measures 4 separate dimensions, which may facilitate development of individually-tailored fatigue management programs.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

People with rheumatoid arthritis (RA) consider fatigue to be an important physical and cognitive symptom that is overwhelming, uncontrollable, unpredictable, unearned, and affects every aspect of life, and it is experienced by up to 98% of patients (by 40% daily) (1–3). RA fatigue is complex and multicausal with components, such as pain, stress, depression, inflammation, and disability, that are likely to contribute in varying degrees at different times (4). International consensus has recommended that RA fatigue should now be measured in all RA studies alongside the core set, using an instrument validated in RA fatigue (5).

When developing scales or instruments to measure patient-reported outcomes such as fatigue, it is essential to include the issues that are important to patients (6, 7), and qualitative research suggests that RA fatigue is multidimensional (3, 8, 9). A systematic review identified only 6 instruments with some evidence of validation in RA, none of which were thoroughly grounded in the patient experience (10). Further, many visual analog scales (VAS) differed substantially in their wordings and timeframes, preventing comparisons between studies (10). Among the conclusions made in the review was the need for work to develop and validate a standardized VAS, and the need to ensure that instruments capture the essence of fatigue in RA as experienced by patients, including its severity, its impact, and the perceived ability of the patient to cope.

As first steps to meeting this requirement and working in close collaboration with patients, we used content and inductive thematic analysis of in-depth patient interviews to identify appropriate language and experiences, focus groups to develop appropriate wording for VAS and numerical rating scales (NRS), and cognitive interviewing methodology to explore understanding of candidate questions for a new RA fatigue scale. These approaches, fully reported previously (11, 12), are recommended by the US Food and Drug Administration (6, 13). Patients' proposals were clarified into draft versions of VAS and NRS for fatigue severity, effect, and coping (the Bristol RA Fatigue [BRAF] short scales [see Supplementary Appendix A, available in the online version of this article at http://www3.interscience.wiley.com/journal/77005015/home]), and a 45-item draft questionnaire that included 12 fatigue categories derived from the qualitative analyses (cognition, coping, emotion, energy, frequency, impact, planning, quality of life, relationships, severity, sleep, and social life). These categories are either not covered or not adequately covered in the 4 best-validated instruments currently used in RA (10), the Functional Assessment of Chronic Illness Therapy–Fatigue (FACIT-F) subscale (14), the Multidimensional Assessment of Fatigue (MAF) scale (15), the Profile of Mood States (POMS) (16), and the Short Form 36 (SF-36) vitality scale (17). Further, existing multi-item fatigue questionnaires all produce a single, global fatigue score (14–21). However, if there are different dimensions of fatigue, as suggested by our qualitative analyses (11, 12), then an instrument that could identify and score such dimensions separately would be advantageous. Because of the way it was derived, we anticipated that the draft BRAF questionnaire would be multidimensional.

The first aim of the present study was therefore to evaluate whether the BRAF short scales correlate strongly with existing fatigue instruments (evidence to support criterion validity) and whether they correlate only moderately with related constructs of pain, disability, and mood (construct validity) (6, 7, 13, 22). The second aim was to identify the most appropriate of the 45 items in the draft questionnaire to form a coherent and internally consistent final questionnaire; to explore it for robust, distinct, and consistent fatigue dimensions; and then to evaluate its criterion and construct validity.

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

Following research ethics committee approval, consecutive patients from the outpatient clinic of a large teaching hospital were invited to take part if they had a confirmed diagnosis of RA (23), were ages ≥18 years, had English as a first language, and had a score ≥5 on a 10-cm fatigue VAS (ranging from no fatigue to extreme fatigue, adapted from Crosby) (24). After giving informed consent, participants completed the BRAF short scales, the draft 45-item questionnaire, and 4 existing comparator fatigue instruments (for criterion validity), the FACIT-F, MAF, POMS, and SF-36 vitality (14–17). In order to evaluate construct validity, variables potentially associated with RA fatigue were assessed: disability (the Health Assessment Questionnaire) (25, 26), the Hospital Anxiety and Depression Scale (27), the Arthritis Helplessness Index (28), and pain (10-cm VAS) (29). Two versions of the questionnaire booklet, one used at random for each patient, presented these in different orders to reduce potential order effect (30). Patients completed their booklet without assistance from research staff, either in the clinic or at home. Plasma viscosity was recorded if taken for clinical reasons. Sample size was calculated on the basis of 5 patients per draft questionnaire item for factor analysis (n = 225).

Data were analyzed using SPSS, versions 14 and 15 (SPSS), and because data were not normally distributed, Spearman's correlations were used. For the draft questionnaire, iterative rounds of analyses allowed the removal of less informative items and retention of more informative items. Cronbach's alpha was used as the measure of internal consistency and repeated factor analyses for the identification of dimensions. Together with clinical judgment concerning face validity, at each step the item appearing to contribute least to the structure of the questionnaire was removed. When removal of further questions resulted in a noticeable reduction in Cronbach's alpha or collapse of the factor structure, the final question structure was set. In order to check the stability and robustness of the resultant factors (dimensions) in the final set of questions, repeated factor analyses were performed on 20 random samples of 50% of the patients (bootstrapping). The final questionnaire, the BRAF Multi-Dimensional Questionnaire (BRAF-MDQ), was then evaluated for criterion and construct validity using Spearman's correlation in a similar way to that undertaken for the VAS and NRS.

There are different opinions regarding the strength of the correlation coefficient (31–33). For the purposes of this work, correlations of r = ≥0.7 are referred to as strong, r = <0.7 to r = ≥0.5 as moderate, and r = <0.5 as weak.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

Four hundred twenty-eight patients with RA were invited to complete the screening VAS, of whom 59 declined and 95 scored <5 of 10 for fatigue. Of the 274 eligible patients, 249 consented to participate, 229 returned their booklets, and 221 had completed the draft 45-item questionnaire (Figure 1). Patients reflected a wide range of personal and disease characteristics (Tables 1 and 2). The MAF could not be calculated for 49 patients due to nonresponse to >2 questions (Tack BB: personal communication), giving a MAF response rate of 78.6%.

thumbnail image

Figure 1. Recruitment to study. VAS = visual analog scale.

Download figure to PowerPoint

Table 1. Demographic data (n = 229)
 Frequency (%)
Demographics 
 Men54 (23.6)
 Women175 (76.4)
 Age 
  <40 years23 (10.0)
  40–59 years87 (38.0)
  ≥60 years119 (52.0)
Employment status 
 Paid employment58 (25.3)
 Student3 (1.3)
 Homemaker23 (10.0)
 Unemployed1 (0.4)
 Incapacity benefit50 (21.8)
 Retired93 (40.6)
 Missing data1 (0.4)
Education 
 Did not complete school6 (2.6)
 School education130 (56.8)
 College/apprenticeship38 (16.6)
 University31 (13.5)
 Missing data24 (10.5)
Table 2. Fatigue and disease characteristics*
 Patients, no.Score, mean ± SD
  • *

    VAS = visual analog scale; NRS = numerical rating scale; MAF = Multidimensional Assessment of Fatigue; POMS = Profile of Mood States; FACIT-F = Functional Assessment of Chronic Illness Therapy–Fatigue; SF-36 = Short Form 36; HAQ = Health Assessment Questionnaire; AHI = Arthritis Helplessness Index; HADS = Hospital Anxiety and Depression Scale; mPa-s = millipascal-second.

  • Higher scores indicate better outcome.

Fatigue characteristics  
 Draft 45-item questionnaire221 
 Severity VAS (0–10)2286.7 ± 1.8
 Severity NRS (0–10)2296.8 ± 1.8
 Effect VAS (0–10)2286.4 ± 2.4
 Effect NRS (0–10)2296.5 ± 2.2
 Coping VAS (0–10)2285.2 ± 2.5
 Coping NRS (0–10)2295.7 ± 2.3
 MAF (0–50)18032.9 ± 8.8
 POMS (0–25)20918.6 ± 6.1
 FACIT-F (0–45)21821.2 ± 9.9
 SF-36 vitality scale (0–100)22428.6 ± 6.1
Disease characteristics  
 Pain VAS (0–10)2256.0 ± 2.2
 Disability HAQ (0–3)2131.7 ± 0.69
 Helplessness AHI (5–30)22618.9 ± 4.5
 Anxiety HADS (0–21)2287.7 ± 3.8
 Depression HADS (0–210)2288.7 ± 4.3
 Plasma viscosity, mPa-s1101.89 ± 0.17
  <1.7247 
  >1.7263 

Evaluation of the BRAF short scales.

Mean VAS and NRS scores for fatigue severity, effect, and coping are shown in Table 2. For each variable, the NRS and VAS versions correlated (r = 0.784, r = 0.777, and r = 0.684 for severity, effect, and coping, respectively), and although the NRS version gave a slightly higher mean score, differences between the two scales were not significant and there was no bias on Bland-Altman plots (34) (data not shown). The BRAF severity and effect scales correlated with each other, but correlations between these and the coping scale were weak, supporting the notion that coping with RA fatigue is a new construct (Table 3).

Table 3. Correlations with BRAF short scales (n = 229)*
 Severity BRAFEffect BRAFCoping BRAF
VASNRSVASNRSVASNRS
  • *

    Values are the correlation (number of patients). BRAF = Bristol Rheumatoid Arthritis Fatigue. See Table 2 for additional definitions.

  • P < 0.001.

  • P < 0.01.

  • §

    Higher scores indicate better outcome.

  • P < 0.05.

Fatigue      
 BRAF      
  Severity VAS 0.784 (228)0.720 (228)0.615 (228)−0.357 (228)−0.268 (228)
  Severity NRS  0.684 (228)0.712 (229)−0.332 (228)−0.235 (229)
  Effect VAS   0.777 (228)−0.434 (228)−0.352 (228)
  Effect NRS    −0.411 (228)−0.289 (229)
  Coping VAS§     0.684 (228)
 MAF0.659 (179)0.798 (180)0.700 (179)0.746 (180)−0.474 (179)−0.382 (180)
 POMS0.725 (208)0.763 (209)0.661 (208)0.706 (209)−0.364 (208)−0.302 (209)
 FACIT-F§−0.651 (217)−0.702 (218)−0.686 (217)−0.682 (218)0.388 (217)0.341 (218)
 SF-36§−0.583 (223)−0.652 (224)−0.596 (223)−0.651 (224)0.446 (223)0.373 (224)
Disease variables      
 HAQ0.305 (212)0.331 (213)0.413 (212)0.376 (213)−0.272 (212)−0.214 (213)
 AHI0.361 (225)0.445 (226)0.487 (225)0.494 (226)−0.350 (225)−0.324 (226)
 HADS anxiety0.272 (227)0.306 (228)0.394 (227)0.362 (228)−0.374 (227)−0.290 (228)
 HADS depression0.360 (227)0.415 (228)0.433 (227)0.456 (228)−0.472 (227)−0.424 (228)
 Pain0.433 (225)0.379 (225)0.442 (214)0.339 (229)−0.156 (225)−0.082 (225)
 Plasma viscosity      
  <1.720.090 (55)0.045 (55)−0.092 (55)−0.142 (55)0.123 (55)−0.052 (55)
  >1.720.199 (62)0.254 (63)0.227 (62)0.228 (63)−0.026 (62)−0.001 (63)

The BRAF severity scale correlated strongly with the MAF, FACIT-F, and POMS fatigue instruments, supporting criterion validity (Table 3), and correlated moderately with the SF-36 vitality subscale. There were only weak associations with pain, disability, depression, and helplessness, suggesting that the BRAF severity scale is associated with but does not directly measure these constructs, hence supporting construct validity. There was no correlation between the BRAF severity scale and inflammation. The BRAF effect scale correlated strongly with the MAF and POMS and moderately with FACIT-F and SF-36 vitality, supporting criterion validity (Table 3). There were only weak correlations with disability, helplessness, mood, and pain, supporting construct validity. For the BRAF coping scale there was only weak correlation with the existing fatigue scales, further supporting the notion that coping with RA fatigue is a construct not encompassed within these scales. There were only weak correlations between the coping scale and disability, helplessness, mood, and pain, supporting construct validity. Perceived ability to cope with fatigue was not associated with pain or inflammation. Thus, overall the BRAF short scales were correlated with other measures of fatigue (particularly the MAF and POMS), but were not closely correlated with other measures such as disability or mood. The BRAF coping (with RA fatigue) scale appears to measure an aspect of fatigue not well captured by existing measures.

Question reduction to derive the BRAF-MDQ.

Of the 45 draft questions, 5 were marked “Does not apply to me” by >10% of participants and were therefore removed. Cronbach's alpha on the remaining 40 questions was high (α = 0.961), and initial factor analysis suggested 7 potential dimensions. In an exploratory factor analysis, Cronbach's alpha calculated for each factor suggested that some items contributed little, implying potential for item reduction. Therefore, calculations of Cronbach's alpha and further factor analyses were performed after the stepwise removal of 1 item at a time in a series of iterative rounds. After each round, the question contributing the least (the “weakest” question), as identified by Cronbach's alpha and factor analysis (tempered occasionally by clinical judgment), was removed. When removal of a question significantly disrupted factor structure and stability, it was reinserted and the next weakest question removed. After 27 rounds, a 20-item questionnaire emerged that appeared to contain 4 separate dimensions. The factor structure of the proposed final 20-item BRAF-MDQ was then tested for robustness and stability in a further 20 rounds of factor analysis, each using a random subset of 50% of the patients (bootstrapping). This final 20-item BRAF-MDQ had excellent overall internal consistency (α = 0.932) and consistently showed 4 distinct dimensions (Table 4). After discussion with the patient research partner (MU), the dimensions were given formal labels: living (α = 0.906), cognition (α = 0.915), emotion (α = 0.889), and physical (α = 0.713).

Table 4. Factor analysis of the final Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire
Dimension, itemsFactors
1234
  • *

    Items loaded highly (>0.6). The remaining items showed low loading (<0.35).

Living    
 Difficult to dress0.839*0.1120.0920.058
 Bath or shower0.817*0.1710.1550.028
 Refused invitations0.705*0.2120.1750.288
 Affected social life0.650*0.2610.2560.299
 Difficult to work/daily activities0.609*0.1640.3720.325
 Cancelled plans0.608*0.1920.3230.321
 Avoided making plans0.605*0.1870.3850.350
Cognition    
 Forgotten things0.2880.829*0.1280.115
 Concentrate0.1680.816*0.3000.096
 Think clearly0.1470.794*0.3420.051
 Lacked mental energy0.0830.788*0.1760.271
 Made mistakes0.2590.744*0.2410.177
Emotion    
 Upset you0.2240.3040.805*0.188
 Down or depressed0.2640.2980.737*0.186
 Less control in areas of life0.2560.2730.708*0.346
 Felt embarrassed0.2820.3440.658*0.124
Physical    
 How many days0.0560.0050.1680.810*
 Numerical scale fatigue0.2310.1620.2650.701*
 How long each episode0.3090.2300.0350.642*
 Lacked physical energy0.3080.3400.2720.583*

Two patient research partners were consulted regarding the best order for the BRAF-MDQ dimensions and questions. They proposed that the order should be physical (as it has a different layout) followed by living, cognition, and finally emotion (as those questions may feel challenging [35]) (see Supplementary Appendix B, available in the online version of this article at http://www3.interscience.wiley.com/journal/77005015/home). The physical dimension contains an NRS and questions on frequency and duration, but the response options to all other questions are scored 0–3 (where 0 = not at all, 1 = a little, 2 = quite a bit, and 3 = very much). Simple summation yields a global BRAF-MDQ score of 0–70 (with higher scores indicating worse fatigue), whereas the score for each dimension is different due to the varied number of questions (0–22 for physical, 0–21 for living, 0–15 for cognition, and 0–12 for emotion) (see Supplementary Appendix C, available in the online version of this article at http://www3.interscience.wiley.com/journal/77005015/home). Questions 1 and 2 are compulsory, and only 1 answer may be missing from each dimension (maximum 3 missing answers in total). Missing data are replaced by calculating the individual's average score for the remaining questions in that dimension (as performed in this evaluation process).

Evaluation of the final 20-item BRAF-MDQ.

The global and dimension BRAF-MDQ scores were calculated for each patient. The mean ± SD scores were 38.4 ± 13.7 for global (maximum 70), 16.7 ± 4.0 for physical (maximum 22), 9.6 ± 5.5 for living (maximum 21), 6.1 ± 3.7 for cognition (maximum 15), and 5.8 ± 3.4 for emotion (maximum 12). The distribution patterns for the global score and for each dimension differed (Figure 2), reinforcing the notion that RA fatigue is not a single concept.

thumbnail image

Figure 2. Frequency and distribution of the (top) global Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire (BRAF MDQ) and its dimensions: (middle left) emotion, (middle right) cognition, (bottom left) living, and (bottom right) physical.

Download figure to PowerPoint

The BRAF-MDQ global score correlated strongly with the MAF, POMS, and FACIT-F, supporting criterion validity (Table 5), although the correlation with the SF-36 vitality subscale was weak. The global score correlated only moderately with depression, anxiety, helplessness, and disability, and correlated weakly with pain. These correlations provide supporting evidence for construct validity and are similar to those shown by existing fatigue instruments. The BRAF-MDQ correlated slightly more strongly with emotions (none of the existing instruments contain questions about emotions) but less strongly with pain (Table 5).

Table 5. Correlations between Bristol Rheumatoid Arthritis Fatigue Multi-Dimensional Questionnaire (BRAF-MDQ) global score, BRAF dimensions, and other variables*
 BRAF-MDQBRAF dimensionsDepressionAnxietyHAQHelplessPain
PhysicalLivingCognitionEmotion
  • *

    Values are the correlation (number of patients). See Table 2 for definitions.

  • Higher scores indicate better outcome.

BRAF-MDQ 0.801 (221)0.884 (221)0.750 (221)0.848 (221)0.627 (220)0.517 (220)0.501 (207)0.563 (218)0.340 (217)
BRAF dimensions          
 Physical  0.608 (225)0.465 (223)0.586 (225)0.400 (225)0.259 (225)0.369 (211)0.451 (223)0.321 (222)
 Living   0.527 (223)0.650 (226)0.607 (226)0.450 (226)0.613 (211)0.562 (224)0.380 (224)
 Cognition    0.627 (223)0.485 (224)0.489 (224)0.207 (211)0.325 (222)0.144 (221)
 Emotion     0.544 (226)0.566 (226)0.347 (211)0.451 (223)0.251 (223)
Depression      0.541 (227)0.403 (213)0.489 (225)0.145 (224)
Anxiety       0.211 (212)0.327 (226)0.088 (224)
HAQ        0.505 (211)0.404 (209)
Helplessness         0.433 (222)
BRAF          
 Severity VAS 0.709 (225)0.491 (226)0.390 (224)0.493 (226)     
 Severity NRS 0.767 (226)0.507 (227)0.389 (225)0.520 (227)     
 Effect VAS 0.681 (225)0.602 (226)0.406 (224)0.633 (226)     
 Effect NRS 0.692 (226)0.566 (227)0.381 (225)0.576 (227)     
 Coping VAS −0.350 (225)−0.406 (226)−0.320 (224)−0.415 (226)     
 Coping NRS −0.264 (226)−0.342 (227)−0.306 (225)−0.356 (227)     
MAF0.815 (175)0.834 (178)0.664 (178)0.548 (178)0.658 (179)0.504 (180)0.372 (180)0.426 (171)0.490 (179)0.424 (176)
POMS0.712 (201)0.718 (206)0.595 (207)0.481 (205)0.539 (207)0.438 (209)0.334 (209)0.400 (198)0.461 (207)0.419 (205)
FACIT-F−0.813 (210)−0.741 (215)−0.743 (216)−0.521 (214)−0.649 (216)−0.551 (217)−0.360 (218)−0.555 (203)−0.565 (216)−0.442 (214)
SF-36−0.643 (216)−0.679 (221)−0.537 (222)−0.399 (220)−0.496 (222)−0.499 (223)−0.227 (223)−0.388 (209)−0.435 (221)−0.277 (220)

Reviewing each of the BRAF-MDQ dimensions separately, the physical dimension was correlated most strongly with existing fatigue measures and other variables, living less so, emotion less so, and cognition the least so (Table 5). The pattern of the correlations was as follows: the physical dimension correlated weakly with all variables, living correlated moderately with helplessness and depression and weakly with pain, cognition correlated weakly with anxiety, and emotion correlated moderately with anxiety and weakly with helplessness, disability, and pain. This broadly concurs with the overall character of the BRAF-MDQ item content. When compared with the BRAF short scales, the BRAF-MDQ physical dimension correlated strongly with fatigue severity and moderately or weakly with effect and coping. Living correlated moderately with both the effect and the severity short scales, but weakly with the cognition short scale, and the emotion dimension had a similar pattern. The cognition dimension correlated weakly with all of the short scales. These differences reinforce the construction of the internal dimensions of the BRAF-MDQ.

Exploratory analysis of the BRAF-MDQ.

An exploratory analysis compared the BRAF-MDQ global fatigue and individual fatigue dimensions between women and men (using independent samples t-tests). Women showed higher fatigue than men for physical fatigue, where the mean ± SD scores were 17 ± 3.8 versus 15.7 ± 4.6 (P = 0.035), and emotional fatigue, where the mean ± SD scores were 6.1 ± 3.2 versus 4.9 ± 3.6 (P = 0.024). In contrast, there was no difference between the sexes for global BRAF-MDQ (mean ± SD scores 39.1 ± 3.2 versus 36.1 ± 13.5; P = 0.17), cognitive fatigue (mean ± SD scores 6.2 ± 3.7 versus 5.8 ± 3.6; P = 0.5), or living with fatigue (9.7 ± 5.3 versus 9.6 ± 5.4; P = 0.9).

As an example of the different ways in which fatigue might affect people, the varying experiences of 4 patients (age range 40–59 years) are illustrated in Figure 3 using the BRAF short scales. Patients A and B (women) both had severe fatigue (score 9 of 10) with high effect scores (8 and 9 of 10). However, whereas patient A perceived that she could cope well (8 of 10, with higher scores indicating better coping), patient B perceived that she could not cope (1 of 10). Patients C and D (men) both had moderately severe fatigue (6 of 10) with little effects on their lives (2 and 3 of 10). However, whereas patient C would require no support for coping (10 of 10), patient D still perceived that his coping was not optimum (8 of 10) (Figure 3). Using the BRAF-MDQ, 2 female patients, for example, in the same age range (40–59 years) and with similar global scores (28, 29), differed significantly in their underlying dimensions of fatigue, particularly for cognition and emotion, with physical scores of 12 versus 16, living scores of 6 versus 5, cognition scores of 3 versus 6, and emotion scores of 8 versus 1.

thumbnail image

Figure 3. Comparison of fatigue severity, effect, and coping in 4 patients. For the cope scores, higher values indicate better coping. NRS = numerical rating scale.

Download figure to PowerPoint

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

It is recommended that RA fatigue should now be measured in all RA studies alongside the core set, using an instrument validated in RA fatigue (5). In the initial phase of the development of such instruments (11, 12), we reported how the wording and questions were chosen to capture the patient perspective using interviews, focus groups, and cognitive interviewing as the recommended best practice (6, 7, 13). The draft versions of short scales that emerged (11) have been shown in the current study to have construct and criterion validity, and a 20-item multidimensional questionnaire (the BRAF-MDQ) derived from the draft questions has been shown to include 4 dimensions of RA fatigue, which we have termed physical, living, cognition, and emotion.

Global BRAF-MDQ scores correlated only moderately with anxiety, depression, helplessness, and disability, and correlated weakly with pain, suggesting that the BRAF-MDQ score is associated with but does not directly measure these constructs. It correlated strongly with existing fatigue instruments but has the advantage of assessing fatigue in 4 dimensions. The physical dimension correlated strongly with the existing fatigue instruments, which also appear to measure the physical severity of fatigue. It had weak correlations with mood, disability, and pain. The living dimension, which correlated moderately with the existing fatigue instruments, includes questions that relate to the unpredictability of RA fatigue, which makes fulfilling roles and planning life difficult, potentially leading to poor self-image and self-identity (36). It correlated moderately with measures of depression and helplessness. The emergence of a robust cognition dimension for RA fatigue reflects a feature that many patients report (3, 8, 9), yet which is not measured in existing fatigue instruments. Cognitive effects are important as they may lead to errors, lack of concentration, and suboptimal performance, impacting on function and work (3, 9, 37, 38). The cognition dimension correlated only weakly or moderately with the existing fatigue instruments and weakly with other variables, suggesting that it is capturing a unique concept of fatigue that is also different from pain, disability, or mood. The emotion dimension also acknowledges an area of fatigue measurement that has been neglected. It correlated weakly or moderately with the other fatigue instruments and with anxiety and helplessness. Higher correlations would have indicated that the BRAF-MDQ was actually measuring these constructs rather than acknowledging them, and lower correlations would have suggested no association between fatigue, emotion, and mood, which would have been illogical. There was only a weak correlation between the emotion dimension and the POMS (a fatigue mood instrument), but the POMS is not RA specific.

This study has demonstrated that it is possible to identify different dimensions of RA fatigue. This is supported by a recent study by Pollard et al, in which questions from several existing fatigue questionnaires completed by patients with RA were combined into a single, large-factor analysis. Five potential dimensions emerged: severity, anxiety/depression (psychological factors), distress/cognition, physical interference, and social interference (39). These broad categories reflect the 4 dimensions of the BRAF-MDQ.

Fries et al recommend that outcomes should be measured in the patient's value system (25). The strength of the BRAF-MDQ lies in its development from the patient perspective, with every phrase, question, and dimension grounded in the fatigue that is experienced by patients, as captured through interviews, focus groups, and cognitive testing (11, 12). The wording came from patients, ensuring that it is understandable. Complex wording and phrasing can be difficult to comprehend (40, 41). Questions that are easy to understand may perform better, reducing the sample sizes required for trials because there will be fewer missing data (40). For the only existing RA-specific fatigue instrument (the MAF), 20% of returned questionnaires could not be scored because of missing data, a finding also reported by others (42).

Although VAS and NRS have been used to measure fatigue severity prior to this study, no standardized wording had been developed or evaluated to our knowledge. We concluded from our earlier studies (11, 12) that measuring severity in isolation does not give the full picture of the patient fatigue experience; therefore, VAS and NRS were also developed in this study to measure the perceived effects and ability to cope with fatigue. Our results indicate satisfactory criterion and construct validity of the BRAF short scales for severity, effect, and coping. The data also demonstrate a potential disconnect between the ability to cope with fatigue and its severity, which offers the possibility that patients might be able to improve their ability to cope with fatigue and thus reduce its effect, even if fatigue severity per se cannot be changed (Figure 3).

A lengthy questionnaire is not always necessary or desirable, and a short, 1-page scale comprising all 3 BRAF short scales may be all that is required at a routine consultation as a screening tool to gain an understanding of the main fatigue issues (43). A single-item VAS for fatigue performs equally as well as existing longer questionnaires that give global scores, and patients prefer brevity (44). This current study suggests that the BRAF VAS and NRS are equally valid, which supports previous research in other symptoms (45–47). However, the NRS scored slightly higher than the VAS, which means that they are not interchangeable (47, 48). Although the BRAF VAS and NRS short scales performed in similar ways, there are practical reasons for recommending the NRS versions. NRS are easier and quicker to score, and some patients find the concept of VAS difficult to understand, and annotate with words or sentences (45).

The advantage of the 20-item BRAF-MDQ is that insight can be gained into the different dimensions of fatigue, enabling the exploration of different predictors and interventions for each dimension. In addition, the different dimensions of the BRAF-MDQ, perhaps used in conjunction with the BRAF coping NRS, may allow patient-specific self-management strategies to be developed and encouraged. The BRAF scales therefore have the potential to change the way that fatigue is managed for individual patients, leading to improved quality of life.

Evaluation of instruments is a continuous process, and further evaluation of the BRAF instruments is required for test–retest reliability, sensitivity to change, and minimum clinically important differences (49). For other fatigue severity VAS used in RA, a minimum clinically important difference of 10% has been calculated (50). The BRAF instruments could also be evaluated for relevance in other rheumatologic conditions, which might allow comparison across conditions.

The development and evaluation of the BRAF-MDQ, with its clear dimensions of physical fatigue, living, cognition, and emotion, represents an important step forward in our understanding of RA fatigue. The BRAF-MDQ and BRAF short scales together provide the tools for understanding the quality of the patient's fatigue experience for comparison across studies, offer an opportunity to explore predictors or causal pathways for different fatigue dimensions, and enable clinicians to individualize the teaching of self-management strategies according to patient profiles and target interventions, as well as providing tools for assessing the effectiveness of those interventions.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be submitted for publication. Dr. Nicklin had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Nicklin, Cramp, Kirwan, Greenwood, Urban, Hewlett.

Acquisition of data. Nicklin.

Analysis and interpretation of data. Nicklin, Cramp, Kirwan, Greenwood, Urban, Hewlett.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

The authors would like to thank the patients and staff of the Bristol Royal Infirmary Rheumatology Department for their help in this research and Bev Davis, patient research partner, for her assistance in designing the layout of the final questionnaire.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information
  • 1
    Wolfe K, Hawley D, Wilson K. The prevalence and meaning of fatigue in rheumatic disease. J Rheumatol 1996; 23: 140716.
  • 2
    Milton H, Hewlett S, Kirwan J. Fatigue in rheumatoid arthritis [abstract]. Rheumatology (Oxford) 2002; 4 Suppl 1: 73.
  • 3
    Hewlett S, Cockshott Z, Byron M, Kitchen K, Tipler S, Pope D, et al. Patients' perceptions of fatigue in rheumatoid arthritis: overwhelming, uncontrollable, ignored. Arthritis Rheum 2005; 53: 697702.
  • 4
    Hewlett S. Fatigue in rheumatoid arthritis: from apathy to action. Future Rheumatol 2007; 2: 43942.
  • 5
    Kirwan JR, Hewlett S. Patient perspective: reasons and methods for measuring fatigue in rheumatoid arthritis. J Rheumatol 2007; 34: 11713.
  • 6
    Patrick DL, Burke LB, Powers JH, Scott JA, Rock EP, Dawisha S, et al. Patient-reported outcomes to support medical product labeling claims: FDA perspective. Value Health 2007; 10 Supp 2: S12537.
  • 7
    Fitzpatrick R, Davey C, Buxton MJ, Jones DR. Evaluating patient-based outcomes measures for use in clinical trials. Health Technol Assess 1998; 2: 174.
  • 8
    Tack BB. Fatigue in rheumatoid arthritis: conditions, strategies, and consequences. Arthritis Care Res 1990; 3: 6570.
  • 9
    Repping-Wuts H, Uitterhoeve R, van Riel P, van Achterberg T. Fatigue as experienced by patients with rheumatoid arthritis (RA): a qualitative study. Int J Nurs Stud 2008; 45: 9951002.
  • 10
    Hewlett S, Hehir M, Kirwan JR. Measuring fatigue in rheumatoid arthritis: a systemic review of scales in use. Arthritis Rheum 2007; 57: 42939.
  • 11
    Nicklin J. The development of scales to measure fatigue in people with rheumatoid arthritis. Bristol (UK): University of the West of England; 2009.
  • 12
    Nicklin J, Cramp F, Kirwan J, Hewlett S. Do existing scales capture the multi-dimensional aspects of rheumatoid arthritis fatigue [abstract]? Rheumatology (Oxford) 2008; 47: 545.
  • 13
    Frost MF, Reeve BB, Liepa AM, Stauffer JW, Hays RD. What is sufficient evidence for the reliability and validity of patient-reported outcome measures? Value Health 2007; 2: S94105.
  • 14
    Cella D, Young S, Sorensen M, Chartash E, Sengupta N, Grober J. Validation of the functional assessment of chronic illness therapy fatigue scale relative to other instrumentation in patients with rheumatoid arthritis. J Rheumatol 2005; 32: 8119.
  • 15
    Tack BB. Dimensions and correlates of fatigue in older adults with rheumatoid arthritis. San Francisco: University of California; 1991.
  • 16
    McNair D, Lorr M, Droppleman L. Profile of mood states manual. New York: Multihealth Systems; 1992.
  • 17
    Ware JE Jr, Sherbourne CD. The MOS 36-item Short-Form health survey (SF-36). I. Conceptual framework and item selection. Med Care 1992; 30: 47383.
  • 18
    Bowman SJ, Booth DA, Platts RG. Measurement of fatigue and discomfort in primary Sjögren's syndrome using a new questionnaire tool. Rheumatology (Oxford) 2004; 43: 75864.
  • 19
    Goodchild CE, Treharne GJ, Booth DA, Kitas GD, Bowman SJ. Measuring fatigue among women with Sjögren's syndrome or rheumatoid arthritis: a comparison of the Profile of Fatigue (ProF) and the Multidimensional Fatigue Inventory (MFI). Musculoskeletal Care 2008; 6: 3148.
  • 20
    Smets EM, Garssen B, Bonke B, De Haes JC. The Multidimensional Fatigue Inventory (MFI) psychometric qualities of an instrument to assess fatigue. J Psychosom Res 1995; 39: 31525.
  • 21
    Hartz A, Bentler S, Watson D. Measuring fatigue severity in primary care patients. J Psychosom Res 2003; 54: 51521.
  • 22
    StreinerD, NormanG, editors. Health measurement scales: a practical guide to their development and use. Oxford: Oxford University Press; 1989.
  • 23
    Arnett FC, Edworthy SM, Bloch DA, McShane DJ, Fries JF, Cooper NS, et al. The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum 1988; 31: 31524.
  • 24
    Crosby LJ. Factors which contribute to fatigue associated with rheumatoid arthritis. J Adv Nurs 1991; 16: 97481.
  • 25
    Fries J, Spitz P, Kraines G, Holman H. Measurement of patient outcome in arthritis. Arthritis Rheum 1980; 23: 13745.
  • 26
    Kirwan JK, Reeback JS. Stanford Health Assessment Questionnaire modified to assess disability in British patients with rheumatoid arthritis. Br J Rheumatol 1986; 25: 2069.
  • 27
    Zigmond AS, Snaith RP. The Hospital Anxiety and Depression Scale. Acta Psychiatr Scand 1983; 67: 36170.
  • 28
    Stein MJ, Wallston KA, Nicassio PM. Factor structure of the Arthritis Helplessness Index. J Rheumatol 1988; 15: 42732.
  • 29
    Wolfe F, Pincus T, O'Dell J. Evaluation and documentation of rheumatoid arthritis disease status in the clinic: which variables best predict change in therapy? J Rheumatol 2001; 28: 17127.
  • 30
    Oppenheim AN. Questionnaire design, interviewing and attitude measurement. 2nd ed. London: Pinter Publishers; 1992.
  • 31
    Pallant J. SPSS survival manual: a step by step guide to data analysis using SPSS for Windows, version 12. 2nd ed. Buckingham (UK): Open University Press; 2005.
  • 32
    Hunt N, Tyrrell S, Nicholson J. Discuss regression and correlation. 2002. URL: www.coventry.ac.uk/ec/∼nhunt/regress/good4.html.
  • 33
    Cohen J. Statistical power analysis for the behavioural sciences. Hillsdale (NJ): Erlbaum & Associates; 1988.
  • 34
    Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986; 1: 3079.
  • 35
    Foddy W. Constructing questions for interviews and questionnaires: theory and practice in social research. Cambridge (UK): Cambridge University Press; 1993.
  • 36
    Scott DL, Lempp HK. Outcomes associated with early rheumatoid arthritis. Expert Rev Pharmacoeconomics Outcome Res 2006; 6: 495508.
  • 37
    Van der Linden D, Frese M, Meijman TF. Mental fatigue and the control of cognitive processes: effects on perseveration and planning. Acta Psychol (Amst) 2003; 113: 4565.
  • 38
    Lacaille D, White MA, Backman CL, Gignac MA. Problems faced at work due to inflammatory arthritis: new insights gained from understanding patients' perspective. Arthritis Rheum 2007; 57: 126979.
  • 39
    Pollard LC, Scott DL, Donaldson N, Choy EH. Fatigue in rheumatoid arthritis: what are we measuring? A factor analysis of fatigue instruments [abstract]. Rheumatology (Oxford) 2009; 48: i135.
  • 40
    Fries JF, Bruce B, Bjorner J, Rose M. More relevant, precise, and efficient items for assessment of physical function and disability: moving beyond the classic instruments. Ann Rheum Dis 2006; 65 Suppl 3: iii1621.
  • 41
    Mota DD, Pimenta CA. Self-report instruments for fatigue assessment: a systematic review. Res Theory Nurs Pract 2006; 20: 4978.
  • 42
    Wolfe F. Fatigue assessments in rheumatoid arthritis: comparative performance of visual analog scales and longer fatigue questionnaires in 7760 patients. J Rheumatol 2004; 31: 1896902.
  • 43
    Dittner AJ, Wessely SC, Brown RG. The assessment of fatigue: a practical guide for clinicians and researchers. J Psychosom Res 2004; 56: 15770.
  • 44
    Bengtsson M, Ohlsson B, Ulander K. Development and psychometric testing of the Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS). BMC Gastroenterology 2007; 7: 16.
  • 45
    Pincus T, Bergman B, Sokka T, Roth J, Swearingen C, Yazici Y. Visual analog scales in formats other than a 10-centimeter horizontal line to assess pain and other clinical data. J Rheumatol 2008; 35: 15508.
  • 46
    Kaufman BJ, Bijur PE, Latimer C, Gallagher EJ, Einstein A. Can a numerical rating scale be substituted for a visual analogue scale for pain? Acad Emerg Med 2002; 9: 4034.
  • 47
    Hollen PJ, Gralla RJ, Kris MG, McCoy S, Donaldson GW, Moinpour CM. A comparison of visual analogue and numerical rating scale formats for the Lung Cancer Symptom Scale (LCSS): does format affect patient ratings of symptoms and quality of life? Qual Life Res 2005; 14: 8347.
  • 48
    Holdgate A, Asha S, Craig J, Thompson J. Comparison of a verbal numeric rating scale with the visual analogue scale for the measurement of acute pain. Emerg Med (Fremantle) 2003; 15: 4416.
  • 49
    Pouchot J, Kherani RB, Brant R, Lacaille D, Lehman AJ, Ensworth S, et al. Determination of the minimal clinically important difference for seven fatigue measures in rheumatoid arthritis. J Clin Epidemiol 2008; 61: 70513.
  • 50
    Wells G, Li T, Maxwell L, MacLean R, Tugwell P. Determining the minimal clinically important differences in activity, fatigue, and sleep quality in patients with rheumatoid arthritis. J Rheumatol 2007; 34: 2809.

Supporting Information

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. Acknowledgements
  9. REFERENCES
  10. Supporting Information

Additional Supporting Information may be found in the online version of this article.

FilenameFormatSizeDescription
ACR_20282_sm_AppendixA.pdf44KSupplementary Information
ACR_20282_sm_AppendixB.pdf86KSupplementary Information
ACR_20282_sm_AppendixC.pdf50KSupplementary Information
ACR_20282_sm_OnlineonlySupplements.docx18KSupplementary Information

Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.