Correlation of fatigue with pain and disability in rheumatoid arthritis and osteoarthritis, respectively

Abstracts

OBJETIVO: Investigar a correlação de fadiga com dor em pacientes com artrite reumatoide e de fadiga com incapacidade em pacientes com osteoartrite. MÉTODOS: Foram avaliados 20 pacientes com artrite reumatoide e 20 com osteoartrite. Fadiga foi avaliada com escala visual analógica e questionário de avaliação multidimensional de fadiga. Utilizou-se a escala visual analógica para avaliar dor e para a avaliação global da doença pelo paciente. Incapacidade foi avaliada pelo questionário de avaliação de saúde. Idade, gênero, duração da doença, escolaridade, renda mensal, uso de drogas antirreumáticas e comorbidades foram obtidos. A análise estatística incluiu teste exato de Fisher, Shapiro-Wilk, Kruskal-Wallis e Spearman. O nível de significância foi de 0,05. RESULTADOS: A fadiga mostrou-se significativamente aumentada na osteoartrite em comparação à artrite reumatoide quando se utilizou o questionário de avaliação multidimensional de fadiga (P < 0,05). Dor correlacionou-se com fadiga ao se utilizar a escala visual analógica ou o questionário de avaliação multidimensional de fadiga em artrite reumatoide (r = 0,46; P < 0,05). O questionário de avaliação de saúde foi associado à fadiga por escala visual analógica em osteoartrite (r = 0,54; P < 0,05). Avaliação global da doença pelo paciente correlacionou-se com fadiga pela escala visual analógica (r = 0,44; P < 0,003). Todas as pacientes eram mulheres, predominantemente idosas, com médias de idade semelhantes, longa duração de doença e baixa renda. CONCLUSÃO: Nossos resultados confirmam que em pacientes com artrite reumatoide a fadiga correlaciona-se com dor, enquanto em pacientes com osteoartrite ela associa-se à incapacidade. Portanto, fadiga tem diferentes correlatos em osteoartrite e artrite reumatoide. Sugerimos que incapacidade, e não dor, seja o correlato da fadiga em pacientes com osteoartrite.

artrite reumatoide; osteoartrite; fadiga; dor; incapacidade física

ORIGINAL ARTICLE

^IFull Professor of the Pontifícia Universidade Católica de São Paulo - PUC-SP

^IIPhD candidate in Medicine at PUC-SP

^IIIOngoing Specialization in Rheumatology at PUC-SP

^IVFull Professor in Preventive and Social Medicine of the PUC-SP; Professor of the Post-graduation Course of the Medical School of the Universidade de São Paulo - USP

Correspondence to

ABSTRACT

OBJECTIVE: To investigate the correlation of fatigue with pain in rheumatoid arthritis patients and with disability in osteoarthritis patients.

METHODS: Twenty patients with rheumatoid arthritis and 20 patients with osteoarthritis were evaluated. The degree of fatigue was evaluated with a visual analogue scale and the Multidimensional Assessment of Fatigue. Pain was evaluated with a visual analogue scale as well as Patient Global Assessment. For disability evaluation, the Health Assessment Questionnaire was performed. Age, gender, disease duration, education, income, antirheumatic drugs used and comorbidity were also obtained. Statistical analysis included Fisher exact, Shapiro-Wilk, Kruskal-Wallis and Spearman tests. The significance level was 0.05.

RESULTS: Fatigue was more significantly increased in patients with osteoarthritis than in patients with rheumatoid arthritis when evaluated with Multidimensional Assessment of Fatigue (P < 0.05). Pain was found to correlate with fatigue evaluated with visual analogue scale or Multidimensional Assessment of Fatigue in patients with rheumatoid arthritis (r = 0.46; P < 0.05). Health Assessment Questionnaire was associated with fatigue visual analogue scale in patients with osteoarthritis (r = 0.54; P < 0.05). Patient Global Assessment correlates with fatigue visual analogue scale (r = 0.44; P < 0.003). Patients were similar in both groups: all females, similar mean age, with long disease duration and low income.

CONCLUSION: Our results corroborate that fatigue in rheumatoid arthritis patients correlates with the degree of pain, while in osteoarthritis patients it is associated with disability. Therefore, we found that fatigue has different correlates in osteoarthritis and rheumatoid arthritis, and we suggest that disability, not pain, is a correlate of fatigue in osteoarthritis patients.

Keywords: rheumatoid arthritis, osteoarthritis, fatigue, pain, disability assessment.

INTRODUCTION

Fatigue is a subjective symptom of low vitality experienced by patients as tiredness, exhaustion, weariness, weakness, and depleted energy followed by a decreased capacity for physical and mental work. Fatigue measured by visual analogue scale (VAS) was present in 88%-98% of rheumatic patients.¹ Clinically relevant levels of fatigue were present in roughly 40%-80% of patients with rheumatoid arthritis (RA) or osteoarthritis (OA).^1,2

In RA patients, more than 80% have fatigue (> 2 cm VAS), and more than 50% have high levels of fatigue (> 5 cm VAS).² Forty percent of RA patients experience persistent fatigue, that is mainly predicted by general health and disability.² Fatigue decreases with disease-modifying antirheumatic drugs (DMARDs) and with anti-TNF therapy.^3,4 This improvement is mainly related to improvement in pain.³

Fatigue was less studied in OA patients than in RA patients, although high levels of fatigue were also experienced by OA patients and it seems to have a substantial impact in their lives.^1,5 In one study, higher levels of fatigue were reported in OA patients than in RA patients.⁶ Fatigue in OA patients was much more probably related to physical activity when measured by daily life activities than to momentary pain,⁷ and was considered one of the strongest predictors of functional impairment in OA.⁸

Fatigue in RA patients has been associated with female gender, pain, depression or history of affective disorder, functional disability, poor sleep, comorbid conditions, and duration of disease.^1,9-13 The relation with inflammation, disease activity, or anemia was not found.^1,2,9 Meanwhile, fatigue in OA patients was described as associated with the same correlates, such as pain, sleep disturbance, depression, physical disability and lower physical activity level.^1,6-8,14

More information about fatigue correlates in OA and RA patients is needed to gain further insight into the experience of fatigue in RA and OA as well as to support and help patients with these diseases in their self-management strategies, pharmacotherapy, physiotherapy and other treatments of fatigue in RA and OA patients. Therefore, we investigated the possible interrelationship of pain, fatigue and disability among patients with RA and OA.

METHODS

Study population

Data was obtained from 20 patients with RA according to the American Rheumatism Association 1987 revised criteria for the classification of RA¹⁵ and from 20 patients with OA.¹⁶ All study participants were recruited consecutively from the out-patient clinic of the Rheumatology Division, Hospital de Sorocaba, at the Pontifícia Universidade Católica de São Paulo - PUC-SP. Patients were in regular follow-up and signed the informed consent to participate in this study.

Measurement of fatigue, pain, disability, and patient global assessment

Patients' fatigue was evaluated on a 10 cm anchored VAS where 0 was considered "no fatigue" and 10 as "worst possible fatigue". Fatigue was present with VAS > 2 cm, and high levels of fatigue was considered when VAS > 5 cm. Fatigue was also evaluated by the Multidimensional Assessment of Fatigue (MAF) Scale questionnaire.^10,12 The MAF scale consists of 16 items that assess subjective aspects of fatigue including quantity, degree, distress, impact, and timing. The subscales are combined to create a global fatigue index, which ranges from 1 (no fatigue) to 50 (extreme fatigue). Fatigue was considered when fatigue index was > 10 in a scale 1 to 50. Pain was evaluated on a 10 cm VAS score where 0 would mean "no pain" and 10 would mean "worst possible pain", and disability was evaluated by a Portuguese version of the Health Assessment Questionnaire (HAQ).¹⁷ Patient global assessment (PGA) was measured on a 10 cm VAS where 0 was considered the best assessment of disease (doing very well) and 10 the worst (doing very poor).

Socioeconomic-demographic and clinical variables

Age, gender, disease duration (years), education (years), monthly income, antirheumatic drugs used, and comorbidity were obtained at study visit.

Statistical analyses

First, the variables data distribution was analyzed. The Shapiro-Wilk test was employed for quantitative variables to confirm non-parametric data distribution. Proportion, means, and standard deviation were described. To compare RA and OA groups, Fisher exact (categorical variables) or Kruskal-Wallis (quantitative variables) tests were employed. Correlation between quantitative variables was studied by Spearman test. The significance level considered was 0.05.

RESULTS

Fatigue evaluated by VAS was observed in 17 (85%) of RA patients and 19 (95%) of OA patients. High levels of fatigue were noticed in 10 (50%) of RA patients and 18 (90%) of OA patients. When evaluated by MAF scale, 20 (100%) of RA patients and 19 (95%) of OA patients showed fatigue. Fatigue measured by MAF scale was significantly higher in OA patients when compared with RA patients (P < 0.05).

Table 1 shows the analysis of socioeconomic-demographic and clinical features. In general, patients were similar in both groups, all female, with long disease duration and low income. Patients with RA had long disease duration and less comorbidity when compared with patients with OA. The most frequent comorbidity observed in both groups were arterial hypertension (35% on RA patients and 50% on OA), diabetes mellitus (15% on RA and 5% on OA), and gastropathy (10% on RA and 15% on OA).

There was no association between fatigue measured by VAS or MAF scale and education, income categories, anti-rheumatic drugs used and comorbidity. Figure 1 shows the analysis of fatigue and correlates. Pain score was significantly correlated with fatigue measured by VAS and MAF in RA patients (P < 0.05; r = 0.46). HAQ score was significantly correlated with fatigue measured by MAF scale in OA patients (P < 0.05; r = 0.54). PGA correlates with fatigue measured by VAS in RA patients (P < 0.003; r = 0.44). No correlation between PGA and fatigue in OA patients was observed. Figures 2 and 3 show the correlation between pain and MAF in RA patients (r = 0.46), and HAQ scores and MAF in OA patients (r = 0.54).

In summary, fatigue in RA reflects pain and was associated with it, and disability was associated with fatigue in OA patients.

DISCUSSION

In this study of fatigue in RA and OA patients we registered fatigue in both groups of patients using VAS and MAF scales, and compared these measures with sociodemographic and clinical measures as education, disease duration, pain score, HAQ score and PGA. We found evidence for difference in RA and OA fatigue and assessment of pain and disability. Fatigue was significantly associated with pain in RA patients and was significantly correlated with disability in OA patients.

However, in one study, RA patients showed higher level of fatigue on VAS compared with OA patients.¹⁸ In another study, it was reported that OA patients had higher levels of fatigue than RA patients.⁶ We found the highest levels of fatigue in OA than RA patients when measured by MAF. Pain correlation with fatigue was extensively reported in RA patients, and generally pain, depression and fatigue were significantly and positively correlated.^{1,3,4,10,12,19-22} Stebbing et al.²² found that fatigue in RA patients had no significant association with pain, disease activity, disability or erosion, but was associated with depression and anxiety. They also found higher MAF scores in OA patients, and this was dependent on disability.²² Our data corroborate the fact that fatigue in RA patients was strongly associated with pain, regardless of the scale used to assess fatigue. This fact is consistent with the perception that the improvement of fatigue with antirheumatic drugs seen in RA patients is dependent on pain improvement.^3,4

Our results also point out that fatigue in OA patients was correlated with disability measured by MAF scale. Some evidence indicates that higher fatigue in OA patients is not related to increased pain, but to physical and psychological disability.^6,7,14 OA patients described fatigue as impacting physical function and their ability to participate in social and daily life activities.⁵ In one study, younger woman with RA and multiple daily roles seemed to be most vulnerable to the negative impact of fatigue.²³ Our results implied that fatigue in OA patients will be better treated and solved with a strategy to overcome disability than pain. Activities of daily life represented by HAQ could be affected by comorbidities, but the extension and specific disease responsible for this compromise is not yet established. Further studies should be done to confirm our findings and improve the comprehension of fatigue in RA and OA patients.

In summary, our results corroborate that fatigue in RA patients is correlated with the degree of pain, and fatigue in OA patients is associated with disability. Therefore, fatigue has different correlates in OA and RA. We suggest that disability, not pain, is a correlate of fatigue in OA patients.

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Correlation of fatigue with pain and disability in rheumatoid arthritis and osteoarthritis, respectively

Gilberto Santos Novaes^I; Mariana Ortega Perez^II; Maria Beatriz Bray Beraldo^II; Camila Rodrigues Costa Pinto^III; Reinaldo José Gianini^IV

Publication Dates

• Publication in this collection
  04 Oct 2011
• Date of issue
  Oct 2011

History

• Received
  01 Dec 2010
• Accepted
  01 July 2011