International Journal of Rheumatic Diseases 2014; 17: 181–185
ORIGINAL ARTICLE
Validation of the Thai version of the Health Assessment Questionnaire for patients with psoriatic arthritis Wanruchada KATCHAMART, Saovanee BENJAMANUKUL and Praveena CHIOWCHANWESAWAKIT Division of Rheumatology, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
Abstract Objective: To validate the Thai version of the Health Assessment Questionnaire (HAQ) for patients with psoriatic arthritis (PsA). Methods: The Thai version of the HAQ was administered to 47 patients with PsA attending our rheumatology clinic. Clinical assessments included the measures of disease activity, disease severity and functional status. The correlation of the single items and total score of the Thai HAQ with the measures of disease activity, disease severity and functional status was assessed using Pearson’s correlation or Spearman rank correlation, as appropriate. Results: Of 47 patients who fulfilled the Classification Criteria for Psoriatic Arthritis (CASPAR), 21 were male. Their mean age standard deviation (SD) and mean disease duration SD were 49 10 years and 6.97 6.17 years, respectively. Spondylitis was the most common manifestation (38%). The mean Thai HAQ score was 0.47. The single items and total score of the Thai HAQ were moderately to highly correlated with several measures of disease activity (r = 0.32–0.81, P < 0.01), except for swollen joint count (r = 0.16). For functional status and disease severity, the Thai HAQ was moderately correlated with grip strength (r = 0.39, P < 0.01), but poorly correlated with the range of spinal movement and the number of damaged joints. (r = 0.01 to 0.17). Cronbach’s alpha coefficient for internal consistency reliability was 0.88. These results were comparable to the original version. Conclusion: The Thai version of the HAQ is valid for assessing functional status in patients with PsA; however, its validity may be limited in patients who have axial involvement or permanent joint damage. Key words: functional status, Health Assessment Questionnaire, psoriatic arthritis, validation.
BACKGROUND Psoriatic arthritis (PsA) is a chronic inflammatory joint disease related to psoriasis. This disease is considered as a family of diseases historically known as the seronega-
Correspondence: Wanruchada Katchamart, MD, MSc(Clin Epi), Division of Rheumatology, Department of Internal Medicine, Faculty of Medicine, Siriraj Hospital, 8th floor Asadang building, 2 Prannok road, Bangkok-noi, Bangkok, Thailand 10700. Emails: [email protected]; wanda.katchamart@ gmail.com
tive spondyloarthropathies. Like other disease members in this group, arthritis can involve both axial and peripheral joints. Five clinical patterns of PsA are recognized: predominant involvement of distal interphalangeal joints, oligoarthritis, symmetrical polyarthritis, spondyloarthropathy and arthritis mutilans.1 In addition, extra-articular manifestations, including dactylitis, enthesitis and tendonitis commonly occur.2 Many patients with PsA suffer from chronic joint pain and inflammation leading to joint deformities and functional disability; therefore PsA affects the physical, social and psychological aspects of a patient’s life.3 The
© 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd
W. Katchamart et al.
impact of this disease on function and quality of life and the effectiveness of treatment to improve outcomes are increasingly of concern to patients, physicians, regulatory agencies and society. Several tools, both generic and specific measures, have been used to assess functional status and quality of life for PsA in clinical trials.4 The Health Assessment Questionnaire (HAQ) is a generic instrument for assessing health status and physical function in rheumatic conditions.5 It is easily administered and widely used, with a high reliability and validity for a variety of rheumatic diseases, including rheumatoid arthritis (RA),6 ankylosing spondylitis (AS)7 and PsA.8 Although the Thai version is available, it has been validated in only patients with RA.9,10 The objective of this study was to validate the Thai version of the HAQ for patients with PsA.
METHODS Patients and clinical assessments Patients with PsA attending our rheumatology clinic were consecutively enrolled from April 2011 to January 2012. Patients were eligible for this study if they met the following criteria: (i) age 18 years or older; (ii) fulfilled CASPAR criteria (Classification Criteria for Psoriatic Arthritis);11 and (iii) were literate. Patients who were mentally disabled were excluded. Patients were asked to complete the HAQ-Thai version in the waiting area before being examined by their respective treating rheumatologists. A co-investigator was present to provide help if needed. Baseline characteristics and demographics were collected following the standard protocol. Clinical assessments included the measures of disease activity, disease severity and functional status. All patients were assessed by the same rheumatologist. The overall disease activity was evaluated using ASDAS (Ankylosing Spondylitis Disease Activity Score)12 and BASDAI (Bath Ankylosing Spondylitis Disease Activity Index).13 Disease severity was assessed using the number of damaged peripheral joints. A damaged joint was defined as a joint with limited range of motion, deformity, subluxation or ankylosis. Functional status was assessed using grip strength and the range of spinal movements, including modified Schober’s test, lumbar side flexion and cervical rotation. Grip strength of both hands was evaluated using a sphygmomanometer, and the mean of grip strength was then calculated. Additionally, patient and physician rated the global assessment of the disease activity and pain on a 100-mm Visual Analogue Scale (VAS). Erythrocyte sedimentation rate (ESR) was measured.
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The study protocol was approved by the Siriraj institutional review board. This study was conducted in accordance with the ethical principles of the Declaration of Helsinki and adhered to the principles outlined in the Guideline for Good Clinical Practice International Conference on Harmonisation (ICH) Tripartite Guideline (January 1997). The subjects’ written consent was obtained according to the Declaration of Helsinki 2008.
Statistical analysis Sample size calculations were based on the assumption of detecting a significant correlation between HAQ and BASDAI with a correlation coefficient of 0.59.14 On the basis of these assumptions with a two-sided 5% significance level, a sample size of at 26 patients provided the study with 90% power to detect a significant correlation between HAQ and BASDAI. Qualitative data were expressed as percentages or ratio, and quantitative data were presented as mean standard deviation (SD) for normal distributed data and median and range for non-normal distributed data. Construct validity was assessed by the correlation of the single items and total score of the Thai HAQ with the measures of disease activity, disease severity and functional status. For all correlations, Pearson or Spearman’s correlation coefficients were used as appropriate. Internal consistency reliability was assessed using Cronbach’s coefficient alpha. The significance level was set at P < 0.05 (two-sided). Statistical analyses were performed using SPSS version 18 (SPSS Inc., Chicago, IL, USA).
RESULTS A total of 47 patients participated in this study. Their mean age ( SD) was 49 ( 10.1) years; most were female (55%) with seven ( 6.2 SD) years of disease duration. The mean duration of psoriasis was 10 years. Spondylitis was the most common manifestation (38%), followed by oligoarthritis (34%), polyarthritis (17%) and distal interphalangeal joint arthritis (4%). Twelve patients (25%) had oligoarthritis or polyarthritis with spondylitis. Sixteen patients (34%) had damaged joints. Six patients (13%) had no active arthritis of peripheral joints and spondylitis at the time of the study. One was in drug-free remission. Dactylitis and enthesitis were found in six (13%) and seven (15%) patients, respectively. Their current treatments included non-steroidal anti-inflammatory drugs (NSAIDs) (43%), monotherapy (71%) and combination therapy
International Journal of Rheumatic Diseases 2014; 17: 181–185
Thai version of the HAQ in Psoriatic arthritis
Table 1 Thai version of Health Assessment Questionnaire (HAQ) Item and total HAQ score
Mean (SD)
Median (range)
Dressing Arising Eating Walking Hygiene Reach Grip Activity Total HAQ
0.26 (0.49) 0.98 (0.82) 0.34 (0.56) 0.4 (0.54) 0.34 (0.56) 0.6 (0.71) 0.49 (0.75) 0.32 (0.47) 0.47 (0.47)
0 (0–2) 1 (0–3) 0 (0–2) 0 (0–2) 0 (0–2) 0 (0–2) 0 (0–3) 0 (0–1) 0.25 (0–1.63)
SD, standard deviation.
Table 2 Clinical measures of disease activity, functional status and disease severity of 47 patients with psoriatic arthritis Clinical measures
Mean (SD)
Median (range)
Disease activity BASDAI (0–10) 2.4 (2.3) 1.7 (0–7.5) ASDAS 2.6 (1.2) 2.3 (0.7–5.2) Morning stiffness (min) 17.5 (25.2) 5 (0–120) Swollen joint count (0–66) 1.3 (1.6) 1 (0–7) Tender joint count (0–68) 1.6 (3.1) 0 (0–12) Patient global assessment of 28.7 (28.5) 18 (0–100) pain (VAS 0–100 mm) Patient global assessment of 31.1 (26.2) 23 (0–100) disease activity (VAS 0–100 mm) Physician global assessment 24.6 (28.8) 13 (0–98) of disease activity (VAS 0–100 mm) ESR (mm/h) 39 (28.7) 27 (6–112) Function Grip strength (mmHg) 273.3 (69.7) 290 (95–370) Cervical rotation (degree) 57.8 (10.3) 60 (30–80) Modified Schober’s test (cm) 4.3 (1.1) 4 (2–7) Lateral side flexion (cm) 14.8 (3) 14 (8–21) Disease severity Damaged joint count 0.7 (1.4) 0 (0–7) SD, standard deviation; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; ASDAS, Ankylosing Spondylitis Disease Activity Score; VAS, visual analogue scale; ESR, erythrocyte sedimentation rate.
(26%) with non-biologic disease modifying anti-rheumatic drugs (DMARDs), anti-tumor necrotic factor (anti-TNF) (9%), and steroids (2%). The mean (SD) and median (range) of Thai HAQ scores were 0.47 (0.47) and 0.25 (0–1.625), respectively (Table 1). The clinical measures of disease activity, functional status and disease severity of all patients are shown in Table 2.
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HAQ and disease activity Table 3 presents the correlation between the HAQ single items and the total scores with several measures of disease activity. Total HAQ scores were highly correlated with BASDAI (r = 0.81, P = 0.01), ASDAS (r = 0.76, P = 0.01), physician global assessment of disease activity (r = 0.78, P = 0.01), pain (r = 0.71, P = 0.01), and patient global assessment of disease activity (r = 0. 65, P = 0.01). BASDAI, ASDAS, pain and patient and physician global assessment of disease activity had moderate to high correlation with all single items of HAQ, whereas the number of tender and swollen joints was least correlated with HAQ.
HAQ and function and disease severity Table 4 presents the correlation between the HAQ single items and total scores with several measures of function and disease severity. Grip strength was inversely associated with total HAQ score (r = 0.39, P = 0.01) and all single items (r = 0.05 to 0.38). There was no association between HAQ and all assessments of spinal motion and the number of damaged joints.
Reliability For internal consistency reliability, Cronbach’s alpha coefficient was 0.88, which indicates that the items from HAQ have good internal consistency reliability.
DISCUSSION Patients in this study had mild functional disability based on HAQ score. The median of total HAQ and all individual items except the item ‘arising’ were rated as 0. Most patients in our study had long-standing disease with mild disease activity based on the BASDAI. In addition, one was in drug-free remission. Consequently, their functions were not severely impaired. The item ‘arising’ was rated higher than other items, while other activities using upper and lower extremities were not impaired. This may imply that impaired arising was caused by limitation of axial joint movement and weakness of core muscles. Regarding correlation between HAQ and measures of disease activity, we found that HAQ had moderate to high correlation with several measures of disease activity, except for the number of tender and swollen joints. Our findings were similar to previous studies. Taylor et al. found that HAQ was moderately correlated with BASDAI (r = 0.59) and patient global assessment of disease activity (r = 0.52). Our study also found the same
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Table 3 Correlation between HAQ subscale and total HAQ score with measures of disease activity HAQ subscale and total score
BASDAI
ASDAS
AM stiffness
TJC
SJC
Dressing Arising Eating Walking Hygiene Reaching Grip Activity Total
0.56** 0.59** 0.39** 0.75** 0.65** 0.62** 0.66** 0.6** 0.81**
0.52** 0.64** 0.37** 0.68** 0.59** 0.53** 0.63** 0.55** 0.76**
0.32* 0.29* 0.18 0.28 0.36* 0.36* 0.37** 0.38** 0.44**
0.03 0.19 0.27 0.28 0.34* 0.28 0.28 0.24 0.32*
0.09 0.26 0.26 0.07 0.04 0.22 0.05 0.03 0.16
Pain
PGA
PhyGA
ESR
0.4** 0.5** 0.33* 0.68** 0.59** 0.57** 0.64** 0.46** 0.71**
0.43** 0.47** 0.27 0.62** 0.58** 0.46** 0.6** 0.4** 0.65**
0.45** 0.51** 0.44** 0.73** 0.68** 0.58** 0.71** 0.53** 0.78**
0.34* 0.41** 0.21 0.55** 0.41** 0.24 0.49** 0.36* 0.52**
*Correlation is significant at 0.05 level; **correlation is significant at 0.01 level. HAQ, Health Assessment Questionnaire; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; ASDAS, Ankylosing Spondylitis Disease Activity Score; AM stiffness, morning stiffness; TJC, tender joint count; SJC, swollen joint count; PGA, patient global assessment of disease activity; PhyGA, physician global assessment of disease activity; ESR, erythrocyte sedimentation rate.
Table 4 Correlation between HAQ subscale and total HAQ scores with measures of function and disease severity HAQ subscale and total score
Grip strength
Dressing Arising Eating Walking Hygiene Reaching Grip Activity Total
0.05 0.37* 0.4** 0.37* 0.25 0.36* 0.38** 0.07 0.39**
Cervical Modified Lumbar No. of rotation Schober’s side damaged test flexion joints 0.1 0.13 0.02 0.03 0.07 0.02 0.05 0.11 0.03
0.08 0.09 0.05 0.07 0.1 0.07 0.17 0.17 0.01
0.29* 0.17 0.12 0.02 0.17 0.02 0.07 0.05 0.09
0.16 0.03 0.12 0 0.15 0.07 0.04 0.26 0.03
*Correlation is significant at 0.05 level; **correlation is significant at 0.01 level. HAQ, Health Assessment Questionnaire.
limitation as shown in a previous study in the use of HAQ score for PsA. HAQ poorly correlated with tender joint count (r = 0.34) and swollen joint count (r = 0.18);14 however, if we combined the number of tender and swollen joint counts and then defined them as ‘actively inflamed joints’, the correlation between actively inflamed joints and HAQ was higher as was previously shown in the Blackmore et al.15 study (r = 0.49). Another limitation of HAQ in PsA as found in a previous study14 is that it was not correlated with all measures of spinal function. The HAQ items mainly assess function of peripheral joints, therefore, only grip strength had an inverse correlation with HAQ, while all other measures of function, which were measurements of spinal movement, had no association with HAQ in both our and previous studies. Although the modifica-
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tion of HAQ for spondyloarthropathy (HAQ-S) was developed for use in patients with spondyloarthropathy,7 psychometric properties in PsA were comparable to the original HAQ.15 Thus, it is not widely used in clinical trials or daily practice. This may be because spondylitis in PsA is less severe than that seen in ankylosing spondylitis, so most patients with PsA may not be severely disabled and are able to maintain their spinal functions. Similar to previous studies,14,15 HAQ did not correlate with clinical measures of damaged joints. In our study, most patients had damaged joints at the distal interphalangeal joints of the hands and feet. These joints may not have much impact on functions of the hands and feet or daily activities. Furthermore, most patients had no pain on damaged joints, so they were able to use their hands and feet without notable limitation. A limitation of this study is the sample size, which is quite small; however, this number has enough power to detect the significant correlations as mentioned above. As a result of a cross-sectional design in nature, we were unable to demonstrate the test–retest reliability and responsiveness to treatment of the Thai version. Another limitation of this study concerns the generalizability of the results. We used a cohort of consecutive patients in tertiary care, where the patients usually have more severe disease; however, most patients in our study had only mild to moderate disease activity based on several measures of disease activity. Thus our population should be close to patients found in general practice. Finally, the total score and individual items of Thai HAQ in this study were quite low with the median HAQ of 0 in all items, except ‘arising’ and ‘total score’. This means that half of them had possible minimum
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Thai version of the HAQ in Psoriatic arthritis
score (HAQ score = 0) reflecting that this score may have floor effect or most patients included in this study had very low disease activity with mild functional disability. Therefore, the validity of HAQ for PsA with more severe disease activity and functional impairment needs to be further investigated. In conclusion, our study demonstrated that the Thai version of the HAQ retained the psychometric properties of the original version. It correlated with disease activity and functions of peripheral joints; however, its validity may be limited in patients who have axial joint involvement or permanent joint damage. Validity of the use of Thai HAQ in a large population of PsA patients with a variety of disease activities and manifestations and its usefulness in longitudinal studies need further evaluation.
CONFLICTS OF INTEREST The authors declare no conflicts of interest.
FINANCIAL SUPPORT Siriraj grant for research development.
REFERENCES 1 Moll JMH, Wright V (1973) Psoriatic arthritis. Semin Arthritis Rheum 3, 55–78. 2 Dhir V, Aggarwal A (2013) Psoriatic arthritis: a critical review. Clin Rev Allergy Immunol 44, 141–8. 3 Lee S, Mendelsohn A, Sarnes E (2010) The burden of psoriatic arthritis: a literature review from a global health systems perspective. PT 35, 680–9. 4 Mease PJ (2009) Assessing the impact of psoriatic arthritis on patient function and quality of life: lessons learned from other rheumatologic conditions. Semin Arthritis Rheum 38, 320–35. 5 Bruce B, Fries JF (2003) The stanford Health Assessment Questionnaire: dimensions and practical applications. Health Qual Life Outcomes 1, 20.
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6 Wolfe F, Kleinheksel SM, Cathey MA, Hawley DJ, Spitz PW, Fries JF (1988) The clinical value of the stanford Health Assessment Questionnaire functional disability index in patients with rheumatoid arthritis. J Rheumatol 15, 1480–8. 7 Daltroy LH, Larson MG, Roberts NW, Liang MH (1990) A modification of the Health Assessment Questionnaire for the spondyloarthropathies. J Rheumatol 17, 946–50. 8 Husted JA, Gladman DD, Long JA, Farewell VT (1995) A modified version of the Health Assessment Questionnaire (HAQ) for psoriatic arthritis. Clin Exp Rheumatol 13, 439–43. 9 Osiri M, Deesomchok U, Tugwell P (2001) Evaluation of functional ability of Thai patients with rheumatoid arthritis by the use of a Thai version of the Health Assessment Questionnaire. Rheumatology 40, 555–8. 10 Osiri M, Wongchinsri J, Ukritchon S, Hanvivadhanakul P, Kasitanon N, Siripaitoon B (2009) Comprehensibility, reliability, validity, and responsiveness of the Thai version of the Health Assessment Questionnaire in Thai patients with rheumatoid arthritis. Arthritis Res Ther 11 (4), R129. 11 Taylor W, Gladman D, Helliwell P, Marchesoni A, Mease P, Mielants H (2006) Classification criteria for psoriatic arthritis: development of new criteria from a large international study. Arthritis Rheum 54, 2665–73. 12 Lukas C, Landewe R, Sieper J et al. (2009) Development of an ASAS-endorsed disease activity score (ASDAS) in patients with ankylosing spondylitis. Ann Rheum Dis 68, 18–24. 13 Garrett S, Jenkinson T, Kennedy LG, Whitelock H, Gaisford P, Calin A (1994) A new approach to defining disease status in ankylosing spondylitis: the Bath Ankylosing Spondylitis Disease Activity Index. J Rheumatol 21, 2286– 91. 14 Taylor WJ, Harrison AA (2004) Could the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) be a valid measure of disease activity in patients with psoriatic arthritis? Arthritis Rheum 51, 311–5. 15 Blackmore MG, Gladman DD, Husted J, Long JA, Farewell VT (1995) Measuring health status in psoriatic arthritis: the Health Assessment Questionnaire and its modification. J Rheumatol 22, 886–93.
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Copyright of International Journal of Rheumatic Diseases is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Copyright of International Journal of Rheumatic Diseases is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
ORIGINAL ARTICLE
Validation of the Thai version of the Health Assessment Questionnaire for patients with psoriatic arthritis Wanruchada KATCHAMART, Saovanee BENJAMANUKUL and Praveena CHIOWCHANWESAWAKIT Division of Rheumatology, Department of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand
Abstract Objective: To validate the Thai version of the Health Assessment Questionnaire (HAQ) for patients with psoriatic arthritis (PsA). Methods: The Thai version of the HAQ was administered to 47 patients with PsA attending our rheumatology clinic. Clinical assessments included the measures of disease activity, disease severity and functional status. The correlation of the single items and total score of the Thai HAQ with the measures of disease activity, disease severity and functional status was assessed using Pearson’s correlation or Spearman rank correlation, as appropriate. Results: Of 47 patients who fulfilled the Classification Criteria for Psoriatic Arthritis (CASPAR), 21 were male. Their mean age standard deviation (SD) and mean disease duration SD were 49 10 years and 6.97 6.17 years, respectively. Spondylitis was the most common manifestation (38%). The mean Thai HAQ score was 0.47. The single items and total score of the Thai HAQ were moderately to highly correlated with several measures of disease activity (r = 0.32–0.81, P < 0.01), except for swollen joint count (r = 0.16). For functional status and disease severity, the Thai HAQ was moderately correlated with grip strength (r = 0.39, P < 0.01), but poorly correlated with the range of spinal movement and the number of damaged joints. (r = 0.01 to 0.17). Cronbach’s alpha coefficient for internal consistency reliability was 0.88. These results were comparable to the original version. Conclusion: The Thai version of the HAQ is valid for assessing functional status in patients with PsA; however, its validity may be limited in patients who have axial involvement or permanent joint damage. Key words: functional status, Health Assessment Questionnaire, psoriatic arthritis, validation.
BACKGROUND Psoriatic arthritis (PsA) is a chronic inflammatory joint disease related to psoriasis. This disease is considered as a family of diseases historically known as the seronega-
Correspondence: Wanruchada Katchamart, MD, MSc(Clin Epi), Division of Rheumatology, Department of Internal Medicine, Faculty of Medicine, Siriraj Hospital, 8th floor Asadang building, 2 Prannok road, Bangkok-noi, Bangkok, Thailand 10700. Emails: [email protected]; wanda.katchamart@ gmail.com
tive spondyloarthropathies. Like other disease members in this group, arthritis can involve both axial and peripheral joints. Five clinical patterns of PsA are recognized: predominant involvement of distal interphalangeal joints, oligoarthritis, symmetrical polyarthritis, spondyloarthropathy and arthritis mutilans.1 In addition, extra-articular manifestations, including dactylitis, enthesitis and tendonitis commonly occur.2 Many patients with PsA suffer from chronic joint pain and inflammation leading to joint deformities and functional disability; therefore PsA affects the physical, social and psychological aspects of a patient’s life.3 The
© 2013 Asia Pacific League of Associations for Rheumatology and Wiley Publishing Asia Pty Ltd
W. Katchamart et al.
impact of this disease on function and quality of life and the effectiveness of treatment to improve outcomes are increasingly of concern to patients, physicians, regulatory agencies and society. Several tools, both generic and specific measures, have been used to assess functional status and quality of life for PsA in clinical trials.4 The Health Assessment Questionnaire (HAQ) is a generic instrument for assessing health status and physical function in rheumatic conditions.5 It is easily administered and widely used, with a high reliability and validity for a variety of rheumatic diseases, including rheumatoid arthritis (RA),6 ankylosing spondylitis (AS)7 and PsA.8 Although the Thai version is available, it has been validated in only patients with RA.9,10 The objective of this study was to validate the Thai version of the HAQ for patients with PsA.
METHODS Patients and clinical assessments Patients with PsA attending our rheumatology clinic were consecutively enrolled from April 2011 to January 2012. Patients were eligible for this study if they met the following criteria: (i) age 18 years or older; (ii) fulfilled CASPAR criteria (Classification Criteria for Psoriatic Arthritis);11 and (iii) were literate. Patients who were mentally disabled were excluded. Patients were asked to complete the HAQ-Thai version in the waiting area before being examined by their respective treating rheumatologists. A co-investigator was present to provide help if needed. Baseline characteristics and demographics were collected following the standard protocol. Clinical assessments included the measures of disease activity, disease severity and functional status. All patients were assessed by the same rheumatologist. The overall disease activity was evaluated using ASDAS (Ankylosing Spondylitis Disease Activity Score)12 and BASDAI (Bath Ankylosing Spondylitis Disease Activity Index).13 Disease severity was assessed using the number of damaged peripheral joints. A damaged joint was defined as a joint with limited range of motion, deformity, subluxation or ankylosis. Functional status was assessed using grip strength and the range of spinal movements, including modified Schober’s test, lumbar side flexion and cervical rotation. Grip strength of both hands was evaluated using a sphygmomanometer, and the mean of grip strength was then calculated. Additionally, patient and physician rated the global assessment of the disease activity and pain on a 100-mm Visual Analogue Scale (VAS). Erythrocyte sedimentation rate (ESR) was measured.
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The study protocol was approved by the Siriraj institutional review board. This study was conducted in accordance with the ethical principles of the Declaration of Helsinki and adhered to the principles outlined in the Guideline for Good Clinical Practice International Conference on Harmonisation (ICH) Tripartite Guideline (January 1997). The subjects’ written consent was obtained according to the Declaration of Helsinki 2008.
Statistical analysis Sample size calculations were based on the assumption of detecting a significant correlation between HAQ and BASDAI with a correlation coefficient of 0.59.14 On the basis of these assumptions with a two-sided 5% significance level, a sample size of at 26 patients provided the study with 90% power to detect a significant correlation between HAQ and BASDAI. Qualitative data were expressed as percentages or ratio, and quantitative data were presented as mean standard deviation (SD) for normal distributed data and median and range for non-normal distributed data. Construct validity was assessed by the correlation of the single items and total score of the Thai HAQ with the measures of disease activity, disease severity and functional status. For all correlations, Pearson or Spearman’s correlation coefficients were used as appropriate. Internal consistency reliability was assessed using Cronbach’s coefficient alpha. The significance level was set at P < 0.05 (two-sided). Statistical analyses were performed using SPSS version 18 (SPSS Inc., Chicago, IL, USA).
RESULTS A total of 47 patients participated in this study. Their mean age ( SD) was 49 ( 10.1) years; most were female (55%) with seven ( 6.2 SD) years of disease duration. The mean duration of psoriasis was 10 years. Spondylitis was the most common manifestation (38%), followed by oligoarthritis (34%), polyarthritis (17%) and distal interphalangeal joint arthritis (4%). Twelve patients (25%) had oligoarthritis or polyarthritis with spondylitis. Sixteen patients (34%) had damaged joints. Six patients (13%) had no active arthritis of peripheral joints and spondylitis at the time of the study. One was in drug-free remission. Dactylitis and enthesitis were found in six (13%) and seven (15%) patients, respectively. Their current treatments included non-steroidal anti-inflammatory drugs (NSAIDs) (43%), monotherapy (71%) and combination therapy
International Journal of Rheumatic Diseases 2014; 17: 181–185
Thai version of the HAQ in Psoriatic arthritis
Table 1 Thai version of Health Assessment Questionnaire (HAQ) Item and total HAQ score
Mean (SD)
Median (range)
Dressing Arising Eating Walking Hygiene Reach Grip Activity Total HAQ
0.26 (0.49) 0.98 (0.82) 0.34 (0.56) 0.4 (0.54) 0.34 (0.56) 0.6 (0.71) 0.49 (0.75) 0.32 (0.47) 0.47 (0.47)
0 (0–2) 1 (0–3) 0 (0–2) 0 (0–2) 0 (0–2) 0 (0–2) 0 (0–3) 0 (0–1) 0.25 (0–1.63)
SD, standard deviation.
Table 2 Clinical measures of disease activity, functional status and disease severity of 47 patients with psoriatic arthritis Clinical measures
Mean (SD)
Median (range)
Disease activity BASDAI (0–10) 2.4 (2.3) 1.7 (0–7.5) ASDAS 2.6 (1.2) 2.3 (0.7–5.2) Morning stiffness (min) 17.5 (25.2) 5 (0–120) Swollen joint count (0–66) 1.3 (1.6) 1 (0–7) Tender joint count (0–68) 1.6 (3.1) 0 (0–12) Patient global assessment of 28.7 (28.5) 18 (0–100) pain (VAS 0–100 mm) Patient global assessment of 31.1 (26.2) 23 (0–100) disease activity (VAS 0–100 mm) Physician global assessment 24.6 (28.8) 13 (0–98) of disease activity (VAS 0–100 mm) ESR (mm/h) 39 (28.7) 27 (6–112) Function Grip strength (mmHg) 273.3 (69.7) 290 (95–370) Cervical rotation (degree) 57.8 (10.3) 60 (30–80) Modified Schober’s test (cm) 4.3 (1.1) 4 (2–7) Lateral side flexion (cm) 14.8 (3) 14 (8–21) Disease severity Damaged joint count 0.7 (1.4) 0 (0–7) SD, standard deviation; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; ASDAS, Ankylosing Spondylitis Disease Activity Score; VAS, visual analogue scale; ESR, erythrocyte sedimentation rate.
(26%) with non-biologic disease modifying anti-rheumatic drugs (DMARDs), anti-tumor necrotic factor (anti-TNF) (9%), and steroids (2%). The mean (SD) and median (range) of Thai HAQ scores were 0.47 (0.47) and 0.25 (0–1.625), respectively (Table 1). The clinical measures of disease activity, functional status and disease severity of all patients are shown in Table 2.
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HAQ and disease activity Table 3 presents the correlation between the HAQ single items and the total scores with several measures of disease activity. Total HAQ scores were highly correlated with BASDAI (r = 0.81, P = 0.01), ASDAS (r = 0.76, P = 0.01), physician global assessment of disease activity (r = 0.78, P = 0.01), pain (r = 0.71, P = 0.01), and patient global assessment of disease activity (r = 0. 65, P = 0.01). BASDAI, ASDAS, pain and patient and physician global assessment of disease activity had moderate to high correlation with all single items of HAQ, whereas the number of tender and swollen joints was least correlated with HAQ.
HAQ and function and disease severity Table 4 presents the correlation between the HAQ single items and total scores with several measures of function and disease severity. Grip strength was inversely associated with total HAQ score (r = 0.39, P = 0.01) and all single items (r = 0.05 to 0.38). There was no association between HAQ and all assessments of spinal motion and the number of damaged joints.
Reliability For internal consistency reliability, Cronbach’s alpha coefficient was 0.88, which indicates that the items from HAQ have good internal consistency reliability.
DISCUSSION Patients in this study had mild functional disability based on HAQ score. The median of total HAQ and all individual items except the item ‘arising’ were rated as 0. Most patients in our study had long-standing disease with mild disease activity based on the BASDAI. In addition, one was in drug-free remission. Consequently, their functions were not severely impaired. The item ‘arising’ was rated higher than other items, while other activities using upper and lower extremities were not impaired. This may imply that impaired arising was caused by limitation of axial joint movement and weakness of core muscles. Regarding correlation between HAQ and measures of disease activity, we found that HAQ had moderate to high correlation with several measures of disease activity, except for the number of tender and swollen joints. Our findings were similar to previous studies. Taylor et al. found that HAQ was moderately correlated with BASDAI (r = 0.59) and patient global assessment of disease activity (r = 0.52). Our study also found the same
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Table 3 Correlation between HAQ subscale and total HAQ score with measures of disease activity HAQ subscale and total score
BASDAI
ASDAS
AM stiffness
TJC
SJC
Dressing Arising Eating Walking Hygiene Reaching Grip Activity Total
0.56** 0.59** 0.39** 0.75** 0.65** 0.62** 0.66** 0.6** 0.81**
0.52** 0.64** 0.37** 0.68** 0.59** 0.53** 0.63** 0.55** 0.76**
0.32* 0.29* 0.18 0.28 0.36* 0.36* 0.37** 0.38** 0.44**
0.03 0.19 0.27 0.28 0.34* 0.28 0.28 0.24 0.32*
0.09 0.26 0.26 0.07 0.04 0.22 0.05 0.03 0.16
Pain
PGA
PhyGA
ESR
0.4** 0.5** 0.33* 0.68** 0.59** 0.57** 0.64** 0.46** 0.71**
0.43** 0.47** 0.27 0.62** 0.58** 0.46** 0.6** 0.4** 0.65**
0.45** 0.51** 0.44** 0.73** 0.68** 0.58** 0.71** 0.53** 0.78**
0.34* 0.41** 0.21 0.55** 0.41** 0.24 0.49** 0.36* 0.52**
*Correlation is significant at 0.05 level; **correlation is significant at 0.01 level. HAQ, Health Assessment Questionnaire; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; ASDAS, Ankylosing Spondylitis Disease Activity Score; AM stiffness, morning stiffness; TJC, tender joint count; SJC, swollen joint count; PGA, patient global assessment of disease activity; PhyGA, physician global assessment of disease activity; ESR, erythrocyte sedimentation rate.
Table 4 Correlation between HAQ subscale and total HAQ scores with measures of function and disease severity HAQ subscale and total score
Grip strength
Dressing Arising Eating Walking Hygiene Reaching Grip Activity Total
0.05 0.37* 0.4** 0.37* 0.25 0.36* 0.38** 0.07 0.39**
Cervical Modified Lumbar No. of rotation Schober’s side damaged test flexion joints 0.1 0.13 0.02 0.03 0.07 0.02 0.05 0.11 0.03
0.08 0.09 0.05 0.07 0.1 0.07 0.17 0.17 0.01
0.29* 0.17 0.12 0.02 0.17 0.02 0.07 0.05 0.09
0.16 0.03 0.12 0 0.15 0.07 0.04 0.26 0.03
*Correlation is significant at 0.05 level; **correlation is significant at 0.01 level. HAQ, Health Assessment Questionnaire.
limitation as shown in a previous study in the use of HAQ score for PsA. HAQ poorly correlated with tender joint count (r = 0.34) and swollen joint count (r = 0.18);14 however, if we combined the number of tender and swollen joint counts and then defined them as ‘actively inflamed joints’, the correlation between actively inflamed joints and HAQ was higher as was previously shown in the Blackmore et al.15 study (r = 0.49). Another limitation of HAQ in PsA as found in a previous study14 is that it was not correlated with all measures of spinal function. The HAQ items mainly assess function of peripheral joints, therefore, only grip strength had an inverse correlation with HAQ, while all other measures of function, which were measurements of spinal movement, had no association with HAQ in both our and previous studies. Although the modifica-
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tion of HAQ for spondyloarthropathy (HAQ-S) was developed for use in patients with spondyloarthropathy,7 psychometric properties in PsA were comparable to the original HAQ.15 Thus, it is not widely used in clinical trials or daily practice. This may be because spondylitis in PsA is less severe than that seen in ankylosing spondylitis, so most patients with PsA may not be severely disabled and are able to maintain their spinal functions. Similar to previous studies,14,15 HAQ did not correlate with clinical measures of damaged joints. In our study, most patients had damaged joints at the distal interphalangeal joints of the hands and feet. These joints may not have much impact on functions of the hands and feet or daily activities. Furthermore, most patients had no pain on damaged joints, so they were able to use their hands and feet without notable limitation. A limitation of this study is the sample size, which is quite small; however, this number has enough power to detect the significant correlations as mentioned above. As a result of a cross-sectional design in nature, we were unable to demonstrate the test–retest reliability and responsiveness to treatment of the Thai version. Another limitation of this study concerns the generalizability of the results. We used a cohort of consecutive patients in tertiary care, where the patients usually have more severe disease; however, most patients in our study had only mild to moderate disease activity based on several measures of disease activity. Thus our population should be close to patients found in general practice. Finally, the total score and individual items of Thai HAQ in this study were quite low with the median HAQ of 0 in all items, except ‘arising’ and ‘total score’. This means that half of them had possible minimum
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Thai version of the HAQ in Psoriatic arthritis
score (HAQ score = 0) reflecting that this score may have floor effect or most patients included in this study had very low disease activity with mild functional disability. Therefore, the validity of HAQ for PsA with more severe disease activity and functional impairment needs to be further investigated. In conclusion, our study demonstrated that the Thai version of the HAQ retained the psychometric properties of the original version. It correlated with disease activity and functions of peripheral joints; however, its validity may be limited in patients who have axial joint involvement or permanent joint damage. Validity of the use of Thai HAQ in a large population of PsA patients with a variety of disease activities and manifestations and its usefulness in longitudinal studies need further evaluation.
CONFLICTS OF INTEREST The authors declare no conflicts of interest.
FINANCIAL SUPPORT Siriraj grant for research development.
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Copyright of International Journal of Rheumatic Diseases is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Copyright of International Journal of Rheumatic Diseases is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
