Gout Assessment Questionnaire: Initial results of reliability, validity and responsiveness

Reliability and Validity of the Korean Version of the Gout Impact Scale

BACKGROUND

The Gout Impact Scale (GIS), part of the Gout Assessment Questionnaire 2.0, measures gout-specific health-related quality of life (HRQOL). This study aimed to translate the GIS into Korean and validate the Korean version (K-GIS) using generic HRQOL measures.

METHODS

The GIS was translated into Korean and back-translated into English. We asked patients aged 18 years or older who met the 2015 gout classification criteria to fill out the questionnaires (from January 2022 to June 2022); the K-GIS (5 scales [0-100 scores each]), along with the Korean version of Health Assessment Questionnaire (HAQ) and EuroQol-5 dimension (EQ-5D). We investigated the internal consistency, construct validity, and discriminative validity for gout characteristics of K-GIS. The K-GIS form was administrated to patients 4 weeks later to assess the test-retest reliability using the intraclass correlation coefficient (ICC).

RESULTS

One hundred patients completed the questionnaire. The mean ± standard deviation age of the patients was 53.0 ± 15.1 years, and 99.0% of the patients were men. All scales had high degree of internal consistency (Cronbach's α = 0.59 to 0.96) and test-retest reliability (n = 18, ICC = 0.83 to 0.94, all P < 0.001), except for unmet gout treatment needs. Weak-to-moderate correlations were observed between the K-GIS scales and HAQ or EQ-5D (r = 0.21 to 0.46). The K-GIS scores were significantly higher in the presence of bone erosion, absence of urate-lowering therapy, serum urate levels > 6 mg/dL, frequent gout flares in the past year, and fewer comorbidities. In contrast, neither the HAQ nor the EQ-5D could discern these subsets of patients.

CONCLUSION

The K-GIS is a reliable and valid HRQOL measure for patients with gout. Higher K-GIS scores were associated with clinical characteristics leading to unfavorable outcomes, which were not demonstrated by the HAQ and EQ-5D.

Gender differences in illness perceptions and disease management in patients with gout, results from a questionnaire study in Western Sweden

BACKGROUND

Aims were to examine gender differences in patients with gout with regard to a) self-reported gout severity, b) illness perceptions (IP), c) impact on daily activities and Quality of Life (QoL), d) advice from healthcare professionals, e) having changed dietary- or alcohol habits.

METHODS

Adult patients with gout identified in primary and secondary care in Sweden between 2015 and 2017 (n = 1589) were sent a questionnaire about demographics, gout disease severity, IP (using the Brief Illness Perception Questionnaire, (B-IPQ)) and disease management. T-tests, Chi square tests, ANalysis Of VAriance (ANOVA) and linear regression models were used for gender comparisons.

RESULTS

Eight hundred sixty-eight patients responded to the questionnaire. Women, n = 177 (20%), experienced more severe gout symptoms (p = 0.011), albeit similar frequencies of flares compared to men. Women experienced modest but significantly worse IP with regard to consequences, identity, concerns and emotional response (p < 0.05) as well as daily activities such as sleeping (p < 0.001) and walking (p = 0.042) and QoL (p = 0.004). Despite this and a higher frequency of obesity in women (38 vs 21%, P < 0.001) and alcohol consumption in men (p < 0.001), obese women had received significantly less advice regarding weight reduction (47 vs 65%, p = 0.041) compared to obese men. On the other hand, women reported having acted on dietary advice to a larger degree.

CONCLUSIONS

Despite only modestly worse gout severity and perception, women appear to have been given less information regarding self-management than men. These gender differences should be given attention and addressed in clinical care.

Translation, internal consistency, reliability and validity of the Thai version of Gout Assessment Questionnaire version 2.0 (GAQ 2.0)

OBJECTIVES

To translate the Gout Assessment Questionnaire version 2.0 (GAQ2.0) with Gout Impact (GI) Scale (GIS) into Thai and determine its psychometric property in gout patients with acute arthritis (acute arthritis group) and during the intercritical period (chronic gout group).

METHODS

Translation followed the ISPOR recommendations. Cronbach's α, intraclass correlation coefficient (ICC) and standardized response mean (SRM) were used to determine internal consistency, reliability and responsiveness to change, respectively. Correlations between GI subscales with generic health-related quality of life (HRQoL) questionnaires (SF-36, HAQ-DI and EQ-5D-5L) and gout clinical parameters were determined.

RESULTS

The acute arthritis group and the chronic gout group comprised 27 and 92 patients, respectively. Internal consistency was sufficient for all GI subscales (Cronbach's α = 0.80-0.98), reliability was moderate to good in most GI subscales (ICC = 0.54-0.88) and responsiveness to change was moderate to large in most GI subscales (SRM = 0.43-0.98). The GI subscales correlated better with SF-36 than HAQ-DI and EQ-5D-5L. In the acute arthritis group, the unmet gout treatment needs subscale showed large and moderate negative correlation with tophi and serum uric acid, respectively. In the chronic gout group, the gout concern overall subscale had statistically significant, moderate correlation with overall gout severity rated by the patients and number of gout attacks over the past year, while the well-being during attack subscale and total GIS score had statistically significant, moderate correlation with overall gout severity rated by the patients.

CONCLUSION

The Thai GAQ2.0 GIS showed acceptable internal consistency, reliability and responsiveness to change and correlated significantly with generic HRQoL questionnaires and clinical parameters. Key Points • The Thai GAQ2.0 GIS showed acceptable internal consistency, reliability and responsiveness to change in gout patients both during acute attack and during the intercritical period • The GI subscales showed significant correlation with SF-36 and HAQ questionnaires and gout clinical parameters in gout patients both during acute attack and during the intercritical period • The Thai GAQ2.0 GIS subscales should be used in conjunction with generic HRQoL for complete HRQoL assessment in gout patients.

An assessment of the psychometric properties of the Chinese version of the Gout Impact Scale

Objective: To assess the psychometric properties of the Chinese version of the Gout Impact Scale (GIS), a gout-specific HRQoL measure.Methods: This was a single-center, cross-sectional, observational survey of patients with gout recruited from the Taipei Medical University Hospital from November 2017 to April 2018. The respondents were recruited by convenience sampling. The reliability of the Chinese GIS was tested by Cronbach's α coefficient and adjusted using the Spearman-Brown prophecy formula. Content validity was assessed and confirmed by rheumatologists and pharmacists before the administration of the survey. Convergent validity was tested by Spearman correlation analysis to examine the association of the EQ-5D-5L with GIS total and subscale scores. Construct validity of the Chinese GIS was assessed by hypothesis testing.Results: A total of 311 patients were included in the analysis. The majority of these respondents were male (93.2%) with no comorbidities (69.5%) and they had a mean age of 52.9 (±14.2) years. The internal consistency of the Chinese GIS subscales was acceptable to excellent (Cronbach's α = 0.73-0.98) after adjusting to a 10 item scale with the Spearman-Brown prophecy formula. The GIS total and subscale scores were significantly associated with lower EQ-5D-5L scores ([-0.14] - [-0.27], p < .05). In addition, the GIS total and all subscale scores had a significant positive correlation with gout attack severity (r_s = 0.13-0.57, p < .05) and gout attack pain (r_s = 0.17-0.54, p < .01). Moreover, respondents' most recent sUA concentration was associated with both the GIS gout concern overall subscale (r_s = 0.13, p < .05) and the unmet gout treatment need subscale (r_s = 0.18, p < .01).Conclusions: The present study demonstrates that the Chinese version of the GIS shows good internal consistency and association with gout-related characteristics. Future studies may consider using this gout-specific instrument to assess the HRQoL of gout patients in Taiwan.

Development and validation of a patient-reported gout attack intensity score for use in gout clinical studies

OBJECTIVE

Inflammation-related symptoms such as pain, swelling and tenderness of the affected joint are frequently assessed using 5-point diary rating scales in gout clinical trials. Combining these into a single gout attack symptom intensity score may be a useful summary measure for these data, which is potentially more responsive to change compared with the individual components. The objective of this study was to develop a patient-reported gout flare intensity score, the Gout Attack Intensity Score (GAIS), for use in clinical studies, that includes components for gout-related pain, swelling and tenderness.

METHODS

Data from a randomized controlled trial comparing anakinra to standard of care for the treatment of acute gout attacks were used for this study. A 7-day flare diary was completed by patients, including questions relating to intensity of pain, swelling and tenderness (5-point rating scales). Scalability of these items was assessed using Mokken Scale Analysis, and reliability using greatest lower bound reliability coefficients. Known-groups validity was evaluated, as well as the responsiveness to change and the presence of floor and ceiling effects.

RESULTS

Scalability of the single items was supported, and GAIS scores were reliable (greatest lower bound >0.80). GAIS scores demonstrated responsiveness to change with high effect sizes (>0.8), and discriminated better between responders and non-responders compared with its single-item components. No floor and ceiling effects were found.

CONCLUSION

The GAIS seems to be a reliable and responsive instrument for assessing patient-reported gout attack intensity that may be used in gout clinical studies.

Patient-reported gout attack frequency and allopurinol use in general practice in the Netherlands: a prospective observational cohort study protocol

INTRODUCTION

Gout is the most common inflammatory arthritis in the Dutch general practice population and is often managed with long-term uric acid lowering treatment. The clinical relevance of this treatment in preventing gout attacks is unclear.

PRIMARY RESEARCH QUESTION

What is the frequency of self-reported gout attacks and what is the effect of allopurinol use in patients diagnosed with gout in general practice?

METHODS AND ANALYSIS

Adult patients with a diagnostic consultation code for gout in the year 2013, 2014 or 2015 will be invited to participate in this prospective observational cohort study. Patients with a limited life expectancy will be excluded. Baseline measurements will include blood pressure, body mass index and a blood sample (estimated glomerular filtration rate, serum uric acid, cholesterol (low-density lipoprotein (LDL) and high-density lipoprotein), glucose (fasting)). At the 2-year follow-up, patients will receive questionnaires every 3 months. The questionnaires at baseline, 12 months and 24 months assess the frequency of gout attacks, the presence of tophi, comorbidity, medication use, quality of life, diet and lifestyle. The questionnaires in between only assess the frequency of gout attacks and medication use for gout. Descriptive statistics will be used to calculate the mean frequency of self-reported gout attacks during the 2-year follow-up. The propensity score for each patient being offered allopurinol is estimated and used to match patients with and without allopurinol treatment. We will compare the frequency of gout attacks in these groups using multilevel Poisson regression analyses. With this type of analysis, we can calculate the corrected estimated effect of allopurinol on gout attack frequency.

ETHICS AND DISSEMINATION

The research protocol was approved by the Medical Ethical Committee of the Erasmus Medical Centre in Rotterdam. The knowledge generated by this study will be transferred to the Dutch College of General Practitioners, conferences and to (inter)national peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NTR6329; Pre-results.

What Outcomes are Important for Gout Patients? In-Depth Qualitative Research into the Gout Patient Experience to Determine Optimal Endpoints for Evaluating Therapeutic Interventions

Background and Objectives

Characterized by sudden onset of severe joint pain, swelling, redness, and tenderness to touch, gout ‘flare ups’ have a substantial impact on quality of life (QoL). This research employed a patient-centered approach to explore the symptoms and impacts of gout, and assess the content validity of existing patient-reported outcomes (PROs).

Methods

Qualitative interviews were conducted with 30 US gout patients (non-tophaceous: n = 20, tophaceous: n = 10) and five expert rheumatologists. Each interview included both concept elicitation (CE) questioning to learn about the patient experience and cognitive debriefing to assess the content validity of three PRO instruments (HAQ-DI, GAQ, and TIQ-20). Nine of the patients provided further real-time qualitative data through a smart phone application. All qualitative data were subject to thematic analysis using Atlas.ti. Two patient advisors and three expert clinicians were engaged as advisors at key stages throughout the research.

Results

Interview and real-time data identified the same core symptoms and proximal impact concepts. Severe pain (typically in joints of extremities) was described as the cardinal symptom, often accompanied by swelling, redness, heat, sensitivity to touch, and stiffness. Domains of QoL impacted included physical functioning, sleep, daily activities, and work. The PRO instruments were generally well-understood by patients, but each included items with questionable relevance to at least some of the sample, dependent on the specific joints affected.

Conclusions

Gout patients experience severe pain in affected joints, resulting in substantial limitations in physical functioning. Both the HAQ-DI and the TIQ-20 are useful for specific research purposes in the gout population, although modifications are recommended.

Electronic supplementary material

The online version of this article (doi:10.1007/s40271-016-0184-x) contains supplementary material, which is available to authorized users.

Pilot study of a multidisciplinary gout patient education and monitoring program

OBJECTIVE

Gout patient self-management knowledge and adherence to treatment regimens are poor. Our objective was to assess the feasibility and acceptability of a multidisciplinary team-based pilot program for the education and monitoring of gout patients.

METHODS

Subjects completed a gout self-management knowledge exam, along with gout flare history and compliance questionnaires, at enrollment and at 6 and 12 months. Each exam was followed by a nursing educational intervention via a structured gout curriculum. Structured monthly follow-up calls from pharmacists emphasized adherence to management programs. Primary outcomes were subject and provider program evaluation questionnaires at 6 and 12 months, program retention rate and success in reaching patients via monthly calls.

RESULTS

Overall, 40/45 subjects remained in the study at 12 months. At 12 months, on a scale of 1 (most) to 5 (least), ratings of 3 or better were given by 84.6% of subjects evaluating the usefulness of the overall program in understanding and managing their gout, 81.0% of subjects evaluating the helpfulness of the nursing education program, and 50.0% of subjects evaluating the helpfulness of the calls from the pharmacists. Knowledge exam questions that were most frequently answered incorrectly on repeat testing concerned bridge therapy, the possibility of being flare-free, and the genetic component of gout.

CONCLUSIONS

Our multidisciplinary program of gout patient education and monitoring demonstrates feasibility and acceptability. We identified variability in patient preference for components of the program and persistent patient knowledge gaps.

Discrepancies in how the impact of gout is assessed in outcomes research compared to how health professionals view the impact of gout, using the lens of the International Classification of Functioning, Health and Disability (ICF)

The International Classification of Functioning, Disability and Health (ICF) provides a common language to understand what health means. An ICF core set, a list of ICF categories affected by a certain disease, is useful to objectify the content validity of a health status measurement. This study aims to identify the potential items of a gout specific 'ICF core set'. A three-round Delphi exercise was conducted, using web-based questionnaires. Health professionals, specialized in gout, nominated and subsequently rated the relevance of life areas divided into ICF categories. Agreement was determined by using the UCLA/RAND criteria. Simultaneously, a systematic review of gout measure outcomes was conducted. The results of these studies were compared using the second level of the ICF categories. In the Delphi study, consensus was found for 136 relevant ICF categories. The literature study extracted 134 different ICF categories in 149 articles. Three hundred and ten were non-defined outcomes. A large number of ICF categories were deemed to be relevant for people with gout. Only 29.7 % (19/64) of the level 2 categories, deemed to be relevant by health professionals, had been assessed as relevant in at least 5 % of gout outcome studies. Conversely, 70 % (19/27) of level 2 ICF categories assessed in at least 5 % of outcome studies were deemed relevant by health professionals. These ICF codes, which are found relevant in both studies, should be considered as mandatory in further research to a validated and practical core set of ICF categories. Published gout outcomes research fails to evaluate many life areas that are thought relevant by health professionals.

A Systematic Review of the Economic and Humanistic Burden of Gout

BACKGROUND

Gout is a chronic and inflammatory form of arthritis that is often overlooked despite the associated pain caused by acute flares and associated joint damage caused by the development of debilitating tophi. The increasing burden of gout, due to an aging population and the increased prevalence of known risk factors for hyperuricaemia, means that there is a continued need for new and effective urate-lowering treatments. The evaluation of these treatments will require a comprehensive and comparative evidence base describing the economic and humanistic burden of gout, taken from the perspective of patients, the healthcare system, and wider society.

OBJECTIVE

The objective of this study is to review and summarise the current evidence of the disease burden related to chronic gout, assessed in terms of both cost and health-related quality of life (HRQL), and to identify key factors correlated with an increased burden. The overall aim is to support the economic evaluation of new treatments for gout, and to highlight key data gaps that may need further study and exploration.

METHODS

Relevant literature dating from January 2000 to July 2014 was sourced through searches of the MEDLINE database via PubMed and The Cochrane Library. Articles published in English and reporting either the economic burden (cost) or the humanistic burden (HRQL/utility) of gout were identified, and key data were extracted and summarised, with key themes and data gaps identified and discussed.

RESULTS

Of the 323 studies identified, 39 met the inclusion criteria, of which 17 and 26 were relevant to the economic and humanistic burden, respectively. The economic burden of gout varied according to numerous factors, most notably serum urate acid levels and number of flares and tophi, resulting in higher healthcare resource use most often attributed to hospitalisation and inpatient stay. The incremental direct cost of gout has been suggested in the range of US$3165 to US$5515 (2004 and 2005 values, respectively) climbing to US$10,222 to US$21,467 (2008 values) per annum where patients are experiencing regular acute flares and have tophi present. The humanistic burden of gout was largely due to physical disability and pain resulting from chronic clinical manifestations. Short Form 6 dimensions (SF-6D) assessed utility weights are estimated at 0.53 for a patient with severe gout (≥3 flares/year and tophi) compared with 0.73 for an asymptomatic gout patient with serum acid levels <6 mg/dl.

CONCLUSIONS

The evidence confirms that gout has a growing overall prevalence and represents a significant burden in terms of both direct healthcare cost and HRQL outcomes. In light of this, effective urate-lowering treatments are likely to be valued if they can be clearly demonstrated to be both clinically effective and cost effective. Published data to support healthcare decision making in non-US countries with regards to treatments for gout are currently limited, which is a key limitation of the current evidence base. More research is also required to extend our understanding of the impact of gout on indirect costs, and a need also exists to develop a more comprehensive set of comparative HRQL utility assessments.

Patient-reported outcomes in core domain sets for rheumatic diseases

Patient-reported outcomes (PROs) are abundant in rheumatology and their numbers continue to increase. But which of the available measures are most important? Core outcome sets-including groups of domains and instruments for measuring them-have been defined for many rheumatic diseases, with the aim that all these outcomes should be measured in every clinical trial. The subgroup of PROs included in these core sets is, therefore, undoubtedly important. This Review summarizes the PROs included in core outcome sets developed for use in clinical trials across a wide range of rheumatic diseases. Three PROs are commonly utilized across the majority of rheumatic conditions: pain, physical functioning and the patient global assessment of disease activity. However, additional research is needed to fully understand the role of the patient global assessment of disease activity, to distinguish specific domains within the broad concept of health-related quality of life, and to work towards consensus on the choice between generic and disease-specific instruments in various contexts.

Experiences of gout-related disability from the patients' perspective: a mixed methods study

Disability is a common problem in patients with gout. Recently, the Health Assessment Questionnaire Disability Index (HAQ-DI) was recommended for assessing patient reported activity limitations in gout. However, few studies have explored experiences and issues of disability from the perspective of gout patients themselves. The objectives of this study were to explore disability issues in patients with gout and to examine the content validity of the HAQ-DI in this patient group. Two studies were performed: a semi-structured interview study with seven male gout patients and a cross-sectional survey study among 34 other patients with gout. In both studies, specific examples of activity limitations were elicited using open-ended methods. The survey study additionally aimed to quantify the relevance of the activities listed in the HAQ-DI. Most patients experienced several gout attacks in the previous year. Limitations were reported to occur during a flare, but patients were generally not limited between attacks. During an attack, patients mainly experienced limitations related to mobility, especially walking and climbing stairs. Patients also mentioned limitations in activities related to domestic life, such as gardening and doing housework. Limitations related to self-care or activities requiring the use of the upper extremities were rarely mentioned. Corresponding HAQ-DI items were skewed towards very low disability scores over the past week. Assessments of gout-related disability should particularly focus on mobility and lower extremity functioning and should consider the intermittent nature of the disease. The HAQ-DI may not adequately meet these requirements, suggesting the need to explore other measures of gout-related disability

Health-related quality of life and treatment satisfaction in patients with gout: results from a cross-sectional study in a managed care setting

BACKGROUND

Patient satisfaction with treatment directly impacts adherence to medication.

OBJECTIVE

The objective was to assess and compare treatment satisfaction with the Treatment Satisfaction Questionnaire for Medication (TSQM), gout-specific health-related quality of life (HRQoL) with the Gout Impact Scale (GIS), and generic HRQoL with the SF-12v2(®) Health Survey (SF-12) in patients with gout in a real-world practice setting.

METHODS

This cross-sectional mail survey included gout patients enrolled in a large commercial health plan in the US. Patients were ≥18 years with self-reported gout diagnosis, who filled ≥1 prescription for febuxostat during April 26, 2012 to July 26, 2012 and were not taking any other urate-lowering therapies. The survey included the TSQM version II (TSQM vII, score 0-100, higher scores indicate better satisfaction), GIS (score 0-100, higher scores indicate worse condition), and SF-12 (physical component summary and mental component summary). Patients were stratified by self-report of currently experiencing a gout attack or not to assess the discriminant ability of the questionnaires.

RESULTS

A total of 257 patients were included in the analysis (mean age, 54.9 years; 87% male). Patients with current gout attack (n=29, 11%) had worse scores than those without gout attack on most instrument scales. Mean differences between current attack and no current attack for the TSQM domains were: -20.6, effectiveness; -10.6, side effects; -12.1, global satisfaction (all P<0.05); and -6.1, convenience (NS). For the GIS, mean differences were: 30.5, gout overall concern; 14.6, gout medication side effects; 22.7, unmet gout treatment needs; 11.5, gout concern during attack (all P<0.05); and 7.9, well-being during attack (NS). Mean difference in SF-12 was -6.6 for physical component summary (P<0.05) and -2.9 for mental component summary (NS). Correlations between several TSQM and GIS scales were moderate.

CONCLUSION

The TSQM and GIS were complementary in evaluating the impact of gout flare on treatment satisfaction and HRQoL. Correlations between the two instruments supported the relationship between treatment satisfaction and HRQoL.

Development of a patient-reported outcome measure of tophus burden: the Tophus Impact Questionnaire (TIQ-20)

Background

Tophus burden is currently measured using physical examination and imaging methods. The aim of this study was to develop a patient-reported outcome (PRO) tool to assess tophus burden in people with gout.

Methods

The responses from interviews with 25 people with tophaceous gout were used to generate items for a preliminary PRO tool. Following cognitive testing of each item, a preliminary 34-item questionnaire was administered to 103 people with tophaceous gout. Rasch analysis generated a 20-item Tophus Impact Questionnaire (TIQ-20). Test-retest reproducibility and construct validity of the TIQ-20 were assessed.

Results

The TIQ-20 responses fit the Rasch model and demonstrated unidimensionality, adequate precision, absence of differential item functioning and adequate person separation index. The TIQ-20 included items related to pain, activity limitation, footwear modification, participation, psychological impact and healthcare use due to tophi. In the 103 patients with tophaceous gout, floor effects were observed in 4.9% and ceiling effects in 1%. The TIQ-20 test-retest intraclass correlation coefficient was 0.76 (95% CI 0.61 to 0.85). All predicted correlations for construct validity testing were observed, including weak correlation with serum urate concentrations (r<0.30), moderate correlation with subcutaneous tophus count and dual energy CT urate volume (r=0.30–0.50), and stronger correlation with Health Assessment Questionnaire scores (r>0.50).

Conclusions

We have developed a tophus-specific PRO in patients with tophaceous gout. The TIQ-20 demonstrates acceptable psychometric properties. Initial results show internal, face and construct validity, reproducibility and feasibility. Further research is required to determine responsiveness to change.

Functional assessment measures in rheumatologic disorders

Rheumatologic disorders cause functional impairment and significantly affect health-related quality of life. Functional assessment and health-related quality of life scales are increasingly being used as outcome measures to assess the influence of the diseases and health outcome in clinical studies of patients with rheumatologic diseases. In this article, we review the functional assessment and health-related quality of life measures which have been commonly used as outcome measures in rheumatologic disorders. These measures are Short form-36 (SF-36), SF-12, Nottingham Health Profile, Sickness Impact Profile, EuroQol, SF-6D, Health Utilities Index mark 2 and 3, Stanford Health Assessment Questionnaire, Rheumatoid Arthritis Quality of Life Questionnaire, Arthritis Impact Measurement Scales, McMaster Toronto Arthritis Patient Preference Disability Questionnaire, Western Ontario and McMaster Universities Osteoarthritis Index, Lequesne Index, Knee Disability and Osteoarthritis Outcome Score, Knee Disability and Osteoarthritis Outcome Score-Physical Function Short-form, Hip Disability and Osteoarthritis Outcome Score, Hip Disability and Osteoarthritis Outcome Score-Physical Function SF, Fibromyalgia Impact Questionnaire, Psoriatic Arthritis Quality of Life Scale, Gout Assessment Questionnaires, Dougados Functional Index, Bath Ankylosing Spondylitis Functional Index, and Ankylosing Spondylitis Quality of Life Scale.

The Gout Assessment Questionnaire 2.0: cross-cultural translation into Dutch, aspects of validity and linking to the International Classification of Functioning, Disability and Health

OBJECTIVES

The Gout Assessment Questionnaire 2.0 (GAQ2.0) is a disease-specific patient-reported outcome measure for gout that distinguishes five different subscales and comprises overall 31 questions. The aims of this study were to translate the GAQ2.0 into Dutch and to test clinimetric properties.

METHODS

Recommendations for translation and cross-cultural adaptation were followed and no cultural adaptations were needed. The resulting Dutch GAQ2.0 was administered to patients registered at the rheumatology outpatient clinic diagnosed with gout. Internal consistency was tested using Cronbach's α, reliability using intraclass correlation coefficient (ICC), content validity by linkage to the International Classification of Functioning, Disability and Health (ICF) and construct validity by correlating the subscales of the GAQ2.0 with the HAQ disability index (HAQ-DI) and 36-item Short Form Health Survey (SF-36).

RESULTS

A total of 126 patients [106 (84%) male, mean age 66.6 years (s.d. 10.4), mean disease duration 11.2 years (s.d. 10.6)] completed a number of questionnaires, including the GAQ2.0, HAQ-DI and SF-36, and underwent a clinical examination. Internal consistency was sufficient (Cronbach's α = 0.83-0.94), except for the subscale gout medication side effects (Cronbach's α = 0.51). Test-retest reliability was good (ICCs 0.73-0.86) for all subscales, but moderate for the subscale unmet gout treatment need (ICC 0.56). Gout impact (GI) subscale scores showed only weak to moderate correlations with HAQ-DI and SF-36, but stronger emphasis on the emotional consequences of gout. Also, it correlated better with gout-specific outcomes such as the number of gout flares and pain.

CONCLUSION

The Dutch GAQ2.0 shows sufficient evidence of validity to assess disease-specific functioning and health in patients with gout and seems to capture different aspects than those represented in the HAQ and SF-36.

Health-related quality of life in gout: a systematic review

Objectives. To identify the instruments that have been used to measure health-related quality of life (HRQOL) in gout and assess their clinimetric properties, determine the distribution of HRQOL in gout and identify factors associated with poor HRQOL.

Methods. Medline, CINAHL, EMBASE and PsycINFO were searched from inception to October 2012. Search terms pertained to gout, health or functional status, clinimetric properties and HRQOL. Study data extraction and quality assessment were performed by two independent reviewers.

Results. From 474 identified studies, 22 met the inclusion criteria. Health Assessment Questionnaire Disability Index (HAQ-DI) and Short Form 36 (SF-36) were most frequently used and highest rated due to robust construct and concurrent validity, despite high floor and ceiling effects. The Gout Impact Scale had good content validity. Gout had a greater impact on physical HRQOL compared to other domains. Both gout-specific features (attack frequency and intensity, intercritical pain and number of joints involved) and comorbid disease were associated with poor HRQOL. Evidence for objective features such as tophi and serum uric acid was less robust. Limitations of existing studies include cross-sectional design, recruitment from specialist clinic settings and frequent use of generic instruments.

Conclusion. Most studies have used the generic HAQ-DI and SF-36. Gout-specific characteristics and comorbidities contribute to poor HRQOL. There is a need for a cohort study in primary care (where most patients with gout are treated) to determine which factors predict changes in HRQOL over time. This will enable those at risk of deterioration to be identified and better targeted for treatment.

Disability due to gouty arthritis

PURPOSE OF REVIEW

Disability, or activity limitation, is a common problem in patients with gout. This study explores recent studies examining the nature and extent of disability in gout and addresses the merits and limitations of current self-reported measures of disability.

RECENT FINDINGS

Gout has a significant impact on patients' ability to perform normal self-care activities, recreational and social activities, and work. Comparative studies indicate that gout patients' physical functioning is strongly reduced and comparable to those with other severe rheumatic conditions. Moreover, gout has been shown to result in substantial work absence and reduced productivity. However, few studies have thoroughly examined the concept of disability in gout. Additionally, assessment of disability due to gout still seems particularly challenging and it is unclear whether current measurement instruments are sufficiently valid and accurate.

SUMMARY

Gout-related disability is an underestimated and understudied problem. More qualitative and quantitative studies are needed that examine the concept of disability in gout and its impact on patients' lives, both during and between disease flares. Moreover, future studies should try to identify gout-specific disability issues and examine the relevance and comprehensiveness of existing measures to further improve the assessment of disability in gout.

Serum urate in chronic gout--will it be the first validated soluble biomarker in rheumatology?

OBJECTIVE

To summarize evidence for and endorsement of serum urate (SU) as having fulfilled the OMERACT filter as a soluble biomarker in chronic gout at the 2010 Outcome Measures in Rheumatology Meeting (OMERACT 10).

METHODS

Data were presented to support the use of SU as a soluble biomarker in chronic gout and specifically the ability to utilize it to predict future patient-reported outcomes.

RESULTS

SU was accepted as having fulfilled the OMERACT filter by 78% of voters. However, consensus was not obtained regarding its use as a soluble biomarker in chronic gout. Although the majority of the criteria for a soluble biomarker were fulfilled, the key criterion of association of the biomarker with outcomes was not agreed upon. It was agreed that the appropriate choice of endpoint must be linked to its clinical importance to the individual with the disorder and its temporal relationship to the intervention. Appropriate outcomes in chronic gout may therefore include gout flares, reduction in tophi, and patient-reported outcomes.

CONCLUSION

SU is a critical outcome measure. It has the potential to fulfil criteria for a soluble biomarker. Further analyses of existing data from randomized controlled trials will be required to determine whether SU can predict future important outcomes, in particular disability.

Patient-reported outcomes in chronic gout: a report from OMERACT 10

OBJECTIVE

To summarize the endorsement of measures of patient-reported outcome (PRO) domains in chronic gout at the 2010 Outcome Measures in Rheumatology Meeting (OMERACT 10).

METHODS

During the OMERACT 10 gout workshop, validation data were presented for key PRO domains including pain [pain by visual analog scale (VAS)], patient global (patient global VAS), activity limitation [Health Assessment Questionnaire-Disability Index (HAQ-DI)], and a disease-specific measure, the Gout Assessment Questionnaire version 2.0 (GAQ v2.0). Data were presented on all 3 aspects of the OMERACT filters of truth, discrimination, and feasibility. One PRO, health-related quality of life measurement with the Medical Outcomes Study Short-form 36 (SF-36), was previously endorsed at OMERACT 9.

RESULTS

One measure for each of the 3 PRO of pain, patient global, and activity limitation was endorsed by > 70% of the OMERACT delegates to have appropriate validation data. Specifically, pain measurement by VAS was endorsed by 85%, patient global assessment by VAS by 73%, and activity limitation by HAQ-DI by 71%. GAQ v2.0 received 30% vote and was not endorsed due to several concerns including low internal consistency and lack of familiarity with the measure. More validation studies are needed for this measure.

CONCLUSION

With the endorsement of one measure each for pain, patient global, SF-36, and activity limitation, all 4 PRO for chronic gout have been endorsed. Future validation studies are needed for the disease-specific measure, GAQ v2.0. Validation for PRO for acute gout will be the focus of the next validation exercise for the OMERACT gout group.

Progress in Measurement Instruments for Acute and Chronic Gout Studies

Consensus exercises have identified and prioritized domains of measurement for studies in acute and chronic gout. In parallel, the technical properties of instruments for measurement in many of these domains have been assessed, with the main objective to consider the instruments in the context of the OMERACT filter of truth, discrimination, and feasibility. These data were presented and discussed at OMERACT 9 in the gout workshop, in breakout groups, and at informal meetings of the gout group. In acute gout, instruments for domains of pain, joint swelling, joint tenderness, and patient and physician global assessment have been assessed. In chronic gout, some validation exercises have been performed in instruments for domains serum urate, tophus measurement, health-related quality of life (HRQOL). In voting at OMERACT 9, the Medical Outcomes Study Short-Form 36 was endorsed as a valid instrument for measurement of HRQOL. Methods of tophus measurement were considered to have met some criteria of the OMERACT filter, but these require further work, particularly regarding sensitivity to change over shorter time periods. Priorities for future research include measurement of joint inflammation in acute gout and disability in acute and chronic gout.

[Measurement of health-related quality of life and functional capacity in patients with chronic tophaceous gout]

INTRODUCTION

In gout there are few instruments validated for the evaluation of activity, functional capacity or quality of life. It is not known if generic instruments such as the MOS-20, or specific for other illnesses, such as the AIMS, can be applied to patients with Gout.

OBJECTIVE

To evaluate the clinimetric characteristic of the MOS-20 and AIMS questionnaires, and their correlation with HAQ-DI, as well as with clinical variables in patient with tophaceous gout (TG).

METHODS

49 patients with TG were included. Demographic and clinical variables were obtained. The 3 questionnaires were applied at the basal evaluation. A second evaluation was applied to 20 patients, 8 weeks later.

RESULTS

All patients were male. The time of since onset of the illness was 14.9±8.3 years. The HAQ-DI was 0.43±0.56 with an alpha of Cronbach (αC) of 0.95 and the intraclass correlation coefficient (ICC) was 0.86. The MOS-20 had an αC of 0.68 to 1.0 and a ICC of 0.27 to 0.61 between the several components. The AIMS had an αC of 0.66 to 0.96, and a ICC of 0.11 to 0.79 between the several components. Reliability was better between the physical components in MOS-20 and AIMS. The MOS-20, AIMS and the HAQ-DI correlated with the presence of joints with functional limitation. There weren't any significant differences among the patients with inflamed joints, nor in those with tophi. The HAQ-DI was best correlated with the physical component than with the mental component of the AIMS and the MOS-20.

CONCLUSION

The AIMS, the MOS-20 and the HAQ-DI are useful in measuring the functional capacity and the quality of life in patient with TG.

Quality of life and disability in patients with treatment-failure gout

OBJECTIVE

The relationship between self-reported quality of life and disability and disease severity was evaluated in subjects with treatment-failure gout (n = 110) in a prospective, 52-week, observational study.

METHODS

Subjects had symptomatic crystal-proven gout of at least 2 years' duration and intolerance or refractoriness to conventional urate-lowering therapy. Serum uric acid (sUA) concentration, swollen and tender joint counts, frequency and severity of gout flares, tophus assessments, comorbidities, and patient-reported outcomes data [Medical Outcomes Study Short Form-36 (SF-36), Health Assessment Questionnaire-Damage Index] were collected. Analyses included correlations of patient-reported outcomes with clinical variables and changes in clinical status.

RESULTS

Mean age of study subjects was 59 years. Mean scores on SF-36 physical functioning subscales were 34.2-46.8, analogous to persons aged >or= 75 years in the general population. Subjects with more severe gout at baseline had worse health-related quality of life (HRQOL) in all areas (p < 0.02 for all measures), compared to patients with mild-moderate disease. Number of flares reported in past year, number of tender joints, swollen joints, and tophi correlated significantly with some or all HRQOL and disability measures. sUA was not significantly correlated with any HRQOL or disability measure. Subjects with comorbidities experienced worse physical, but not mental, functioning.

CONCLUSION

Severe gout is associated with poor HRQOL and disability, especially for patients who experience more gout flares and have a greater number of involved joints. Subject perceptions of gout-related functioning and pain severity appear to be highly sensitive indicators of HRQOL and disability.