The impact of gout as described by patients, using the lens of The International Classification of Functioning, Disability and Health (ICF): a qualitative study

Background

The International Classification of Functioning, Disability and Health (ICF) aims to comprehensively describe the ways in which a person’s health condition affects their life. This study aimed to contribute to the development of an ICF core set for gout through patient opinion derived from focus groups and interviews.

Methods

We conducted a secondary qualitative analysis of data from three studies investigating the patient experience of gout. In total there were 30 individual interviews and 2 focus groups (N = 17) comprising 47 participants. We conducted thematic analysis of the textual data to extract meaning units, which were then linked to the ICF.

Results

A large number of ICF categories were relevant to patients with gout. Participants mentioned 93 third level categories, 17 of which were mentioned by more than 50% of patients. The most references for a single category was for b280, Sensation of pain, followed by personal factors (not yet categorised by the ICF). The most participants mentioned the environmental factor e355, Health professional support, followed by b280, Sensation of pain.

Conclusion

The categories identified in this study as relevant to patients with gout highlight the severe pain associated with this disease, the impact on mobility and corresponding life areas. The roles of health professional support, medication, and personal attitudes to disease management are also reflected in the data. These results will contribute to the development of the ICF core set for gout.

A systematic literature review of patient-reported outcome measures used in gout: an evaluation of their content and measurement properties

Background

Gout is a common, monosodium urate crystal-driven inflammatory arthritis. Besides its clinical manifestations, patients often also suffer from pain, physical impairment, emotional distress and work productivity loss, as a result of the disease. Patient-reported outcome measures (PROMs) are commonly used to assess these consequences of the disease. However, current instrument endorsements for measuring such outcomes in acute and chronic gout clinical settings are based on limited psychometric evidence. The objective of this systematic literature review was to identify currently available PROMs for gout, and to critically evaluate their content and psychometric properties, in order to evaluate the current status regarding PROMs for use in gout patients.

Methods

Systematic literature searches were performed in the PubMed and EMBASE databases. The methodological quality of included papers was appraised using the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) checklist, and evaluation of measurement properties (reliability, responsiveness, construct validity, floor and ceiling effects) was done in accordance with published quality criteria. Item content was appraised by linking health concepts to the International Classification of Functioning Disability and Health (ICF) framework.

Results

In total, 13 PROMs were identified, of which three were targeted specifically at gout patients. The majority of the PROMs were rated positively for content validity. For most instruments, limited evidence was available for construct validity and reliability. Instruments to assess pain scored well on responsiveness and floor and ceiling effects, but not much is known about their reliability in gout.

Conclusions

The physical functioning subscale of the SF-36v2 (Short Form-36 item version 2) is the only PROM that had sufficient supporting evidence for all its psychometric properties. Many of the commonly used PROMs in gout are currently not yet well supported and more studies on their measurement properties are needed among both acute and chronic gout populations.

Electronic supplementary material

The online version of this article (10.1186/s12955-019-1125-x) contains supplementary material, which is available to authorized users.

Predictors of activity limitation in people with gout: a prospective study

The objective of the study was to determine clinical factors associated with activity limitation and predictors of a change in activity limitation after 1 year in people with gout. Two hundred ninety-five participants with gout (disease duration < 10 years) attended a baseline assessment which included medical and disease-specific history, pain visual analog score and plain radiographs scored for erosion and narrowing. Activity limitation was assessed using the Health Assessment Questionnaire-II (HAQ-II). After 1 year, participants were invited to complete a further HAQ-II; follow-up questionnaires were available for 182 participants. Fully saturated and stepwise regression analyses were used to determine associations between baseline characteristics and HAQ-II at baseline and 1 year, and to determine predictors of worsening HAQ-II in those with normal baseline scores. Median (range) baseline HAQ-II was 0.20 (0-2.50) and 0.20 (0-2.80) after 1 year of follow-up. Pain score was the strongest independent predictor of baseline HAQ-II, followed by radiographic narrowing score, type 2 diabetes, swollen joint count, BMI, age and urate (model R² = 0.51, P < 0.001). Baseline HAQ-II was the strongest predictor of change in HAQ-II at 1 year, followed by tender joint count (model R² = 0.19, P < 0.001). Of those with HAQ-II scores of 0 at baseline (n = 59, 32% of those with follow-up data), most did not progress (n = 52, 88%); however, baseline pain score, type 2 diabetes and flare frequency were significant predictors of worsening HAQ-II in this group (R² = 0.34, P < 0.001). People with gout experience a wide range of activity limitation, and levels of activity limitation are, on average, stable over a 1-year period. Baseline pain scores are strongly associated with activity limitation and predict development of activity limitation in those with normal HAQ-II scores at baseline.

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.

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

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.

The Work Instability Scale predicts absenteeism in people with gout and suggests a higher risk for those in manual occupations

BACKGROUND

Gout occurs in working-age people and may be associated with significant work disability. There are no longitudinal studies to examine risk factors for work disability in people with gout.

OBJECTIVES

The purpose of this study was to determine the validity of the Work Instability Scale (WIS) in patients with gout and to see if baseline WIS scores predicted future work absences.

METHODS

We conducted a longitudinal, cohort study with patients who had gout for less than 10 years. Sick leave over the previous 3 months was recorded by patient recall at baseline and at 12 months. Self-report health status measures and disease characteristics including C-reactive protein and serum urate were measured at baseline. Work Instability Scale scores were fitted to a Rasch model, and nonparametric statistics were used to determine associations between disease features or future sick leave and WIS scores.

RESULTS

One hundred seventy-six participants were recruited, and follow-up information was available for 133 (76%). The WIS instrument showed satisfactory internal, construct, and predictive validity. Participants in nonmanual occupations had lower (better) WIS scores (median, 0 vs. 5.5; P < 0.001). Only 7% of working participants reported any sick leave in the 3 months before the 12-month follow-up. Work Instability Scale scores were associated with future sick leave: a cutoff of 4.5 was found to have the best combined sensitivity (88%) and specificity (72%) for predicting at least 1 day of sick leave.

CONCLUSIONS

The WIS instrument can identify people with gout who have a higher risk of future work disability and might be a useful guide to targeted vocational counseling or job modification, especially in people in manual occupations. However, further research is required to confirm these findings and to refine the instrument for optimal performance in this population.

Performance of the Dutch SF-36 version 2 as a measure of health-related quality of life in patients with rheumatoid arthritis

Background

The aim of this study was to examine the measurement properties of the Dutch SF-36 version 2 (SF-36v2) health survey in patients with rheumatoid arthritis (RA).

Methods

Scaling assumptions, internal reliability, and internal construct validity were examined using available data from 1884 RA patients included in the Dutch Rheumatoid Arthritis Monitoring (DREAM) registry. External construct validity and responsiveness to change were examined using baseline and 6-month follow-up data from a subset of 387 early RA patients participating in the DREAM remission induction cohort.

Results

The individual items of the SF-36v2 adequately met scaling assumptions, although four items correlated too highly with items from different scales. Internal consistency was high for all eight scales and the physical and mental health components underlying the scales were replicated, supporting the use of the standard scoring algorithms. The SF-36v2 scales demonstrated minimal floor effects and ceiling effects were noteworthy only for the role-physical, social functioning, and role-emotional scales. Correlations with other core measures were as expected and the SF-36v2 showed excellent known-groups validity in distinguishing between patients with low or moderate-high disease activity. All scales related to physical health showed moderate to large responsiveness to change in patients that achieved low disease activity at six months.

Conclusion

The SF-36v2 appears to be a psychometrically sound tool for the assessment of health-related quality of life of Dutch patients with RA.

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.

Measurement properties of physical function scales validated for use in patients with rheumatoid arthritis: a systematic review of the literature

Background

The aim of this study was to systematically review the content validity and measurement properties of all physical function (PF) scales which are currently validated for use with patients with rheumatoid arthritis (RA).

Methods

Systematic literature searches were performed in the Scopus and PubMed databases to identify articles on the development or psychometric evaluation of PF scales for patients with RA. The content validity of included scales was evaluated by linking their items to the International Classification of Functioning Disability and Health (ICF). Furthermore, available evidence of the reliability, validity, responsiveness, and interpretability of the included scales was rated according to published quality criteria.

Results

The search identified 26 questionnaires with PF scales. Ten questionnaires were rated to have adequate content validity. Construct validity, internal consistency, test-retest reliability and responsiveness was rated favourably for respectively 15, 11, 5, and 6 of the investigated scales. Information about the absolute measurement error and minimal important change scores were rarely reported.

Conclusion

Based on this literature review, the disease-specificHAQ and the generic SF-36 can currently be most confidently recommended to measure PF in RA for most research purposes. The HAQ, however, was frequently associated with considerable ceiling effects while the SF-36 has limited content coverage. Alternative scales that might be better suited for specific research purposes are identified along with future directions for research.