A delphi exercise to identify characteristic features of gout - opinions from patients and physicians, the first stage in developing new classification criteria

Articular mobilization promotes improvement in functional and inflammatory parameters in a gouty arthritis model

OBJECTIVE

Gouty arthritis is characterized by painful inflammation due to the deposition of monosodium urate crystals in joint tissues. Despite available treatments, many patients experience ineffective management and adverse effects. This study evaluated a manual therapy protocol involving passive joint mobilization at the peak of inflammation in a gouty arthritis model using functional and inflammatory parameters.

METHODS

Twenty male Wistar rats, 12 weeks old, were divided into two groups (n=10 each): Gouty Arthritis and Control Groups, which were further subdivided into treated and untreated groups (n=5 each). The Gouty Arthritis Group received intraarticular knee injection of 50µL of monosodium urate crystals, while the Control Group received 50µL of phosphate buffered saline. The treatment involved a 9-minutes session of grade III joint mobilization (according to Maitland). Nociception, grip strength, and edema were evaluated before induction (EV0), 7 hours after assessment (EV1), immediately after treatment (EV2), and 1 hour after treatment (EV3). The animals were euthanized, and synovial fluid was collected to analyze leukocyte migration.

RESULTS

The model mimicked the signs of the Gouty Arthritis Group, with a decrease in the threshold of nociception and strength and an increase in edema and leukocyte count. The mobilization protocol significantly increased the nociceptive threshold and grip strength and reduced edema; however, it did not reverse the increase in leukocyte count.

CONCLUSION

Our results suggest that mobilization promotes analgesia and may modulate the inflammatory process owing to reduced edema and subtle attenuation of cell migration, which contributes to strength gain.

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.

Gout Classification Criteria: Update and Implications

Gout is the most common inflammatory arthritis, with a rising prevalence and incidence worldwide. There has been a resurgence in gout research, fueled, in part, by a number of advances in pharmacologic therapy for gout. The conduct of clinical trials and other observational research in gout requires a standardized and validated means of assembling well-defined groups of patients with gout for such research purposes. Recently, an international collaborative effort that involved a data-driven process with state-of-the art methodology supported by the American College of Rheumatology and the European League Against Rheumatism led to publication of new gout classification criteria.

Development of Preliminary Remission Criteria for Gout Using Delphi and 1000Minds Consensus Exercises

OBJECTIVE

To establish consensus for potential remission criteria to use in clinical trials of gout.

METHODS

Experts (n = 88) in gout from multiple countries were invited to participate in a web-based questionnaire study. Three rounds of Delphi consensus exercises were conducted using SurveyMonkey, followed by a discrete-choice experiment using 1000Minds software. The exercises focused on identifying domains, definitions for each domain, and the timeframe over which remission should be defined.

RESULTS

There were 49 respondents (56% response) to the initial survey, with subsequent response rates ranging from 57% to 90%. Consensus was reached for the inclusion of serum urate (98% agreement), flares (96%), tophi (92%), pain (83%), and patient global assessment of disease activity (93%) as measurement domains in remission criteria. Consensus was also reached for domain definitions, including serum urate (<0.36 mm), pain (<2 on a 10-point scale), and patient global assessment (<2 on a 10-point scale), all of which should be measured at least twice over a set time interval. Consensus was not achieved in the Delphi exercise for the timeframe for remission, with equal responses for 6 months (51%) and 1 year (49%). In the discrete-choice experiment, there was a preference towards 12 months as a timeframe for remission.

CONCLUSION

These consensus exercises have identified domains and provisional definitions for gout remission criteria. Based on the results of these exercises, preliminary remission criteria are proposed with domains of serum urate, acute flares, tophus, pain, and patient global assessment. These preliminary criteria now require testing in clinical data sets.

Development and First Validation of a Disease Activity Score for Gout

Objective

To develop a new composite disease activity score for gout and provide its first validation.

Methods

Disease activity has been defined as the ongoing presence of urate deposits that lead to acute arthritis and joint damage. Every measure for each Outcome Measures in Rheumatology core domain was considered. A 3‐step approach (factor analysis, linear discriminant analysis, and linear regression) was applied to derive the Gout Activity Score (GAS). Decision to change treatment or 6‐month flare count were used as the surrogate criteria of high disease activity. Baseline and 12‐month followup data of 446 patients included in the Kick‐Off of the Italian Network for Gout cohort were used. Construct‐ and criterion‐related validity were tested. External validation on an independent sample is reported.

Results

Factor analysis identified 5 factors: patient‐reported outcomes, joint examination, flares, tophi, and serum uric acid (sUA). Discriminant function analysis resulted in a correct classification of 79%. Linear regression analysis identified a first candidate GAS including 12‐month flare count, sUA, visual analog scale (VAS) of pain, VAS global activity assessment, swollen and tender joint counts, and a cumulative measure of tophi. Alternative scores were also developed. The developed GAS demonstrated a good correlation with functional disability (criterion validity) and discrimination between patient‐ and physician‐reported measures of active disease (construct validity). The results were reproduced in the external sample.

Conclusion

This study developed and validated a composite measure of disease activity in gout. Further testing is required to confirm its generalizability, responsiveness, and usefulness in assisting with clinical decisions.

Study for Updated Gout Classification Criteria: Identification of Features to Classify Gout

OBJECTIVE

To determine which clinical, laboratory, and imaging features most accurately distinguished gout from non-gout.

METHODS

We performed a cross-sectional study of consecutive rheumatology clinic patients with ≥1 swollen joint or subcutaneous tophus. Gout was defined by synovial fluid or tophus aspirate microscopy by certified examiners in all patients. The sample was randomly divided into a model development (two-thirds) and test sample (one-third). Univariate and multivariate association between clinical features and monosodium urate-defined gout was determined using logistic regression modeling. Shrinkage of regression weights was performed to prevent overfitting of the final model. Latent class analysis was conducted to identify patterns of joint involvement.

RESULTS

In total, 983 patients were included. Gout was present in 509 (52%). In the development sample (n = 653), the following features were selected for the final model: joint erythema (multivariate odds ratio [OR] 2.13), difficulty walking (multivariate OR 7.34), time to maximal pain <24 hours (multivariate OR 1.32), resolution by 2 weeks (multivariate OR 3.58), tophus (multivariate OR 7.29), first metatarsophalangeal (MTP1) joint ever involved (multivariate OR 2.30), location of currently tender joints in other foot/ankle (multivariate OR 2.28) or MTP1 joint (multivariate OR 2.82), serum urate level >6 mg/dl (0.36 mmoles/liter; multivariate OR 3.35), ultrasound double contour sign (multivariate OR 7.23), and radiograph erosion or cyst (multivariate OR 2.49). The final model performed adequately in the test set, with no evidence of misfit, high discrimination, and predictive ability. MTP1 joint involvement was the most common joint pattern (39.4%) in gout cases.

CONCLUSION

Ten key discriminating features have been identified for further evaluation for new gout classification criteria. Ultrasound findings and degree of uricemia add discriminating value, and will significantly contribute to more accurate classification criteria.

Foot and ankle muscle strength in people with gout: A two-arm cross-sectional study

BACKGROUND

Foot and ankle structures are the most commonly affected in people with gout. However, the effect of gout on foot and ankle muscle strength is not well understood. The primary aim of this study was to determine whether differences exist in foot and ankle muscle strength for plantarflexion, dorsiflexion, inversion and eversion between people with gout and age- and sex-matched controls. The secondary aim was to determine whether foot and ankle muscle strength was correlated with foot pain and disability.

METHODS

Peak isokinetic concentric muscle torque was measured for ankle plantarflexion, dorsiflexion, eversion and inversion in 20 participants with gout and 20 matched controls at two testing velocities (30°/s and 120°/s) using a Biodex dynamometer. Foot pain and disability was measured using the Manchester Foot Pain and Disability Index (MFPDI).

FINDINGS

Participants with gout demonstrated reduced muscle strength at both the 30°/s and 120°/s testing velocities for plantarflexion, inversion and eversion (P<0.05). People with gout also displayed a reduced plantarflexion-to-dorsiflexion strength ratio at both 30°/s and 120°/s (P<0.05). Foot pain and disability was higher in people with gout (P<0.0001) and MFPDI scores were inversely correlated with plantarflexion and inversion muscle strength at the 30°/s testing velocity, and plantarflexion, inversion and eversion muscle strength at the 120°/s testing velocity (all P<0.05).

INTERPRETATION

People with gout have reduced foot and ankle muscle strength and experience greater foot pain and disability compared to controls. Foot and ankle strength reductions are strongly associated with increased foot pain and disability in people with gout.

Foot-related pain and disability and spatiotemporal parameters of gait during self-selected and fast walking speeds in people with gout: A two-arm cross sectional study

OBJECTIVES

To examine gait parameters in people with gout during different walking speeds while adjusting for body mass index (BMI) and foot-pain, and to determine the relationship between gait parameters and foot-pain and disability.

METHOD

Gait parameters were measured using the GAITRite™ walkway in 20 gout participants and 20 age- and sex-matched controls during self-selected and fast walking speeds. Foot-pain and disability was measured using the Manchester Foot Pain and Disability Index (MFPDI) which contains four domains relating to function, physical appearance, pain and work/leisure.

RESULTS

At the self-selected speed, gout participants demonstrated increased step time (p=0.017), and stance time (p=0.012), and reduced velocity (p=0.031) and cadence (p=0.013). At the fast speed, gout participants demonstrated increased step time (p=0.007), swing time (p=0.005) and stance time (p=0.019) and reduced velocity (p=0.036) and cadence (p=0.009). For participants with gout, step length was correlated with total MFPDI (r=-0.62, p=0.008), function (r=-0.65, p=0.005) and physical appearance (r=-0.50, p=0.041); stride length was correlated with total MFPDI (r=-0.62, p=0.008), function (r=-0.65, p=0.005) and physical appearance (r=-0.50, p=0.041); and velocity was correlated with total MFPDI (r=-0.60, p=0.011), function (r=-0.63, p=0.007) and work/leisure (r=-0.53, p=0.030).

CONCLUSION

Gait patterns exhibited by people with gout are different from controls during both self-selected and fast walking speeds, even after adjusting for BMI and foot-pain. Additionally, gait parameters were strongly correlated with patient-reported functional limitation, physical appearance and work/leisure difficulties, while pain did not significantly influence gait in people with gout.

2015 Gout classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative

Objective

Existing criteria for the classification of gout have suboptimal sensitivity and/or specificity, and were developed at a time when advanced imaging was not available. The current effort was undertaken to develop new classification criteria for gout.

Methods

An international group of investigators, supported by the American College of Rheumatology and the European League Against Rheumatism, conducted a systematic review of the literature on advanced imaging of gout, a diagnostic study in which the presence of monosodium urate monohydrate (MSU) crystals in synovial fluid or tophus was the gold standard, a ranking exercise of paper patient cases, and a multi-criterion decision analysis exercise. These data formed the basis for developing the classification criteria, which were tested in an independent data set.

Results

The entry criterion for the new classification criteria requires the occurrence of at least one episode of peripheral joint or bursal swelling, pain, or tenderness. The presence of MSU crystals in a symptomatic joint/bursa (ie, synovial fluid) or in a tophus is a sufficient criterion for classification of the subject as having gout, and does not require further scoring. The domains of the new classification criteria include clinical (pattern of joint/bursa involvement, characteristics and time course of symptomatic episodes), laboratory (serum urate, MSU-negative synovial fluid aspirate), and imaging (double-contour sign on ultrasound or urate on dual-energy CT, radiographic gout-related erosion). The sensitivity and specificity of the criteria are high (92% and 89%, respectively).

Conclusions

The new classification criteria, developed using a data-driven and decision-analytic approach, have excellent performance characteristics and incorporate current state-of-the-art evidence regarding gout.

2015 Gout Classification Criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative

OBJECTIVE

Existing criteria for the classification of gout have suboptimal sensitivity and/or specificity, and were developed at a time when advanced imaging was not available. The current effort was undertaken to develop new classification criteria for gout.

METHODS

An international group of investigators, supported by the American College of Rheumatology and the European League Against Rheumatism, conducted a systematic review of the literature on advanced imaging of gout, a diagnostic study in which the presence of monosodium urate monohydrate (MSU) crystals in synovial fluid or tophus was the gold standard, a ranking exercise of paper patient cases, and a multicriterion decision analysis exercise. These data formed the basis for developing the classification criteria, which were tested in an independent data set.

RESULTS

The entry criterion for the new classification criteria requires the occurrence of at least 1 episode of peripheral joint or bursal swelling, pain, or tenderness. The presence of MSU crystals in a symptomatic joint/bursa (i.e., synovial fluid) or in a tophus is a sufficient criterion for classification of the subject as having gout, and does not require further scoring. The domains of the new classification criteria include clinical (pattern of joint/bursa involvement, characteristics and time course of symptomatic episodes), laboratory (serum urate, MSU-negative synovial fluid aspirate), and imaging (double-contour sign on ultrasound or urate on dual-energy computed tomography, radiographic gout-related erosion). The sensitivity and specificity of the criteria are high (92% and 89%, respectively).

CONCLUSION

The new classification criteria, developed using a data-driven and decision analytic approach, have excellent performance characteristics and incorporate current state-of-the-art evidence regarding gout.

Characteristics of the first metatarsophalangeal joint in gout and asymptomatic hyperuricaemia: a cross-sectional observational study

Background

This study aimed to identify patient-reported outcomes and clinician-assessed characteristics of the first metatarsophalangeal joint (1MTPJ) in people with gout and with asymptomatic hyperuricaemia by comparing them to normouricaemic controls.

Methods

Twenty four people with gout (without current symptoms of acute arthritis), 29 with asymptomatic hyperuricaemia and 34 age- and sex-matched controls participated in this cross-sectional observational study. Patient-reported outcomes included 1MTPJ pain, foot pain and disability, body pain, lower limb function, activity limitation and overall wellbeing. Clinician-assessed characteristics of the 1MTPJ included range of motion (ROM), plantar- and dorsi-flexion force, foot posture, temperature and hallux valgus severity.

Results

Compared to controls, participants with gout reported greater 1MTPJ pain (p = 0.014), greater foot pain and disability (p < 0.001), increased odds of having disabling foot pain (odds ratio (OR) 13.4, p < 0.001), decreased lower limb function for daily living (p = 0.002) and recreational (p < 0.001) activities, increased activity limitation (p = 0.002), reduced overall wellbeing (p = 0.034), reduced ROM (p < 0.001), reduced plantarflexion force (p = 0.012), increased 1MTPJ plantar (p = 0.004), dorsal (p = 0.003) and medial (p = 0.004) temperature and had increased odds of having more severe hallux valgus (OR 0.3 p = 0.041). Compared to controls, participants with asymptomatic hyperuricaemia had increased odds of having disabling foot pain (OR 4.2, p = 0.013), increased activity limitation (p = 0.033), decreased lower limb function for daily living (p = 0.026) and recreational (p = 0.010) activities, increased 1MTPJ plantarflexion force (p = 0.004) and a more pronated foot type (p = 0.036).

Conclusions

People with gout demonstrate 1MTPJ-specific changes indicative of subclinical inflammation, even in the absence of acute arthritis. People with asymptomatic hyperuricaemia, who exhibit no features or symptoms of gout, also report high levels of foot- and lower limb-related pain and disability.

Validity of gout diagnosis in Swedish primary and secondary care - a validation study

Background

The diagnostic golden standard for gout is to detect monosodium urate (MSU) crystals in synovial fluid. While some gout classification criteria include this variable, most gout diagnoses are based on clinical features. This discrepancy between clinical practice and classification criteria can hinder gout epidemiological studies. Here, the objective was to validate gout diagnoses (International Classification of Diseases (ICD)-10 gout codes) in primary and secondary care relative to five classification criteria (Rome, New York, ARA, Mexico, and Netherlands). The frequency with which MSU crystal identification was used to establish gout diagnosis was also determined.

Methods

In total, 394 patients with ≥1 ICD-10 gout diagnosis between 2009 and 2013 were identified from the medical records of two primary care centers (n = 262) and one secondary care center (n = 132) in Gothenburg, Sweden. Medical records were assessed for all classification criteria.

Results

Primary care patients met criteria cutoffs more frequently when ≥2 gout diagnoses were made. Even then, few primary care patients met the Rome and New York cutoffs (19 % and 8 %, respectively). The ARA, Mexico, and Netherlands cutoffs were met more frequently by primary care patients with ≥2 gout diagnoses (54 %, 81 %, and 80 %, respectively). Mexico and Netherlands cutoffs were met more frequently by the rheumatology department patients (80 % and 71 %, respectively), even when patients with only 1 gout diagnosis were included. Analysis of MSU crystals served to establish gout diagnoses in only 27 % of rheumatology department and 2 % of primary care cases.

Conclusions

If a patient was deemed to have gout at ≥2 primary care center or ≥1 rheumatology-center visits according to an ICD-10 gout code, the positive predictive value of this variable in relation with the Mexico and Netherlands classification criteria was ≥80 % for both primary care and rheumatology care settings in Sweden. MSU crystal identification was rarely used to establish gout diagnosis.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-015-0614-2) contains supplementary material, which is available to authorized users.

Diagnosis and Treatment of Acute Gout at a University Hospital Emergency Department

Background :

Acute gout attacks account for a substantial number of visits to the emergency department (ED). Our aim was to evaluate acute gout diagnosis and treatment at a University Hospital ED.

Methods :

Our study was a retrospective chart review of consecutive patients with a diagnosis of acute gout seen in the ED 1/01/2004 - 12/31/2010. We documented: demographics, clinical characteristics, medications given, diagnostic tests, consultations and whether patients were hospitalized. Descriptive and summary statistics were performed on all variables.

Results :

We found 541 unique ED visit records of patients whose discharge diagnosis was acute gout over a 7 year period. 0.13% of ED visits were due to acute gout. The mean patient age was 54; 79% were men. For 118 (22%) this was their first attack. Attack duration was ≤ 3 days in 75%. Lower extremity joints were most commonly affected. Arthrocentesis was performed in 42 (8%) of acute gout ED visits.

During 355 (66%) of ED visits, medications were given in the ED and/or prescribed. An anti-inflammatory drug was given during the ED visit during 239 (44%) visits. Medications given during the ED visit included: NSAIDs: 198 (56%): opiates 190 (54%); colchicine 32 (9%) and prednisone 32 (9%). During 154 (28%) visits an anti-inflammatory drug was prescribed. Thirty two (6%) were given no medications during the ED visit nor did they receive a prescription. Acute gout rarely (5%) led to hospitalizations.

Conclusion :

The diagnosis of acute gout in the ED is commonly clinical and not crystal proven. Anti-inflammatory drugs are the mainstay of treatment in acute gout; yet, during more than 50% of ED visits, anti-inflammatory drugs were not given during the visit. Thus, improvement in the diagnosis and treatment of acute gout in the ED may be required.

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 effect of good and poor walking shoe characteristics on plantar pressure and gait in people with gout

BACKGROUND

Previous research has shown that good footwear characteristics may reduce foot pain and foot-related disability in people with gout. The aim of this study was to determine the effect of good and poor footwear characteristics on plantar pressure and spatiotemporal parameters of gait in people with gout.

METHODS

Thirty-six people with gout participated in a cross-sectional repeated measures study. Plantar pressure and spatiotemporal parameters were recorded in two shoe conditions: (1) the participants own footwear, and (2) either a new pair of walking shoes with good footwear characteristics (n=21) or poor characteristics (n=15). Differences between good and poor shoe groups compared to participants own shoes were also determined.

FINDINGS

Compared to participant's own shoes, footwear with good characteristics significantly reduced peak pressure at metatarsal 3 and 5, reduced pressure time integrals beneath the heel and metatarsals 3 and 5 and increased pressure time integrals beneath the midfoot. The footwear with poor characteristics significantly increased peak pressure beneath the heel and lesser toes, reduced peak pressure at metatarsal 3 and reduced pressure time integrals in the midfoot compared to participants own shoes. Both good and poor footwear significantly increased walking velocity, step length, and stride length compared to participants own shoes.

INTERPRETATION

Walking shoes with good footwear characteristics can influence plantar pressure values and encourage a more efficient heel to toe gait pattern in people with gout. These changes may contribute to the reduction in foot pain and foot-related problems in this population.

New classification criteria for gout: a framework for progress

The definitive classification or diagnosis of gout normally relies upon the identification of MSU crystals in SF or from tophi. Where microscopic examination of SF is not available or is impractical, the best approach may differ depending upon the context. For many types of research, clinical classification criteria are necessary. The increasing prevalence of gout, advances in therapeutics and the development of international research collaborations to understand the impact, mechanisms and optimal treatment of this condition emphasize the need for accurate and uniform classification criteria for gout. Five clinical classification criteria for gout currently exist. However, none of the currently available criteria has been adequately validated. An international project is currently under way to develop new validated gout classification criteria. These criteria will be an essential step forward to advance the research agenda in the modern era of gout management.