Focus of This Summary
This is a summary of two systematic reviews. One review evaluated the evidence regarding the accuracy and safety of tests used to initially diagnose gout in the primary care, urgent care, or emergency care setting. The other review examined the evidence base for treating patients with acute gout attacks in the primary care setting. The former systematic review included 27 articles published through February 29, 2016. The latter systematic review included 154 articles published through March 1, 2016. This summary is provided to assist in informed clinical decisionmaking. However, reviews of evidence should not be construed to represent clinical recommendations or guidelines.
Gout is a form of inflammatory arthritis that presents as joint swelling and pain, referred to as a gout flare or a gout attack. Upon resolution of a gout attack, patients enter a symptom-free period. However, gout attacks recur in many patients. Patients with gout may develop gouty arthritis or tophaceous gout (solid deposits of monosodium urate [MSU] crystals in skin, soft tissue, and joints) in the long term.
Most patients with gout are diagnosed and managed in the primary care, urgent care, or emergency care setting. It is critical to exclude septic arthritis and other causes of inflammatory arthritis in the acute care setting.
Recent guidelines use assessment of MSU crystals in joints and synovial fluid as the gold standard for gout diagnosis along with history and a physical exam. However, joint aspiration for synovial fluid can be challenging to perform in small joints (such as in toes) and to interpret. The role of clinical algorithms (which often draw upon clinical signs, symptoms, and laboratory tests) in the diagnosis of gout is being investigated in clinical studies. Imaging methods (such as dual-energy computed tomography [DECT] and ultrasound) are mainly used in the diagnosis of complex cases of gout.
Treatments for gout attacks include nonsteroidal anti- inflammatory drugs (NSAIDs), colchicine, and corticosteroids to control pain and inflammation.
Nonpharmacological methods advocated for managing hyperuricemia in patients with gout include weight loss, exercise, alcohol restriction, sufficient hydration, and dietary changes. Urate-lowering medications are the primary pharmacological intervention for managing hyperuricemia.
The two systematic reviews summarized here assessed the accuracy of tests to diagnose gout and also examined the evidence regarding the treatment of gout in the primary care setting.
- Two recently developed clinical algorithms to diagnose gout—the Diagnostic Rule and the Clinical Gout Diagnosis—demonstrated sensitivities of 88 percent and 97 percent, respectively, and specificities of 75 percent and 96 percent, respectively, when compared with MSU crystal analysis (see Table 1).
- The strength of evidence (SOE) supporting the use of these clinical algorithms was moderate; these algorithms have not yet been validated in primary care, emergency care, and urgent care settings.
- The strength of evidence regarding the use of DECT (sensitivity: 85–100%; specificity: 83–92%) or of ultrasound (sensitivity: 74%; specificity: 88%) to diagnose gout was low.
- Effective treatments for gout attacks include NSAIDs, colchicine, and corticosteroids (high SOE; see Table 2).
- Urate-lowering therapy (ULT), including allopurinol and febuxostat, reduced serum urate levels (high SOE; see Table 3).
- ULT did not reduce the frequency of gout attacks during the initial 6 months of therapy (high SOE), likely because of increased risk of gout attacks with initiation of ULT.
- The increased risk of gout attacks with initiation of ULT was ameliorated with the concomitant use of prophylactic agents (such as colchicine or NSAIDs) against gout attack (high SOE).
- After 12 months of ULT, the frequency of gout attacks was reduced (moderate SOE).
- The evidence was too limited to determine if dietary and lifestyle changes are effective in managing gout. This does not mean that dietary and lifestyle changes do not work. Clinicians may wish to consult clinical guidelines (www.guideline.gov) regarding the role of diet and lifestyle changes in the management of gout.
Overview of Clinical Research Evidence
- Two clinical algorithms, the Diagnostic Rule and Clinical Gout Diagnosis, were evaluated as tools for diagnosing gout. Both of these algorithms were developed and validated with patients first identified in primary care and whose diagnosis did not include an MSU assessment.
- The Diagnostic Rule: The diagnostic components of this algorithm include clinical characteristics (>1 attack of acute arthritis, maximum inflammation developed within 1 day, redness observed over joints, painful or swollen first metatarsophalangeal joint) and risk factors (hyperuricemia, male sex, hypertension, or >1 cardiovascular disease event). Additional information is available in the article by Janssens and colleagues (Arch Intern Med. 2010 Jul;170:1120-6. PMID: 20625017).
- Clinical Gout Diagnosis: The diagnostic components of this algorithm include clinical characteristics (>1 attack of acute arthritis, maximum inflammation developed within 1 day, monoarthritis/oligoarthritis attack, redness observed over joints, painful or swollen first metatarsophalangeal joint, unilateral tarsal joint attack, tophi) and risk factors (hyperuricemia). Additional information is available in the article by Vazquez-Mellado and colleagues (Clin Rheumatol. 2012 Mar;31:429-34. PMID: 21979446).
- Diagnostic imaging studies that were evaluated in this review included DECT and ultrasound.
|Diagnostic Method||N Studies||N Subjects||Finding||SOE|
|MSU = monosodium urate; N = number; SOE = strength of evidence|
|Clinical algorithm: The Diagnostic Rule||3||1383||Sensitivity: 88%; Specificity: 75%||[evidence medium]|
|Clinical algorithm: Clinical Gout Diagnosis||3||1383||Sensitivity: 97%; Specificity: 96%||[evidence medium]|
|Dual-energy computed tomography||4||235||Sensitivity: 85% to 100%; Specificity: 83% to 92%||[evidence low]|
|Ultrasound||8||633||Sensitivity: 74%; Specificity: 88%||[evidence low]|
|Strategy||N Studies||N Subjects||Finding||SOE|
|ACTH = adrenocorticotropic hormone; N = number; NSAIDs = nonsteroidal anti-inflammatory drugs; RCT = randomized controlled trial; SOE = strength of evidence
†The known anti-inflammatory action of these agents was considered when assessing SOE.
|Colchicine||2 RCTs||229||Reduces pain when compared with placebo||[evidence high]|
|1 RCT||184||A lower dose of colchicine is as effective as a higher dose but with fewer side effects||[evidence medium]|
|NSAIDs†||1 RCT and observational data||30 (in RCT)||Reduce pain||[evidence high]|
|16 RCTs||1280||No differences among NSAIDs in effectiveness||[evidence medium]|
|Corticosteroids||4 RCTs||297||Reduce pain as much as NSAIDs||[evidence high]|
|Animal-derived ACTH (not commonly used in clinical practice)||2 RCTs||107||Reduces pain as much as NSAIDs||[evidence medium]|
Strength of Evidence Scale†
High: [evidence high]
High confidence that the evidence reflects the true effect. Further research is very unlikely to change our confidence in the estimate of effect.
Moderate: [evidence medium]
Moderate confidence that the evidence reflects the true effect. Further research may change our confidence in the estimate of effect and may change the estimate.
Low: [evidence low]
Low confidence that the evidence reflects the true effect. Further research is likely to change our confidence in the estimate of effect and is likely to change the estimate.
Evidence is either unavailable or does not permit a conclusion.
†The overall evidence grade was assessed based on the ratings for the following domains: study limitations, directness, consistency, precision, and reporting bias. Other domains that were considered, as appropriate, included dose-response association, plausible confounding, and strength of association (i.e., magnitude of effect). For additional details on the methodology used to assess strength of evidence, please refer to: Owens DK, Lohr KN, Atkins D, et al. AHRQ series paper 5: grading the strength of a body of evidence when comparing medical interventions—Agency for Healthcare Research and Quality and the Effective Health-Care Program. J Clin Epidemiol. 2010 May;63(5):513-23. PMID: 19595577.
|Strategy||Type of Study||N Studies||N Subjects||Finding||SOE|
|N = number; NR = not reported; NSAIDs = nonsteroidal anti-inflammatory drugs; RCT = randomized controlled trial; SOE = strength of evidence; ULT = urate-lowering therapy|
|Management of hyperuricemia||ULT vs. placebo||4 RCTs||1378||Reduces serum urate||[evidence high]|
|2 RCTs||1129||Does not decrease the risk of acute gout attacks within the first 6 months||[evidence high]|
|1 open-label extension study||NR||Reduces the risk of acute gout attacks after 1 year||[evidence medium]|
|Febuxostat vs. allopurinol||1 RCT||2269||No difference in serum urate-lowering effect||[evidence high]|
|1 systematic review||NR||No statistically significant differences in overall adverse events||[evidence high]|
|Subgroup of 1 RCT||2269||Age and race do not affect the efficacy of either drug||[evidence low]|
|Prophylactic therapy with colchicine or NSAIDs||3 RCTs||4103||Reduces the risk of acute gout attacks when initiating ULT||[evidence high]|
|1 RCT||190||Longer durations of prophylaxis (>8 weeks) are more effective than a shorter duration when initiating ULT||[evidence medium]|
|3 RCTs||4103||Longer durations of prophylaxis (>8 weeks) are more effective than a shorter duration when initiating ULT||[evidence medium]|
|Monitoring treatment||Treating to a specific target serum urate level||1 systematic review and 8 studies||NR||Reduces the risk of gout attacks||[evidence low]|
|NSAIDs = nonsteroidal anti-inflammatory drugs|
|Corticosteroids||Dysphoria and mood disorders, elevation in blood glucose, high blood pressure, weight gain, insomnia, and fluid retention may occur with short-term use|
Gaps in Knowledge
Clinical algorithms for diagnosing gout
Diagnostic clinical algorithms such as the Diagnostic Rule and Clinical Gout Diagnosis need to be validated more broadly in primary care, emergency care, and urgent care settings.
Diet, lifestyle, and complementary and alternative medicine therapies for managing gout
- There has been limited research regarding how specific dietary changes (reducing intake of dietary purines, red meat, shellfish, sugary drinks, or alcohol; increasing intake of cherries, modified milk products, or supplemental vitamin C) or lifestyle changes (achieving weight loss) affect symptomatic outcomes in patients with gout.
- Evidence is insufficient to determine the effectiveness of traditional Chinese medicine (e.g., acupuncture, herbal mixtures) in improving symptomatic outcomes in patients with gout.
Urate-lowering therapy for managing hyperuricemia in patients with gout
While lowering serum urate levels should minimize clinical gout sequelae, the exact target level has yet to be formally evaluated in randomized controlled trials, and guidelines vary in the recommended target levels.
Effectiveness of therapy for gout in subpopulations
The efficacy of pharmacological therapies for gout when stratified by patient demographics, comorbid conditions, disease severity, or clinical presentation remains to be determined.
- When initiating ULT, comorbidities and the benefits and harms of prophylactic agents should be considered (e.g., possible contraindications of NSAIDs in patients with cardiovascular disease, renal disease, or both).
- The studies assessing treatment interventions for gout did not clearly state if they enrolled patients in the primary care setting. The applicability of the findings of this review to patients with gout in the primary care setting is unclear.
What To Discuss With Your Patients and Their Caregivers
- What a gout attack is and how to prevent the recurrence of gout attacks
- The effectiveness of the various treatment strategies for gout
- The adverse effects associated with the various treatment strategies
- The role of ULT in patients with gout and the potential adverse effects of long-term use
Although further evidence is needed, providers may wish to discuss diet and lifestyle with their patients, as such discussions may offer general health benefits and are commonly supported by guidelines (www.guideline.gov).
- It may be prudent to counsel patients on maintaining a healthy diet, losing weight, and exercising to promote general health.
- It may also be prudent to advise patients to limit high-purine foods (especially organ meats), shellfish, sugar-sweetened beverages, and alcohol and to maintain hydration.
The information in this summary is based on these systematic reviews:
- Newberry SJ, FitzGerald J, Maglione MA, O'Hanlon CE, Han D, Booth M, Motala A, Tariq A, Dudley W, Shanman R, Shekelle PG. Diagnosis of Gout. Comparative Effectiveness Review No. 158. (Prepared by the Southern California Evidence-based Practice Center under Contract No. 290-2012-00006-I.) AHRQ Publication No. 15(16)-EHC026-EF. Rockville, MD: Agency for Healthcare Research and Quality; February 2016.
- Shekelle PG, FitzGerald J, Newberry SJ, Motala A, O'Hanlon CE, Okunogbe A, Tariq A, Han D, Dudley W, Shanman R, Booth M. Management of Gout. Comparative Effectiveness Review No. 176. (Prepared by the RAND Southern California Evidence-based Practice Center under Contract No. 290-2012-00006-I.) AHRQ Publication No.16-EHC017-EF. Rockville, MD: Agency for Healthcare Research and Quality; March 2016.
Additional information comes from the articles "Diagnosis of Gout: A Systematic Review in Support of an American College of Physicians Clinical Practice Guideline" (Ann Intern Med. 2016 Nov 1. DOI: 10.7326/M16-0462. PMID: 27802505) and "Management of Gout: A Systematic Review in Support of an American College of Physicians Clinical Practice Guideline" (Ann Intern Med. 2016 Nov 1. DOI: 10.7326/M16-0461. PMID: 27802478).
This summary was prepared by the John M. Eisenberg Center for Clinical Decisions and Communications Science at Baylor College of Medicine, Houston, TX. It was written by Geetha Achanta, Ph.D., Sandeep Agarwal, M.D., Matthew Wanat, Pharm.D., Frank Domino, M.D., and Michael Fordis, M.D.