Osteoarthritis and Gout in Primary Care: Diagnosis, First-Line Drugs and Urate-Lowering Therapy

Osteoarthritis and gout are both common causes of joint pain in primary care, and the NP boards test them as a pair because the distinction drives everything that follows. Osteoarthritis is diagnosed clinically and treated first with exercise, weight loss and self-management, with oral or topical NSAIDs and intra-articular glucocorticoids as the core drug options under the 2019 American College of Rheumatology and Arthritis Foundation (ACR/AF) guideline. Gout is confirmed by monosodium urate crystals, flares are treated with low-dose colchicine, an NSAID or a glucocorticoid, and urate-lowering therapy (ULT) with start-low allopurinol is titrated to a serum urate below 6 mg/dL when the 2020 ACR indications are met.

Telling the joint diseases apart

A red, hot, swollen single joint is gout or septic arthritis until proved otherwise. Fever, immunosuppression, a prosthetic joint or a patient who looks ill shifts the answer to same-day aspiration with Gram stain, culture and crystal analysis, because crystals and infection can coexist.

Osteoarthritis: assessment and diagnosis

Osteoarthritis is a clinical diagnosis. NICE guidance (NG226, 2022) supports diagnosing it without imaging in a person aged 45 or older who has activity-related joint pain and either no morning stiffness or stiffness lasting no more than 30 minutes. The older ACR classification criteria for the knee (Altman, 1986) use knee pain plus at least three of: age over 50, morning stiffness under 30 minutes, crepitus, bony tenderness, bony enlargement and no palpable warmth.

Radiographs, when obtained, show joint space narrowing, osteophytes, subchondral sclerosis and subchondral cysts, but radiographic severity correlates poorly with pain. Order imaging for atypical features (rapid progression, marked inflammation, night pain, weight loss), a suspected alternative diagnosis, or when the patient is being considered for joint replacement.

Osteoarthritis: first-line management

The 2019 ACR/AF guideline is organized by strength of recommendation and by joint. It deliberately does not impose a fixed ladder: providers combine options according to the joint involved, comorbidities and patient preference. What the exam rewards is knowing which interventions carry a strong recommendation and which are rejected.

Nonpharmacologic care: the foundation

Strongly recommended for knee, hip and hand disease as relevant:

• Exercise, for knee, hip and hand osteoarthritis. Both land-based strengthening and aerobic programs count; no single type is preferred.
• Weight loss for overweight or obese patients with knee or hip disease. The guideline notes benefit beginning at a loss of 5 percent of body weight, with greater benefit from larger losses.
• Self-efficacy and self-management programs.
• Tai chi for knee and hip osteoarthritis.
• A cane for knee or hip disease that impairs walking.
• A tibiofemoral knee brace for knee disease, and a first carpometacarpal orthosis for thumb-base disease.

Conditionally recommended: heat or cold, cognitive behavioral therapy, acupuncture, kinesiotaping, and balance training. Transcutaneous electrical nerve stimulation is strongly recommended against.

Drug therapy

For knee osteoarthritis in an older adult, a reasonable sequence on the exam is exercise and weight loss with a topical NSAID, then an oral NSAID if the patient's renal, cardiovascular and GI risk allow it, with an intra-articular glucocorticoid injection for a flare. Standard oral options include ibuprofen 400 to 800 mg up to three times daily or naproxen 250 to 500 mg twice daily, with a proton pump inhibitor for patients at elevated GI risk. Patients whose function and pain remain poor despite a full trial of conservative care are referred to orthopedics to discuss arthroplasty.

Gout: diagnosis

Gout results from monosodium urate crystal deposition. Hyperuricemia is necessary but not sufficient: many people with high urate never develop gout, and the 2020 ACR guideline conditionally recommends against ULT for asymptomatic hyperuricemia.

The reference standard is identification of needle-shaped, negatively birefringent crystals in synovial fluid or a tophus. The 2015 ACR/EULAR classification criteria let the provider score a probable case clinically when aspiration is not possible: first MTP or ankle and midfoot involvement, erythema, inability to bear weight or tolerate touch, a time course reaching maximum pain in under 24 hours with resolution within 14 days, tophi, serum urate level and imaging features (urate deposition on dual-energy CT or a double-contour sign on ultrasound) all add points.

Two diagnostic facts appear on exams repeatedly:

• Serum urate may be normal during a flare. A normal level does not exclude gout; recheck two or more weeks after the flare resolves.
• Pseudogout (calcium pyrophosphate deposition) typically affects the knee or wrist in an older adult and shows rhomboid, weakly positively birefringent crystals and chondrocalcinosis on radiographs.

Before starting treatment, look for contributing factors: thiazide or loop diuretics, low-dose aspirin, cyclosporine, CKD, alcohol (especially beer and spirits), high-fructose beverages, obesity and metabolic syndrome.

Gout flare management

The 2020 ACR guideline strongly recommends colchicine, NSAIDs or glucocorticoids (oral, intra-articular or intramuscular) as first-line flare treatment, choosing among them by comorbidity. Treatment works best when started within 24 hours of onset.

Adjuncts: ice to the joint is conditionally recommended. If the patient already takes ULT, continue it unchanged through the flare; stopping it is a classic wrong answer.

Urate-lowering therapy: who, what and how

Indications

Drug choice and dosing

• Allopurinol is strongly recommended as the first-line agent for all patients, including those with moderate to severe CKD.
• Start low: allopurinol at no more than 100 mg daily, and lower in CKD stage 3 or worse; febuxostat at no more than 40 mg daily. Starting low reduces flares on initiation and, for allopurinol, the risk of severe hypersensitivity reactions.
• Titrate in steps, rechecking serum urate after each change, to the treat-to-target goal of below 6 mg/dL. Doses above 300 mg daily are often needed and are appropriate with titration, even in CKD.
• Test for HLA-B*5801 before allopurinol in patients of Southeast Asian descent (for example Han Chinese, Korean, Thai) and in African American patients, who carry a higher prevalence of the allele and a higher risk of allopurinol hypersensitivity syndrome.
• Febuxostat: for patients on febuxostat with a history of cardiovascular disease or a new cardiovascular event, the guideline conditionally recommends switching to an alternative agent when consistent with the treat-to-target goal.
• Probenecid, a uricosuric, is an option when xanthine oxidase inhibitors fail or are not tolerated; it is less effective with reduced kidney function and is avoided with a history of kidney stones. Pegloticase is reserved for refractory tophaceous gout and is a specialist decision.

Prophylaxis when starting ULT

Lowering urate mobilizes crystals and triggers flares. The guideline strongly recommends anti-inflammatory prophylaxis (colchicine, an NSAID or low-dose prednisone) for 3 to 6 months after starting ULT, continued longer if flares persist. A common colchicine prophylaxis dose is 0.6 mg once or twice daily, adjusted for renal function.

Comorbidity and lifestyle choices

• Hypertension: losartan is conditionally preferred because of its modest uricosuric effect; switch hydrochlorothiazide to another antihypertensive when feasible.
• Limit alcohol, purine-rich meat and seafood, and high-fructose corn syrup, and pursue weight loss in overweight patients (conditional).
• Vitamin C supplementation is conditionally recommended against.

Monitoring and follow-up

For osteoarthritis, reassess function, pain and medication safety every few months: blood pressure, renal function and GI symptoms on NSAIDs, and limit intra-articular glucocorticoid injections to the frequency the orthopedic or rheumatology provider recommends.

For gout, check serum urate every few weeks during titration until the target is reached, then periodically (often every 6 months) to confirm it stays below 6 mg/dL. Monitor renal function and liver enzymes, watch for rash (stop allopurinol at once for any rash), and review the colchicine dose against kidney function. Tophi shrink only when urate stays below target for months to years; some rheumatologists aim lower for heavy tophus burden, so confirm the target with the treating specialist.

Referral triggers

• Same day: a hot joint with fever or a prosthetic joint (septic arthritis until excluded).
• Rheumatology: diagnostic uncertainty, gout refractory to maximal ULT, intolerance of allopurinol and febuxostat, a candidate for pegloticase, or inflammatory arthritis that is not gout or osteoarthritis.
• Orthopedics: osteoarthritis with persistent pain and functional limitation despite full conservative management, mechanical locking, or rapid radiographic progression.
• Dermatology or emergency care: any rash, fever, mucosal involvement or eosinophilia after starting allopurinol.

Patient and caregiver education

Patients with osteoarthritis need to hear that exercise reduces pain rather than wearing the joint out, that even 5 percent weight loss helps the knee and hip, and that supplements such as glucosamine have not been shown to work.

Patients with gout need to understand that ULT is long term, often lifelong, that flares may increase during the first months, and that this is why prophylaxis is prescribed. They should keep a flare plan (start colchicine or the prescribed agent at the first twinge), not stop ULT during a flare, stay hydrated, and report any rash immediately. Family members preparing meals benefit from guidance on alcohol, sugary drinks and purine-heavy foods.

How the exam tests this

• The normal uric acid trap. A classic podagra presentation with a normal serum urate is still gout; the answer is aspiration or treatment, not "rule out gout."
• Stopping allopurinol during a flare. Wrong: continue it.
• Starting allopurinol at 300 mg. The correct start is 100 mg or less, lower in CKD, then titrate to target.
• No target. Any ULT answer that omits titrating to a serum urate below 6 mg/dL is incomplete.
• Starting ULT after a first uncomplicated flare. Not indicated unless CKD stage 3 or worse, urate above 9 mg/dL or kidney stones.
• Forgetting prophylaxis. ULT without 3 to 6 months of colchicine, an NSAID or low-dose prednisone invites flares.
• Glucosamine, hyaluronic acid, TENS or methotrexate for osteoarthritis. Each is rejected by the guideline and appears as a distractor.
• Ordering knee films to diagnose typical osteoarthritis. The diagnosis is clinical.

Practice question

A 62-year-old man with hypertension treated with hydrochlorothiazide and stage 3a chronic kidney disease (eGFR 52 mL/min/1.73 m2) returns two weeks after his third gout flare this year. The current flare resolved with prednisone. He has a small tophus on the right olecranon. Serum urate today is 9.4 mg/dL. He is of Korean descent. Which of the following is the most appropriate plan?

• A. Start allopurinol 300 mg daily and recheck serum urate in 6 months
• B. Check HLA-B*5801; if negative, start allopurinol at a low dose with colchicine prophylaxis, titrate to a serum urate below 6 mg/dL, and replace hydrochlorothiazide with losartan
• C. Defer urate-lowering therapy because his kidney function is reduced, and treat future flares with colchicine
• D. Start febuxostat 80 mg daily without prophylaxis

Answer: B. He has a tophus and frequent flares, both strong indications for ULT, and allopurinol is first-line even with CKD; his Korean ancestry calls for HLA-B*5801 testing first, and the drug must start low with 3 to 6 months of anti-inflammatory prophylaxis and be titrated to target, while losartan is the preferred antihypertensive in gout. Option A starts at too high a dose for a patient with CKD and omits both prophylaxis and the treat-to-target rechecks. Option C is wrong because CKD is a reason to treat, not to withhold, ULT. Option D uses a starting dose above the recommended 40 mg or less, omits prophylaxis, and bypasses the preferred first-line agent.

Key points

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