OVERVIEW AND EPIDEMIOLOGY OF GOUT

GARY M. OWENS, MD President, Gary Owens Associates Medical Management and Pharmaceutical Consulting Glen Mills, PA OVERVIEW AND EPIDEMIOLOGY OF GOUT ...
Author: Alyson Blake
2 downloads 0 Views 1MB Size
GARY M. OWENS, MD President, Gary Owens Associates Medical Management and Pharmaceutical Consulting Glen Mills, PA

OVERVIEW AND EPIDEMIOLOGY OF GOUT

Gout in the 21st Century • Gout has markedly increased in prevalence and clinical complexity over the last 2 decades • Prevalence rise is influenced by diet, aging, comorbidities, and the obesity epidemic • Diagnostic criteria and imaging tools are evolving • Treatment-refractory gouty arthritis and hyperuricemia are growing challenges • New treatments are available

1

Gout: Disease Definition “Arthritis resulting from excess uric acid in body” • Can lead to: • Gouty arthritis: • Inflammation in joints; frequently occurs in big toe • Tophi: • Deposits of urate crystals that form subcutaneous nodules • Renal disease: • Kidney stones from uric acid crystals in the kidneys • Chronic interstitial nephropathy (in severe cases)

Gout: A Typical Case • Middle-aged male • Presentation with acute and excruciatingly painful arthritis associated with swelling and redness • Big toe, midfoot, ankle involvement are classic • Recurrent self-limited episodes of arthritis • Kidney stones can occur • Serum urate is elevated Source: American College of Rheumatology Slide Collection

Gout Epidemiology • Affects up to 6 million individuals in US • 1%–2% prevalence in adult males • Renal insufficiency is the most common cause of gout • 9 times more common in young men (65 years of age* • Among those >75 years, the prevalence increased (1990 to 1999) from 21 to 41 per 1000 enrollees • Among those 65-74 years of age, prevalence increased from 21 to 31 per 1000 enrollees (1990 to 1999) * Gout defined by ICD-9-CM codes 274xx or use of uric acid–lowering drugs Wallace Kl, et al. J Rheumatol. 2004;31:1582–1587.

4

Gout: Economic Burden • Direct costs for new cases of acute gout: ~$27 million • Care of chronic gout is approximately 6% of a patient's all-cause yearly health care costs • Diagnosis of gout is independently associated with higher medical/arthritic comorbidity, higher utilization of health care • Significant costs to employers: • Patients with acute gouty arthritis miss an average of 3–5 days of work annually • Estimated total annual cost of gout to employer per employee: • Employee with gout >$6500 • Employee without gout 1 attack of acute arthritis

• Unilateral tarsal joint attack

• Maximum inflammation develops within 1 day

• Tophus

• Monoarthritis attack • Redness over joints

• Asymmetric swelling within a joint on x-ray

• 1st MTP joint painful or swollen

• Subcortical cysts without erosions on x-ray

• Unilateral first MTP joint attack

• Synovial fluid cultures (-) for organisms

MTP: metatarsophalangeal Wallace SL, et al. Arthritis Rheum. 1977;20:895–900.

• Hyperuricemia

When using 6 ACR criteria, diagnosis of gout is correct only in ≤80%

Role of Laboratory Testing in Diagnosing Gout • Laboratory diagnosis of elevated uric acid alone is not enough to make diagnosis • Identification of uric acid crystals in joint aspiration is definitely confirmatory, but not practical in primary care setting • Therefore, alternatives to existing criteria are needed for primary care

6

Netherlands Proposal: Diagnosis Without Joint Aspiration 7 variables "easily ascertainable in primary care": • Male gender • Previous patient-reported arthritis attack • Onset within 1 day • Joint redness • Involvement of the 1st MTP • Hypertension or 1 or more cardiovascular diseases • Serum uric acid level of more than 5.88 mg/dL Janssens HJ, et al. Arch Intern Med. 2010;170(13):1120-1126.

Role of Imaging in Diagnosis of Gout • Does not play a major role in diagnosis • Only ACR Criteria mention use of plain X-rays • However, plain x-rays are insensitive in early disease

• Although advanced imaging can identify soft tissue collections, there are no imaging modalities than can specifically diagnose tophi • In general, use of and coverage for advanced imaging technologies is not an issue for MCOs Wallace SL, et al. Arthritis Rheum. 1977;20:895–900.

Gout: Cost of Treatment Failure • MarketScan database: 10/2003 to 9/2008 • Criteria: • Diagnosed with gout (ICD-9-CM: 274) in a claims database • ≥3 flares within a 12-month period • First flare occurrence date was index date

• Gout flare defined as episode with gout diagnosis followed by: • Claim for NSAIDs, colchicine, corticosteroids, ACTH, or intra-articular aspiration or injection within 7 days, OR • Diagnosis for joint pain (ICD-9-CM: 719.4) followed by claim for colchicine within 7 days Wu EQ, et al. Presentation at ACR/SHRP Scientific Meeting, October 2009. Presentation 1112.

7

Gout: Cost of Treatment Failure • General findings: • 373 186 had diagnosis of gout/679 met criteria for treatment failure • Average age: 50 • 82% male

• Costs: • Mean total annual cost estimated at $17 603 for treatment failure for gout patients vs $6891 for control group • After adjusting for confounding factors, incremental total cost of treatment failure was $10 222 (P < .01)

• Excess cost of these patients attributable to • Higher adjusted outpatient costs ($3814; P < .01) • Higher inpatient costs ($3056; P < .01) • Higher drug costs ($879; P < .01)

• Subgroup of 195 gout patients with ≥6 flares: adjusted incremental costs at $22 237 (P < .01) Wu EQ, et al. Presentation at ACR/SHRP Scientific Meeting, October 2009. Presentation 1112.

MANAGING GOUT

Long-Term Management Goals in Gout Are Closely Linked Identify and manage comorbidities and causes of hyperuricemia

PATIENT EDUCATION AND TREATMENT ADHERENCE Diagnose, treat, and prevent acute flares

Urate-lowering drugs: Target SUA