What is the treatment algorithm for psoriasis?

Psoriasis Treatment Algorithm

Initial Disease Severity Assessment

Treatment selection for psoriasis depends on disease severity, with mild disease (<5% body surface area, minimal symptoms, minimal quality of life impact) treated with topical therapy alone, while moderate-to-severe disease (≥5% BSA, symptomatic with pain/bleeding/itching, significant quality of life impact, or inadequate response to topicals) requires systemic therapy or phototherapy. 1, 2

Assessment must include:

• Body surface area (BSA) - threshold of 5% separates mild from moderate-to-severe disease 1, 2
• Symptom burden - presence of pain, bleeding, or itching 1, 3
• Quality of life impact - measured by DLQI 2
• Special site involvement - face, genitals, hands/feet, nails, scalp, or intertriginous areas warrant more aggressive treatment regardless of BSA 1
• Psoriatic arthritis screening - joint symptoms change treatment approach 1

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Algorithm for Mild Psoriasis (<5% BSA)

First-Line: Combination Topical Therapy

Start with calcipotriene/betamethasone dipropionate combination product once daily for 4-8 weeks, which achieves clear or almost clear status in 48-74% of patients. 1, 3

Strength of recommendation: A 1

• Apply once daily to affected areas for initial 4-8 weeks 3
• Maximum calcipotriene use: 100g per week to avoid hypercalcemia 3
• This combination is more effective than either agent alone 1

Site-Specific Modifications

For scalp psoriasis: Use calcipotriene foam or calcipotriene plus betamethasone dipropionate gel for 4-12 weeks 1

For facial/intertriginous psoriasis: Use low-potency corticosteroids (hydrocortisone) combined with calcipotriene, OR tacalcitol ointment for 8 weeks to avoid skin atrophy 1, 3

• Never use high-potency corticosteroids on face or flexures - risk of severe atrophy and telangiectasia 3

For nail psoriasis: Calcipotriene combined with betamethasone dipropionate reduces nail thickness and onycholysis, though efficacy is limited by poor nail matrix penetration 1

• Alternative: Tazarotene 0.1% cream under occlusion for 12 weeks 1

For thick, chronic plaques on body/extremities: Use ultrahigh-potency (class 1) corticosteroids like clobetasol propionate 0.05% or halobetasol propionate 0.05% 3, 4

• Maximum continuous use: 4 weeks to prevent skin atrophy, striae, and HPA axis suppression 3

Maintenance Therapy After Initial Control

Transition to weekend-only high-potency corticosteroid application (twice daily on weekends) with weekday vitamin D analogue therapy (twice daily on weekdays) to minimize corticosteroid exposure while maintaining efficacy. 1, 3

Strength of recommendation: B 1

Alternative maintenance regimen: Apply high-potency topical corticosteroid in the morning and vitamin D analogue in the evening 1

Strength of recommendation: B 1

Second-Line Topical Options

If combination therapy inadequate:

• Tazarotene 0.1% gel once daily for 8-12 weeks, achieving treatment success in 40-51% of patients 1
  • Combining tazarotene with medium/high-potency corticosteroids increases efficacy and reduces irritation 3
  • Apply sparingly to lesions only, avoiding perilesional skin 3
• Coal tar preparations - effective but stain skin and clothing, limiting practical use 3, 5
• Anthralin - effective but causes staining 3, 5

Critical Pitfalls to Avoid

Never combine salicylic acid with calcipotriene simultaneously - the acidic pH completely inactivates calcipotriene and eliminates its effectiveness. 1

Never use systemic corticosteroids in psoriasis - they cause severe disease flare during taper. 2, 6

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Algorithm for Moderate-to-Severe Psoriasis (≥5% BSA or Inadequate Response to Topicals)

First-Line Options (Choose Based on Clinical Scenario)

Option 1: Phototherapy

Narrowband UVB phototherapy 2-3 times weekly is highly effective for moderate-to-severe psoriasis and is the preferred first-line option for pregnant women. 1, 2, 7

• Requires significant time commitment (2-3 times weekly) 1
• Lacks systemic toxicities and immunosuppressive properties of systemic agents 1
• Can be combined with methotrexate or acitretin for synergistic effect, reducing treatment duration and cumulative UV exposure 1
• 308-nm excimer laser allows selective targeting of localized resistant areas like scalp and skin folds 3

PUVA (psoralen plus UVA) is an alternative phototherapy option 1, 2

• Acitretin combined with PUVA suppresses development of cutaneous squamous cell carcinoma 1

Option 2: Biologic Agents (Preferred for Most Patients)

The American Academy of Dermatology-National Psoriasis Foundation guidelines recommend biologics as first-line treatment for moderate-to-severe plaque psoriasis due to superior efficacy and acceptable safety profiles. 7

TNF-α inhibitors:

• Infliximab, adalimumab, etanercept, certolizumab 1, 7
• Also effective for psoriatic arthritis 1, 7

IL-17 inhibitors:

• Secukinumab, ixekizumab, brodalumab, bimekizumab 7
• Also approved for psoriatic arthritis 7

IL-12/23 (p40) inhibitor:

• Ustekinumab 7
• Also approved for psoriatic arthritis 7

IL-23 (p19) inhibitors:

• Guselkumab, tildrakizumab, risankizumab, mirikizumab 7

Option 3: Traditional Systemic Agents

Methotrexate - FDA-approved since 1972, competitive inhibitor of dihydrofolate reductase 3, 7

• Can be given subcutaneously to bypass liver 1
• Avoid conception in males until 3 months after discontinuation 1
• Synergistic when combined with phototherapy 1

Cyclosporine 3-5 mg/kg/day - provides rapid onset of action 1, 3, 7

• Use in short 3-4 month "interventional" courses 1, 3
• Particularly effective for erythrodermic psoriasis requiring rapid response 1, 3

Acitretin - decreases keratinocyte hyperproliferation 1, 3, 7

• Cannot be used in women of childbearing potential due to teratogenicity 1, 3
• Slower onset of action than cyclosporine 1, 3
• Effective when combined with phototherapy 1

Apremilast - oral phosphodiesterase 4 inhibitor 7

Combination Strategies to Enhance Efficacy

Adding topical therapy to systemic agents accelerates clearance and improves outcomes:

• Ultrahigh-potency corticosteroid added to etanercept for 12 weeks (Level I evidence) 3
• Calcipotriene/betamethasone added to adalimumab for 16 weeks accelerates clearance 3
• Calcipotriene added to methotrexate (Level I evidence) 3
• All topical corticosteroids can be combined with any biologic 3

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Special Clinical Scenarios

Erythrodermic Psoriasis (Medical Emergency)

For systemically ill patients with erythrodermic psoriasis, initiate oral cyclosporine 4 mg/kg/day immediately for rapid control, with dramatic improvement expected within 2-3 weeks. 1, 6, 3

Treatment algorithm for erythrodermic psoriasis:

Initially for all patients:

• Appropriate wet dressings with mid-potency topical steroids 1
• Attention to fluid balance with control of ankle edema 1
• Rule out sepsis with blood cultures 1

First-line systemic options (in alphabetical order):

• Acitretin 1, 6
• Biologic agents (infliximab, adalimumab, ustekinumab) 1, 6
• Cyclosporine 3-4 month course 1, 6, 3
• Methotrexate 1, 6

Second-line combinations (if first-line inadequate):

• Acitretin + cyclosporine 1
• Acitretin + TNF blocker 1
• Cyclosporine + methotrexate 1
• Etanercept 1
• Methotrexate + TNF blocker 1

Base therapy on short-term efficacy rather than long-term considerations, then transition to maintenance therapy after acute illness improves. 3

Pustular Psoriasis

Ustekinumab at 90mg dose is recommended as monotherapy for moderate-to-severe pustular psoriasis, showing 67% clearance rate. 6

Strength of recommendation: C 6

For palmoplantar pustular psoriasis: Acitretin and oral PUVA appear to provide improvement, with combination superior to either alone 1

Guttate Psoriasis

UVB phototherapy has the most robust evidence for efficacy in treating guttate psoriasis. 6

First-line topical options: Low concentrations of coal tar and dithranol due to lower tolerance of erupting guttate psoriasis to topical treatments 6

Psoriatic Arthritis

For mild enthesitis/dactylitis: NSAIDs, physical therapy, local corticosteroid injections 1

For moderate disease: DMARDs 1

For severe disease: TNF inhibitors (infliximab, etanercept, adalimumab) 1

Strength of recommendation: A 1

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Monitoring and Safety Considerations

Long-term use of high-potency corticosteroids beyond 12 weeks requires careful physician supervision to monitor for skin atrophy, striae, telangiectasia, and HPA axis suppression. 3

Phototherapy must be supervised by adequately trained personnel with regular equipment calibration. 6

Commercial sunbeds (emitting UVA) are rarely effective in psoriasis and may cause significant side effects - their use is not recommended. 6

Vitamin D analogues should be applied after phototherapy treatment to avoid inactivation by UVA and blocking of UVB radiation. 1, 3