What are the treatment algorithms for psoriasis?

Treatment Algorithms for Psoriasis

The treatment of psoriasis should follow a stepwise approach based on disease severity, with topical agents for mild disease, phototherapy for moderate disease, and systemic agents for severe or resistant disease. 1, 2

Disease Classification and Assessment

• Psoriasis severity is categorized as mild or moderate-to-severe based on objective and subjective measures 1:

  • Mild psoriasis: BSA ≤10% AND PASI ≤10 AND DLQI ≤10
  • Moderate-to-severe psoriasis: (BSA >10% OR PASI >10) AND DLQI >10
  • Special clinical situations may upgrade mild psoriasis to moderate-to-severe, including involvement of visible areas or severe nail involvement 1, 3

• Assessment should include both patient perception of disability ("need for treatment") and objective assessment of extent and severity 1

Treatment Algorithm for Mild Psoriasis (Limited Disease)

1. First-line: Topical therapy 1

   • Topical corticosteroids (start with moderate potency)
     • Use no more than 100g of moderately potent preparation monthly
     • Regular clinical review required with no unsupervised repeat prescriptions
     • Periods each year when alternative treatment is employed 1
   • Vitamin D analogs (calcipotriene/calcitriol)
     • Less irritating formulations (calcitriol) better for face and flexures
     • Maximum 100g weekly to avoid hypercalcemia 1
   • Combination products (calcipotriene/betamethasone dipropionate)
     • Simplifies regimen and improves compliance 1

2. Second-line options 1

   • Topical tazarotene (retinoid) - can be combined with corticosteroids to reduce irritation
   • Coal tar preparations (0.5-10% concentration)
   • Dithranol/anthralin (starting at 0.1-0.25%, increasing as tolerated)
   • Salicylic acid for thick, scaly plaques 1

3. For localized resistant plaques 1

   • 308-nm excimer laser for targeted treatment
   • Intralesional corticosteroid injections 1

Treatment Algorithm for Moderate-to-Severe Psoriasis

1. Phototherapy 1

   • First-line for widespread disease without comorbid psoriatic arthritis
   • Options include:
     • Narrowband UVB (NB-UVB) - first choice for most patients
     • PUVA (psoralen + UVA) - more effective but higher skin cancer risk
     • Combination with acitretin increases efficacy and decreases cumulative UV exposure 1

2. Traditional Systemic Agents 1

   • Methotrexate
     • Often first-choice systemic agent due to efficacy, cost-effectiveness, and long safety record
     • Contraindicated in pregnancy, breastfeeding, significant hepatic damage 1
   • Cyclosporine
     • Rapid onset of action (3 weeks)
     • Best used as short-term intervention (3-4 months)
     • Monitor blood pressure and renal function 1
   • Acitretin (oral retinoid)
     • Slower onset (6 weeks)
     • Particularly effective for pustular and erythrodermic forms
     • Strict contraception required (pregnancy contraindicated for 2 years after stopping) 1

3. Biologic Agents 1, 4, 5, 2

   • First-line options for moderate-to-severe disease according to American Academy of Dermatology-National Psoriasis Foundation guidelines 2
   • TNF-α inhibitors:
     • Adalimumab, etanercept, infliximab, certolizumab 4, 5, 2
   • IL-17 inhibitors:
     • Secukinumab, ixekizumab, brodalumab 2, 6
   • IL-23 inhibitors:
     • Guselkumab, tildrakizumab, risankizumab 2, 6
   • IL-12/23 inhibitor:
     • Ustekinumab 2

4. Small Molecules 2

   • Apremilast (phosphodiesterase-4 inhibitor) 2

Special Clinical Scenarios

Psoriatic Arthritis

• Mild peripheral arthritis: NSAIDs and intra-articular corticosteroid injections 1
• Moderate-to-severe peripheral arthritis: DMARDs (methotrexate, leflunomide, sulfasalazine) 1
• Resistant or severe disease: TNF inhibitors (adalimumab, etanercept, infliximab) 1, 4, 5
• Axial disease: NSAIDs and TNF inhibitors 1

Erythrodermic Psoriasis

• Initial management 1:
  • Wet dressings with mid-potency topical steroids
  • Attention to fluid balance
  • Rule out sepsis
• First-line systemic options 1:
  • Cyclosporine (4 mg/kg/day) - rapid onset of action
  • Infliximab, adalimumab, ustekinumab
  • Acitretin (for non-systemic illness cases)
  • Methotrexate 1

Inverse (Flexural) Psoriasis

• First-line 1:
  • Lower potency topical corticosteroids
  • Topical calcineurin inhibitors (tacrolimus)
  • Vitamin D analogs (calcitriol preferred due to less irritation) 1

Treatment Goals and Monitoring

• Treatment goals 3:

  • After induction phase (16-24 weeks): Continue treatment if PASI reduction ≥75%
  • Modify treatment if PASI reduction <50%
  • If PASI reduction is 50-75%: continue if DLQI ≤5, modify if DLQI >5 3

• Monitoring requirements 1:

  • Methotrexate: CBC, liver function, renal function
  • Cyclosporine: Blood pressure, serum creatinine
  • Acitretin: Lipid profile, liver function
  • Biologics: Screening for tuberculosis and other infections 1, 5

Common Pitfalls and Caveats

• Avoid systemic corticosteroids in psoriasis as they can cause disease flare during taper 1
• All systemic agents are contraindicated in pregnancy; ensure adequate contraception 1
• Combination of systemic agents should be used with extreme caution due to additive toxicity 1
• Lithium, beta-blockers, NSAIDs, and antimalarials may worsen psoriasis 1
• Phototherapy is particularly useful for pregnant women with moderate-to-severe disease 1
• Consider disease impact on quality of life when determining treatment approach, not just physical severity 1, 3