Psoriasis: What You Need to Know

At a Glance

About Psoriasis

Psoriasis is a chronic immune-mediated skin disease characterised by accelerated keratinocyte proliferation — skin cells that normally renew every 28 days are replaced every 3–7 days, producing the characteristic scaly plaques. It affects approximately 2% of South Africans. Plaque psoriasis (psoriasis vulgaris) accounts for 85–90% of cases; other forms include guttate, pustular, erythrodermic, and inverse psoriasis.

Psoriasis is not contagious. It is driven by IL-17, IL-23, TNF-alpha, and related inflammatory cytokines — the same pathways targeted by modern biologics used in rheumatoid arthritis and Crohn's disease. This shared immunological basis means psoriasis patients frequently develop psoriatic arthritis (PsA) and carry elevated risk for cardiovascular disease, metabolic syndrome, and depression.

Types of Psoriasis

Plaque psoriasis (psoriasis vulgaris): Well-demarcated, raised, erythematous plaques with silvery-white scale. Typically affects elbows, knees, scalp, and lumbosacral area. Most common form.

Guttate psoriasis: Small, teardrop-shaped lesions; often triggered by streptococcal throat infection. More common in children and young adults.

Pustular psoriasis: Sterile (non-infectious) pustules on erythematous skin. Localised (palmoplantar) or generalised (Von Zumbusch pattern — a medical emergency with systemic toxicity).

Erythrodermic psoriasis: Near-total body surface involvement (> 90% BSA) with profound systemic effects (temperature dysregulation, high-output cardiac failure risk, protein loss). Medical emergency requiring hospitalisation.

Inverse psoriasis: Affects skin folds (axillae, groin, inframammary). Minimal scale due to moisture; easily misdiagnosed as fungal infection.

Disease Severity Assessment

Psoriasis severity is quantified using: - PASI (Psoriasis Area and Severity Index): The clinical standard. Accounts for area of involvement and severity of redness, thickness, and scale. PASI < 10 = mild; 10–20 = moderate; > 20 = severe. - BSA (Body Surface Area): Percentage of body skin affected. < 3% = mild; 3–10% = moderate; > 10% = severe. - DLQI (Dermatology Life Quality Index): Patient-reported quality-of-life impact. Scalp, nail, palmoplantar, and genital psoriasis often cause disproportionate DLQI impact relative to PASI.

Treatment Pathway

Step 1 — Topical Therapy

First-line for all psoriasis: - Topical corticosteroids (betamethasone, clobetasol): Anti-inflammatory; most effective for acute plaques. Tachyphylaxis and skin atrophy with prolonged use. - Vitamin D analogues (calcipotriol/Daivonex): Antiproliferative; synergistic with corticosteroids. Calcipotriol/betamethasone combination (Daivobet) is highly effective. - Coal tar: Antiproliferative and antipruritic; effective but cosmetically unacceptable to many patients. - Salicylic acid: Keratolytic; removes scale before other treatments penetrate.

Step 2 — Phototherapy

Narrowband UVB (nbUVB) phototherapy is highly effective for moderate psoriasis. Three sessions per week at a dermatology centre. Typical course: 20–30 sessions over 2–3 months. Approximately R200–R300 per session at private centres (~R800/month on-maintenance). Not CDL-funded; claimed from scheme dermatology benefit.

Step 3 — Conventional Systemic (csDMARDs)

• Methotrexate (7.5–25mg weekly oral or SC): Effective, inexpensive (~R200/month), requires regular monitoring (FBC, LFTs, renal function). Teratogenic — contraception mandatory. First-line systemic in SA due to cost.
• Cyclosporine (2.5–5mg/kg/day): Rapid response; useful for severe flares and erythrodermic/pustular psoriasis. Not for long-term use (nephrotoxicity, hypertension). ~R1,800/month.
• Acitretin (oral retinoid): Effective for pustular and palmoplantar psoriasis. Teratogenic — strict contraception required; not suitable for women of childbearing potential.

Step 4 — Biologic Therapy

For moderate-to-severe psoriasis failing two or more csDMARDs or with significant DLQI impairment:

Annual biologic cost: R120,000–R200,000. None of these are CDL-funded. None are mandatory PMB. Access depends entirely on scheme exceptional needs authorisation or OOP funding.

The Psoriatic Arthritis Pivot

Psoriatic arthritis (PsA) develops in approximately 30% of psoriasis patients. PsA involves peripheral joint inflammation, enthesitis (tendon insertions), dactylitis (sausage digits), and axial disease (sacroiliitis). PsA is potentially a Chronic Disease List condition under the inflammatory arthritis category — if confirmed, it unlocks biologic funding through the scheme exceptional needs pathway with CDL support. This is a material change in the financial landscape. Any psoriasis patient who develops joint symptoms should see a rheumatologist promptly.

Annual Cost Estimates

The Talk to Eldon Angle

Psoriasis is unusual in the AURA Phase 1a set: it is NOT CDL, NOT PMB, and carries potentially the highest biologic drug cost of any condition in the set (~R200,000/year for premium IL-23 agents). The advisory is therefore not about scheme registration or gap cover — it is about biologic access strategy. Members on or approaching biologics should be directed to schemes with established dermatology exceptional needs programmes. Gap cover does not solve the biologic access problem.

The secondary advisory: plan for PsA. Thirty percent of psoriasis patients will develop it. If PsA develops, the entire financial framework shifts.

Sources

1. SA Dermatological Association Psoriasis Management Guidelines 2022.
2. Menter A et al. Biologics for psoriasis. J Am Acad Dermatol, 2024.
3. SAHPRA SEP database — biologic prices require verification.

Ready to check what your scheme covers for psoriasis? Run your AURA medical aid check