Psoriasis

Question 1

Epidemiology of psoriasis

Answer 1

• Incidence between 1-3%, with greater incidence in Europe and North America than East and South-East Asia* Estimated 40,000 people in Singapore with psoriasis* Same incidence in males as in females* Bimodal distribution-75% have onset before age of 40* Two peak ages of onset at 20 -30 and again at 50-60

Question 2

Psychosocial burden of psoriasis

Answer 2

• 33% experience depression and anxiety- 10% attempt suicide- 1 in 5 report being rejected due to their condition

Question 3

Eiology of psoriasis

Answer 3

• Fam Hx/genetic: TNFa- Infections: B-hemolytic streptococci, HIV -> 2wks after viral of streptococci infection- Hormonal: early age of onset in females- psychogenic: stress- drugs: lithium, b-blockers (timolol)- Koebner phenomenon -> psoriasis developing after tattoo- smoking, alcohol, obesity might be factors too

Question 4

Comorbidities assoc with psoriasis

Answer 4

• crohn disease- psoriatic arthritis- depression, alcoholism- metabolic syndrome: CVD risk, obesity, HTN etc- increases rate of mortality

Question 5

Clinical presentations of psoriasis

Answer 5

1. Lesions: ertythematous, red-violet colour, at least 0.5cm in diameter, well demarcated, typically covered by silver flaking scales2. Skin involvement: knees, elbows (extensor distribution) or generalised over a wide BSA. Mild: <=5% BSAMod: PASI >=8Sev: PASI >=10 or BSA >= 10%. 3. Pruritis: >50% will experience4. Plaques raides from skinInverse psoriasis: affects flexor surfaces, no scalesNail psoriasis: pitting, complete nail distrophy

Question 6

What is guttate psoriasis?

Answer 6

• Gutta (Greek)-a droplet* Commonest in childhood* 2 weeks post streptococcal (haemolytic group A) pharyngitis or tonsillitis* Centripetal distribution (mainly on torso then spread to arm and leg)* In children usually self- limiting* Approx. 40% develop chronic plaque psoriasis* look like chicken pox

Question 7

What is psoriatic arthritis (PsA)?

Answer 7

• An inflammatory arthritis associated with psoriasis* Rheumatoid factor negative* Rheumatoid nodules absent* Develops after onset of psoriasis (~10yrs ltr) but can appear first in some pts* TNF-a and HLA-CW6 is linked to PsA and psoriasis -> use of MTX + NSAIDs* Swollen-like inflammation in joints, severe deformity in hand joints

Question 8

What are the goals of tx of psoriasis?

Answer 8

1. Minimizing or eliminating the signs of psoriasis, such as plaques 2. Alleviating pruritus and minimizing excoriations3. Reducing the frequency of flare ups4. Ensuring appropriate management of co-morbid conditions 5. Avoiding or minimising adverse effects6. Providing cost-effective therapy7. Guidance and counselling as needed8. Maintain or improving the patient’s quality of life

Question 9

What to counsel to patients with psoriasis?

Answer 9

• nature of disease (chronic skin disorder?)- no cure- treatment is suppressive, not curative- not contagious

Question 10

What are the non-pharm management of psoriasis?

Answer 10

• stress reduction- moisturisers- oatmeal baths- sunscreens

Question 11

Overview of pharm management strategies for psoriasis (excluding biologics)

Answer 11

Mild (75%): TOP CS, TOP Vitamin D3 analogue, Tazarotene, Dithranol, Coal tar, Keratolytic (eg. salicylic acid), emollientsMod: PUVA or UVB phototherapySevere: hydroxyurea, MTX, cyclosporin, aeitretin

Question 12

Treatment algorithm for mild-mod psoriasis

Answer 12

first line: topical agentsif ineffective: topical agents + phototherapy.If ineffective: topical agents + systemic agentsAll of them shld add on moisturiser too.

Question 13

What topical corticosteroids is used for psoriasis?

Answer 13

hydrocortisone 1% or 2.5%: cream, lotion, ointment

Question 14

What is the use of vitamin D3 analogues in psoriasis?

Answer 14

• First line monotherapy or in combination regimens* Effective as all but the most potent TCS* Calcipotriol, calcitriol, tacalcitol* Binding to vitamin D receptors which results on inhibition of keratinocyte proliferation and enhancement of keratinocyte differentiation* Inactivated by salicylic acid

Question 15

What are the side effects of vitamin D3 analogues?

Answer 15

• common: mild irritant contact dermatitis, burning, pruritis, edema, peeling, dryness, erythema- systemic: hyperCa, parathyroid hormone depression, impaired renal func, impaired Ca metabolism

Question 16

What is the use of retinoids in psoriasis?

Answer 16

• Tazarotene acts by normalising abnormal keratinocyte differentiation, diminishing keratinocyte hyperproliferation and clearing the inflammatory infiltrate in the psoriatic plaque* Tazarotene 0.1% gel has similar efficacy to Calcipotriol 0.05% cream but less effective than Clobetasol propionate 0.05% cream* Tazarotene may be combined with TCD to increase efficacy* Tazarotene-apply once a night and avoid sun exposure* Tazarotene is contraindicated in pregnancy unless effective contraception is used at the same time

Question 17

What are the side effects of tazarotene?

Answer 17

• high incidence of irritation at site (can be reduced by using cream formulation or low conc)- burning- itching- erythema

Question 18

What is the use of coal tar in psoriasis?

Answer 18

• keratolytic, anti-proliferative, may have anti-infl. - bethamethasone valroate more effective altho coal tar has similar efficacy to calcipotriol.- conc of 0.5% - 5% is considered safe- not well accepted due to black appearance, smell, staining of clothes- limited efficacy- SE: acne, local irritation, phototoxicity

Question 19

What is the use of salicylic acid in psoriasis?

Answer 19

• keratolytic properties- use with combi of TCS as it helps enhance steroid penetration into skin, increasing efficacy- not used w UVB light phototherapy due to filtering effect of SA that reduces efficacy of phototherapy- Salicylic acid 2-3% is used for psoriasisNote: 15-27% for viral warts and corns. 0.5% for acne as cleanser

Question 20

What is the use of phototherapy and photochemotherapy?

Answer 20

• used w crude coal tar- treat psoriatic lesions- PUVA is more effective than UVB but risk of skin cancer is higher so is less used

Question 21

Treatment algorithm for mod-sev psoriasis

Answer 21

First line: systemic agent +/- TOP agent or phototherapy, consider BRM (costly) if comorb existsIf ineffective: more potent systemic agentIf ineffective: biological response modifier (BRM) +/- other agentsMoisturisers shld be used tgt for all.

Question 22

What systemic treatments are available?

Answer 22

1. Acitretin2. MTX3. Biologics (eg. Infliximab, Tofacitinib)

Question 23

What is the use of acitretin and its SE in psoriasis

Answer 23

• less effective than MTX when used as monotherapy but initial response may be more rapid for severe psoriasis- replaced with isotretinoin now due to SE- teratogenic unless birth control is used and 2yrs after discontinuing - alcohol shld be avoided and after 2months of discontinuation SE: nail thinning, diffuse hair loss, dryness of eye, chapped lips, angular cheilitis, xerosis, burning. Less common: retinoid dermatitis, decreased colour vision, photosensitivity

Question 24

What is the use of MTX in psoriasis?

Answer 24

• more efficacious than acitretin and similar efficacy to cyclosporine. - direct anti-infl effect due to effect on T-cell gene expression- slow down growth of skin cells to stop scales- inhibit folate biosynthesisOther conditions which MTX is used to treat: atopic eczema, bullous pemphigoid, psoriasis

Question 25

What is the use of biologics for psoriasis?

Answer 25

• esp if comorb exists- can be considered as 1st line in mod-sev psoriasis- infliximab is one of the more efficacious drug. clears in 10wks - tofacitinib dose: 5mg/day PO