Could psoriasis be affecting my joints?
Five yes/no questions — the PEST screen, the same validated questionnaire dermatologists use to spot psoriatic arthritis in people with psoriasis. One point per Yes; a score of 3 or more is the published level where a rheumatology assessment is suggested. Everything stays on this device.
In the validation study, a score of 3 or more picked up most true cases of psoriatic arthritis (sensitivity ≈0.92–0.97) while also flagging some people who turn out not to have it (specificity ≈0.78–0.79) — a high score means “worth checking”, not “you have it”.
This is an educational self-assessment, not a diagnosis — a positive screen means it's worth talking to your GP or dermatologist about a rheumatology referral, not that you have psoriatic arthritis. Whatever your score, see a doctor about any joint that is changing, swollen, or painful.
PEST — Ibrahim GH, Buckley C, Helliwell PS. Clin Exp Rheumatol. 2009;27(3):469–474.
PEST covers the joints psoriasis can silently affect — the part of the disease no mirror will show you. For the skin side, it pairs naturally with the BSA calculator to measure how much of your body surface is involved, and the PASI calculator to score how severe the plaques themselves are. Re-screen your joints every few months, or whenever a joint becomes sore, stiff, or swollen.
Saved only on this device — and browsers erase site data. A history clear, a private window, or Safari's automatic deletion after seven days without a visit will take this log with it. The fix is a free DermApproved account: it backs this up automatically and puts it on every device you sign in to — details in how storage works.
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How the PEST screen works
The Psoriasis Epidemiology Screening Tool — PEST — is a validated five-question screen developed to find psoriatic arthritis in people who have psoriasis (Ibrahim, Buckley & Helliwell, Clinical and Experimental Rheumatology, 2009). Each question targets a hallmark of the disease: joint swelling, a prior arthritis diagnosis, nail pitting, heel pain from enthesitis, and dactylitis — a whole finger or toe swelling up like a sausage. Every Yes scores one point, giving a total from 0 to 5, and a score of 3 or more is the published threshold at which a rheumatology assessment is suggested. At that cut-off the questionnaire catches most true cases (sensitivity ≈0.92–0.97) while flagging some people who turn out not to have psoriatic arthritis (specificity ≈0.78–0.79) — which is exactly what a good screen should do: err on the side of a conversation. The original paper instrument also includes a joint manikin for sketching which joints hurt; it describes symptoms to the clinician but is never scored, so this tool focuses on the five scored questions.
Screening matters because up to a third of people with psoriasis develop joint involvement, the skin almost always arrives first, and joint damage from untreated psoriatic arthritis can be permanent — catching it early is what protects the joints, which is why guidelines recommend re-screening regularly rather than once. A questionnaire can only flag that psoriatic arthritis is possible; confirming or excluding it takes a clinical assessment, usually by a rheumatologist. Save your score here each time you screen and the tool builds a dated history you can bring to appointments, alongside the skin-side companions — the BSA calculator for extent and the PASI calculator for plaque severity. Everything runs and stays on this device — nothing is uploaded anywhere.
Common questions
What does a PEST score of 3 or more actually mean?
A score of 3 or more is the published referral threshold — the point where the study behind the questionnaire found psoriatic arthritis likely enough to justify a rheumatology assessment. In the validation work it caught most true cases (sensitivity around 0.92–0.97) while also flagging some people who turn out not to have it (specificity around 0.78–0.79). So a positive screen means the question is worth a clinician’s time, not that the answer is yes.
Why should someone with psoriasis screen their joints at all?
Because up to a third of people with psoriasis go on to develop psoriatic arthritis, and the skin usually shows up years before the joints do. Joint damage from untreated psoriatic arthritis can be permanent, which is exactly why dermatology guidelines recommend re-screening people with psoriasis regularly rather than waiting for joints to fail loudly. Five questions once every few months is a cheap insurance policy.
My score is under 3 — can I stop worrying about my joints?
Not permanently, no. A low score means your answers don’t point strongly to psoriatic arthritis today — reassuring, but not a guarantee, since psoriasis can involve the joints at any point. Re-screen every few months, or sooner if a joint becomes sore, stiff, or swollen, and mention any change to your GP or dermatologist regardless of the number.
Which symptoms is the questionnaire actually looking for?
Each of the five questions maps to a hallmark of psoriatic arthritis: joint swelling, a prior arthritis diagnosis, nail pitting (the nail changes that track closely with joint involvement), heel pain (enthesitis — inflammation where tendons anchor to bone), and a whole finger or toe swelling up like a sausage (dactylitis). That last one is one of the most distinctive signs of psoriatic arthritis, which is why it earns its own question.
Where do my saved screening scores go?
Into your own browser’s local storage on this device — nothing is uploaded to DermApproved or anywhere else. The trade-off is that clearing browser data erases the history and it won’t follow you to another device, so download a backup from My Library if you’re building a record worth keeping. A dated history of screens is genuinely useful at appointments.