MCCQE1 CDM Cases: Format, Scoring, and Study Strategy
MDReview Editorial — written with input from Canadian residents and medical students.
The Clinical Decision Making (CDM) section is the part of MCCQE1 that trips up the most first-time writers. It's not that the medicine is harder — it's that no other exam trains you for the format. Here's what CDM actually looks like, how it's scored, and how to study for it without wasting weeks.
Format at a glance
- 38 cases delivered on exam day, split across a 4-hour block.
- Short-answer — you type your responses. Most cases ask for 2–4 answers.
- Question types include short menu (pick N from a list), short answer (type N answers), and write-in.
- Structured mark scheme — each acceptable answer earns points; the total is capped so you can't "shotgun" the response.
The exam interface warns you if you exceed the answer cap. Extras beyond the cap are ignored, not penalized — but you waste time.
How CDM is scored
Every case has a pre-defined answer key and a maximum score. Common patterns:
- "List 4 investigations" → the key has 6–8 acceptable answers. You get 1 point each for your first 4 correct answers. A 5th correct answer earns nothing.
- "List 3 management steps" → same logic — pick the 3 highest-yield.
- Weight is specificity-focused: "CBC" scores; "bloodwork" doesn't. "Chest X-ray" scores; "imaging" doesn't.
The critical implication: the marker doesn't reward completeness — the marker rewards precision inside the requested count.
The three CDM mistakes that cost the most points
- Vague answers. "Fluids" instead of "0.9% NaCl 1L bolus." "Antibiotics" instead of "ceftriaxone 2g IV daily."
- Overrun. Writing 6 answers when the prompt asked for 3. The marker takes the first 3, in order — so your best answers had better be first.
- Missing the ask. The prompt says "management" — you write differentials. Zero points.
How to actually study CDM
Volume matters, but format practice matters more. You need 80–150 CDM cases minimum, graded against a rubric. Reading them isn't enough — you have to type the answer, then check.
A practical 3-week CDM block:
- Week 1: 8 cases/day, un-timed, no order pressure. Grade every answer against the rubric.
- Week 2: 12 cases/day, timed at 6 minutes per case. Enforce the answer cap.
- Week 3: 15 cases/day, mixed-system. Simulate a 4-hour block twice.
MDReview's CDM engine grades every short-answer response against a rubric — not a keyword match — and flags when your answers are close but not specific enough. That's the fastest way to close the vague-answer gap that costs most first-time writers a pass.
What "passing CDM" looks like
The MCC doesn't publish CDM section pass marks separately — CDM contributes to your overall MCCQE1 score. In practice, hitting 65% on rubric-graded CDM cases in the two weeks before exam day is a strong predictor. If you're below 55%, add another 2 weeks of CDM-only work before the exam.