Governing Equations

3-State Markov Model:
  States: Stable (S) → Progression (P) → Death (D)

Transition Matrix (per cycle):
  P(S→S) = 1 - p1,  P(S→P) = p1,  P(S→D) = 0
  P(P→S) = 0,       P(P→P) = 1-p2, P(P→D) = p2
  P(D→S) = 0,       P(D→P) = 0,    P(D→D) = 1

QALY Accumulation:
  QALY_t = u_S · P(S)_t + u_P · P(P)_t
  Discounted: QALY_d = Σ QALY_t / (1 + r)^t

ICER (Incremental Cost-Effectiveness Ratio):
  ICER = ΔCost / ΔQALY
  NICE Threshold: £20,000-£30,000/QALY

Net Monetary Benefit:
  NMB = λ · QALY - Cost  (λ = willingness-to-pay)

Probabilistic Sensitivity Analysis:
  Monte Carlo: sample from parameter distributions
  CE Plane: scatter plot of ΔCost vs ΔQALY
  CEAC: probability cost-effective at varying λ