Figure 1.

Schematic of the Markov model structure. Ovals represent the four health states: high-impact chronic pain (substantial activity limitations); no pain; and two without activity limitations, but with higher (moderate-impact) or lower (low-impact) pain.

Arrows represent the probability of transitions within and between health states and each therapy has its own set of transition probabilities. Patients begin in one of the three right-hand side health states and can transition to other health states in 6-week cycles.