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Fig. 1 | BMC Medical Research Methodology

Fig. 1

From: Relationship between risk, cumulative burden of exacerbations and mortality in patients with COPD: modelling analysis using data from the ETHOS study

Fig. 1

a Description of the multi-state model using the Markov assumption; and b Paths for four hypothetical patients through the model. All patients were in the ‘no exacerbation’ state at randomisation. The model only allowed transition to a worsened health state. Transitions did not have to be to the next adjacent state; however, transitions directly from no exacerbations to ≥ 2 moderate exacerbations were not permitted. Markov assumption: transition to future states depends only on the current state at time t and not previously occupied states. Panel b shows paths for four hypothetical patients: for example, patient 1 (overlapping with patient 2 up to week 20) was in State 1 (no exacerbations) up to week 8, then transitioned to State 2 (1 moderate exacerbation) and stayed there up to week 20. At week 24, the patient transitioned to State 3 (≥ 1 moderate exacerbations) then to State 4 (≥ 1 severe exacerbations) at week 28. The patient remained in State 4 until week 36 and died at week 40. exac exacerbation, mod moderate, sev severe

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