Figure 2. The Markov model (the multistate life table methods) applied in our study. In this scheme, three states (non-disabled, disabled, and dead) and four transitions over time were shown: that is (a) from non-disabled to disabled (an incidence of a disabled status), (b) from disabled to non-disabled (a recovery from a disabled status), (c) from non-disabled to dead, and (d) from disabled to dead. Each circulated arrows showed the retention process.