One-Year Transitions Among Three Health States for Age 65. P(A | B) is the probability of being in state A at age 66 for a person who is in state B at age 65. For example, P(S|H) is the probability that a healthy 65-year-old will be sick at age 66. The quantities in parentheses represent the generic interventions that would affect the relevant transition probability, as follows. HP/DP is health promotion and disease prevention, which affects the probability that healthy persons become sick. Treatment makes sick persons healthier. The ICU reduces the probability that sick persons die. The Safety intervention reduces the chance that healthy persons die.