Fig. 4.
Varying the levels of transition probability pA, t (t = 0, 1, 2,.., 25) in a Markov model for screening compliance for sensitivity analysis. The results on this sensitivity analysis are shown in Table 2. Note: PA, t is the probability of attending the screening at each time T = t (t = 1, 2,…, 25) given the person attended the previous screening at time T = t-1(transition probability). The red curve is the transition probability (pA, t) extrapolated based on the estimation using the PLCO data that have only four screenings (T = 0, 1, 2, and 3), and hence data points for T4 were predicted based on the log-transformed regression (see “Evaluation of the USPSTF-recommended and the NLST-like screening program with lifetime screening and follow-up”). In order to take into account uncertainty raised from this extrapolation, we conducted sensitivity analysis varying the levels of pA, t over t. The orange curve obtained by fitting log-transformed regression by including one hypothetical data point at t = 20 with a value pA, 20 = 0.6 (increased from pA, 20 = 0.41 in the red curve for the PLCO projection). Similarly, Level 2, Level 3, and Level 4 curves were obtained by restraining the value of pA, 20 as 0.7, 0.8, and 0.9, respectively. Finally the top blue line is the transition probability under perfect compliance