Segmented Linear Regression Modelling of Time-Series of Binary Variables in Healthcare

Figure 3

Modelling of the time-series of 120-day mortality. Solid red line is the best model. Solid black lines are the other models. Dashed vertical line is the onset of the HFU. Data values are not shown as they are points at either y = 0 or 1. (i) Plateau model  = 0.1221. (ii) Line model  = −0.000030t + 0.1531. (iii) Plateau-line model  = 0.1291 for t = 0 to 1358.1 days and  = −0.000341t + 0.1291 for t = 1358.1 to 1995 days. (iv) Line-line model  = −0.000015t + 0.1423 for t = 0 to 1731.2 days and  = −0.000328 (t − 1731.2) + 0.1172 for t = 1731.2 to 1995 days.