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

Figure 2

Modelling of the time-series of 30-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  = 0.0505. (ii) Line model  = −0.000020t + 0.0711. (iii) Plateau-line model  = 0.0706 for t = 0 to 25.1 days and  = −0.000020 (t − 25.1) + 0.0706 for t = 25.1 to 1995 days. (iv) Line-line model  = −0.000016t + 0.0683 for t = 0 to 1880.4 days and  = −0.000328 (t − 1880.4) + 0.0375 for t = 1880.4 to 1995 days.