Functional entropy VS SSPI score. Panel (a, b): The FCE held a significantly (r = 0.705, P = 0.034) positive correlation with SSPI score in patients < 5 years (left panel), while it displayed a significantly (r = −0.543, P = 0.024) negative correlation in those ≥ 5 years (right panel). Panel (c, d): The secondary FCE showed a significant (r = 0.737, P = 0.023) positive correlation with SSPI score in patients < 5 years (left panel), while the primary functional entropy displayed a significant (r = −0.642, P = 0.006) negative correlation in those ≥ 5 years (right panel). Linear effects of age, sex, and dose have been removed. [Color figure can be viewed in the online issue, which is available at http://wileyonlinelibrary.com.]