E-R relationships, using local polynomial regression (developmental cohort). Shown in the blue line is the local polynomial regression (ie, Loess smooth regression) for E-R relationships for 3 exposure variables: (A) C_{trough_1}; (B) C_{max_1}; and (C) AUC₁. The shaded area represents the 95% CI. C_{trough_1} showed the lowest P value (logistic regression). Each dot represents a single patient and associated C_{trough_1} and the probability of the event (0 [−], event absent; 1 [+], event present). AUC₁, AUC of abatacept concentration-time; C_{max_1}, maximum abatacept concentration after the first dose.