Laura B. Ramsey

Selective serotonin reuptake inhibitors (SSRI) are the first‐line pharmacologic treatment for anxiety and depressive disorders in children and adolescents. Many patients experience side effects that are difficult to predict, are associated with significant morbidity, and can lead to treatment discontinuation. Variation in SSRI pharmacokinetics could explain differences in treatment outcomes, but this is often overlooked as a contributing factor to SSRI tolerability. This study evaluated data from 288 escitalopram‐treated and 255 sertraline‐treated patients ≤ 18 years old to develop machine learning models to predict side effects using electronic health record data and Bayesian estimated pharmacokinetic parameters. Trained on a combined cohort of escitalopram‐ and sertraline‐treated patients, a penalized logistic regression model achieved an area under the receiver operating characteristic curve (AUROC) of 0.77 (95% confidence interval (CI): 0.66–0.88), with 0.69 sensitivity (95% CI: 0.54–0.86), and 0.82 specificity (95% CI: 0.72–0.87). Medication exposure, clearance, and time since the last dose increase were among the top features. Individual escitalopram and sertraline models yielded an AUROC of 0.73 (95% CI: 0.65–0.81) and 0.64 (95% CI: 0.55–0.73), respectively. Post hoc analysis showed sertraline‐treated patients with activation side effects had slower clearance ( P = 0.01), which attenuated after accounting for age ( P = 0.055). These findings raise the possibility that a machine learning approach leveraging pharmacokinetic data can predict escitalopram‐ and sertraline‐related side effects. Clinicians may consider differences in medication pharmacokinetics, especially during dose titration and as opposed to relying on dose, when managing side effects. With further validation, application of this model to predict side effects may enhance SSRI precision dosing strategies in youth.