Utilization and Predictors of Adjuvant Metformin for Children and Adolescents on Mixed Receptor Antagonists (Second-Generation Antipsychotics)

Objective To examine utilization and predictors of adjuvant metformin among pediatric recipients of second-generation antipsychotics (SGAs) (mixed receptor antagonist).Method This study used 2016-2021 data of a national electronic medical record database. Eligible participants were children aged 6 to 17 with a new SGA prescription for at least 90 days. Predictors of prescribing adjuvant metformin in general and to nonobese pediatric SGA recipients in particular were assessed using conditional logistic regression and logistic regression analyses, respectively.Results Of 30,009 pediatric SGA recipients identified, 2.3% (n = 785) received adjuvant metformin. Among 597 participants with a body mass index z score documented during the 6-month period before metformin initiation, 83% were obese, and 34% had either hyperglycemia or diabetes. Significant predictors for metformin prescribing were high baseline body mass index z score (odds ratio [OR] 3.5, 95% CI 2.8-4.5, p < .0001), having hyperglycemia or diabetes (OR 5.3, 95% CI 3.4-8.3, p < .0001), and undergoing a switch from a higher metabolic risk SGA to a lower risk one (OR 9.9, 95% CI 3.5-27.5, p = .0025) or a switch in the opposite direction (OR 4.1, 95% CI 2.1-7.9, p = .0051) compared with no switch. Nonobese metformin users were more likely to have a positive body mass index z score velocity before metformin initiation than their obese counterparts. Receiving the index SGA prescribed by a mental health specialist was associated with higher likelihood of receiving adjuvant metformin and receiving metformin before the development of obesity.Conclusion Utilization of adjuvant metformin among pediatric SGA recipients is uncommon, and early introduction of the medication among nonobese children is rare.