SPLiT: Standardized Prediction of Lithium Titers Using Routine Clinical Monitoring Data

This record contains a preregistered-style analytical plan for the SPLiT study (Standardized Prediction of Lithium Titers). The document specifies the study objectives, primary confirmatory hypothesis, study design, population, sample size justification, and statistical analysis strategy prior to primary data analysis. The study aims to develop and validate a hierarchy of models for standardizing measured serum lithium concentrations to an equivalent 12-hour level and for predicting individual therapeutic lithium doses using routine clinical monitoring data. This preregistration is published to ensure transparency, reproducibility, and clear separation between confirmatory and exploratory analyses. Any deviations from the preregistered plan will be explicitly documented in subsequent publications.