Delirium and Iatrogenic Withdrawal Profiles in the Pediatric Intensive Care Unit (PICU): A Latent Profile Analysis of Nurse-Administered Bedside Scales

Background/Objectives: Delirium and iatrogenic withdrawal syndrome (IWS) overlap clinically in critically ill children. We used latent profile analysis (LPA) of nurse-administered assessments to identify score patterns, not diagnoses; no independent reference standard was available. Methods: This single-center retrospective cohort included 203 pediatric intensive care unit (PICU) records from 84 patients. Raw scores from the IWS and delirium subscores of the Japanese Sophia Observation withdrawal Symptoms–Paediatric Delirium (SOS-PD) scale, the Richmond Agitation–Sedation Scale (RASS), and the Face, Legs, Activity, Cry, Consolability (FLACC) scale were modeled using tied-diagonal Gaussian mixtures for K = 1–5. Selection used the Bayesian information criterion (BIC), entropy, and posterior probabilities. Results: The selected four-profile solution had BIC = 3245.4, entropy = 0.887, and 91.6% of records had a maximum posterior probability ≥ 0.70. Patient-level analyses provided partial support (adjusted Rand index = 0.833); standardization yielded an adjusted Rand index of 0.977. The profiles were Profile 1 (Delirium-predominant), Profile 2 (High-symptom mixed), Profile 3 (Withdrawal-predominant), and Profile 4 (Low-symptom at-target). Separation was strongest and inverse on the SOS-PD subscores (within-input |d| = 3.05 withdrawal; 2.26 delirium), describing input-scale divergence rather than diagnostic discrimination. Untied, categorical, and count models favored two profiles. Conclusions: Joint bedside scores contained model-specific candidate patterns, and profile number was model-dependent. Before prospective external validation, profiles should be treated only as descriptive score summaries and should not be used in clinical care.