OBJECTIVES:We examined associations between patients' socioeconomic and clinical factors and the thoroughness of clinical notes for children visiting the pediatric emergency department (ED) for headache. METHODS:This is a secondary analysis of data from a retrospective chart review of first-time visits for patients (ages 5-17) seen for headache at 1 pediatric ED, excluding visits related to infection or injury. We extracted fields from the provider note relevant to headache diagnosis (eg, pain severity) and used backward stepwise log-binomial regressions to identify demographic and clinical factors associated with missing data for a single field. For our sensitivity analysis, we included imputed pain severity as another predictor. RESULTS:From 1000 randomly selected ED visits, we found 629 eligible visits, skewing toward adolescents (median: 13.0 y [IQR: 10.0-15.8 y]) and females (58.5%). Non-Hispanic black children had lower odds of being triaged at moderate or severe acuity even after adjusting for pain severity, age, and sex assigned at birth (OR: 0.07 [95% CI: 0.03-0.16]). Older patients (RR 0.99 per year [0.98-0.99], P<0.001) and those with moderate (0.79 [0.75-0.82], P<0.001) or high-acuity (0.90 [0.85-0.96], P=0.001) triage scores had a decreased risk of missing data; boys had an increased risk (1.04 [1.00-1.08], P=0.046). After pain severity was included, patients with severe pain (0.92 [0.88-0.97], P=0.003) had a decreased risk of missing data while sex differences became nonsignificant (P=0.063). CONCLUSIONS:Provider notes for children seen in the ED for headache are less thorough for younger patients, boys, and those with lower triage acuity scores. After accounting for pain severity, patients reporting mild pain also had less thorough notes. If the quality of medical documentation represents the health care interaction, relationships between missingness and demographic factors such as sex warrant exploration of potential interventions.