OBJECTIVES: Psychiatric hospitalisation rates are particularly high amongst patients with severe mental disorders. Frequency of hospitalisation is, in part, responsible for the high treatment costs of patients with mental disorders. This study aimed to understand the association between specific symptoms, frequency of symptoms and frequency of hospitalisation in patients with mental disorders.

METHODS: A retrospective cohort study using U.S. based de-identified Electronic Health Record data, analysed using the NeuroBlu platform. Adults (≥18 years old) seen at centres with both inpatient and outpatient services, with ≥2 distinct encounters on different days with the same ICD-9/10 mental disorder diagnosis and 12 months of follow up data were included in the study. The index date was defined as the first recorded diagnosis. Natural language processing techniques were applied to the semi-structured text of the Mental State Examination recorded on or before the index date to identify 18 symptoms grouped by the categories of delusion, mood, and cognition. The frequency of psychiatric hospitalisation within 12 months of the index date was recorded (no hospitalisation, 1-2 and ≥3).

RESULTS: Of the 47,545 patients included in the study, 73.1% (n=34,760) had no recorded hospitalisations, 22.6% (n=10,723) had 1-2 recorded hospitalisations and 4.3% (n=2,062) had ≥3 hospitalisations. The most frequently reported symptoms for all groups were depressed mood (26.9%), anxious mood (20.7%) and angry mood (7.1%). A multivariable multinomial logistic regression analysis found a greater number of symptoms was associated with both 1-2 hospitalisations ((z score 8.72, OR = 1.19 95%CI 1.15-1.24) and 3 or more (z score 7.2, OR = 1.30 95%CI 1.21-1.40) compared with no hospitalisations.

CONCLUSIONS: These results suggest that number of symptoms may be associated with a higher frequency of hospitalisation. Symptom specific treatment may help reduce rates of hospitalisations and the high cost of treatment amongst patients with mental disorder diagnoses.