The health service contact patterns of people with psychotic and non-psychotic forms of severe mental illness in New South Wales, Australia: A record-linkage study

Abstract

Objective: To describe and compare the health profiles and health service use of people hospitalised with severe mental illness, with and without psychotic symptoms. Methods: We conducted a historical cohort study using linked administrative datasets, including data on public hospital admissions, emergency department presentations and ambulatory mental health service contacts in New South Wales, Australia. The study cohort comprised 169,306 individuals aged 12 years and over who were hospitalised at least once with a mental health diagnosis between 1 July 2002 and 31 December 2014. Of these, 63,110 had a recorded psychotic illness and 106,196 did not. Outcome measures were rates of hospital, emergency department and mental health ambulatory service utilisation, analysed using Poisson regression. Results: People with psychotic illnesses had higher rates of hospital admission (adjusted incidence rate ratio (IRR) 1.26; 95% confidence interval [1.23, 1.30]), emergency department presentation (adjusted IRR 1.17; 95% confidence interval [1.13, 1.20]) and ambulatory mental health treatment days (adjusted IRR 2.90; 95% confidence interval [2.82, 2.98]) than people without psychotic illnesses. The higher rate of hospitalisation among people with psychotic illnesses was driven by mental health admissions; while people with psychosis had over twice the rate of mental health admissions, people with other severe mental illnesses without psychosis (e.g. mood/affective, anxiety and personality disorders) had higher rates of physical health admissions, including for circulatory, musculoskeletal, genitourinary and respiratory disorders. Factors that predicted greater health service utilisation included psychosis, intellectual disability, greater medical comorbidity and previous hospitalisation. Conclusion: Findings from this study support the need for (a) the development of processes to support the physical health of people with severe mental illness, including those without psychosis; (b) a focus in mental health policy and service provision on people with complex support needs, and (c) improved implementation and testing of integrated models of care to improve health outcomes for all people experiencing severe mental illness.

Hospital service utilisation of people previously hospitalised with different subtypes of psychotic disorder: A record linkage study

“…The current study examines this question using data derived from large linked hospital administrative data sets from New South Wales (NSW), Australia. In a previous study using this cohort, we showed that people initially hospitalised with psychotic disorders (all subtypes combined) later utilised hospital services including emergency departments (EDs), public inpatient and ambulatory mental health services more frequently than people initially hospitalised with non-psychotic severe mental illness (Cvejic et al, 2021). The current study aims to extend these findings by elucidating how health profiles and subsequent rates of engagement with different hospital services differ for people previously hospitalised with different psychotic disorder subtypes.…”

“…people with intellectual disability, lower socioeconomic status and/or high rates of comorbidity) were more likely to go on to access acute hospital services (i.e. ED and hospital admissions) (Cvejic et al, 2021). The current study further elucidates the associations between specific subtypes of psychotic disorders and patterns of hospital service use.…”

“…The study population comprised individuals aged 12–100 years who were identified as having a psychotic disorder through a recorded hospitalisation with a psychotic mental health diagnosis (as the principal diagnosis) in NSW on at least one occasion from 1 July 2002 to 31 December 2014 (Cvejic et al, 2021). The index date for the study was the first date of discharge following admission with a principal diagnosis of a psychotic mental health diagnosis.…”

“…Deidentified linkage was performed by the NSW Centre for Health Record Linkage. The datasets and record linkage methods for the study are described in Cvejic et al (2021) and Reppermund et al (2019)…”

“…The index date for the study was the first date of discharge following admission with a principal diagnosis of a psychotic mental health diagnosis. Psychotic mental health diagnoses were identified from the APDC and included the International Classification of Diseases, 10th Revision, Australian Modification (ICD-10-AM) diagnosis codes previously specified in Cvejic et al (2021).…”