Factors associated with hospitalisations over the two years following first episode psychosis in a remote setting: A retrospective cohort study

Introduction/background

The effectiveness of early intervention services for psychotic disorders increasingly recognises the heterogeneity of psychotic presentations among different populations. While there is reasonable evidence linking an increased risk of psychosis with certain ethnic sub-populations among populations in urban Australia, ¹ New Zealand, ² and Canada, ³ there is limited data on the effect of ethnicity on rates of psychosis or interventions in regional Australia.

Adverse health outcomes in the NT disproportionately affect Aboriginal and Torres Strait Islander peoples, particularly regionally. ⁴ Substance use is also elevated across NT, with the highest per capita consumption of cannabis, nicotine, and alcohol in Australia. ⁵ Psychiatric services are limited, with a large geographical area and only two specialist mental health services in the main metropolitan area.

This study explores the incidence of FEP and factors associated with hospitalisations in the two years following initial diagnosis in young persons in the Top End of the Northern Territory. Previous studies on comparable Australian populations have focused on remote North Queensland, demonstrating elevated rates of psychosis among Aboriginal and Torres Strait Islander people.^6,7 However, studies from metropolitan areas suggest that there is no statistically significant difference in the prevalence of psychotic symptoms between Aboriginal people and other Australians. ⁸ This heterogeneity of psychotic presentations, coupled with a disproportionately high burden of illness in these remote populations, supports the need for more detailed research.

Methods

Results

Demographic and clinical characteristics

313 patients’ data were analysed. Slightly over three-quarters were male, and two-thirds identified as Aboriginal or Torres Strait Islander. Gender ratios were similar across Indigenous and non-Indigenous groups. Indigenous patients were significantly more likely to live remotely, be prescribed an LAI and use some substances (see Figure 1 for details). Engagement was primarily through the government mental health service (90% of the group). The remainder were managed by the specialist Non-Government Organisation (NGO) early intervention service, although it was only initiated halfway through the study period in 2015, and numbers are likely underrepresented.

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Figure 1.

Summary of demographics and associated characteristics across Indigenous and Non-indigenous groups.

Psychosis incidence

High rates of first episode psychosis were observed within the Top End 15–24-year-old demographic. This number trended upward during the study period with a mean of 44.7 new cases per year, reaching a total of 313. Incidence was calculated on the 2016 census year, yielding an overall rate of 203 per 100,000 person-years.^14,15 Aboriginal or Torres Strait Islander people were disproportionately more likely to present with psychotic symptoms per capita, with 34 new cases in 2016 equating to a rate of 435 per 100,000 person-years. The incidence in the non-Indigenous population was 95 per 100,000 person-year.

See Figure 2 for full details.

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Figure 2.

Hospitalisation, Service Utilisation, and associated characteristics.

Young people presenting with FEP had a mean of 1.55 admissions (median = 1) during the 2-year follow-up period. This ranged between zero and six admissions, with no statistical difference between ethnicities (p = .376).

The mean number of hospitalisation days for the whole sample was 25.6 days over the first two years’ service engagement. Aboriginal or Torres Strait Islander patients experienced significantly longer (p = .008) admissions (Median = 21 days, Mean = 26.92 (SD 25.24)) than other Australians (Median = 14, Mean = 22.83 (SD 25.17)). There were no statistical differences between the sexes on either the numbers or durations of hospitalisations.

Regional differences were compared between RA3 ‘urban’, and RA4-RA5 ‘remote’ locations. Presentations from the RA4 and RA5 areas accounted for over half of the total sample (55%) and had a predominantly Indigenous demographic at over 76% of remote presentations (p < .001). Remote status was associated with a significantly higher number of total days hospitalised (Median = 21, Mean = 26.6 (SD 23.27), when compared with youth from an urban area (Median = 14, Mean = 24.30 (SD 27.57, p = .006). The number of admissions did not significantly differ between geographical locations. The urban sub-population engaging the specialist NGO service had significantly lower service utility outcomes in comparison with the wider population (p < .001), with 10.5 days mean hospitalisation (Median = 0) and 0.84 mean admissions (Median = 0) over the study period.

Over half of the study population were taking an antipsychotic at 12 months from index presentation, with 35.78% using an LAI antipsychotic. No statistically significant differences were found in the frequency of LAI use in Indigenous versus non-Indigenous youths, or the frequency and duration of hospitalisations based on antipsychotic use. There was a relatively low use of community treatment orders (CTO) of 12.46%, predominantly applied to non-Indigenous youth, with no statistical difference in CTO use between ethnicities. Although difficult to interpret, this relatively low use of CTOs likely reflects challenges with implementation in a regional and remote setting, leading to lower overall use in this population.

Substance use was noted to be high among the study population, with 83.4% of youth having a clinically relevant substance use pattern at the time of service engagement, although this was not associated with increased service utilisation. Aboriginal and Torres Strait Islander peoples were statistically more likely to use cannabis (p = .001) and volatile substances (p < .001), while non-Aboriginal Australians were more likely to use amphetamines (p = .005).

Discussion

To our knowledge, this is the first study that explores in-depth the characteristics of first episode psychosis and its medium-term trajectory within the context of the Top End of the NT. This research sought to better understand the high incidence of psychosis in this region, and the factors that contribute to this, as well as the impact on service delivery outcomes. The Top End of the NT is a complex public health landscape, typified by having a large Indigenous population and disproportionate burden of disease in terms of both overall health outcomes and substance use patterns.

This study demonstrated a substantially elevated incidence of FEP, with rates approximately double those of age-matched populations in other major Australian cities. ¹⁶ Aboriginal youth face a disproportionate burden of this disease, with a rate of over four times that of the wider non-Indigenous NT population. These findings are consistent with other studies from the NT showing elevated incidence of FEP among Indigenous peoples, ¹⁷ as well as studies noting elevated rates of psychosis in Aboriginal people of North Queensland.^6,7 Similar disparities in FEP incidence rates within study populations have been observed in other Australian research, with up to 65% higher treated incidence rates in populations from more socially deprived areas. ¹⁸ The elevated incidence of FEP observed in this study also corresponded with higher requirements for hospitalisation for Indigenous peoples, although there is insufficient research to compare with other Australian populations.

While a geographic divide between urban and rural areas was demonstrated in this study, the two days longer hospitalisation for regional patients was likely influenced by the predominantly Indigenous demographic in these areas. Indigenous Australians from urban areas also required greater amounts of hospitalisation relative to non-Indigenous, suggesting a wider ethnic disparity beyond simply an urban-rural divide. The population subset treated under the exclusively urban-based specialist NGO service showed the least requirements for service utility for both Indigenous and non-Indigenous people. This potentially reflects the clinical efficacy of this service delivery model, although this outcome is likely influenced by a comparatively more rigorous admissions selection process favouring higher functioning and lower acuity patients in an earlier stage of illness.

Both the high incidence and elevated hospital burden for psychosis among Indigenous Australians likely has a multifactorial genesis. The adverse health implications of entrenched social and economic disadvantage faced by Indigenous Australians are well established. ⁴ Present academic literature links developmental factors such as childhood adversities, history of obstetric complications, stressful events during adulthood, and low developmental serum folate level with the development of schizophreniform illness. ¹⁹ This transcends other metrics associated with reduced health outcomes, such as geographic isolation.

Over 83% of the study population had a clinically significant substance use issue at the time of service engagement. Use of cannabis was substantially higher than some other Australian FEP cohorts at 78.2%, while use of amphetamines was lower at 14%.^20,1 Despite this, our study was unable to establish an association between substance use patterns and an increased need for hospitalisation during the study period. It is likely that a high overall use pattern in the general population contributed to the lack of a definitive statistical relationship with hospitalisations, even for well-evidenced risk factors for psychosis such as cannabis. ¹⁹ The elevated prevalence of cannabis use in the FEP population is corroborated by empirical wastewater testing data, with regional NT having the highest per capita cannabis consumption in Australia. ⁵ This is suggestive that the broader pattern of substance use is a problem that extends beyond the FEP cohort. It is probable that further research distinguishing patterns of ongoing substance use would be required to discern if there is a definitive link between this and FEP service engagement.

While the use of either oral or LAI antipsychotic treatment at 12 months was over 50%, this was not shown to be statistically associated with rates of hospitalisation in this study. Use of an LAI treatment appeared high at over one third of the population, although this was not effected by ethnicity. Studies from similar populations in North Queensland indicate much higher rates of LAI use at over 69% among Aboriginal or Torres Strait Islander peoples, suggesting use of LAIs is a broader clinical approach across regional areas in Northern Australia. ⁶ Over half our study population was Aboriginal and from a remote area, inclining treatment in this direction. The lack of a definitive effect on hospitalisation appears to contradict large-scale international data demonstrating clear reductions in re-hospitalisation rates on LAI treatment. ²¹ It is probable that this difference reflects challenges in remote service delivery, challenges in follow-up, and case complexity rather than a unique response to medications in this population. Inconsistency in LAI effect has been recognised in other populations, where higher use of LAI treatments were typically applied to cases of more severe illness and therefore poorer outcomes. ²² Primary health records were often not accessible for remote patients, which likely obscured the difference between patients in remission, and those without access to recommended treatment. In this context, it is difficult to conclusively comment on the association between current treatments and hospitalisation in this population.

Although not a primary outcome variable, it is noteworthy that 12.4% of the study population were treated under a community treatment order during the study period. There was a small trend toward non-Indigenous youth being placed under an order, although this was not statistically significant. This is lower than the 17% treatment order rate recorded in other Australian FEP studies, ²³ as well as Canadian rates of over 19%. ²⁴ We hypothesise that challenges with implementing CTOs in a remote setting likely has the biggest influence on these discrepancies. This is supported by studies from remote Central Australia, which show ever lower rates of CTO of 2.8%. ²⁵

The rate of completed suicide in the study was 1.3%. Overall, this is roughly consistent with national prevalence estimates of suicide in FEP between 1 and 3% over a 4-5 year follow-up period. ²⁶ Of this cohort however, it is noteworthy that 75% were Aboriginal or Torres Strait Islander, suggesting additional risk and severity within this population although it was not possible to draw statistical significance with this sample size.

Conclusion

This study demonstrates elevated incidence rates of FEP in youths in the Top End of the NT between 2012 and 2018, with Aboriginal and Torres Strait Islander Australians experiencing a disproportionate burden of disease. This incidence is also greater than in the non-Indigenous population and urban populations elsewhere in Australia. This likely increased the requirements for hospitalisation during the initial 2-year period from service engagement, with both Indigenous ethnicity and remote geography being significant risk factors. The relationship between psychosis and broader sociocultural factors is complicated. This needs to be better understood through further research. However, FEP is a crucial issue in this region, and concerted efforts and resources should be targeted to support this high-risk group.