Pareto’s law of the vital few: Patient requirements for hospital based non-acute care

Introduction

There has been debate in Australian & New Zealand Journal of Psychiatry (ANZJP) about the required numbers of psychiatric beds in Australia (Allison et al., 2019; Benjamin et al., 2018). While debate has focused on acute beds, Australia also has relatively few hospital based adult non-acute beds (10 per 100,000 persons, according to the Australian Institute of Health and Welfare: www.aihw.gov.au/reports-data/health-welfare-services/mental-health-services/overview). In contrast, the World Health Organisation (www.who.int/mental_health/evidence/atlas/mental_health_atlas_2017/en/) reports that high-income countries have 31 beds per 100,000 in stand-alone mental health hospitals, while Europe has 34 per 100,000.

The Royal Australian and New Zealand College of Psychiatrists (RANZCP) Faulty of Adult Psychiatry endorsed a major submission from 48 psychiatrists to the Royal Commission into Victoria’s Mental Health System, which recommends increasing the state’s hospital based adult non-acute beds from 3 per 100,000 to around New South Wales’ (NSW’s) level of 14 per 100,000 – with new beds in university-linked ‘Mental Health Rehabilitation Centres’ that would ‘facilitate much needed research on treatment-resistant psychiatric conditions, and on optimal psychosocial practices in rehabilitation psychiatry’ (The Adult Psychiatry Imperative: https://s3.ap-southeast-2.amazonaws.com/hdp.au.prod.app.vic-rcvmhs.files/2915/6765/3776/The_Adult_Psychiatry_Imperative.pdf). Hospital based non-acute care is designed to reduce the adverse outcomes associated with chronic treatment-resistant illness (Sisti et al., 2015).

Western Australia: the consequences of closing non-acute beds

Western Australia (WA) is following the contrary policy of reducing hospital based adult non-acute bed numbers below the national average. From 2010/2011 to 2016/2017, the WA government closed 55 beds (going from 134 to 79) – a 45% reduction from 9 to 5 beds per 100,000. Closing out-dated beds without commissioning new beds risked patients having longer rehabilitation stays on acute wards that are not designed for this purpose. Such long stays reduce flow to the acute wards, increasing access block in the emergency departments (EDs).

During this period of bed closures, demand was rising on WA’s EDs with a 61% increase in mental health presentations from 2013/2014 to 2017/2018 (compared to a national increase of 5%, according to the Australian Institute of Health and Welfare). Access to inpatient care was limited, with a 90th percentile ED length of stay (LOS) of over 15 hours in 2017/2018, 23% above the national average of 12 hours. Over 2,000 patients had 3 or more ED visits in the week before admission in 2013/2017. During the month of August 2019, 156 mental health patients spent over 24 hours in an ED waiting for a bed with the longest stay being over 100 hours.

In a recent report to Parliament, the Western Australian Auditor General (https://audit.wa.gov.au/) identified 1,500 adult mental health patients who had hospital inpatient stays of 100 days or more during 2013/2017. Their diagnostic profiles were not reported, but probably included adults with treatment-resistant mental illness, and older adults with cognitive impairment and aggression. Of these, 126 patients stayed for 12 months or more in acute bed, reducing available capacity by 83,000 inpatient days, at an estimated cost of AUD$115 million: acute beds are the most expensive option for non-acute care. Another 158 patients had multiple acute admissions that totalled 365 days or more. The Auditor General concluded ‘These long stays mean that hospitals must operate with less capacity for people who also need urgent access to care, reducing the availability of services overall’ (p. 9).

Vilfredo Pareto would not have been surprised that a few patients need disproportionate amounts of hospital care. Pareto was an Italian economist who observed that 80% of a country’s wealth was owned by 20% of the population (Burton et al., 2018). His observation has been variously described as the Pareto principle, the 80/20 Rule, the power law phenomenon and the ‘law of the vital few’. The phenomenon is characterised by non-uniform exponential distributions whereby a few ‘causes’ have disproportionately large ‘effects’ (Wright and Bates, 2010). In healthcare, high utilising cohorts use considerable amounts of the available resources (Burton et al., 2018). For example, the WA Auditor General found 10% of the total number of mental health patients (21,000 people in a 5-year period) used 90% of all inpatient care, and 50% of all emergency and community mental health services. This high utilising cohort of state mental health services represented only 0.8% of WA’s total population.

Conclusion

WA’s Auditor General has focused attention on the vital few – the high service utilising group that present frequently to EDs, and have repeated or extended hospital stays. While bursts of ED activity may settle, a small number of patients need long-term inpatient care. Insufficient non-acute beds can result in patients having extended stays on acute wards for treatment-resistant conditions that are associated with high levels of aggression. Detailed audits of the demographic, diagnostic and risk profiles of the vital few in state mental health services around Australia could better inform future policy on non-acute care.