Estimating the number of people with psychotic illness treated by public specialised mental health services

The 2010 national survey of psychotic illness provides information on the prevalence of psychotic disorders and the number of people receiving treatment. The prevalence is the proportion of people in the population who meet criteria for a diagnosis of these disorders at a given point in time.

Prevalence was determined for Australians with an ICD-10 psychotic illness in contact with public specialised mental health services in March 2010 and in the eleven months prior.

In March 2010, an estimated 3.1 cases per 1,000 population aged between 18 and 64 years had a psychotic illness and were in contact with public specialised mental health services.

The prevalence of psychotic disorders was higher in males than females (3.7 cases per 1,000 compared to 2.4 per 1,000) (figure 1).

Males aged 25-34 years had the highest rates of psychotic illness (5.2 cases per 1,000).

• Almost 8,500 men in this age group were estimated to be in contact with publicly funded mental health services.
• The age groups with the next highest prevalence for males were those aged 35-44 and 45-54 years.

For females prevalence was more even across age groups at almost 3 cases per 1,000 population in those aged between 25 and 54 years.

• Young females aged 18-24 years had the lowest prevalence rates at 1.6 cases per 1,000 population.

Prevalence was also estimated for the 12-month period at 4.5 cases per 1,000 population. Scaled to the national level, this suggests that almost 64,000 people aged 18 to 64 years have a psychotic illness and are in contact with public specialised mental health services in a year.

Types of disorders

The most common psychotic disorder was schizophrenia (47.0%), accounting for the majority of males (56.3%) and one third (33.2%) of females (figure 2).

Age of onset

Two thirds (64.8%) of people experienced their first episode before the age of 25 years.

For 32.3% of males and 38.2% of females, onset was on or after 25 years (figure 3).

The mean age of onset was 23 years for men and 24 years for women.

For 29.1% of people the onset was gradual, taking between one and six months, and for 42.2% it took more than six months to develop.

Figure 1: One-month treated prevalence in specialised public mental health services by sex

Text version of figure 1

Age (years)	Males - Prevalence (cases per 1,000)	Females - Prevalence (cases per 1,000)
18 - 24	2.5	1.6
25 - 34	5.2	2.6
35 - 44	4.7	2.8
45 - 54	3.7	2.7
55 - 64	1.8	2.2
All	3.7	2.4

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Figure 2: Diagnostic profile of ICD-10 psychotic disorders

Text version of figure 2

Proportion of diagnostic profile of ICD-10 psychotic disorders:

• Schizophrenia - 47.0%
• Bipolar, mania - 17.5%
• Schizoaffective disorder - 17.5%
• Severe depression without psychosis - 8.7%
• Delusional, other non organic psychoses - 5.0%
• Depressive psychosis - 4.4%
• Other - 1.4%

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Figure 3: Age of onset by sex

Text version of figure 3

Age (years)	Males - Proportion (%)	Females - Proportion (%)
Under 15	4	7.9
15 - 19	35.9	30.8
20 - 24	27	22.9
25 - 29	14.8	12.6
30 - 34	8.3	10.7
35 - 39	3.4	6.2
40 - 44	2.4	4.1
45 - 49	2.1	2.6
50 - 54	0.6	1.6
55 - 59	0.4	0.4
60 - 64	0.3	-