Mental health and addiction information in the IDI

This guide provides an overview of the range of mental health and addiction data in the IDI as at August 2019. Key sources of mental health and addiction information are described along with some of the strengths and limitations of these datasets. Major gaps in mental health and addiction information are also discussed.

Background

Mental distress, mental illness, and addictions are common. It is estimated that each year approximately 20% (1 in 5) New Zealanders experience significant mental distress (Cunningham et al 2018). Internationally there is well-established evidence of a “treatment gap” where the majority of those with diagnosable mental illness do not receive formal treatment (Kohn et al, 2004).

Currently in New Zealand, district health boards and non-governmental organisations (NGOs) provide specialist (secondary and tertiary) mental health and addiction care to approximately 4% of the population. This represents the group with the highest mental health needs and with mental health problems that are likely to be most disruptive to their lives. The vast majority (over 90%) of this care is provided in community settings. A small number of inpatient beds are available and are mostly used for short stays. This care includes mainstream as well as services using Māori and Pacific service models.

The majority of formal mental health care in New Zealand is provided in a primary care setting by general practitioners and other primary care staff. Data from 2004 indicated that each year approximately 9% of the New Zealand population visit a general medical health provider for a mental health problem (Oakley Browne et al., 2006), and this is likely to have increased in the intervening period.

While most psychiatric care in New Zealand is publicly funded, there are some private mental health services in New Zealand. These are mainly community services, where psychiatrists and clinical psychologists provide care for those not meeting the high severity criteria for specialist public care.

What data can I find in the IDI?

The key IDI dataset for mental health information is Programme for Integration of Mental Health Data (PRIMHD, formerly MHINC), and this is described below. In addition to PRIMHD there are a range of other administrative and survey datasets in IDI that contain mental health information. These are summarized in Table 1.

PRIMHD

The PRIMHD dataset is the key mental health data collection in IDI. It records all service uses for publicly funded specialist mental health and addiction services nationally. This includes all publicly funded inpatient and community based services, including children, young people’s, and NGO mental health services. PRIMHD does not include primary care mental health services. At the time of writing PRIMHD data in IDI was available from July 2008 to end 2017. Similar information for the years 2000-2008 is available in MHINC.

In IDI the PRIMHD data is split into three parts: the main PRIMHD dataset containing information about service use; the diagnosis dataset containing formal psychiatric diagnoses (DSM, ICD); and the legal status dataset containing information about compulsory mental health care. An additional dataset also contains supplementary consumer record information.

PRIMHD includes the date, location and provider for all contact episodes. It also includes some information on the type of service provided. Records in PRIMHD can relate to a wide range of service types^[1] including face-to-face treatment contacts, assessments, inpatient and residential bednights, family support contacts where the client may or may not be present, phone calls, text messages and letters. Many data users are interested in distinguishing ‘face to face’ or ‘treatment’ service contacts from assessments, phone calls and other types of contacts that are recorded in PRIMHD. This is not straightforward and relies on a combination of activity type and activity setting codes. The code examples accompanying this guide demonstrate one way to define ‘face to face’ contacts.

[1] https://www.health.govt.nz/publication/guide-primhd-activity-collection-and-use

Table 1. IDI datasets containing mental health information

Dataset	Description of contents	Mental health information available	Time period covered
PRIMHD / MHINC	Publically funded service uses for specialist mental health and addiction services in NZ	Information about service use (eg date, service type, team, provider)	PRIMHD July 2008-
			MHINC 2000-June 2008
		Diagnosis information	Diagnosis 2000-
		Legal status information for treatment provided under relevant acts	Legal status July 2008-
		Supplementary consumer records	Supplementary consumer records 2016-
Public hospital discharges (NMDS)	Discharges from publically funded hospital admissions	Admissions to mental health inpatient facilities (also recorded in PRIMHD)	1998-
Public hospital discharges (NMDS)	Discharges from publically funded hospital admissions	Mental health and addiction diagnoses (ICD-9 / ICD-10) may be recorded against admissions	1998-
Pharmaceutical Collection	Community dispensings of publicly funded medications in New Zealand	Date, cost, detailed information about type of medication dispensed	2005- (data are most reliable from 2007 onwards)
Mortality	Underlying cause of death for all deaths in NZ	Date of death (month and year), ICD codes for cause of death	1998- (latest records delayed by 2 to 3 years)
NNPAC	Publically funded medical, surgical and ED outpatient visits	Date of attendance, type of service provided (purchase unit)	2007-
ACC	Injury claims	Flag for self-inflicted injury	1994-
SOCRATES	Needs assessments for disability support services	Diagnostic dataset contains some mental health diagnoses	2003- (data are most reliable from 2010 onwards)
MSD Benefits	Administration of social welfare benefits	Incapacity codes include some mental health conditions	1992-
Auckland City Mission	Use of Auckland City Mission Services	Use of detoxification and crisis services, requests to see mental health nurse, drug and alcohol use	One-off extract as at 30 April 2016
Survey of Family, Income and Employment (SoFIE)	Panel survey of work, family, household and economic circumstances	Health module in waves 3, 5 and 7 contained Kessler-10 (K-10) scores and questions about alcohol use	8 waves spanning October 2002 to September 2010
General Social Survey	Nationally representative survey of wellbeing	SF-12 (mental health, mental distress and functioning)	2008, 2010, 2012, 2014 and 2016
Te Kupenga.	Post-censal survey of Maori wellbeing	Mental health, life satisfaction, spirituality, social connectedness	2013

Limitations and Gaps

The majority of IDI mental health and addiction data sources record service use. Using these data sources it is possible to reliably identify individuals who are using publicly funded specialist mental health and addiction services and individuals who die by suicide. This cohort is likely to over-represent people who have the most severe and disruptive illnesses; the majority of formal mental health care, especially for mild to moderate problems, occurs in a primary care setting and this information is not available in the IDI. In addition, it is possible to identify individuals who have received mental health pharmaceuticals, but care should be taken with this approach as many pharmaceuticals have uses that are unrelated to mental health and there is a risk of over-counting the mental health service use population. Combining those using secondary specialist services with those prescribed medications will produce a very heterogeneous cohort.

Private (patient funded) treatment such as visits to psychiatrists, clinical psychologists, and counsellors, is not captured in the IDI. There are also a range of NGOs that provide mental health care that is not funded from the mental health budget; this data is not included in PRIMHD and is not available in the IDI.

Not all DHBs report mental health treatment for people aged over 65 to PRIMHD and therefore coverage for this age group is incomplete. Coverage is more complete for Northern and Midland DHB regions.

Further information

This guide is a condensed version of ‘Guide to Mental Health and Addiction Data in IDI’, available on the VHIN website. This document contains a more detailed description of the data sources and their limitations, along with links to data dictionaries and other documents containing additional information.

The code examples accompanying this guide provide examples of of identifying suicides, self-harm hospitilisations, schizophrenia diagnoses, and mental health service use events including inpatient bednights, forensic bednights, rehab/residential/respite bednights, and community clinical and support contacts.

New users of mental health data in IDI are strongly encouraged to read the full version of the guide, the relevant data dictionaries and to seek advice from MoH, mental health researchers or clinicians before starting their work.

Summary

The IDI contains a range of information about mental health and addiction data. Most of this information is mental health service use data, especially specialist mental health service use that captures the 4% of people with the most severe mental health problems. Therefore, we are likely to miss individuals with less severe problems and those who do not seek treatment. Pharmaceutical dispensing data can be used to identify individuals who are being treated in primary care, but many mental health pharmaceuticals have other (non-mental health) uses and there is a risk of over-counting when using this method.