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Study Details


Study Design.
Study procedures.


Secondary objectives

Study Design

The IDACC study design included a nested randomised controlled trial within a prospective cohort study of hospitalised cardiac patients.

The prospective cohort study enabled the prevalence and natural history of depressive symptoms to be monitored during the year after hospitalisation for a variety of cardiac conditions. Depressive symptoms were identified using depression screening tests.
The nested randomised controlled trial was designed to test whether identification of depression followed by provision of expert advice and support for GPs in the management of depression in cardiac patients was effective in reducing depression and improving other outcomes during 12 months of follow-up.
A qualitative study of a small subset of depressed cardiac patients, their GPs, psychiatrists, cardiologists and cardiac rehabilitation nurses was conducted.
Depression screening was also conducted in a representative community survey undertaken in parallel with the IDACC study.

Setting and Participants

Men and women were eligible to participate in the study if they were
(a) admitted to a cardiac unit in one of the 4 major teaching hospitals in Adelaide, South Australia during the IDACC study period from Aug 2000 to Dec 2001, with a 6 month extension in one hospital:
Royal Adelaide Hospital (Aug 2000 - Dec 2001)
Flinders Medical Centre (Oct 2000 - June 2002)
The Queen Elizabeth Hospital (Feb 2001 - Dec 2001)
Lyell McEwin Health Service (Mar 2001 - Dec 2001)

(b) with cardiac admission reason:

(c) and aged 18 - 84 years.

Patients were excluded from the study if language difficulties prevented them from completing the self-report questionnaires, or they had serious physical or cognitive impairment.

Of 3358 patients assessed for eligibility, 1245 were excluded primarily due to inability to complete questionnaires in English (35%), severe cognitive or physical impairment (40%), or participation in other trials (21%). Of the 2113 assessed as eligible and approached, 531 refused to participate, resulting in a cohort of 1541. The consent rate was 73%.

Details of study participant characteristics have been described in Cheok et al. 2003. A comparison of consenters and non-consenters showed that non-consent was associated with being older and female (p<0.001).

The IDACC study protocol was approved by the Human Research Ethics Committees of each participating hospital.

Study procedures

Project Assistants approached patients who fitted the eligibility criteria criteria after the first day of admission to hospital and invited them to participate in the study. Patients who consented completed tick-box questionnaires including depression screening tests, assessments of general health and wellbeing (eg. quality-of-life, perceived social support) and experience of traumatic events.

Depression Screening Tests

IDACC recruits were classified as `Not depressed' or `Depressed' according to their baseline scores on the Center for Epidemiological Studies Depression Scale (CES-D) and Hospital Anxiety and Depression Scale (HADS). Higher scores indicate more symptoms of depression. Both instruments have been validated and widely used in cardiac and older populations with comorbid physical health problems. Both tests have good test-retest reliability.

Patients were classified as `Depressed' if they scored above standard threshold scores scores:

Prospective cohort study of cardiac patients.

All patients who consented to participate were followed-up with further questionnaires posted at 3, 6 and 12 months after hospitalisation. Details of questionnaires are shown in Table 1.

Table 1. QUESTIONNAIRE DATA collected from patients

Aspect(s) measured
Collection time (months):
Emotional Health
(Depression screening questionnaires)
Current depressive symptomatology
Present state anxiety and depressive symptomatology
Severity of depression
Health and Wellbeing
Health-related quality of life
Health status
Generalised dispositional optimism (`life orientation')
Perceived social support
Cardiac and depression risk factors
Traumatic Events
PTSD module- CIDI
Lifetime occurrence of traumatic events
Symptoms of post-traumatic stress

1 For full names and details of measures, see Questionnaires
2 The BDI-11 was completed by all patients identified as depressed according to their score on the CES-D and HADS Emotional Health questionnaires at baseline (screening), and also by some non-depressed patients for the purpose of comparison.


Reply paid envelopes were provided to patients for the return of all questionnaires. Non-respondents were contacted twice by mail and also by phone (as per the method of Dillman DA. Mail and internet surveys: the tailored design method. 2nd ed. Chichester NY. John Wiley; 2000).

Randomised controlled trial of an intervention for depression in cardiac patients

Everyone classified as `Depressed' at baseline was randomised to the intervention or control (`usual care') group of the trial via a central telephone randomisation system. Randomisation was based on the GP caring for them.

Control (`usual care')

Patients randomised to the Control or `usual care' group were followed up by postal questionnaire at 3, 6 and 12 months. The IDACC research team did not initiate any contact with the GP.


In addition to usual care:
1. The patient was referred to be seen by the hospital Liaison Psychiatrist and Cardiac Rehabilitation Nurse
2. The General Practitioner (GP) was notified that depressive symptoms had been reported, and providing copies of the patient's depression screening tests along with evidence based guidelines for managing depression in cardiac patients i.e. GP Education.
3. Psychiatrist advice was provided to support GP management of comorbid depression via Case Conference or Telephone Advice.

1. Referral to Liaison Psychiatry and Cardiac Rehabilitation Nurse

Intervention patients were referred to be seen by the hospital Psychiatry Liaison registrar and also the Cardiac Rehabilitation Nurse. Each completed a form detailing psychological or cardiac issues for the patient. This form was developed for the IDACC study as a template for the Case Conference discussion with the GP. The cardiac rehabilitation nurse gave IDACC intervention patients an information brochure titled Heart Disease and your emotional health.
(NB. Discharge was not delayed if these consultations had not taken place. Patients who returned their questionnaires in the post after discharged could not be referred for these visits).

2. GP Education

Each GP received a copy of their patient's depression screening tests results (CES-D and HADS), along with an information booklet (Depression and Heart Disease, Guidelines for management in General Practice) providing evidence based advice for the management of depression with comorbid cardiac disease.
Details were also provided about Case Conferencing using the new Enhanced Primary Care (EPC) Package, the reimbursement procedure, and a blank copy of a Case Conference Checklist. (Details of the Enhanced Primary Care Package can be found at )

3. Case Conference

If the patient was seen by both the Liaison Psychiatrist and the Cardiac Rehabilitation Nurse prior to discharge from hospital, the IDACC Project Coordinator attempted to schedule a telephone case conference between the GP, Liaison Psychiatrist and Cardiac Rehabilitation Nurse.
The telephone case conference lasted 15-30 minutes, during which the patient's scores on the depression screening tests were discussed, as well as any specific issues noted by the cardiac nurse or psychiatrist, and a management strategy developed.
The GP was offered further assistance in the form of:

Alternative Intervention: Psychiatrist Telephone Advice Call

During the early stages of the IDACC trial, it became evident that even with substantial infrastructure supporting the project, multidisciplinary case conferences were difficult to implement. An `alternative intervention' was introduced from November 2000 to provide support to GPs whenever a case-conference could not take place.
If the patient was discharged from hospital before being seen by both the Liaison Psychiatrist and the Cardiac Rehabilitation Nurse, or no mutually convenient time for a case conference could be arranged, then a Case Conference could not take place within the EPC requirements.

The IDACC psychiatrist Chief Investigator contacted the GP to provide brief telephone advice about managing depression as a comorbid condition. The psychiatrist had not seen the patient, but engaged the GP in a discussion based on the GPs knowledge of the patient's history and view of the patient's current depression scores. The discussion generally lasted 5-10 minutes.


The GP was also offered further assistance:

If a Case Conference or Telephone Advice was not able to be delivered, then GP Education was the only component of the intervention provided to the GP.

GP Feedback Survey and IDACC 3 month follow-up
After the intervention patient had returned the IDACC questionnaire sent 3 months after discharge from hospital, the depression test results (CES-D and HADS) were copied to their GP. Additional supports were again offered to the GP eg. psychiatrist telephone advice, a fast tracked psychiatrist appointment, or access to free CBT sessions for the IDACC patient.
A `GP Feedback Survey' form was posted to intervention GPs, along with the 3 month follow-up information, during the period from June 2001 to December 2001. GPs received one questionnaire for each IDACC patient. The survey sought information on the GPs' perceptions and actions in relation to their patient's depression, and their views about the IDACC trial. Reply-paid envelopes were provided with the survey, but no follow-up was undertaken for non-returned questionnaires.
No further contact was initiated with the GPs by the IDACC study team after the 3 month follow-up stage.


Depression categories based on standard CES-D depression threshold scores:
Not depressed CES-D < 16
Mild depression CES-D 16 - 26
Moderate to severe depression CES-D > 26.
Categories were used for data analysis for the following reasons: (a) Clinical usefulness, as clinicians may base management decisions on these categories; (b) evidence of adverse outcomes associated with depression categories; (c) the skewed distribution of the depression scales raw scores.
Sample size
A sample size of 183 randomised to each arm of the trail was calculated to be required to detect a 15% difference in the level of moderate to severe depressive symptoms at 12 months, between the intervention and control groups, assuming a spontaneous resolution of 50% of depressed cases (Schleifer et al. 1989) using a Chi-squared 2 sided test with alpha of 0.05 and 80% power.
Statistical Analysis:
Results were analysed using SPSS for Windows (version 11.0) and STATA (version 7.0). Analyses performed included unpaired t-tests to compare means, Chi-squared tests to assess differences in prevalence of depressive symptoms between groups, linear regression and logistic regression analysis to analyse treatment effects and prediction of outcomes.

Additional IDACC Study components

Qualitative and other Feedback
An independent qualitative researcher conducted a series of semi-structured face-to-face interviews and focus groups to gather qualitative data on the experiences and opinions of a small random sample of study participants and their GPs, and hospital staff who had participated in the study.
The interviews and focus group sessions were taped and transcribed, and the information was analysed for essential themes.

Economic Evaluation - the cost of comorbid depression.
Economic evaluation will determine the cost of comorbid depression on utilisation of health services including hospital admissions, pharmaceuticals and medical services.
Data was gathered from various sources. Mortality and hospital readmissions were accessed for the 12 months after the patient's hospitalisation by data linkage with the register of Births, Deaths and Marriages and to the state health department Integrated South Australian Activity Collection (ISAAC). Patients' usage of services covered by the Medicare Benefits Scheme and the Pharmaceutical Benefits Scheme for the period two years prior and one year after their cardiac hospital admission was collected from the Health Insurance Commission. Patients gave additional consent for this information to be accessed.

The economic evaluation will compare the health care related costs for `depressed' and `not depressed' cardiac patients and assess the impact of the study intervention on costs and outcomes including quality of life. An analysis of the sustainability and generalisability of the IDACC intervention from various perspectives such as service costs, barriers and facilitators to implementation and application, system capacity and organisational implications, is also planned.

The Assessment of Quality of Life (AQoL) utility measure will be used in the economic analyses.

Communtity Survey
A comparison was undertaken between the hospitalised IDACC participants and a community sample.
A Health Omnibus Survey was conducted in October/November 2000 and provided information about the prevalence of depressive symptoms and cardiovascular illnesses in the community. This incorporated the CES-D depression questionnaire, and questions relating to cardiovascular illness and risk factors. Age and sex standardisation enabled characteristics of the community sample and IDACC study participants to be compared.
The Health Omnibus Surveys ( ) routinely collect health-related data from the community. The survey is administered to a metropolitan and rural community sample of 4,400 households by face-to-face interview.
Phone: (08) 8226 6024
Fax: (08) 8226 6700
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