Prediction of future episodes of depression in primary medical care: evaluation of a risk factor profile (PREDICT)

Lead Research Organisation: Medical Research Council

Abstract

Depression will rank second to heart disease as a global cause of disability by 2020. It occurs in up to a quarter of general practice attendees and relapse is frequent up to 10 years from first presentation. The likelihood of depression is determined by a persons exposure to certain risk factors such as low social status, being female, unemployment, work stress, and poor housing. There is a need to estimate the overall risk to help prevent depression, but there is a lack of reliable or valid ways of doing this. In all countries the study will prospectively recruit consecutive general practice attendees that will then be followed up after six and 12 months. PREDICT will develop and test a risk estimation tool across six European and one South American country. The accuracy of the tool in each setting will be compared.

Technical Summary

Prevention of depression must address multiple risk factors. Estimating overall risk across a range of putative risk factors is fundamental to prevention of depression. However, we lack reliable and valid methods of risk estimation. PREDICT, is an international research study to address this risk estimation.

This is a prospective study in which consecutive general practice attendees in six European countries are recruited and followed up after six and 12 months. The study will aim to test the following hypotheses:

1) A reliable and valid multi-factor scale can be developed to determine the risk for the onset and maintenance of depression in primary care attendees
2) The overall risk equation derived from data for all countries combined will have similar accuracy in prediction episodes of depression for each country

Prevalence of depression is assessed at baseline and each follow up point. Consecutive attendees between April 2003 and September 2004 who were aged 18 to 75 were asked to take part. The presence of a depressive episode was assessed using the Depression Section of the Composite International Diagnostic Interview. A selection of presumed risk factor questions that were developed specifically, or adapted, for the PREDICT study. In a separate reliability study conducted between January and November 2003, consecutive general practice attendees in the six participating European countries completed the risk factor items on two occasions, two weeks apart. The overall response rate at entry to the study was 69%. We exceeded our expected recruitment rate, achieving a total of 10,048 people in all. Reliability coefficients were generally good to excellent.

Response rate to follow-up all countries was uniformly high, which suggests that prediction will be based on almost a full cohort. The rules of our reliability analysis are encouraging and suggest that data collected during the course of PREDICT will have a satisfactory level of stability. The development of a multi-factor risk score for depression will the foundation for future research on risk reduction in primary care. Our data will also provide the necessary evidence base on which to develop and evaluate interventions to reduce the prevalence of depression.

This study was funded by the European Commission V Framework Public Health Initiative for Quality of Life and has been developed as a collaboration between GPRF and the UCL.

Publications

10 25 50