Predictive Outcome Validity of General Health Questionnaire (GHQ-28) in Substance Abuse Patients Treated in Therapeutic Communities

Abstract

Objective: The use of psychoactive substances has been one of the most important global public health problems over the last few decades. Among the problems associated with substance use, dual diagnosis is one of the most relevant. This study aims to investigate the predictive validity of the GHQ-28 (General Health Questionnaire-28; “probable psychiatric cases”) in relation to poor treatment outcome measured by (a) “early treatment dropout” and (b) “nonclinically relevant improvement at discharge.” Methods: A longitudinal prospective design was used. A sample of 219 substance use disorder patients, who received treatment in a therapeutic community, was selected. Patients were assessed using the GHQ-28 and the outcome variables were registered. A hierarchical logistic regression model was performed to identify factors independently associated with the outcome measure (“early treatment dropout” and “nonclinically relevant improvement at discharge”). Results: Of the total sample, 79 subjects (36%) were considered “early treatment dropouts” and 56.6% (102) presented a “nonclinically relevant improvement at discharge.” The two hierarchical logistic regression results show that being classified as a “probable psychiatric case” was significantly and directly associated with “early treatment dropout” and “nonclinically relevant improvement at discharge,” as a poor in-treatment outcome indicator. Conclusions: The results of this study support the notion that the probable psychiatric cases identified by the GHQ-28 scale have a greater probability of “early treatment dropout” and have a greater probability of “nonclinically relevant improvement in discharge” of the therapeutic community. These data indicate that GHQ-28 is a suitable clinical instrument for predicting dropout and treatment effect in residential substance use disorder treatment.

KEYWORDS:

• GHQ-28
• substance abuse
• dual diagnosis
• predictive validity
• therapeutic communities
• outcome variable

Acknowledgments

EVM and FGS initiated the project, contributed to project design, did the statistical analysis, interpretation of the results, wrote the manuscript and approved the final manuscript. The authors would like to thank all the workers and the patients from therapeutic communities and other department of the Agency of Social Services and Dependence of Andalusia (Spain) that supported this research in any way.

Disclosure statement

FGA have received occasional support for research and educational activities from Reckitt-Benckiser, Janssen and Eli-Lilly. EVM declare no financial interests or potential conflicts of interest related directly or indirectly to this work.

Additional information

Funding

This article has been funded by the National Plan on Drugs, Ministry of Health, Consumption and Social Welfare, Government of Spain [2007 no.2007i078].