Criterion validity of the French version of Patient Health Questionnaire (PHQ) in a hospital department of internal medicine

Abstract

Objectives. Depressive disorders are overrepresented among the patients admitted to non‐psychiatric units in general hospitals. However, the majority of depressed patients fail to be identified within this care setting. Since a self‐administered questionnaire (Patient Health Questionnaire, PHQ‐9) has given encouraging results in English and Spanish, new research should test its criterion validity in a French‐speaking environment.Design. The study included 292 patients admitted to the internal medicine units of the University Hospitals of Geneva. Each patient filled the PHQ‐9; 212 patients also underwent a blinded DSM‐IV diagnostic assessment by a psychiatrist.Methods. In order to assess the validity of PHQ‐9 against the gold standard of the psychiatrist's DSM‐IV diagnosis, we calculated overall accuracy, sensitivity, specificity, positive predictive value and Cohen kappa coefficients. We also studied the relationship between the PHQ‐9 diagnostic and the severity of depression. Finally, analysis focused on the presence of a diagnosis of depression.Results. Within the framework of the study, PHQ‐9 showed an acceptable level of specificity. However, its sensitivity in detecting major depression was low (about 50% of false‐negative results). As regards the overall presence of depressive disorders, this instrument performed hardly any better (35% of false negatives). Other characteristics of the population under investigation may have affected the data.Conclusions. The French version of PHQ‐9 demonstrated low sensitivity as compared with psychiatrist‐established diagnosis of DSM‐IV A criterion and major depressive episode.