Validation study of a nonspecific psychological distress scale.

BACKGROUND: Psychological distress scales are often used in national epidemiological surveys to monitor the mental health status and predict demands in mental health services. These scales have the advantage of being easy to administer and inexpensive to use. The goal of this study is to assess the clinical validity of the Psychological Distress Manifestations Measure Scale (PDMMS) by comparing it to a standard criterion.
METHOD: The validation study is based on data from a large-scale mental health survey conducted in 1999 in the Montreal area (Canada). The target population was constituted of adults living in private households. A telephone survey was carried out with a probability sample of 4,704 respondents using the Composite International Diagnostic Interview Simplified (CIDIS) to detect mental disorders. Then, subsequent face-to-face interviews with a subsample of 359 of these respondents were conducted to validate other measures for assessing mental health needs for care and services including the PDMMS.
RESULTS: Our study showed that high psychological distress is highly associated with mental disorder (OR=5.94). However, a large majority of the people in the high psychological distress category does not have a known mental problem.
CONCLUSIONS: These data confirm that like other psychological distress scales, the PDMMS is not a diagnostic tool. Rather, it is designed to explore comorbidity among symptoms, independent of caseness. The prevalence of psychological distress in the population allows us to identify people who have subclinical symptoms substantial enough to precipitate dysfunctioning in everyday life and who utilize health services more frequently. The use of this tool for epidemiological surveys is useful for mental health service planning because it provides information on the needs of individuals whose state of mental health affects social functioning even though they do not suffer from pathology.