Background: Psychological symptoms that do not reach the threshold for formal diagnosis are disregarded in prevalence rates and are apparently assumed to be transient and of little clinical importance.
Method: Consecutive primary care attenders (n = 2379) were screened using the 12-item General Health Questionnaire (GHQ-12) and a stratified random sample (n = 704) completed baseline structured diagnostic interview, disability assessment, and the 28-item version of the GHQ (GHQ-28). Subjects with significant psychiatric symptoms and a random sample of those without (n = 263) were evaluated with the same measures 12 months later.
Results: While 25 % of the baseline sample scored 5 or more on the GHQ-28, only 10 % met the ICD-10 criteria for one or more disorders. At baseline, caseness on either the GHQ or ICD-10 was associated with poor self-rated overall health, interviewer-rated occupational disability and with more disability days in prior month. At 12-month follow-up, being a case on the GHQ at baseline, but not on ICD-10, was associated with disability, poor health perception and high health service utilization.
Conclusion: Psychological symptoms that may not reach diagnostic threshold are associated with impaired functioning over 12 months. Individuals with such symptoms may be identified using self-report questionnaires for dimensional symptoms, such as the GHQ-28.