Background: Milder forms of depression are highly prevalent in the clinical setting as well as in primary care. However, it is still unclear whether there are distinguishable groups among the various subthreshold syndromes and to what extent they are associated with impairment, thus requiring treatment. Therefore, the study aimed at comparing the degree of impairment in 2 groups of subthreshold depressive patients (nonspecific and minor depressive) with nondepressive patients and with major depressive patients. Another aim of the study was to evaluate the spectrum hypothesis of depressive syndromes.
Sampling and methods: A sample of 619 primary care patients was studied using the self-administered Patient Health Questionnaire (PHQ). After defining subthreshold depressive syndromes on a criterion basis, frequencies, sociodemographic factors, and impairment of nondepressive, subthreshold depressive, and major depressive patients were compared.
Results: Nonspecific depressive symptoms (NDS) were diagnosed in 9.1% of the study subjects and minor depression in 6.2%. Subjects with subthreshold depressive disorders did not differ from each other or from subjects with major depression regarding sociodemographic risk factors such as age, sex, or marital status. Yet, a continually increasing impairment from NDS to minor depression to major depression could be found. Moreover, the investigated groups differed with regard to the severity index.
Conclusions: The results of the study are in accordance with the spectrum hypothesis of depressive syndromes ranging from NDS to minor depression to major depression. Patients with subsyndromal depression showed significant functional impairment to the extent that at least some of these patients probably had a disorder requiring treatment.