Depression, anxiety and somatization in primary care: syndrome overlap and functional impairment.
OBJECTIVE
To determine diagnostic overlap of depression, anxiety and somatization as well as their unique and overlapping contribution to functional impairment.


METHODS
Two thousand ninety-one consecutive primary care clinic patients participated in a multicenter cross-sectional survey in 15 primary care clinics in the United States (participation rate, 92%). Depression, anxiety, somatization and functional impairment were assessed using validated scales from the Patient Health Questionnaire (PHQ) (PHQ-8, eight-item depression module; GAD-7, seven-item Generalized Anxiety Disorder Scale; and PHQ-15, 15-item somatic symptom scale) and the Short-Form General Health Survey (SF-20). Multiple linear regression analyses were used to investigate unique and overlapping associations of depression, anxiety and somatization with functional impairment.


RESULTS
In over 50% of cases, comorbidities existed between depression, anxiety and somatization. The contribution of the commonalities of depression, anxiety and somatization to functional impairment substantially exceeded the contribution of their independent parts. Nevertheless, depression, anxiety and somatization did have important and individual effects (i.e., separate from their overlap effect) on certain areas of functional impairment.


CONCLUSIONS
Given the large syndrome overlap, a potential consideration for future diagnostic classification would be to describe basic diagnostic criteria for a single overarching disorder and to optionally code additional diagnostic features that allow a more detailed classification into specific depressive, anxiety and somatoform subtypes.
Löwe
Bernd
B
Department of Psychosomatic Medicine and Psychotherapy, University Medical Center Hamburg-Eppendorf and Hamburg-Eilbek (Schön Clinics), Germany. b.loewe@uke.uni-hamburg.de
Spitzer
Robert L
RL
Williams
Janet B W
JB
Mussell
Monika
M
Schellberg
Dieter
D
Kroenke
Kurt
K
D000203:Activities of Daily Living / Q000523:psychology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001008:Anxiety Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D003865:Major Depressive Disorder / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D003937:Diagnosis, Differential; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D008875:Middle Aged; D010555:Personality Inventory; D011320:Primary Health Care; D013001:Somatoform Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology