Empirical foundations for the diagnosis of somatization: implications for DSM-5.
BACKGROUND
The aim of this study was to develop empirically validated criteria for the diagnoses of clinically relevant somatization.


METHODS
This study was performed in a population-representative cohort consisting of 461 males (47.8%) and 503 females (52.2%), with an average age of 55.8 years (s.d.=11.1). Somatization, anxiety and depression were derived from the Composite International Diagnostic Interview. Mplus was used to perform confirmative factor analyses on the current DSM-IV symptom groups; on alternative symptom clusters previously suggested; and to perform latent class analysis in order to define an empirically derived cut-off for somatization.


RESULTS
The existence of symptom groups as described in DSM-IV was not supported by our data, whereas a differentiation between cardiopulmonary, musculoskeletal, gastrointestinal and general somatic symptoms did fit our data. Latent class analysis revealed two classes characterized by few (n=859) and many (n=105) symptoms. The class of subjects could be approached by a simple cut-off of four functional symptoms (sensitivity 79%, specificity 98%, positive predictive value 82%, negative predictive value 97%) regardless of the number of organ systems involved.


CONCLUSIONS
This study in a large population-representative cohort suggests that a simple symptom count can be used as a dimensional diagnosis of somatization. In those instances in which a categorical diagnosis is preferred, a simple cut-off of four out of 43 functional symptoms best fitted our data. We did not find any added value for incorporating the number of symptom clusters into the diagnostic criteria.
Rosmalen
J G M
JG
University of Groningen, Groningen, The Netherlands. j.g.m.rosmalen@med.umcg.nl
Tak
L M
LM
de Jonge
P
P
D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D001008:Anxiety Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D002318:Cardiovascular Diseases / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D059350:Chronic Pain / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D015897:Comorbidity; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D003937:Diagnosis, Differential; D039721:Diagnostic and Statistical Manual of Mental Disorders; D019348:Empiricism; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D009426:Netherlands; D010698:Phobic Disorders / Q000145:classification / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology; D012737:Sex Factors; D013001:Somatoform Disorders / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology; D013577:Syndrome