Misclassification and the use of register-based indicators for depression.
OBJECTIVE
To study the degree to which depression indicators based on register data on hospital and antidepressant treatment suffer from differential misclassification with respect to gender, age and social group.


METHODS
Data on 7378 persons were obtained by linking a cross-sectional survey of Danish adults aged 40 and 50 years with population-based registers. Misclassification was analysed by comparing survey data to register data on major depression using the method proposed by Rothman and Greenland.


RESULTS
Differential misclassification was found. Adjustment for misclassification reduced women's odds ratios from 2.18 to 1.00 for hospital treatment and from 1.70 to 1.10 for antidepressants. For the lower social group, the corresponding odds ratios increased from 1.18 to 3.52, and from 1.35 to 2.32 respectively, whereas odds ratios with respect to age remained almost unchanged.


CONCLUSIONS
Differential misclassification should be considered when register-based information about hospital and antidepressant treatment are used as depression indicators.
Thielen
K
K
Section of Social Medicine, Department of Public Health at the University of Copenhagen, Copenhagen, Denmark. k.thielen@socmed.ku.dk
Nygaard
E
E
Andersen
I
I
Rugulies
R
R
Heinesen
E
E
Bech
P
P
Bültmann
U
U
Diderichsen
F
F
D000328:Adult; D000928:Antidepressive Agents / Q000627:therapeutic use; D003430:Cross-Sectional Studies; D003865:Major Depressive Disorder / Q000145:classification* / Q000175:diagnosis* / Q000628:therapy; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012042:Registries
D000928:Antidepressive Agents