Does the presence of anxiety affect the validity of a screening test for depression in the elderly?
BACKGROUND
Depression in the elderly is frequently detected by screening instruments and often accompanied by anxiety. We set out to study if anxiety will affect the ability to detect depression by a screening instrument.


OBJECTIVE
To validate the short Zung depression rating scale in Israeli elderly and to study the affect of anxiety on its validity.


METHODS
The short Zung was validated against a psychiatric evaluation, in a geriatric inpatient and outpatient service. The overall validity was determined, as well as for subgroups of sufferers and non-sufferers of anxiety.


METHODS
An urban geriatric service in Israel.


METHODS
150 medical inpatients and outpatients, aged 70 years and older.


METHODS
Psychiatric evaluation of modified Anxiety Disorders Interview Schedule for DSM-IV as criterion standard for anxiety and depression and short Zung instrument for depression.


RESULTS
By criterion validity, 60% suffered from depression. The overall validity of the short Zung was high (sensitivity 71.1%, specificity 88.3%, PPV 90.1%, NPV 67.1%). The validity for those not suffering from anxiety was good (sensitivity 71.1%, specificity 90.2%, PPV 84.4%, NPV 80.7%). In those with anxiety, sensitivity, specificity and PPV were high (71.2%, 77.8%, 94.9% respectively), although the specificity was less than in non-suffers. However major difference was in the NPV rate being much lower (31.8%).


CONCLUSIONS
The short Zung, an easily administered instrument for detecting depression, is also valid in the Israeli elderly. However, anxiety limits the usefulness of this instrument in correctly ruling out depression. The clinician must be aware, therefore, that those suffering from anxiety may score negatively for depression on a screening instrument, such as the short Zung.
Sinoff
Gary
G
Department of Geriatrics, Carmel Medical Center, Haifa, Israel. sinoff@netvision.net.il
Ore
Liora
L
Zlotogorsky
David
D
Tamir
Ada
A
D000368:Aged; D001007:Anxiety / Q000150:complications*; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000150:complications* / Q000175:diagnosis*; D015577:Geriatric Assessment; D006801:Humans; D007406:Interview, Psychological; D007557:Israel; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity