Development and validity of a diagnostic screening instrument for depression

Objective To develop a screening instrument to improve the identification of depression in persons with physical illnesses in China and to assess its validity.Methods We developed and revised a culturally sensitive screening instrument for depression based on DSM-IV diagnostic criteria of major depressive disorder.During the pilot test for the screening instrument psychiatric nurses who administered the scale to 99 secondary-level general hospital inpatients had excellent inter-rater reliability(ICC=1.00)and when blindly re-administered to 85 of the patients the test-retest reliability was also excellent(ICC=0.91).In the main study a stratified random sample of 35 primary,8 secondary and 7 tertiary general hospitals in Beijing was identified and trained psychiatric nurses administered the screening instrument to 2,877 sequentially identified outpatients and 2,925 inpatients hospitalized at the time of the survey who were 15 years of age or older,well enough to complete the interview and who did not have serious difficulties communicating.The interview took 15～20 minutes to complete.All subjects screened positive and a random selection of 10% of those screened negative(565 subjects in total)were administered the 'Structured Clinical Interview for DSM-IV Axis I Disorders'(SCID)by a trained attending-level psychiatrist who did not know the results of the screening interview.Results The nurses' screening result of 'Major Depressive Episode' accurately predicted a 'gold-standard' psychiatrist's SCID diagnosis of 'Major Depressive Disorder' in 96.8% of cases(Kappa=0.87);the sensitivity was 98.6%,specificity 96.6%,false positive rate 3.4%,and false negative rate 1.4%.Conclusions The screening instrument we developed has good reliability,validity,sensitivity and specificity and can be effectively used by non-psychiatrists,so it is suitable for use as an alternative to the more complex SCID examination in epidemiological or clinical studies of depression.