Getting the questions right: An example of loss of validity during transfer of a brief screening approach for depression in the elderly

Screening for depression in the elderly has been advocated to improve detec tion and management. This article summarises the trend towards briefer scre ening instruments, and the integration of mental health screening with othe r assessments. The study aimed to validate a single question depression scr een which had previously shown adequate sensitivity and specificity in a ne w context: a multi-faceted assessment instrument used by nurse practitioner s within a community sample of over 75 year olds. The GMS-ACECAT computeris ed interview assessment was used as a 'gold standard' to determine the accu racy of the depression question in this new setting. Three hundred and twen ty-eight patients were screened by their own nurse practitioners, of whom 1 00 consenting patients underwent a further interview with a research assist ant using the GMS-AGECAT. The prevalence of depression was 30%, the sensiti vity of the question was 67%, and its specificity 60% (compared with 88% an d 71% previously). Responses indicating disability and loneliness were more closely correlated with depression than the depression screen itself. Rele vant factors may include: the derivation of the question, the effect of a d ifferent sample, altered reliability when used by multiple interviewers, di ffering patient expectations, and the wording and context of the question w ithin the multi-faceted screening instrument. Depression screening question s need repeated validation when used in different contexts. Patient and sta ff expectations may influence how screening instruments are used in practic e in a way that may also alter reliability. Further studies are needed to e stablish the causes of loss of validity when screening approaches are used in new settings. Copyright (C) 2000 John Wiley ge Sons, Ltd.