CG123 Common mental health disorders - National Institute for ...

Case identification and formal assessmentORs. Based on the approach taken for the updated editions of the Depression guidelines(NCCMH, 2010a and 2010b), when describing the sensitivity and specificityof the different instruments, the GDG defined values above 0.9 as ‘excellent’, 0.8to 0.9 as ‘good’, 0.5 to 0.7 as ‘moderate’, 0.3 to 0.5 as ‘low’ and less than 0.3 as‘poor’. For likelihood ratios, a value of LR5 and LR– 0.3 suggests the test isrelatively accurate. For diagnostic ORs, a value of 20 or greater suggests a goodlevel of accuracy.The GDG aimed to develop recommendations that promoted the cost-effectiveidentification of individuals with anxiety and depressive disorders. The recentlycompleted NICE Depression guideline performed a systematic review of case identificationmethods for depression, and the GDG adapted the recommendations fromthe guideline for case identification (see NCCMH, 2010b, for a full description anddiscussion of the relevant evidence). In contrast, none of the other NICE guidelinesthat focused on anxiety disorders had developed recommendations for the identificationof anxiety. In developing the recommendations for case identification foranxiety disorders, the GDG was mindful that the main focus of this guideline wason primary care services and the requirement to develop a method that not only hadgood sensitivity and specificity for all anxiety disorders but one that was also feasible(that is, had good clinical utility). The GAD-2 instrument performed best, andwas the one measure that met the two key criteria of good diagnostic accuracy andfeasibility. The GDG concluded that, although some of the longer instruments hadgood diagnostic accuracy, these instruments would not be feasible in the context ofprimary care. The GDG therefore decided to adopt the GAD-2 as the recommendedmeasure. However, the GDG was concerned that the GAD-2 focused on anxiety andworry and that a number of people with an established phobic disorder would notbe identified. This was thought possible because those with an established phobicdisorder may avoid phobic objects or situations and, as a consequence of the avoidance,would not experience significant anxiety or worry and would therefore scorelow on the GAD-2. The GDG took the view that it was important to ask a subsidiaryquestion for those people where the practitioner had a significant suspicion of ananxiety disorder but had returned a GAD score of less than three. The question, ‘Doyou find yourself avoiding places or activities and does this cause you problems?’,was designed to detect a number of people with phobia whose functioning wasimpaired but who otherwise would not be identified by the two GAD questions. TheGDG also undertook health economic modelling of the use of the two GAD questions.This modelled a larger part of the care pathway than was covered by the caseidentification questions alone and included the use of the GAD-7 (see Section 5.3)as part of the assessment subsequent to a positive response to the case identificationquestions. The economic model suggested that the combination of the case identificationquestions with the use of a formal assessment tool (the GAD-7) was costeffective and further supports the GDG’s view that a recommendation for the caseidentification of anxiety disorders was appropriate. The recommendations set outbelow were developed in conjunction with the recommendations for assessment setout in Section 5.3.8 of this chapter.117