Background: Non-psychiatric physicians are better at correctly ruling out depressive disorders than appropriately recognising them. However, given large numbers of non-depressed patients, a small percentage of false positives equates to a greater number of patients than the number of depressed patients that GPs fail to detect. Concern thus arises that substantial numbers of patients with falsely identified depression may receive inappropriate interventions.
Methods: Unselected GP consulters were screened with the Hospital Anxiety and Depression Scale (HADS). GPs' perceptions of depression were independently rated on an ICD-10 scale. Case records were reviewed. Analysis related to participants with HADS-D<8. Data were assessed of 660 participants with sub-threshold symptoms. Factors were assessed according to GP ratings.
Results: GP perceived depression in false positive cases were more likely at index visit, to have a mental health presenting problem (OR=6.74 (95% CI=3.21, 14.16); receive antidepressant prescriptions (OR 3.79 (95% CI=1.69, 8.49) and have greater severity of HADS-D score (OR 1.18 (95% CI=1.01, 1.38). Subthreshold cases that GPs identified as depressed, more often had a recording, over subsequent six months, of: depressive symptoms (16 (35%) versus 26 (7%), p<0.001); antidepressant prescriptions (11 (24%) versus 25 (7%), p=0.001); and Community Mental Health Team referrals (4 (9%) versus 1 (<1%), p=0.001). They also consulted GPs more frequently than those not identified (median=5 (IQR 2.8, 6.3) versus median=3 (IQR=2, 5), p=0.004 over six months.
Limitations: The HADS is not a diagnostic tool.
Conclusions: GPs' diagnoses of depressive disorder in patients with sub-threshold symptoms were appropriate. Interventions offered to this group were consistent with documented previous histories.
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