Validation of a clinimetric scale for the diagnosis for depression in patients with diabetes mellitus type 2, in primary healt care

Background. The prevalence of depression in patients with type 2 diabetes mellitus (DM2) is of up to 49.3% in primary care clinics. Nevertheless, medical doctors only recognize only 30% of these cases. Depression is associated with poor glycemic control, increase of diabetes complications, deterioration in patient's quality of life, and increase in demand and resources to provide care. The objective was to design and validate a clinimetric scale for the diagnosis of depression (CSDD in patients with DM2, in primary care units. Patients and methods. The study was conducted on 528 DM2 patients in Family Medicine Unit No. 10 of the Instituto Mexicano del Seguro Social (Mexican Social Security Institute), during 2003. A diagnostic test design was employed, with the golden standard consisting of the composite international diagnostic interview. Samples were constructed around consecutive cases. Depression and its degrees were the dependent variables. Absolute and relative frequencies were calculated, along with the Kappa index, sensibility, specificity, positive predictive values (PPV) and negative predictive values (NPV) and ROC curves. Results. The CSDD presented a concordance between observers of 0.7739. The best cut-off point in the ROC curves for diagnosis of depression was 6, which obtained a sensibility of 95.3%, a specificity of 96.8%, a PPV of 92.2%, and a NPV of 98.1%. Conclusions. The CSDD is a consistent and valid instrument and easy to use for the diagnosis of depression in patients with DM2 in primary care clinic.