Background and objective: Schizophrenia is a high prevalent disorder associated with huge economic and sanitary costs. Negative symptoms represent the main prognostic factors, thus to identify them is important to design effective guidelines of treatment. The Schedule for the Deficit Syndrome (SDS) is the only validated method to evaluate those symptoms as primary and stable. We propose its adaptation and validation into Spanish.
Patients and method: Patients diagnosed of schizophrenia attended at 2 different hospitals were evaluated with SDS (Spanish version) and PANSS (Positive and Negative Symptom Scale). Stable patients were reevaluated 6 months later. One rater acted as gold standard while two 2 raters, naïve to SDS, evaluated patients too.
Results: Twenty-one patients were evaluated (15 men). Raters agreed ranged from kappa = 0.79 to kappa = 0.89 with gold standard and kappa = 0.90 between them. Kappa ranged from 0.60-0.70 for severity criteria and 0.78-0.90 for primary criteria. Temporal stability at 6 months between raters was kappa = 0.72 and 0.87. We also evaluated interclass correlation index and homogeneity of construct.
Conclusions: After a brief training with the Spanish version of SDS, is fast and feasible to categorize patients into deficit or non-deficit forms of schizophrenia.