Validation of clinical symptom IRT scores for diagnosis and severity assessment of common mental disorders.

PURPOSE: We studied the validity and responsiveness of an item response theory (IRT) scoring method for assessing major depressive episode (MDE) and generalized anxiety disorder (GAD) severity based on direct assessment of DSM-IV-TR symptoms. METHODS: Prospective cohort study (baseline, 1-month, 3-months assessments) of patients seeking help for incident or aggravated mood or anxiety symptoms from primary, outpatient and inpatient mental health centers (N = 244; 67.81 % active cases - 100 % under psychiatric treatment). The drop-out rate at 3 months was 24.89 %. Patients were assessed at each follow-up for presence/absence of DSM-IV symptoms of MDE (nine symptoms) and GAD (eight symptoms). IRT scores for depression (INS-D) and anxiety (INS-G), based on response patterns, were obtained by means of a 2-parameter model. Diagnostic accuracy was assessed with receiver operating characteristic analysis, using a blinded MINI interview as gold standard. Scores' construct validity was compared with external clinician-administered (Hamilton Depression Rating Scale, HRSD; Hamilton Anxiety Rating Scale, HAM-A) and self-reported severity measures (PHQ-9; Beck Anxiety Inventory-Subjective Aspects, BAI-Sub). Responsiveness was analyzed based on the evolution of HRSD and HAM-A scores. RESULTS: Both severity scores showed excellent reliability (INS-D: 0.92; INS-G: 0.93) and yielded high diagnostic accuracy (INS-D: AUC = 0.96; INS-G: AUC = 0.91) with respect to MINI diagnoses. INS-D and INS-G had higher correlations with clinician-administered measures of the same disorder (INS-D-HRSD: 0.73; INS-G-HAM-A: 0.53) than with self-reported measures (INS-D-PHQ-9: 0.69; INS-G-BAI-Sub: 0.49). Patients who recovered during follow-up showed important decreases in severity (Cohen's d INS-D:-1.38; INS-G: -1.75). About 90 % variance of INS-D and INS-G score changes over time was associated with changes in clinical status. CONCLUSIONS: INS-D and INS-G are short reliable, valid, and responsive measures that can be used for diagnostic and severity assessment of mood and anxiety disorders in outpatient care.

Predictors of Relapse and Functioning in First-Episode Psychosis: A Two-Year Follow-Up Study.

OBJECTIVE: First-episode psychosis has an annual incidence rate of 24.6 to 40.9 per 100,000 population, and most individuals develop chronic disorders, such as schizophrenia or affective psychosis. The first two to five years are thought to be key determinants of long-term functional and clinical prognosis. This study aimed to determine the two-year course of illness in first-episode psychosis, including diagnosis, relapse, and functioning and factors related to these variables. METHODS: A total of 140 patients who experienced a first episode of psychosis were recruited and evaluated between 2008 and 2012 in a first-episode psychosis program in Barcelona, Spain. Regression models were used to determine factors predicting relapse and functioning. RESULTS: A general trend was noted toward improved functioning and less severe psychotic symptoms. However, after two years, one-third of the patients had a diagnosis of schizophrenia and more than 40% had a diagnosis of affective psychosis. Rates of relapse were 31% after one year and 43% at two years. Cannabis use after illness onset and poor insight were the best predictors of relapse. Being male and severity of negative symptoms at baseline predicted worse functioning at two years. CONCLUSIONS: Patients with first-episode psychosis were found to have high relapse rates during the first years after illness onset. Further studies evaluating treatment strategies focused on reducing cannabis use and improving insight in first-episode psychosis should be encouraged.