Structural validity of the 5-item World Health Organization Well-being Index (WHO-5) in patients with schizophrenia spectrum disorders.

BACKGROUND: When monitoring the severity and impact of schizophrenia spectrum disorders, a measure of subjective well-being should ideally accompany measures of symptom severity and medication side effects. The self-reported 5-item World Health Organization Well-being Index (WHO-5) is a brief, generic, and widely used measure of subjective well-being. However, the structural validity of the WHO-5, namely, whether the individual item scores can be combined to produce a meaningful total score, has not been examined among patients with schizophrenia spectrum disorders. METHOD: Utilizing data from 399 Danish patients with schizophrenia spectrum disorders attending the Psychiatric Services of the Central Denmark Region, we employed Rasch analysis to examine the structural validity (i.e., unidimensionality, overall fit to the Rasch model, and differential item functioning) of the WHO-5. RESULTS: The WHO-5 was found to be unidimensional with no differential item functioning for age, sex, or inpatient/outpatient status. However, in the initial analysis, some misfit to the Rasch model, partially caused by the disordering of response categories, was evident. In adjusted analyses in which the item response categories 2 (Less than half of the time) and 3 (More than half of the time) were merged, overall fit to the model was improved. CONCLUSIONS: When two item response categories were merged, the Danish version of the WHO-5 was found to be structurally valid for patients with schizophrenia spectrum disorders. This suggests that the WHO-5 holds promise as a measure of subjective well-being in this patient population.

Are informants required to obtain valid ratings on the Positive and Negative Syndrome Scale (PANSS)?

Ratings on the Positive and Negative Syndrome Scale (PANSS) are ideally based on both a patient interview and an informant questionnaire. In research and clinical settings, however, the informant questionnaire is often omitted. This study investigated the consequences of omitting informant information by comparing PANSS ratings of patients with schizophrenia (n = 49 patients, 77 ratings) conducted with and without informant information, respectively. Additionally, changes in symptom severity over time based on ratings with and without informant information were also compared for the full PANSS and the six-item version of the PANSS (PANSS-6). PANSS ratings including informant information were higher than those without, both at the total score and individual item level. Additionally, the full PANSS appeared less "responsive" to baseline-to-endpoint changes for ratings without informant information compared to ratings including informant information, while no differences were found for the PANSS-6.

Validation of ratings on the six-item Positive and Negative Syndrome Scale obtained via the Simplified Negative and Positive Symptoms Interview among outpatients with schizophrenia.

BACKGROUND: The six-item Positive and Negative Syndrome Scale (PANSS-6) is a measure of the severity of core symptoms of schizophrenia, which can be administered via the brief Simplified Negative and Positive Symptoms Interview (SNAPSI). A recent study has confirmed the validity of PANSS-6 ratings as derived by SNAPSI (PANSS-6SNAPSI) among inpatients with schizophrenia. AIMS: We aimed to test the validity of PANSS-6SNAPSI among outpatients with schizophrenia using PANSS-6 ratings extracted from the 30-item PANSS-30 as derived by the Structured Clinical Interview for the Positive and Negative Syndrome Scale (PANSS-6SCI-PANSS) as a gold standard reference. METHODS: PANSS-6SNAPSI and PANSS-6SCI-PANSS ratings were obtained at two time points by independent raters with established inter-rater reliability. Agreement between PANSS-6SNAPSI and PANSS-6SCI-PANSS ratings was estimated via intra-class coefficients (ICCs) and responsiveness over time was quantified using Spearman's rank correlation coefficients. Post hoc "leave-one-out" analyses were carried out, in which each rater in turn was excluded from the ICC calculations. RESULTS: Seventy-three outpatients with schizophrenia participated in the study (mean age: 38.3 years; 56% males). The ICC for PANSS-6SNAPSI versus PANSS-6SCI-PANSS was 0.67 [95%CI = 0.56-0.76] and the Spearman's rank correlation coefficient for responsiveness was 0.40 (p = 0.004). When data from a specific outlying rater were excluded, the ICC for PANSS-6SNAPSI versus PANSS-6SCI-PANSS was 0.75 [95% CI = 0.63-0.83] and the Spearman's rank correlation coefficient for responsiveness was 0.55 (p = 0.018). CONCLUSIONS: We found PANSS-6SNAPSI ratings to have acceptable clinical validity, suggesting that PANSS-6SNAPSI can be used for both inpatients and outpatients with schizophrenia.