Mapping the Positive and Negative Syndrome Scale scores to EQ-5D-5L and SF-6D utility scores in patients with schizophrenia

Edimansyah Abdin,Esmond Seow,Kelvin Bryan Tan,Swapna Verma,Mythily Subramaniam,Siow Ann Chong

doi:10.1007/s11136-018-2037-7

Abstract

ObjectiveThe current study aims to map the Positive and Negative Syndrome Scale (PANSS) onto the five-level EuroQol five-dimensional (EQ-5D-5L) and Short Form six-dimensional (SF-6D) utility scores for patients with schizophrenia.MethodsA total of 239 participants with schizophrenia spectrum disorder were recruited from a tertiary psychiatric hospital in Singapore. Ordinary least squares (OLS), censored least absolute deviations and Tobit regression methods were employed to estimate utility scores from the EQ-5D-5L and SF-6D. Model selection of the 18 regression models (three regression methods × six model specifications) was primarily determined by the smallest mean absolute error and mean square error, and the largest R2 and adjusted R2.ResultsThe mean age of the sample was 39.7 years (SD = 10.3). The mean EQ-5D-5L and SF-6D utility scores were 0.81 and 0.68, respectively. The EQ-5D-5L utility scores were best predicted by the OLS regression model consisting of three PANSS subscales, i.e. positive, negative and general psychopathology symptoms, and covariates including age and gender. The SF-6D was best predicted by OLS regression model consisting of five PANSS subscales, i.e. positive, negative, excitement, depression and cognitive subscales.ConclusionThe current study provides important evidence to clinicians and researchers on mapping algorithms for converting PANSS scores into utility scores that can be easily applicable for cost–utility analysis when EQ-5D-5L and SF-6D data are not available for patients with schizophrenia spectrum disorder in Singapore.

Highlights

Schizophrenia is a severe mental disorder which is highly disabling in nature and results in substantial costs to the patient and their family members [1]
The findings provide evidence that different predictive models should be used for mapping EQ-5D-5L and Short Form-6D (SF-6D) in the Asian sample
Our regression analyses showed that the EQ-5D-5L utility scores of schizophrenia spectrum disorder patients in our sample was best predicted by the Ordinary least squares (OLS) model consisting of three Positive and Negative Syndrome Scale (PANSS) factors, i.e. positive, negative and general psychopathology symptoms, and covariates including age and gender (Model 5)

Summary

Introduction

Schizophrenia is a severe mental disorder which is highly disabling in nature and results in substantial costs to the patient and their family members [1]. In the absence of generic preference-based instruments, mapping is a useful tool and can be used as an alternative solution to estimate utility scores from clinical instruments [5,6,7]. This technique is called ‘‘map’’, or “crosswalk”, as it can produce statistical formulas or algorithms that allow a disease-specific or clinical instrument to predict utility scores from generic preference-based measures and subsequently generate QALY for cost–utility analyses in clinical studies [5, 8]. Findings showed that EQ-5D scores were best predicted by age, gender, general psychopathology and depressive symptoms [10]

Methods

Results

Conclusion