QLiS-SF: Development of a short form of the quality of life in schizophrenia questionnaire

T Senin,M Lautenschlager,J Kammerer-Ciernioch,N Bergemann,M Franz,T Meyer,M Deuschle

doi:10.1186/s12888-017-1307-1

Abstract

BackgroundThere is a need for useful standardized Quality of Life (QoL) measures for people diagnosed with schizophrenia. Therefore, a short form of the self-administered Quality of Life in Schizophrenia (QLiS) scale was developed and validated.MethodsFour steps were taken to develop the abridged version using samples from the Clinical Analysis of the Treatment of Schizophrenia (CATS) study. Firstly, a model with second order scales was developed using exploratory factor analysis (EFA). Secondly, it was tested in an independent sample using confirmatory factor analysis (CFA). Thirdly, this model served as the basis for selecting items for the short form. Distributional properties, content reviews, and factor loadings were taken into account in this step. Fourthly, the resulting short form was validated through confirmatory factor analysis (CFA). Composite reliability scores were calculated for the new subscales.ResultsThree second order scales were constructed: illness-related quality of life (QoL), social life and finances, and global subjective well-being. CFA of the new theoretical model resulted in a CFI of 0.67 and absolute fit indices of CMIN/df = 2.55, RMSEA = 0.08, SRMR = 0.09. The selected 13 items showed good statistical properties and good fit of content to subscale. Fit of the underlying theoretical model with the reduced number of items was tested in an independent sample. Absolute and fit indices of the short form model were satisfactory (CFI = 0.95, CMIN/df = 2.23, RMSEA = 0.06, SRMR = 0.04). Composite reliability scores for three subscales were above 0.70.ConclusionsThe short form of the QLIS (QLiS-SF) showed good model fit and reliability. It should only be considered for use if the application of the long version is not suitable.

Highlights

There is a need for useful standardized Quality of Life (QoL) measures for people diagnosed with schizophrenia
The Quality of Life in Schizophrenia (QLiS)-SF can give a general overview of the individual perspective on QoL of persons diagnosed with schizophrenia
The original QLiS should be used for precise measurement and more accurate classification of subjective QoL in persons with a diagnosis of schizophrenia

Summary

Introduction

There is a need for useful standardized Quality of Life (QoL) measures for people diagnosed with schizophrenia. In QoL research a distinction is made between so-called disease-specific measures of QoL which tend to be more responsive and clinically useful, and generic QoL measures which do not focus on any specific condition and have the advantage of enabling comparisons of QOL across diseases [11] In this regard, disease-specific QoL measures based on patients’ perceptions of their own lives should be used [10] to gain adequate information on the various problems experienced by people with a diagnosis of schizophrenia [12], acknowledging that the term schizophrenia does not relate to a circumscribed clinical disease but rather represents a spectrum of different conditions and etiologies. Some QoL scales were developed, tested, and applied in patients with a diagnosis of schizophrenia (see [4, 10]) there is still a need for useful standardized QoL measures for patients with this diagnosis [13]

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