Living with Chronic Illness Scale: Validation in a Type 2 Diabetes Mellitus Population

Abstract

Background: Worldwide, type 2 diabetes mellitus (T2DM) is one of the most prevalent chronic diseases and one of those producing greatest impact on patients’ day-to-day quality of life. Our study aim is to validate the “Living with Chronic Illness Scale” for a Spanish-speaking T2DM population.Methods: In this observational, international, cross-sectional study, 582 persons with T2DM were recruited in primary health care and outpatient hospital consultations, in Spain and Colombia, during the period from May 2018 to June 2019. The properties analysed were feasibility/acceptability, internal consistency, reliability, precision and (structural) content-construct validity. The COSMIN checklist was used to assess the methodological/psychometric quality of the instrument.Results: The instrument has adequate internal consistency and test retest reliability (Cronbach’s alpha = 0.90; intraclass correlation coefficient = 0.96, respectively). In addition, the instrument is accurate (standard error of measurement = 3.34, with values <½SD = 8.52 considered acceptable) and correlates positively with social support (DUFSS) (rs = 0.56), quality of life (WHOQOL) (rs = 0.51-0.30) and satisfaction (SLS-6) (rs = 0.50-0.38). The questionnaire discriminates by the level of severity of the illness (Patient Based Global Impression of Severity Scale), associating lower values with greater severity, and also by male gender. The COSMIN checklist is favourable for all the properties analysed, although some weaknesses are detected for content validity.Conclusions: “Living with T2DM” (LW-T2DM) is a valid, reliable and accurate instrument for use in clinical practice to determine how a person’s life is affected by the presence of diabetes. This instrument correlates well with the associated constructs of social support, quality of life and satisfaction. Additional research is needed to determine how well the questionnaire structure performs when robust factor analysis methods are applied.