Validation of the Subjective Happiness Scale, Oxford Happiness Questionnaire and Pemberton Happiness Index among women with breast cancer in a multi-ethnic Asian setting.

Abstract

Background: It is uncertain if the current tools that are used to measure happiness in the general population are valid in women with breast cancer.

Objective: We determined the psychometric properties of the Subjective Happiness Scale (SHS), Oxford Happiness Questionnaire (OHQ) and Pemberton Happiness Index (PHI) among women with breast cancer in a multi-ethnic Asian setting.

Methods: The internal consistency and construct validity of the SHS, OHQ and PHI were assessed. Criterion validity was determined by measuring the correlations of the study tools with the relevant domains of the European Organisation for the Research and Treatment of Cancer Quality of Life Questionnaire 30 and the Depression, Anxiety and Stress Scale.

Results: Cronbach's alpha of the SHS, OHQ and PHI ranged from 0.75 to 0.92. In the exploratory factor analyses, a one-factor model was recommended for SHS and PHI. A two-factor model was recommended for OHQ. Confirmatory factor analysis indicated that the two-factor model for OHQ demonstrated acceptable convergent and divergent validity with composite reliability >0.70. Both OHQ and SHS revealed a moderately positive correlation with health-related quality of life, and a moderately negative correlation with psychological distress.

Conclusion: This study demonstrated that SHS and OHQ are valid and reliable tools to measure happiness among women with breast cancer in multi-ethnic Asian settings. While the PHI seems promising, we were unable to confirm its criterion validity in the current study.