Abstract
Background: Quality of life (QoL) is traditionally assessed using multiple-item questionnaires. These can be either general, global assessments of QoL or disease-specific questionnaires. However, the use of single-item QoL scales is becoming increasingly popular, as these are more time- and cost-effective, with a readily available and easy-to-interpret outcome. In particular, these are often preferred for quick assessments (e.g., 'at home' testing and mobile phone assessments), and other cases when time constraints are common (e.g., clinical trials and clinical practice). Previous research revealed that multiple-item questionnaires and single-item assessments of QoL have the same validity and reliability. Here we further evaluate the relationship of QoL, assessed with a single-item QoL scale, with well-being, mood, health correlates (e.g., immune fitness, and having underlying diseases), and lifestyle (e.g., sleep, nutrition). Methods: Data from two online surveys are presented. In Study 1, 100 students participated. The single-item QoL score was compared with the World Health Organization Well-Being Index (WHO-5), a single-item score of sleep quality, the Regensburg Insomnia Scale (RIS) score, and the Healthy Diet Scale (HDS). Study 2 comprised a survey among 1415 Dutch adults. Single-item QoL was evaluated and compared with assessments of mood, health correlates (immune fitness and disease status), and lifestyle factors (e.g., sleep, nutrition, stress). Results: The first study revealed significant correlations between QoL and well-being, sleep quality, insomnia ratings, and attaining a healthy diet. The second study revealed significant correlations between QoL and mood, health status, and lifestyle factors (e.g., the ability to cope with stress). Conclusions: The results presented here demonstrate that the single-item QoL scale is an effective and easy-to-implement assessment tool that can be used in both clinical practice and research.