Edelman et al. (1) do not, as their title indicates, measure the “impact of screening on quality of life,” but rather they measure the effect of screening on health status. Their premise is that it is unclear whether being diagnosed with diabetes might have a potentially detrimental “labeling” effect or whether treatment of previously unrecognized symptoms might improve health-related quality of life (HRQoL). Many important studies, including the U.K. Prospective Diabetes Study (UKPDS) (2), have mistakenly assumed that health status, HRQoL, and quality of life (QoL) are interchangeable terms. However, confusing terminology leads to misinterpreted data and misleading conclusions and titles.
Throughout their article, Edelman et al. recognize the 36-Item Short-Form Health Survey (SF-36) (3) as a health status measure. However, the assumption that health status is synonymous with HRQoL flaws their interpretation. This culminates in their ill-advised conclusion that “early HRQoL changes might not have to be considered in the complex calculations that underlie the decision to undertake or not undertake mass screening for diabetes.” From the data presented, it is only evident that changes in perceived health status might not have to be considered.
Bradley (4) has provided a useful commentary on the “importance of differentiating health status from quality of life.” Impaired health or well-being may lead to, or be experienced at the same time as impaired quality of life—but not necessarily. Furthermore, excellent health does not infer excellent quality of life. Ware and Sherbourne (3) describe the SF-36 as a health survey but many others treat it, erroneously, as a measure of quality of life.
It is widely acknowledged that the psychological impact of screening for diabetes can vary among individuals, reassuring some and increasing anxiety in others, although initial distress often wanes over time (5). A more accurate interpretation of the data by Edelman et al. indicates that physical health (measured by the Physical Component Scale) was not affected by undiagnosed diabetes at baseline or by diagnosed diabetes 1 year later. This is unsurprising given that, as the authors acknowledge, complications (which have not been developed yet) and comorbidity are primary determinants of SF-36 scores. However, the controversy regarding screening lies in its impact on mental health, which, in this study, was not affected by undiagnosed diabetes at baseline or by diagnosed diabetes 1 year later. Analysis of the subscales contributing to the Mental Component Scale might provide further insight. “Vitality” might be improved as a result of treating previously undiagnosed symptoms, but improvements might be hidden by deterioration in other subscales, e.g., “mental health.”
Edelman et al. present an interesting article about the effects of diabetes screening on health status and discuss several limitations of their study. However, the major criticism of the article concerns their misinterpretation of the data due to the use of misconstrued terminology. Their misleading use of terminology suggests that they have measured the impact of screening on quality of life; in actuality, however, they have only measured the impact of screening on quality of health.
References
Address correspondence to Jane Speight, MSc, Health Psychology Research, Department of Psychology, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, U.K. E-mail: [email protected].
