The impact of diabetes mellitus and other chronic medical conditions on health-related Quality of Life: is the whole greater than the sum of its parts?

Health Qual Life Outcomes. 2005 Jan 12;3:2. doi: 10.1186/1477-7525-3-2.


Background: Diabetes mellitus (DM) is an important public health concern, the impact of which is increased by the high prevalence of co-existing chronic medical conditions among subjects with DM. The aims of this study were therefore to (1) evaluate the impact of DM and co-existing chronic medical conditions on health-related quality of life (HRQoL) (which could be additive, synergistic or subtractive); (2) to determine the extent to which the SF-6D (a single-index preference measure) captures the multidimensional information provided by the SF-36 (a profile measure).

Methods: Using data from a cross-sectional, population-based survey of Chinese, Malay and Indians in Singapore, we developed 9 separate multiple linear regression models, with each SF-36 scale or SF-6D index score being the dependent variable for one model. The influence of DM and a second chronic medical condition (hypertension (HTN), heart disease (HD), musculoskeletal illnesses (MS)) and their interactions were studied after adjusting for the influence of potential confounding variables.

Results: Among 5,224 subjects, the prevalence of DM, HTN, HD and MS were 5.9%, 10.7%, 2.4% and 26.6% respectively. DM lowered SF-36 scores by more than 2 points on 3 SF-36 scales and lowered SF-6D scores by 0.03 points. Subjects with DM and HTN, DM and HD or DM and MS experienced further lowering of SF-36 scores exceeding 2 points on at least 6 scales and further lowering of SF-6D scores by 0.05, 0.08 and 0.10 points respectively. Generally, DM and co-existing medical conditions exerted additive effects on HRQoL, with the exception of DM and heart disease, where a subtractive effect was noted. SF-6D index scores generally reflected the patterns of influence of DM and chronic medical conditions on SF-36 scores.

Conclusion: DM and chronic medical conditions generally reduced HRQoL in this multiethnic general population in an additive, rather than synergistic or subtractive fashion. In this study, the SF-6D was a reasonably good summary measure for the SF-36.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • China / ethnology
  • Chronic Disease / psychology
  • Comorbidity*
  • Cross-Cultural Comparison
  • Cross-Sectional Studies
  • Diabetes Mellitus / ethnology*
  • Female
  • Heart Diseases / complications
  • Heart Diseases / ethnology
  • Humans
  • Hypertension / complications
  • Hypertension / ethnology
  • India / ethnology
  • Linear Models
  • Malaysia / ethnology
  • Male
  • Middle Aged
  • Musculoskeletal Diseases / complications
  • Musculoskeletal Diseases / ethnology
  • Prevalence
  • Psychometrics / instrumentation
  • Quality of Life*
  • Sickness Impact Profile*
  • Singapore