Health-related Quality of Life
What Is it?
The morbidity focus area aims to capture the health-related quality of life within the community. The term “health-related quality of life” (HRQOL) has evolved to encompass the aspects of overall quality of life that are most clearly affected by either physical or mental health.[1]
Why Do We Measure It?
Health-related quality of life is viewed in the County Health Rankings framework as an outcome of the health factors included in the Rankings. Understanding the HRQOL of the population helps communities identify unmet health needs, assess disparities among demographic and socioeconomic subpopulations, characterize the burden of disabilities and chronic diseases, and track population patterns and trends.[2]
Measurement Strategies
Self-reported health and the number of physically and mentally unhealthy days per month are both widely used measures for overall health and HRQOL of a population. Self-reported health has been used in numerous studies since the 1950s. There is no “gold standard” or clear criterion for the validity of self-reported health, but it is among the most frequently used health indicators in sociological health research.[3]
The “healthy days” questions—those that ask about the number of physically and mentally unhealthy days per month—have been part of the CDC’s core Behavioral Risk Factor Surveillance Survey (BRFSS) questionnaire since 1993. The CDC’s “Measuring Healthy Days” report lists several tools that have been used to assess HRQOL, including Medical Outcomes Study Short Forms (SF-12 and SF-36), Sickness Impact Profile, and Quality of Well-Being Scale.[1] The report notes that although these measurement strategies have been widely used and extensively validated in clinical and population settings, their length makes them impractical to use in population surveillance.[1]
Researchers have consistently found self-reported health to be an informative measure of health status. A strong association between self-reported health status and mortality has been well documented; thus it is a useful indicator of morbidity within a community.[3] In his examination of its advantages and limitations, Jylhä concludes that the use of self-rated health to compare health status between population groups benefits from its comprehensive, inclusive, and non-specific nature.[3] Furthermore, a meta-analysis of the association between mortality and a single item assessing self-rated health found that people with “poor” self-rated health had a twofold higher mortality risk compared with persons with “excellent” self-rated health.[5] This analysis concludes that a single-item measure that takes little time to collect and can be captured routinely is appropriate for measuring health among large populations.[5]
What Is the County Health Rankings Measurement Strategy?
The County Health Rankings uses three county-level measures from the Behavioral Risk Factor Surveillance System (BRFSS) data provided by the CDC as measures of the health-related quality of life: the percent of adults reporting fair or poor health and the average number of physically and mentally unhealthy days reported per month.
Measure Strengths & Limitations
Both self-reported health and healthy/unhealthy days have been widely used and studied for their validity. One study that investigated the reliability of the HRQOL questions included in BRFSS found high retest reliability for self-reported health and healthy days measures.[4]
A study examining the validity of healthy days as a summary measure for county health status found that counties with more unhealthy days were likely to have higher unemployment, poverty, percentage of adults who did not complete high school, mortality rates, and prevalence of disability.[6] Physically unhealthy days were morely strongly associated with all county-level variables than mentally unhealthy days.[6]
One study found that the effect of health problems on self-reported health is stronger among better educated individuals, particularly among women.[7] Researchers cautioned that this phenomenon could lead to an underestimation of the magnitude of health inequalities existing between socioeconomic groups when using self-reported health as a general measure of health.[7] A cohort study in France examined whether the relationship between self-reported health and mortality weakens with increasing socioeconomic advantage among middle-aged individuals; the authors found that self-reported health appears not to measure health status in a similar way across socioeconomic categories.[8]
Another study analyzed responses to a self-reported health question in four national surveys from 1971 to 2007. BRFSS data indicates that Americans were increasingly likely to report “fair” or “poor” health over the last decade, although responses to the Current Population Survey indicate the opposite trend with the greatest inconsistencies among young respondents, Hispanics, and those without a high school education.[9] The authors conclude that the discrepancies suggest that self-reported health may be unsuitable for monitoring changes in population health over time and recommend reconsidering the standard approach of dichotomizing reporting only self-rated health as “fair/poor” versus the other possible responses (excellent, very good, and good).[9]
Andresen et al.’s study of HRQOL questions included in BRFSS found that the healthy days summary measure had slightly higher reliability than each of its component measures, physical health and mental health. This suggests that the summary item is a more consistent measure and that both components are important elements of HRQOL.[4] However, reporting the two components separately highlights the importance of mental health in addition to physical health.
References
[1] Centers for Disease Control and Prevention. Measuring Healthy Days: Population Assessment of Health-related Quality of Life. Atlanta, GA: Centers for Disease Control and Prevention; 2000.
[2] Moriarty D, Zack M, Kobau R. The Centers for Disease Control and Prevention's Healthy Days Measures--population tracking of perceived physical and mental health over time. Health Qual Life Outcomes. 2003;1:37.
[3] Jylhä M. What is self-rated health and why does it predict mortality? Towards a unified conceptual model. Soc Sci Med. 2009;69:307-316.
[4] Andresen EM, Catlin TK, Wyrwich KW, Jackson-Thompson J. Retest reliability of surveillance questions on health related quality of life. J Epidemiol Community Health. 2003;57:339-343.
[5] DeSalvo K, Bloser N, Reynolds K, He J, Muntner P. Mortality prediction with a single general self-rated health question. J Gen Intern Med. 2006;21:267-275.
[6] Jia H, Muennig P, Lubetkin EI, Gold MR. Predicting geographical variations in behavioural risk factors: An analysis of physical and mental healthy days. J Epidemiol Community Health. 2004;58:150-155.
[7] Delpierre C, Lauwers-Cances V, Datta GD, Lang T, Berkman L. Using self-rated health for analysing social inequalities in health: A risk for underestimating the gap between socioeconomic groups? J Epidemiol Community Health. 2009;63:426-432.
[8] Singh-Manoux A, Dugravot A, Shipley MJ, et al. The association between self-rated health and mortality in different socioeconomic groups in the GAZEL cohort study. Int J Epidemiol. 2007;36:1222-1228.
[9] Salomon JA, Nordhagen S, Oza S, Murray CJL. Are Americans feeling less healthy? The puzzle of trends in self-rated health. Am J Epidemiol. 2009;170:343-351.
