Wednesday, June 2, 2010

Health Status Does Not Equal Quality of LIfe

If you asked clinical researchers to describe the most important advances in research methodology over the past generation, many would cite advances in the ability to measure health-related quality of life (HRQOL). Health-related quality of life refers to domains of health that are important to patient's quality of life. By way of example, in a patient with COPD, this could include an instrument to measure dyspnea, or the extent to which COPD symptoms interfere with day to day function. There are many health related quality of life tools that are used in clinical research, and these tools have revolutionized our abilty to understand outcomes important to patients.

Despite the immense value of these tools, recently, some have recognized some problems in how these instruments are used and interpreted. Some of hese issues were articulated in an influential article by Gill and Feinstein. This first issue is that the very term "health related quality of life" is frought with conceptual problems. While health clearly impacts quality of life, it may be a mistake to equate health with quality of life. Quality of life is not the same thing as health, and we all know many who have bad health and good quality of life and vice-versa. A second related issue is that the very term "health-related quality of life" suggests that quality of life can be separated into health and nonhealth components. There is very little evidence that patients actually make this distinction when reflecting on their own quality of life.

Perhaps the most important issue is that if you want to know about a patient's quality of life, the best way to do so may be to just ask the patient to describe their quality of life. It seems that adding this single question to most clinical studies would be very informative. There is little reason for not supplementng the excellent health-related quality of life scales that have been developed with this informative global question.

The distinction between health status and quality of life was very nicely illustrated in a study published in the May issue of the Journal of the American Geriatrics Society. This study, led by Rachel Solomon and Terri Fried followed 185 elders with serious and progressive chronic illness. The patients had one of a number of conditions associated with chronically declining health---either cancer, CHF, or COPD. Patients were asked about their quality of life every 4 months. The findings are instructive:

  • In the interview before death (usually in the last 4 months) 46% of patients rated their quality of life as either good or best possible.
  • Between the pentultimate and final interview between dealth, 21% of patients reported improved quality of life and 39% reported no change. So, not only does quality of life not always decline as health worsens, sometimes it actually improves.
  • Quality of life is strongly innfluenced by many nonmedical factors. For example, one of the strongest predictors of better quality of life was growing closer to one's church.
This study is an important illustration of how we need to be very careful about making assumptions about our patients' quality of life based on their health.

by: [Ken Covinsky]

6 comments:

Christopher Langston said...

Thanks Ken - I very much agree. People only have one life (at least at one time) and therefore one can only have one QoL. At Michigan we all learned from the "Monitoring the Future" research team at ISR to use their 9 point terrible - delighted scale.

I think the real reason that there are specific submeasures of QoL, like health related, is because, as Solomon and Fried report, global QoL is not strongly influenced by health (or much of anything). People adapt and adjust expectations and have a strong QoL equilibrium in any event. About 50% of the variance in many QoL measures looks to be genetic, or at least not related to environmental differences acording to all the twin studies.

In producing more specific measures, you create a dependent variable that will be more (significantly) influenced by your predictors, but you loose sight of a more meaningful measure.

Dan Matlock said...

I saw this article and didn’t know what to do with it, thanks for giving some perspective – this is thought provoking. It reminds me of an article in the Economist from several months (or years) ago stating that measures of a country's per capita GDP did not correlate very well with the country’s overall ‘happiness.’ Also, overall happiness scores in the United States haven’t improved much over the past 100 years even though the per capita GDP continues to improve. The discussion was that the goal of economics should be to improve happiness, not GDP. This is equally challenging. It makes you wonder what are we really doing?

Dan Matlock said...

I saw this article and didn’t know what to do with it, thanks for giving some perspective – this is thought provoking. It reminds me of an article in the Economist from several months (or years) ago stating that measures of a country's per capita GDP did not correlate very well with the country’s overall ‘happiness.’ Also, overall happiness scores in the United States haven’t improved much over the past 100 years even though the per capita GDP continues to improve. The discussion was that the goal of economics should be to improve happiness, not GDP. This is equally challenging. It makes you wonder what are we really doing?

Eric Widera said...

Wouldn't it depend on the definition of "health related"? If we use the WHO definition then health is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity". We can then run a couple of scenarios where we manipulate these three variables (or more if you include spiritual). For example, ones physical health could decline at the end of life but mental and social well-being may actually improve. In this case, overall health-related quality of life may be equal or higher.

ken covinsky said...

thanks for the comments Chris, Dan, and Eric. A few thoughts:

I think Chris illustrates an important reason why health-related quality of life scales were developed. You want to measure something that is responsive and directly related to the medical care you are giving. For example, for COPD, one might hope to improve symptoms of shortness of breath. So a scale that measures the impact of shortness of breath on the ability to do household activites, or its impact on sleep would be meausuring something of clear value to patients and a logical target of therapy. However, when one calls this COPD-related quality of life, it imputes a certain value judgment on these symptoms that may or may not appropriate for a particular patient. So why not just call it what it is---a breathlessness scale.

I think the point Dan is raising about wealth is interesting. I wonder if this is parallel to the concept of adaptation in health. People who are healthy tend to view the impact disability on quality of life very negatively. However, people who are disabled often place less weight on disability as a component of quality of life. Perhaps the economic parallel is that as societies get wealthier, they are not happier because their expectations for wealth increases.

What Eric is suggesting could solve the health-related quality of life problem if most measures of quality of life were that comprehensive. But most aren't--they often just define whatever aspect of health status they are measuring as quality of life. The other problem is that it may be better to view quality of life as something totally subjective, in the eye of the beholder. The utility of the simple, rate your quality of life question is that it imposes no value judgement on what quality of life is, but leaves that judgment to the individual.

Adult Day Care said...

i agree with this issue"health related quality of life"
it is not obvious that a person who have good life style also have a quality of healthy life, ur statements are very true and ur research to solve the health-related quality of life problems is appriciateable,