QUALITY-ADJUSTED LIFE-YEARS (QUALY)

“Live longer” is fairly easy to measure. Obviously, it can be measured in terms of life-years. In other words, we can say that one group as a whole does better if more people are alive at the end of the study. Live-longer measurements are not complicated; they are essentially mortality rates. The benefit from living longer is readily apparent and openly endorsed in most conditions.

It is important, however, to consider the quality of those life-years that are bestowed upon individuals. It is not always beneficial to extend life if each day is a burden. The enjoyment factor is an important part of an individual’s overall satisfaction. There has been a recent surge of interest in methods used to quantify the quality of life (QOL). This outcome is obviously more difficult to measure than life-years since it tends to be subjective and variable among individuals with the same restrictions. In spite of the inherent limitations of this type of research, gallant advances using sophisticated techniques are being made in this arena in an attempt to quantify the so-called well-being factor.

Most QOL measurements are done by questionnaire. The surveys are completed by individuals who have the disease being studied, or by caregivers when the subject is unable to respond. These instruments often use Likert scales to measure graded responses (e.g., poor, fair, good, very good, excellent). They undergo rigorous testing for validity and reliability before they are released for use. Validity addresses the question of whether an instrument measures what is intended. Most methods to check for validity employ another external measure to see how the methods correlate. Reliability is a reflection of reproducibility. A reliable instrument will show some variability but will demonstrate consistency over time.

Some surveys cover generic QOL issues, such as the Short Form Health Status Questionnaire, known as the SF-36^R. This instrument poses 36 questions that cover multiple health-related categories (also known as domains). These attempt to measure physical, emotional, social, and cognitive levels of functioning. They can therefore be used in various situations to assess general functional status and overall well-being. There are several versions of this type of questionnaire. Figure 6-1 shows a breakdown of the types of domains that are captured in one of these instruments.

FIGURE 6-1 The SF-36^R is a simple questionnaire that attempts to capture overall well-being.

Figure 6-2 shows the results when a cross section of patients with varying types of diseases were asked to evaluate their QOL using a generic measure known as the Sickness Impact Profile score. These are descriptive data that compare different disease states in terms of perceived overall well-being, although the results were not adjusted for age or other factors and the disease states shown are by no means all-inclusive. The longer bars represent poorer QOL perception.

FIGURE 6-2 Overall Sickness Impact Profile (SIP) scores for different disease conditions or population groups. Higher scores reflect poorer quality of life (QOL).

(Patrick D. L. and R. A. Deyo, 1989. Generic and disease: specific measures in assessing health status and quality of life. Medical Care, 27(suppl):3, 5220.)

Most of the results are predictable. As expected, patients with chronic disease states causing uncontrollable pain reported poorer QOL in general. Those who reported the worst QOL in this study had a progressive degenerative neurological disorder called amyotrophic lateral sclerosis (ALS, or Lou Gehrig’s disease), which causes lack of strength and motor control but (perhaps regrettably) does not affect intellectual function. It is conceivable that these unfortunate individuals might be compelled to engage a professional to assist in life-ending measures.

On the other hand, a rather surprising result shows that those who have suffered cardiac arrest report an incredibly good quality of life! These folks often have no permanent impairment once the event is reversed, and they may reflect upon their good fortune. Perhaps those who have seen the light at the end of the tunnel are more appreciative of the fact that they are alive, and their other maladies become unimportant by comparison.

In addition to general QOL measures, other instruments focus on disease-specific issues related to QOL. These are more applicable in chronic, prevalent diseases and can also be used to make comparisons over time within the same sample. For instance, surveys have been developed to measure the QOL experienced by patients with congestive heart failure (CHF.) The often-quoted New York Heart Association classification ¹ is a simple instrument that assesses the level of symptoms experienced by the individual, using Class I (asymptomatic during normal activities) through Class IV (symptoms occur at rest.) Physicians use this classification to monitor the success of treatment in the individual patient. It is also applied to groups of CHF patients to assess the efficacy of large-scale programs and interventions.

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