QOL Assessment Instruments

QOL issues, heretofore considered too soft and subjective for specialists to deal with are, in fact, objectively quantifiable and do not merely represent the absence of disease. QOL is gener ally measured by structured questionnaires that can be scored and quantified to generate hard data. Most widely used QOL

assessments include measures of physical, psychosocial, economic, and global well-being. There is an explosion in the QOL literature, with more than 30 generic tools available (to assess global QOL and health considerations) and more than 300 dis ease-specific tools available, including 35 to 45 for cancer patients. The otolaryngologist-head and neck surgeon who ventures into the QOL literature published in journals of psychology, epidemiology, health science, psychosomatic medicine, and sociology may well be confused by the statistical methodology and jargon encountered, such as, "Construct validity was examined in this study through factor analysis using principal components and orthogonal rotation, which revealed that the average scores were function and network properties which did load onto three factors."25

Different methodologies assess different health outcomes. For example, QOL scales (self-assessment questionnaires) measure the patient's perceived quality of health retrospectively, whereas utility scales measure projected health state. An example of the latter is the time/trade-off method that identifies the number of years of perfect health the interviewee (often not a patient) is willing to exchange for 5 to 10 years in each health state. Products of outcomes research often apply linear analogue scoring or category rating not only to physical status, but also to psychological and social well-being by assessing variables such as pain, mobility, capacity for sexual relationships, and symptomfree days. Additional complexity arises when cost-effectiveness of treatment alternatives is included.

In general, articles in the QOL literature show that whatever instrument is under evaluation, is reliable (yields consistent values), valid (targets what it claims to measure), responsive (detects changes over time), sensitive (reflects true changes in individual patients), and practical to administer. Instruments that fail to document these parameters probably do not get published, although it would be interesting to see some scales that have not fulfilled these criteria; possibly much could be learned from them. Often lacking are articles that demonstrate the reproducibility of a given instrument; there appears to be more interest among authors in generating a slightly different instrument that is better than any of the others rather than in validating someone else's. All instruments vary slightly in methodology (e.g., self-response vs proxy, telephone vs mail vs interview) and psychometrically in what is included in the questionnaire. Outcomes research has demonstrated that patients generally like to fill out questionnaires (satisfied patients generally respond more than dissatisfied ones who manifest their dissatisfaction in other ways), but there is concern over how the information gathered will be used; to discriminate against patients in a punitive way? There is also significant concern on the part of providers who are often reluctant to participate in such studies; will patient satisfaction results be used to punish (or reward) providers ("report cards")? The theoretical desire to include all relevant outcomes and costs is daunting, and there are already too many tools to choose from. It is more realistic to select a QOL product that meets most of the needs of the patient population under consideration and to use it in a prospective, longitudinal manner in large numbers of patients.

QOL studies must be performed prospectively and longitudinally over time, as a cancer patient's perception of health often changes, and if QOL is assessed at only one point or over a short interval, a distorted picture will emerge. Recall bias is a well-known factor, and responses often differ when they are asked near to or far after an event. An individual's satisfaction with QOL early after treatment often differs significantly from that perceived years later, especially if side effects become more troublesome or if the cancer recurs. One example from the prostate cancer literature shows that with longer follow-up, persistent incontinence may dampen early enthusiasm over having had a successful operation.26 An analogy in the area of HNC might be that patients who require delayed or have long-term tracheotomies and difficulty swallowing may become depressed, whereas they were initially happy to have their larynx preserved. These conditions may not develop for years after nonsurgical organ preservation treatments, as a result of progressive soft tissue fibrosis in the head and neck, and may not be recognized if cancer follow-up terminates at 5 years, the traditional cure endpoint. Additional surveillance of HNC patients for second primaries should continue indefinitely with yearly chest radiographs that can detect early, operable second primary lung cancers.

Thus, measurement of QOL is dynamic, rather than static, and requires periodic reassessment. Short-term results cannot be extrapolated to reflect long-term outcome. It is likely that prospective, long-term, longitudinal studies, which are lacking in the HNC literature, may better elucidate the patient's true experience in the future. Similarly, isolated observations in long-term survivors are biased if they are meant to represent the population at large, because patients who have had less favorable cancer-control results and outcomes have already expired or otherwise been selected out.27

How often QOL outcomes should be measured depends on the condition and the treatment given. Assessment before treatment and after each component of multimodality treatment, if clearly definable, as well as longer-term assessment, might be reasonable for the HNC population. For example, in patients who undergo surgery followed by radiation or chemoradiotherapy, assessment before treatment, after surgery/before radiotherapy, after radiotherapy, 6 months after the end of treatment, and 1, 3, and 5 years after treatment seems logical. Even longer assessment, at 10 years, for example, is probably indicated to assess functional changes over time caused by progressive tissue fibrosis.

The fact that outcomes and QOL research are not yet exact sciences is demonstrated by highlighting some of the problems in the existing literature. Table 19-1 lists some general problems with questionnaire studies. For example, depending on how questions are phrased, it is easy to get the desired response; a fact that pollsters are well aware of. If identical probabilities are proposed to subjects but are asked in two different ways (chance of survival vs chance of death), subjects usually make different decisions, even though the probabilities are identical.28'29 Table 19-2 lists areas of apparent consensus in the QOL literature.

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