B PHARMACOECONOMICS

QOL in trument - when and where to u e them

It is now universally agreed that health-related quality of life (QOL) is a desirable and appropriate measurement in clinical trials. to be made in addition to the more traditional measures of effectiveness and safety. The inclusion of this parameter offers a significant challenge to companies involved in drug assessment programmes. as such testing is still in its infancy.

NHP tailored to serious illness A nu.mber o~ instruments are already available,

each With speCific advantages and disadvantages. ~ne of th~se, t~e Nottingham Health Profile (NHP), IS a questIOnnaire based upon the perceptions of the general pUblic. In its favour. it is considered to be reliab.le. valid. short. simple to read and respond to, and highly acceptable to patients.

However. it is not suitable for use in all clinical trials as sensitivity has been sacrificed for reliability. Therefore. the best use of the NHP is with 'patients who have quite serious conditions where treatment can be expected to make substantial improvement'l.

SF-36 - a general health ~ For comparing the relative burden of different

diseases and treatments. the Short FoOll-36 (SF-36) has been devised. This general health measure is based on 8 areas covering physical. social and psychological health. It has rapidly acquired popularity amongst clinical researchers. with an estimated I million fonns administered by July 19922.

In a comparative trial of SF-36 scores for a particular domain with equivalent domains in the NHP. fewer problems with floor and ceiling effects were found with the SF-36 questionnaire.

However, it is still an evolving instrument. with its usefulness in clinical trials yet to be established. Therefore it is recommended that in a clinical trial setting, SF-36 should be used in conjunction with a disease-specific questionnaire.

There is also some support for a conversion from the current 8-score end result to one overall value. In addition, concerns over possible insensitivity have been expressed as a result of the general nature of questions.

To address these issues. outcome researchers in the USA are trying to produce condition-specific instruments that are referred to as TyPE (Technology of Patient Experience) measures. At present. 21 TyPEs are available, with many more under development).

QOLw; an internal concept Despite being valuable in certain situations,

health-related QOL scales, such as the NHP and SF-36, have been criticised for a lack of egocentricity, and insensitivity when used in patients with less severe health problems.

A more egocentric approach, the SBQOL. is under development with a particular view towards

5 Dec 1992 INPHARMAe

use in psychiatric patients4•

The scale assumes QOL is an internal concept with assessment made according to changes in the 'self now' to 'ideal self' distance. At present, the scale consists of 28 constructs which have been shown to be both valid and reliable in clinical studies of psychiatric patients.

However, it is far from being fully developed. To aid in the assessment of its usefulness, a large-scale study has been initiated in a variety of clinical settings including general practice and psychiatric outpatient clinics. Its possible use in nonpsychiatric patients will also be studied in patients undergoing bypass cardiac surgery or total hip replacement operations.

QOL w; the capacity to satS'y certain human needs

Another QOL measurement has been based on the theory that' life gains its quality from the ability and capacity of the individual to satisfy certain human needs'. It is claimed that this instrument, the quality of life in depression (QLDS). is the first real measure of QOL, as it is the first to be based on a stated theory5. The content of the measure is derived from depressed patients and the items are expressed in their own words. As a result, patients find it highly relevant to their condition.

In clinical trials. the QLDS has been shown to be both valid and reliable.

... and for I~ severe problems For patients with minor health problems, eg

migraine, or for physical problems associatel with psychological distress such as skin or gynae­cological disorders, very sensitive instruments are required. A possible contender is the General Well-Being Index (GWBI) which was recently adapted for use in the UK6. This has been tested in a study of depressed patients treated with fluoxetine and was considered highly acceptable to patients and a useful tool which provided a reliable measure.

It was also contrasted with the Mood Profile and the Quality Adjusted Life Years toolkit in the assessment of patients with intractable epilepsy and was found to be the most acceptable to patients. The latest trial involves patients receiving a new treatment for dyspepsia. This trial is ongoing, and has appeared successful to date.

Cross-culture comparability? Although the GWBI appears to have adapted

well from use in the USA to the UK, it is generally thought that currently available questionnaires do not have absolute comparability across cultures. With the increase in multinational clinical trials. the demand for such QOL measurements is bound to increase?

This will require a move away from the development of questionnaires in one country alone, with subsequent translation and retesting, and a move towards working with clear conceptual ~odels that aim to transcend culturally bound Issues.

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B PHARMACOECONOMICS

Flexibility needed Incorporating QOL measurements into clinical

trials requires a flexible approach. as a number of methodological advances are likely in the near future. This is also true for economic evaluations, as descriptive QOL data will help to ascertain the main economic benefits of treatment. In this respect. researchers should begin to include utility measures into clinical trials as a secondary endpoint8

.

Another point for consideration is that, instead of simply adding to the collection of measures available, researchers should now try to understand the similarities and differences of the existing pool of instruments9

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I. Hunt S. et al. Uses and abuses of the Nottingham Health Profile. British Journal of Medical Economics 4: 25·35. 19922. Stacey J. Development and use of the SF-36 questionnaire. British Journal of MedICal Economics 4: 37-40. 19923. Lovatt B. An overview of quality of life assessments and outcome measures. British Journal of Medical Economics 4: 1-7. 1992 4. Dunbar G. et al. The development of a questionnaire to measure quality of life in psychiatric patients. British Journal of Medical Economics 4: 63· 73. 1992 S. McKenna S. et al. Conceptual and methodological advances in qual it} of life measurement: depression and the QLDS. British Journal of Medical Economics 4: 51-61, 1992 6. McKenna S, el al. The General Well-Being Index: adapting and re-testing an American measure for use in the United Kingdom. British Journal of Medical Economics 4: 41-50, 1992 7. Hunt S, et al. Cross-cultural comparability of quality of life measures. British Journal of Medical Economics 4: 17·23. 19928. Drummond M. The role and importance of quality of life measurements in economic evaluations. British Journal of Medical Economics 4: 9·16, 19929. Stracke H. et al. Mexiletine in the treatment of diabetic neuropathy. Diabetes Care 15: 1550·1555. Nov 1992 800168310

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