Patient reported outcomes

It is perhaps tempting to think of progress in medicine as characterised by developments such as vaccinations, penicillin and advances in surgery. However, the late 20th century saw a remarkable change in the approach to evaluating healthcare interventions which may have gone largely unnoticed by both the general public and, indeed, many patients. Patients’ reports have now become central to healthcare evaluation, and this was simply not the case historically. Patient reported outcome measures (PROMs) are now regularly used to systematically gain meaningful subjective accounts from those receiving care. This is in stark contrast to the prevailing approach adopted to outcomes measurement throughout most of the 20th century and before; namely, that outcomes should be assessed by professionals, such as clinicians and researchers. Reports from patients were, traditionally, viewed as subjective, and consequently unreliable. Significant evidence, however, has accumulated that patient reports are not only a reliable source of information, but also one of the most important.

Healthcare historically concentrated on the diagnosis and treatment of physiological and anatomical conditions. ¹ Traditionally, evaluation of medical treatment had relied upon measures of morbidity and mortality, whilst medical practitioners based judgements for intervention on traditional clinical, radiological and laboratory measures. ² However, there is a considerable body of evidence to suggest that clinically assessed outcomes of treatment do not always reflect those of patients, ³ and, indeed are not always particularly accurate or reliable. ⁴ Consequently, over the past few decades there has been a shift away from this approach, and patient-based data is now central to the evaluation of care.^5,6 The purpose of such evaluation is to provide more meaningful assessments of patient health and the benefits and harms that may result from healthcare. ⁷ There is, however, a wide variety of applications of health status measures, and the requirements of measures differ across these applications. Some instruments are generic in nature, whilst others are specific to a particular condition or procedure. Furthermore, instruments can vary in their scoring, with some providing a profile of scores across a range of areas (e.g. emotional health, pain, social functioning, activities of daily living, mobility), others a single overall score. Many instruments offer the option of scoring across a variety of concepts, and also deriving an overall summary score. Furthermore, some measures can be used in health economic analyses of healthcare. Consequently, before considering the nature of subjective health measures it is worth considering the variety of applications in which data gained directly and systematically from the patients’ perspective could be of value.

Selection of an appropriate PROM is likely to be determined in large part by the purpose of the work being undertaken. In trials it is commonplace to adopt disease specific questionnaires, for example, the Myocardial Infarction Dimensional Assessment Scale, ⁸ which have been designed specifically with the intention of assessing aspects of a condition that patients themselves have indicated as important to their well-being. Studies evaluating a variety of treatment regimens across conditions are likely to benefit from a more generic approach. Such measures include the 36 and 12 item Short Form Health Surveys (SF-36, SF-12)^9,10 and the Oxford Participation and Activities Questionnaire (Ox-PAQ), ¹¹ which are designed to be used across patient groups and, indeed, in the general population. Whereas disease specific measures are likely to be more sensitive to specific aspects of treatment, generic measures can be used to compare results across conditions and with normative, population-based data. Comparing the outcomes of treatments across conditions may be useful for ongoing monitoring of services, but may also be used in one of the more controversial applications of PROMs, namely health economic evaluation. Measures such as the EQ-5D, ¹² Health Utilities Index (HUI), ¹³ and SF-6D (developed as a preference-based measure from the SF-36) ¹⁴ are designed to provide health utility information on the basis of patient reports. Thus, the responses of patients completing these measures are subjected to weighting from a ‘tariff’ which is intended to reflect societal valuations of the value (‘utility’) of the health state. Such data can then be used in the calculations of ‘quality adjusted life years’ (QALYs) and the cost of treatment per QALY calculated. This can inform decision makers as to what treatments are funded, and such information is used by the National Institute for Health and Care Excellence (NICE) in the UK.

Regardless of their intended use, the benchmark for PROMs has been raised significantly over recent years. The process undertaken in their development is regarded as critical and requires patients to be at the heart of the item generation process. Measures must subsequently conform to the highest psychometric standards of reliability, validity and responsiveness. Indeed, bodies such as the United States Food and Drug Administration (FDA) now provide guidance not only for the selection and reporting of such measures in clinical trials, but also their development. ¹⁵ Such guidelines are now considered best practice, regardless of whether an instrument is being incorporated into, or developed for, trials supporting pharmaceutical label claims. ¹⁶

Despite these advances, a number of issues remain unresolved. For example, can PROMs be useful at the patient/individual level? Furthermore, can thresholds be set for measures to select candidates for, for example, surgery? These, and doubtless other, questions have yet to be answered satisfactorily and more are likely to be raised in the future. There are also exciting new challenges, such as electronic data capture and computer adaptive testing, that have gathered significant momentum in recent years. Consequently the evolution of the field of PROMs is far from complete and, given its prominence, is likely to see further rapid development in the future.