1. Patient involvement in different phases of HTA
1.6. Evaluation of PRO and HRQoL instruments
The traditional clinical outcome endpoints (often changes in mortality or morbidity, survival, risk or symptom reductions) are increasingly complemented by endpoints that focus on changes in the patient’s self assessed health status that occur as a result of a treatment. Assessment of patients’ health status, over and above mortality and morbidity, by instruments to measure patient reported outcome (PRO) or health related quality of life (HRQoL), is particularly relevant in an HTA context where a broad coverage of relevant elements is desirable.
Instruments for measuring health status may be disease-specific or
generic. The advantage of
using disease-specific instruments lies in their focus on a particular disease
and thus often greater sensitivity in relation to changes as a result of
treatment. For example, instruments have been developed for measuring health
status in relation to arthritis, chronic lung disease, diabetes and various
forms of cancer; other instruments measure single dimensions, such as pain or
depression. The disadvantage of disease-specific instruments is that they can
only be used in connection with the specific disease. They are unsuited to
comparisons across disease groups.
Generic instruments are those developed for use among a wide range of patient groups and diseases, and are therefore relevant for broader comparisons across disease areas. A disadvantage of generic instruments may be, however, that they are not sufficiently sensitive in relation to a specific disease and may not pick up changes that are relevant for the patient over time.
Using both types in the same study can be useful for an HTA because it makes comparison between elements easy. On the other hand many patients find generic questionnaires irrelevant because they may not capture the concepts and details that are most relevant to each specific patient group. Decisions on which PRO/HRQoL elements and results to include in an HTA may therefore have a crucial impact on patients.
In an HTA context, the assessment of changes in patients’ health and well-being form a central part of the assessment. Patients can play a role when considering below elements:
Study design: Many instruments have been developed to describe patients’ health status at a particular time, but may also be used to measure changes in health status over time. Patients can critically assess the instrument’s ability to measure the relevant changes over time in the disease of interest to the HTA.
Effect size: The effect size needs to be large enough to allow the identification of significant changes in health status meaningful to patients. Changes in PRO or HRQoL are seldom the primary endpoints because most studies are designed to test significant differences in clinical parameters. Patients can support HTA bodies in critically assessing whether the effect size considered in the studies really captures the relevant difference in health status.
Patient characteristics: These are crucial for the choice of health status instruments. Patients can critically question whether the instrument(s) is/are relevant for the characteristics of the patient population or whether a different version or another instrument should be used. The choice of instrument also depends on the disease status, purpose and domains of interest to the HTA, and of the extent to which different patient groups will be compared.
Method of data collection and analysis: While many instruments are intended for self-completion by the patient, the length or complexity of some instruments require a personal interview (incl. by telephone or video conference). Patients can critically question whether data collection has been conducted at times when clinically relevant changes in health status would be expected to be seen and how data was analysed and interpreted.
Sensitivity assesses how good the instrument is in picking up “meaningful” changes in health status over time – whether these are meaningful with respect to clinical decisions or the patient’s experience of health status changes. Patients can critically question whether "meaningful" has been defined in collaboration with patients.
Language and cultural aspects: Patients can also assess the acceptance of an instrument which is crucial for the success of the measurement and the instrument's level of language and literacy used. This is particularly important in languages other than the instrument’s original language where words may be correctly translated but miss the cultural context.