Health Related Quality of Life

Health Related Quality of Life (HRQoL) is the most established of currently available patient reported outcome (PRO) measures and was developed to evaluate the impact of disease and interventions on emotional, social and physical functioning from the patient's perspective. It has extended outcome assessment beyond traditional efficacy and safety. In recent years, as well as being an important element for demonstrating product value, there has been an increased trend towards reporting PRO results in regulatory documents and approved labels.

There are two main types of instrument available for measuring HRQoL: generic and disease specific. Generic measures are useful in comparing the impact of a wide variety of diseases and treatments on HRQoL, but may lack precision in a particular condition for which disease-specific measures are better suited. Many studies include both types of instrument.

Commonly used generic instruments include The Medical Outcomes Study 36-Item Short Form (SF-36) health survey and The EuroQol Instrument (EQ-5D). Other examples include:

• Quality of Well-Being (QWB) Scale
• Nottingham Health Profile (NHP)
• Sickness Impact Profile (SIP)
• Health Utilities Index (HUI)

Examples of disease specific measures include:

• Arthritis Impact Measurement Scale
• Asthma Quality of Life Questionnaire
• The Inflammatory Bowel Disease Questionnaire

With several hundred available instruments, mainly disease specific, careful consideration has to be given to the selection of an appropriate tool and commonly used criteria include:

• Appropriateness - The extent to which content is appropriate to the particular application
• Acceptability - The extent to which an instrument is acceptable to patients
• Interpretability - The meaningfulness of scores produced
• Precision - The number and accuracy of distinctions made
• Reliability - Whether an instrument is internally consistent and free from measurement error
• Validity - The extent to which an instrument measures what is intended
• Responsiveness - The ability to measure important changes in health

Given the international nature of many studies it is also crucial to ensure that instruments have been properly validated in all of the required languages.

When including a HRQoL measure in any type of study there are important considerations during study design and performance including:

• Providing a clinical rationale for the use of each instrument in the protocol
• Justification of the adequacy of selected instruments, including definition of minimal and clinically important differences, timing and frequency of assessment
• Approach to data quality including handling of missing data
• A statistical analysis plan with pre-specified outcomes, hypotheses and sample size

The extent to which PROs such as HRQoL, can be used to evaluate and communicate the benefit of therapeutic interventions is still evolving including their use as primary outcome measures, however the value of a patient's perspective is clearly established as:

• A unique indicator of the impact of disease
• A means to evaluate treatment efficacy/effectiveness
• Useful for interpreting clinical outcomes

The demand for HRQoL and other PRO information will continue to increase. To find out more and discuss the right Quality of Life tool for your study, contact the PACE Group.