This is lesson 3.3.3, Measuring Quality of Life. In the previous lesson, if you recall we discussed QALYs, or quality-adjusted life years, which are calculated using quality of life measures. In this lesson, we discuss how to calculate those quality of life measures. In order to calculate QALYS we first need to identify a patient's utility in each health state. The health state can be thought of as the health of an individual at a particular point in time. And the health-related quality of life measures are used to help define each health state. Large surveys of the views, attitudes, and preferences of patients and the general public are used to assign utilities to every health state. The typical dimensions or aspects of health related quality of life measures include, health perceptions, social function, psychological function, physical function, and measures of impairment. Health perceptions are simply self reported health statuses. Social function relates to how patients or individuals relate in society. It includes social relations, their usual social role, intimacy, sexual function, as well as communications in speech. Psychological functions are related to their cognitive ability, their emotional levels, and their moods and feelings. Physical functions are what many people typically think of when talking about health-related quality of life measures and these include measures of mobility, physical activity, and self care. Impairment is another common topic of health related quality of life measures and that involves sensory or function loss, the types of symptoms or impairments related with the disease, and levels of pain. Measures of all of these health related quality of life aspects can be ascertained through survey instruments. General surveys, such as the Short Form Health Surveys that are commonly referred to as the SF-36 or SF-12 because they have 36 or 12 questions are common surveys to collect general health related quality of life measures. Additionally, computer programs exist to convert scores from these two types of surveys into scores from the SF-6D questionnaire. Which can then be directly translated into the utilities needed to calculate qualities. There are also many types of disease specific quality of life surveys. Unlike the general surveys, these surveys are designed for particular diseases or conditions. And although they're given to patients with these diseases and conditions, they're also given to the general public to help determine the quality of life and utilities that are needed to estimate the qualities. The disease specific surveys are very specific and often intended to estimate particular treatment effects. They can also be sensitive to small changes in the disease or the status of a condition. The benefits of these types of surveys, however, are that clinicians can link outcomes to specific actions or treatments. Another way to collect quality of life information, is to collect it during a clinical trial. If quality of life information is to be collected during the clinical trial, it needs to be considered before the clinical trial begins and built into the trial design. If it is, you can include a measurement of the quality of life survey to find out how many qualities each treatment in a clinical trial produces. During the trial, you have patients fill out the survey prior to the treatment and after they receive the treatment. Alternatively, you could have them fill out multiple surveys at various points throughout the treatment before and after. Using the results of these surveys you can convert the Health Related Quality of Life measurements from the survey to QALYs. After that you can evaluate the clinical trial directly with QALYs. So with a QALY for each individual in the trial, you can measure the QALYs gained on average as a result of a particular treatment and perform other types of statistical testing using QALYs to help evaluate the success of the clinical trial that was performed.