**4.2 Specific instruments**

The second basic strategy to assessing quality of life focuses on features of health that are relevant to the major concern. The reason for this strategy is that it has the potential to boost responsiveness by focusing on only the most significant parts of HRQoL that is relevant to the patients being examined. The instrument could be tailored to a condition (such as diabetes or heart failure), a patient demographic (such as the frail elderly), a specific function (such as sleep or sexual function), or a problem (such as pain). Aside from the possibility of better responsiveness, specific measures have the advantage of being directly related to areas that clinicians usually investigate.

Health-related quality of life can be assessed using one of the following methods: telephone, self-administered, or replacement responders. Each strategy has its own set of advantages and disadvantages. Aside from the possibility of better responsiveness, specific measures have the advantage of being directly related to areas that clinicians usually investigate. For example, interviewer administered has a high response rate, few or no missing items, and few misinterpretation errors, but it involves a lot of resources, including interview training. It may also make people less reluctant to admit they have a problem. The telephone administration is similar to the interviewer-administered one, although it may limit the instrument combinations. However, when using a self-administered strategy, just a little amount of resources are used, which increases the chances of a poor response rate, missing items, and misunderstanding. In another strategy, termed replacement responders, stress for the target group is lessened but the perspective of the substitutes may be different from the target group [21].
