Health status questionnaires (HSQs) have become a common way to measure and understand the multifaceted aspects of a patient's health and outcome. Health may be defined very broadly, as in The World Health Organization's (WHO) definition as ''physical, mental, and social well-being, not merely the absence of disease and infirmity,(87)'' or much more specifically, in terms of the rheumatic disease being studied. Ln the former instance, HSQs will assess many domains, including socialization, recreation, and role, while in the latter instance, restricted domains will be investigated. Thus, instruments differ in the number and broadness of the domains they assess. Another way to categorize instruments is whether they are generic (suitable for use in any disease) or disease specific (suitable for use in a single disease or group of diseases). HSQs may be described as quality of life instruments when they measure aspects of a patient's existence and illness experience, such as function, psychological health, symptoms, etc. (factors that are personal to the patient). Because quality of life is affected by nonmedical items (e.g., housing conditions), it is usual to restrict the concept to health-related quality of life (HRQL). Quality of life is almost undefinable and has a different meaning to each person,(32, 68) but Kaplan's definition of HRQL as ''function plus symptoms,'' does, in fact, represent the de facto content of a number of HRQL instruments.(15, 42, 63, 71, 73, 77) Thus, almost any instrument, generic or disease specific, that focuses on these issues can be considered an HRQL instrument. Another type of generic HSQ is the utility instrument. Utilities represent the estimate of the patient's overall HRQL or health status. There is much overlap in the content of all of these methods and measures, and there is no best instrument. An important difference between the instruments that will be described below is their usability, or ability to be administered in a clinical setting or study repeatedly. Other important characteristics are sensitivity to change and relevance to the illness being studied. The discussion below focuses on many HSQs that are relevant to rheumatology.
