Medical Outcomes Study

Definition

The Medical Outcomes Study (MOS) was a 2-year observational study of patients with chronic conditions, conducted in a cross-sectional phase among 22,462 patients and in a longitudinal phase among 2,349 patients (Tarlov et al., 1989). One of its two main purposes was to analyze how outcomes vary depending on factors such as the type of delivery system in which a patient receives care, clinician specialty training, and intensity of resource use. Another main purpose was to develop practical tools for monitoring patient outcomes and their determinants. For instance, the MOS core survey includes 116 items that measure quality of life in terms of physical, mental, and general health. In addition, the MOS Short-Form General Health Survey has been used in 12-item, 20-item, and 36-item versions for quality of life assessment in numerous conditions (Stewart et al., 1989). One of the initial publications from the MOS defined the impact of depression on patient functioning and...