Development of a conceptual model of quality of life.

Quality of life is a critically important concept for health care that has been developed predominantly in the past three decades. Conceptual clarity is extremely important, because differences in meaning can lead to profound differences in outcomes for research, clinical practice, and allocation of health care resources. This paper describes the development of the Ferrans conceptual model of quality of life. The model was developed based on the adoption of an individualistic ideology, which recognizes that quality of life depends on the unique experience of life for each person. Individuals are the only proper judge of their quality of life, because people differ in what they value. Consistent with this ideology, quality of life was defined in terms of satisfaction with the aspects of life that are important to the individual. The model was developed using qualitative methodology. Factor analysis of patient data was used to cluster related elements into domains of quality of life. The resulting model identifies four domains of quality of life: health and functioning, psychological/spiritual, social and economic, and family. Subsequent cross-cultural work with African Americans and Mexican Americans has provided evidence that the elements of the model appropriately reflect quality of life for segments of the population not sampled in the original work. The Ferrans and Powers Quality of Life Index was developed based on this model.