The Quality of Life Scale (QOLS): Reliability, Validity, and Utilization – Health and Quality of Life Outcomes
Flanagan did not report internal consistency reliability (Cronbach’s alpha) estimates in his instrument development work. Estimates from the first study of 240 American patients with chronic illness (diabetes, osteoarthritis, rheumatoid arthritis and post-ostomy surgery) indicated that the 15-item QOLS satisfaction scale was internally consistent (α = .82 to .92) and had high test-retest reliability over 3-weeks in stable chronic illness groups (r = 0.78 to r = 0 .84) [13]. Other researchers have reported similar reliability estimates for the 16-item scale [14–17].
The quality and quantity of descriptive work with large numbers of Americans provided strong evidence for content validity of the QOLS during its early development. However, Flanagan, himself, reasoned that some adaptations for persons with chronic conditions or disabilities might be needed and that different rating scales might produce divergent results. In 1981 Professor Flanagan gave the first author permission to adapt the scale for patients with chronic illness. Over the intervening years the QOLS has been called the “Adapted Quality of Life Scale” or “Flanagan Quality of Life Scale.” In this paper it will be called simply the QOLS and always refer to the 16-item scale as adapted by Burckhardt and colleagues for persons with chronic illness.
When the 240 Americans with chronic illness were asked open-ended questions about what the term “quality of life” meant to them and what was important to their QOL, they generated words and phrases that were very similar to those used by the general population that Flanagan had studied. The importance of material comforts and security, health, relationships with both family and friends, understanding of themselves, as well as the ability to socialize, participate in activities and have satisfying work experiences were all apparent in their descriptions. However, they also generated a list of phrases that could be best described as “efforts to remain independent” using words and phrases, such as “independence”, “able to care for myself”, and “being physically active”. This item was added to the QOLS to make a 16-item scale: “Independence, ability to do for oneself” [13]. In addition, during this process the wording of item #8 “activities related to local and national government” was broadened to “participating in organizations and public affairs.” This rewording was based on the qualitative responses from the people with chronic illness who were interviewed. Few of them participated in political activities or local government affairs; but they did participate in clubs, religious groups and other organizations.
In all, 207 of the 240 patients also rated the importance of the 15 items on the original Flanagan QOLS. Table 2 summarizes the findings by total group and gender. More than 50% of the patients rated all items except civic activities as important or very important to their quality of life. Men and women differed on four items with men rating relationships with parents, siblings and other relatives, relationships with friends, helping and encouraging others, and socializing as significantly less important to their quality of life.
Table 2 Importance of the QOLS items by total sample and gender. Percent rating the item as important or very important (In parentheses, the percent rating the item as unimportant).
Full size table
Convergent and discriminant construct validity of the QOLS in chronic illness groups was evidenced first by the high correlations between the QOLS total score and the Life Satisfaction Index-Z (LSI-Z) [18] (r = 0.67 to 0.75) and its low to moderate correlations with the Duke-UNC Health Profile (DUHP) [19] physical health status subscale (r = 0.25 to 0.48) and a disease impact measure, the Arthritis Impact Measurement Scales (AIMS) [20] (r = 0.28 to 0.44) [13]. Later, Burckhardt and colleagues offered evidence that the QOLS could discriminate levels of QOL in populations that would be expected to differ. A group of healthy adults as well as groups with more stable chronic illnesses, such as post-ostomy surgery, osteoarthritis, and rheumatoid arthritis, were shown to have significantly higher scores than groups of patients with the persistent painful condition, fibromyalgia, life-threatening COPD, or insulin-dependent diabetes [21].
More recently, a sample of 1241 chronically ill and healthy adults from American and Swedish databases was used to generate factor analyses for both the 15-item original QOLS and the 16-item chronic illness adaptation. Analysis of the data suggested that the QOLS has three factors in the healthy sample and across chronic conditions, two languages and gender. Factors that could be labeled (1) Relationships and Material Well-Being, (2) Health and Functioning, and (3) Personal, Social and Community Commitment were identified [22].
