Objective: To validate an interview-like questionnaire measuring quality of life, based on the subject's capacity to reach personal goals in different life domains.
Design: One group repeated measures for test-retest reliability (two-week interval) and correlational approach for concurrent validity.
Participants: A total of 171 normal subjects (95 males and 76 females) was interviewed. Mean age was 43.6 years.
Outcome measures: The Quality of Life Systemic Inventory (QLSI), the Beck Depression Inventory, the State-Trait Anxiety Inventory, the Marlowe and Crowne Social Desirability Scale, the Buss and Durkee Hostility Inventory, the Carver and Sheerer self-efficacy scale and the Derogatis Stress Profile were used.
Results: The quality of life score (a gap score representing the difference between a subject's actual state and personal goal) has a high test-retest reliability of 0.838. The two other scores (goal and potential for conflict) also have good test-retest reliability: 0.858 for both. Intercorrelations between scores are low-gap-goal, 0.293; gap-conflict, 0.172; and goal-conflict, 0.115--suggesting their distinctiveness. Correlations between scores and social desirability are also low-gap, 0.106; conflict, -0.024; and goal, -0.128. Finally, correlations with other psychological variables such as depression, anxiety, self-efficacy and stress are moderate to low, showing that the questionnaire measures dimensions different from these variables.
Conclusions: The QLSI has good test-retest reliability, and scores are not much influenced by social desirability despite the fact that the test is used in an interview setting. The questionnaire may be administered in small groups or face-to-face situations. It yields a wealth of clinical information and is easily used in research. Furthermore, patients much prefer this interactive exchange to the long self-administered questionnaires.