From the cultural and social perspectives, spirituality and religion are especially salient in the lives of minority elderly,15,16 particularly within the settings of serious illness and end-of-life care.17 From a population health perspective, increased life expectancy in the United States highlights the importance of health-related quality of life assessment in the areas of chronic illness, aging, and end-of-life care, and Healthy People 2010 has identified quality of life improvement as a specific public health objective.18 By bridging both perspectives, the SIWB has the potential to add a unique and patient-centered dimension to health-related quality of life research.
Methods
Scale and item development
The SIWB was designed as a research tool to measure the effect of patient-reported spirituality on subjective well-being. Our understanding of spirituality and the stimulus material for the index have been described elsewhere.14 In brief, a congruent, meaningful life scheme and a high degree of positive intentionality or self-efficacy promote personal agency, an intermediary between spirituality and subjective well-being Figure.
Life scheme is similar to the construct of sense of coherence, which was described by Antonovsky as a positive, pervasive way of viewing the world, and one’s life in it, lending elements of comprehensibility, manageability, and meaningfulness.19 Positive intentionality shares characteristics with self-efficacy, which is an individual’s belief in the capacity to organize and perform activities that are required for a prescribed goal.20 Self-efficacy beliefs are domain and task specific, and participants in our focus group study depicted these beliefs within the context of overcoming threatened or actual changes to their functioning.
Forty items, 20 for the life scheme domain and 20 for the self-efficacy domain, were developed by investigators who conducted the qualitative study (T.P.D., B.B.F.). The scale was prefaced by the question, “Which statement best describes your feelings and choices,” and each item was a statement accompanied by a 5-point Likert scale response from “strongly agree” to “strongly disagree,” with the midpoint representing “neither agree nor disagree.” Item content consisted of positive and negative statements regarding life scheme (eg, “I haven’t yet found my life’s purpose”) and personal self-efficacy (eg, “Despite any problem that I may face, I can get through the day”).
Study population
Participants were 65 years or older and enrolled in a cohort study to assess the ability of performance measures to predict future health service use, health status, and functional status. Recruitment for the parent study occurred between April and November 1996 from primary care sites within the Veteran’s Affairs network and a Medicare health management organization serving the Kansas City metropolitan area. The study population represented the cohort 36 months after enrollment.
Measures
Demographic information. Participants had the following demographic information collected: age, sex, race, and education level.
Health and functional status. Subjective health status was measured by the EuroQol, a recognized quality-of-life measure,21 in addition to a single-item measure of global health from the Years of Healthy Life (YOHL) Scale.22 The Physical Functioning Index of the Medical Outcomes Study Short Form 36 was used to assess functional status.23
Mental health status. We measured mental health status with the Geriatric Depression Scale (GDS), a 15-item instrument with a dichotomous (yes/no) response format.24 Items from the fear of death domain of the Death Attitude Profile Scale-Revised (DAP-R) were selected as an additional proxy of psychological well-being.25
Religiosity. Five items derived from questions developed by the National Opinion Research Center26 were preferentially selected according to a previously tested and validated model of religiosity.27 Frequency of religious or spiritual service attendance was used to assess organizational religiosity, and frequency of private prayer or spiritual practice was used to measure nonorganizational religiosity. Three items were used to measure subjective or intrinsic religiosity: self-reported strength of religious or spiritual orientation, closeness to God (or a Higher Force), and frequency of affective spiritual experiences..
Data analysis
Item reduction and reliability testing. The initial 40-item pool was reduced to 20 life scheme items and 14 self-efficacy items based on subject response and feedback during survey administration. Items that subjects could not understand or answer by self-report were removed.
First, internal reliability analyses were conducted for each subscale (life scheme, self-efficacy) and for the SIWB scale with a goal of producing high internal consistency as measured by the Cronbach’s α (eg, > .70). Items that contributed to lower internal reliability were discarded, which removed 1 self-efficacy item and 6 life scheme items from the scale.
To further refine the SIWB and its subscales, the remaining items were subjected to principal components analysis by using Varimax rotation. After rotation, the 2 largest factors were readily interpretable, with items loading as expected: self-efficacy items loading on the first factor and life scheme items loading on the second factor. From each factor, the top 6 items ranked by loading magnitude were selected for inclusion into the final scale.