OBJECTIVE -To develop a self-administered questionnaire to address alternative delivery routes of insulin and to investigate aspects of patient satisfaction that may be useful for subsequent assessment and comparison of an inhaled insulin regimen and a subcutaneous insulin regimen. RESEARCH DESIGN AND METHODS -Attributes of patient treatment satisfaction with both inhaled and injected insulin therapy were derived from five qualitative research studies to arrive at a 15-item questionnaire. Each item was analyzed on a five-point Likert scale so that higher item scores indicated a more favorable attitude. There were 69 subjects with type 1 diabetes previously taking injected insulin therapy who were enrolled in a phase II clinical trial. Their baseline responses on the questionnaire were evaluated and subjected to an exploratory factor analysis. Meaningful factors were retained and interpreted based on their psychometric properties. RESULTS -Exploratory factor analysis suggested a two-factor solution accounting for 66 and 20% of the variance, respectively. The first factor contained 10 reliable items (Cronbach' s ␣ = 0.89) relating to convenience and ease of use, and the second contained 5 reliable items (Cronbach' s ␣ = 0.82) relating to social comfort. CONCLUSIONS -Among patients with type 1 diabetes, this analysis highlighted and quantified two key factors contributing to patient satisfaction: convenience/ease of use and social comfort. The questionnaire underwent rigorous development, had reliable properties, and an interpretable and rich factor structure. This report is intended to help advance, in subsequent investigations, the understanding and measurement of treatment satisfaction with novel and existing forms of insulin delivery. Factor analysis of the PSIT ication of any kind was given) for 14 days and maintained a daily diary; and one study (n = 10) included health care professionals (2 primary care physicians, 2 internists, 2 endocrinologists, 2 pharmacists, and 2 certified diabetes educators). Based on these studies, items and content relating to patient satisfaction with insulin treatment were identified. The initial item pool was further reduced to contain only items that were clear and not redundant. Emphasis was placed on using simple and unambiguous wording of items and responses. The resulting questionnaire-the Patient Satisfaction with Insulin Therapy (PSIT) Questionnaire-consisted of 15 items, and responses to each item were based on a five-point Likert scale ranging from strongly agree to strongly disagree. Responses to each item on the questionnaire were analyzed so that a higher item score indicated a more favorable attitude. Each of the 15 items received equal weight when summed to arrive at a global (total) score. The global satisfaction score can therefore be from as low as 15 (least satisfaction) to as high as 75 (most satisfaction). The questionnaire was self-administered at baseline and at week 12 by subjects with type 1 diabetes recruited into a 12-week parallel study of an inhaled insulin regimen versus a conventional subcutaneously injected insulin regimen conducted at 10 centers in the U.S. Subjects completed the baseline questionnaire in ϳ5-10 min. The design and clinical results of this study have been reported elsewhere (3). Subjects were aged 18-56 years and on a stable insulin administration schedule (for at least 2 months) involving two to three prescribed insulin injections daily. Both screening and prerandomization HbA 1c values were between 7.0 and 11.9%, with fasting plasma C-peptide Յ0.2 pmol/ml. All had body weight of 80-130% of ideal (Metropolitan Life Insurance Tables). Subjects were nonsmokers (for at least 6 months) and had a normal chest X-ray, normal pulmonary function test results, and an electrocardiogram with normal sinus rhythm at a rate of 50-100 beats/min. All subjects performed home blood glucose monitoring four times daily. Baseline responses from a total of 69 subjects were considered in the factor analysis. To further understand and identify attributes of patient satisfaction, we conducted an exploratory factor analysis of the baseline questionnaire responses. Factor analysis is a statistical technique that reduces a large number of interrelated questions to a smaller number of underlying common factors or domains that are primarily responsible for covariation in the data (8). We followed a standard approach to conducting an exploratory factor analysis (8,9). Three major sequential steps were undertaken. Step 1 involved identifying the number of meaningful factors to retain based on the scree test (10) and the percentage of (common) variance accounted for by a given factor. Using the scree test, we plotted the eigenvalue (i.e., the amount of variance that is accounted for by a given factor) associated with each factor and looked for a break between the factors with relatively large eigenvalues and those with smaller eigenvalues. Factors that appeared before the break were assumed to be meaningful and were retained for rotation (9-11). Factors appearing on the horizontal line after the break were taken to account only for a trivial amount of variance and were therefore not retained. In addition, we prespecified and required that at least 10% of the variance be explained by a retained factor and that at least 75% of the cumulative variance be explained by the set of retained factors. Step 2 involved a promax (oblique) rotation on the retained factors to help with interpretation. An oblique rotation was applied because it was hypothesized (and later confirmed) that the factors would be correlated with one another. Step 3 involved interpreting the rotated solution by identifying which items load on each retained factor, the conceptual meaning of items that load on the same factor, and conceptual differences in items that load on different factors. Pattern loadings near 0.40 or greater (in absolute value) were used to interpret the results (9,11). Cronbach' s ␣ reliability coefficient (12) was computed for each factor (domain) and total scale to measure internal consistency. An item-total correlation between an individual item and the sum of the remaining items on a factor or total scale was calculated to further assess reliability. A second baseline measurement was not available for baseline test-retest reliability (stability). However, Pearson correlations between baseline ("test") and posttreatment ("retest") scores at 12 weeks were measured among patients who continued with, and were randomized to, traditionally administered subcutaneous insulin. Statistical significance was based on P Ͻ 0.05. Relationship of satisfaction scores with demographic and medical variables We examined the relationship of satisfaction scores with the demographic and medical variables found in Table 1 . Pearson correlation (r) was used to measure the association of satisfaction scores with these variables except race, for which an analysis of variance model was applied. Statistical significance was based on P Ͻ 0.05. Table 1 gives the baseline characteristics of the 69 subjects. Table 2 provides descriptive statistics at baseline for the 15 individual items and the global satisfaction score. RESULTS Satisfaction items Step 1: Determination of the number of retained factors. The scree plot in Fig. 1 depicts an abrupt break or discontinuity before factor 3, suggesting that only the first two factors were meaningful to be retained. (%) 8.5 ± 1.1 (6.4-11.2) Data are n, means ± SD (range), or n (%). A total of 73 men and women with type 1 diabetes were enrolled. One subject was discontinued before randomization, and complete data were not available. Of the remaining 72 subjects, there were no discernible differences between the 3 subjects excluded and the 69 subjects included (3).
Reference REF in their paper -Development and Factor Analysis of Questionnaire to measure Patient Satisfaction with Injected and Inhaled Insulin for Type 1 Diabetes‖ used exploratory factor analysis to evaluate the data collated from the questionnaire.
Development and factor analysis of a questionnaire to measure patient satisfaction with injected and inhaled insulin for type 1 diabetes.
Diabetes care
Diabetes care
Medicine