Takafumi Wakita

Development of a Japanese version of the Epworth Sleepiness Scale (JESS) based on Item Response Theory

BACKGROUND Various Japanese versions of the Epworth Sleepiness Scale (ESS) have been used, but none was developed via standard procedures. Here we report on the construction and testing of the developer-authorized Japanese version of the ESS (JESS). METHODS Developing the JESS involved translations, back translations, a pilot study, and psychometric testing. We identified questions in the ESS that were difficult to answer or were inappropriate in Japan, proposed possible replacements for those questions, and tested them with analyses based on item response theory (IRT) and classical test theory. The subjects were healthy people and patients with narcolepsy, idiopathic hypersomnia, or obstructive sleep apnea syndrome. RESULTS We identified two of our proposed questions as appropriate replacements for two problematic questions in the ESS. The JESS had very few missing data. Internal consistency reliability and test-retest reliability were high. The patients had significantly higher JESS scores than did the healthy people, and higher JESS scores were associated with worse daytime function, as measured with the Pittsburgh Sleep Quality Index. CONCLUSIONS In Japan, the JESS provides reliable and valid information on daytime sleepiness. Researchers who use the ESS with other populations should combine their knowledge of local conditions with the results of psychometric tests.

Effect of a carbonaceous oral adsorbent on the progression of CKD: a multicenter, randomized, controlled trial.

BACKGROUND The carbonaceous oral adsorbent AST-120 slows the deterioration of kidney function in patients with advanced chronic kidney disease (CKD). However, information about AST-120 in patients with less severe stages of CKD is lacking. STUDY DESIGN Randomized controlled trial. SETTING & PARTICIPANTS 75 medical facilities, 460 patients with CKD with serum creatinine (sCr) concentrations less than 5.0 mg/dL (not undergoing dialysis). INTERVENTION Random assignment to either a low-protein diet and antihypertensive medication in the control group or that treatment combined with AST-120 (6 g/d). OUTCOMES & MEASUREMENTS Composite primary end point: doubling of sCr level, increase in sCr level to 6.0 mg/dL or more, need for dialysis or transplantation, or death. SECONDARY OUTCOMES adverse events and changes in estimated creatinine clearance (CCr) rate, proteinuria (protein in milligrams per day), and quality of life. RESULTS Mean sCr level was 2.66 mg/dL and estimated CCr was 22.4 mL/min in both groups. During 56 weeks, numbers of primary end-point events (43 for control versus 42 for AST-120) and event-free survival (P = 0.9) did not differ between groups. Gastrointestinal adverse events were less common in the control group than the AST-120 group (2 versus 32 events). Estimated CCr decreased more in the control group than in the AST-120 group (-15% per year versus -12% per year, relative to the baseline value; [corrected] P = 0.001). Median proteinuria changed from protein of 1,162 to 1,167 mg/d in the control group versus 1,102 to 906 mg/d in the AST-120 group (P = 0.2). LIMITATION Infrequent primary end-point events. CONCLUSION AST-120 did not substantially slow the progression of kidney disease in patients with moderate to severe CKD during 1 year.

Psychological Distance Between Categories in the Likert Scale Comparing Different Numbers of Options

This study examined whether the number of options in the Likert scale influences the psychological distance between categories. The most important assumption when using the Likert scale is that the psychological distance between options is equal. The authors proposed a new algorithm for calculating the scale values of options by applying item response theory and the ideas of Wakita to reveal the influence of the number of categories. Three types of questionnaires that were composed of the same items, but used different numbers of options to assess these items (specifically, 4-, 5-, and 7-point scales), were completed by 722 undergraduate students. The results indicated that the number of options influenced the psychological distance between options, particularly for the 7-point scale. This influence was revealed only by the authors’ algorithm; descriptive statistics and coefficients of reliability did not show that the number of options had a prominent influence. The importance of the number of options and the new algorithm are discussed.

Improving the measurement accuracy of the effort-reward imbalance scales

Background: The effort-reward imbalance (ERI) scale items are answered in a two-step process, but the justification is questioned for the formulation of summary measure by combining information rated in two steps. Purpose: To examine whether the basic prerequisites of the ERI scales are empirically satisfied and to seek ways to improve the rating procedure. Methods: A polytomous item response theory (IRT) model was applied to the responses of 20,256 workers who completed the ERI scales. To determine the most appropriate statistical justification, three alternative scoring algorithms were compared with regard to the test properties revealed by the IRT analyses and efficiencies of screening performance and criterion validity against depressive symptomatology. Results: The rated raw-score units did not reflect the hypothesized order of lowest stress levels to highest stress levels. Exchanging or collapsing the lowest two categories of a Likert scaled item, where data of different quality are combined, solved this problem, thereby making the test content more appropriate. The modified rating improved the efficiencies of screening performance and the correlation of the stress summary measures against health criterion, i.e., depression. Conclusion: An avoidable measurement error exists in the current ERI scales. Modifying the rating procedure can improve the measurement accuracy.

Cost-effectiveness of administering oral adsorbent AST-120 to patients with diabetes and advance-stage chronic kidney disease

AIMS AST-120, an oral adsorbent currently on-label only in Asian countries with phase III trials ongoing in the US, slows renal disease progression in patients with diabetes and advanced-stage chronic kidney disease (CKD). The objective of this study is to evaluate the cost-effectiveness of using AST-120 to treat patients with type 2 diabetes and advanced-stage CKD. METHODS We used Markov model simulating the progression of diabetic nephropathy. Data were obtained from randomized trials estimating the progression of diabetic nephropathy with and without AST-120, and published literature. The base population was patients 60 years of age with type 2 diabetes and Stages 3 and 4 CKD. RESULTS Treating patients with diabetes and advanced-stage CKD was found to be a dominant strategy, and quality of life improved further and more money was saved (0.22 quality-adjusted life years [QALYs] and

Development and Validation of a Symptom Scale to Evaluate Postoperative Patients with Esophagogastric Cancer

15,019 per patient) using AST-120 than the control strategy. Sensitivity analysis results were robust with regard to cost, adherence, and quality of life associated with AST-120 therapy, as well as age at diagnosis. The model was relatively sensitive to the effectiveness of AST-120. CONCLUSIONS Treating patients with type 2 diabetes and advanced-stage CKD with AST-120 appears to extend life and reduce costs.

Impact of Early Referral to Nephrologist on Mental Health among Hemodialysis Patients: A Dialysis Outcomes and Practice Patterns Study (DOPPS)

BACKGROUND Postgastrectomy or esophagectomy symptoms can be a significant burden for patients. However, no standard scale for evaluating these symptoms has been established. We recently developed a postoperative symptom-specific scale. STUDY DESIGN After a draft scale was prepared based on a pilot study, psychometric methods were used to assess its reliability and validity. This study involved specialized and multifaceted discussions by a team consisting of gastrointestinal surgeons, gastroenterologists, psychologists, and epidemiologic researchers. The draft questionnaire included 40 questions and 3 domains. A factor analysis was carried out to refine the items and subscale design. To assess the reliability, Cronbachs alpha and score distributions were estimated. To assess the criterion-related validity, the correlations with the Short Form (SF)-12, Gastrointestinal Symptom Rating Scale (GSRS), endoscopic findings, and nutritional indicators were analyzed. RESULTS A total of 344 patients were enrolled in this study. In an exploratory factor analysis (principal factor method), the eigenvalue attenuation data showed 4 domains. The final scale, named the Esophagus and Stomach Surgery Symptom Scale (ES(4)), included 23 items and 4 domains; 7 items for cervico-thoracic symptoms, 6 for abdominal hypersensitivity symptoms, 4 for abdominal distention symptoms, and 6 items for systemic symptoms. Cronbachs alphas for these domains were 0.82, 0.81, 0.79, and 0.74, respectively. The scale scores were normally distributed, and there were significant associations with the endoscopic findings, nutritional indicators, the summary score of the SF-12, and the GSRS. CONCLUSIONS The ES(4) scale has high psychometric validity and can evaluate the profiles and severity of postoperative symptoms. This scale is applicable as an outcomes measure for various interventional studies on esophagogastric surgery aimed at alleviating postoperative symptoms.

Development and Validation of a Disease-Specific Instrument to Measure Diet-Targeted Quality of Life for Postoperative Patients with Esophagogastric Cancer

Background: Pre-dialysis early referral is associated with improved survival in patients on dialysis. Here, we examined the association between pre-dialysis early referral and post-dialysis Mental Health (MH) in hemodialysis patients. Methods: We examined data from the Dialysis Outcomes and Practice Patterns Study (DOPPS), a prospective and observational study of hemodialysis patients, by performing a cross-sectional and longitudinal analysis of DOPPS data from Japan. The outcome measure was analyzed from the MH subscale of the Medical Outcomes Study Short Form-36 Item Health Survey. Predictors of mean MH were identified using analysis of covariance. The variables evaluated in the multivariate models included age, sex, duration of dialysis and diabetes. Results: A total of 552 patients under hemodialysis participated in the study, with a late referral prevalence of 34.2% (189/552). The estimated mean MH score was 60.7 (95% confidence interval (CI) 57.5–63.8) and 65.6 (95% CI 63.2–68.1) in late and early referrals, respectively. A statistically significant difference in mean MH score of 4.9 was observed between late and early referral groups (p = 0.01). The mean MH score for late referral was significantly lower than that for early referral in the 6–12 and 12–18 month groups. Conclusions: Pre-dialysis early referral is a modifiable and important factor and is associated with improved MH of post-dialysis patients.

A novel Internet-based blended learning programme providing core competency in clinical research.

BackgroundPatients who have undergone esophagectomy or gastrectomy have certain dietary limitations because of changes to the alimentary tract. This study attempted to develop a psychometric scale, named “Esophago-Gastric surgery and Quality of Dietary life (EGQ-D),” for assessment of impact of upper gastrointestinal surgery on diet-targeted quality of life.MethodsUsing qualitative methods, the study team interviewed both patients and surgeons involved in esophagogastric cancer surgery, and we prepared an item pool and a draft scale. To evaluate the scale’s psychometric reliability and validity, a survey involving a large number of patients was conducted. Items for the final scale were selected by factor analysis and item response theory. Cronbach’s alpha was used for assessment of reliability, and correlations with the short form (SF)-12, esophagus and stomach surgery symptom scale (ES4), and nutritional indicators were analyzed to assess the criterion-related validity.ResultsThrough multifaceted discussion and the pilot study, a draft questionnaire comprising 14 items was prepared, and a total of 316 patients were enrolled. On the basis of factor analysis and item response theory, six items were excluded, and the remaining eight items demonstrated strong unidimensionality for the final scale. Cronbach’s alpha was 0.895. There were significant associations with all the subscale scores for SF-12, ES4, and nutritional indicators.ConclusionsThe EGQ-D scale has good contents and psychometric validity and can be used to evaluate disease-specific instrument to measure diet-targeted quality of life for postoperative patients with esophagogastric cancer.

Development and validation of a symptom scale for lumbar spinal stenosis.

RATIONALE, AIMS AND OBJECTIVES We developed a novel Internet-based blended learning programme that allows busy health care professionals to attain core competency in clinical research. This study details the educational strategies and learning outcomes of the programme. METHOD This study was conducted at Kyoto University and seven satellite campuses from September 2009 to March 2010. A total of 176 health care professionals who had never attempted to attain core competency in clinical research were enrolled. The participants were supplied with a novel programme comprising the following four strategies: online live lectures at seven satellite campuses, short examinations after each lecture, an Internet-based feedback system and an end-of-course examination. We assessed the proportion of attendance at the lectures as the main outcome. In addition, we evaluated interaction via the feedback system and scores for end-of-course examination. RESULTS Of the 176 participants, 134 (76%) reported working more than 40 hours per week. The mean proportion of attendance over all 23 lectures was 82%. A total of 156 (89%) participants attended more than 60% of all lectures and were eligible for the end-of-course examination. A total of the participants accessed the feedback system 3564 times and asked 284 questions. No statistically significant differences were noted in the end-of-course scores among medical doctors, pharmacists, registered nurses and other occupations. CONCLUSIONS We developed an Internet-based blended learning programme providing core competency in clinical research. Most busy health care professionals completed the programme successfully. In addition, the participants could attain the core competency effectively, regardless of their occupation.