Impact of the resident duty hours on in-training examination score: A nationwide study in Japan.

PURPOSE: The relationship between duty hours (DH) and the performance of postgraduate residents is needed to establish appropriate DH limits. This study explores their relationship using the General Medicine In-training Examination (GM-ITE). MATERIALS AND METHODS: In this cross-sectional study, GM-ITE examinees of 2019 had participated. We analyzed data from the examination and questionnaire, including DH per week (eight categories). We examined the association between DH and GM-ITE score, using random-intercept linear models with and without adjustments. RESULTS: Five thousand five hundred and ninety-three participants (50.7% PGY-1, 31.6% female, 10.0% university hospitals) were included. Mean GM-ITE scores were lower among residents in Category 2 (45-50 h; mean score difference, -1.05; p < 0.001) and Category 4 (55-60 h; -0.63; p = 0.008) compared with residents in Category 5 (60-65 h; Reference). PGY-2 residents in Categories 2-4 had lower GM-ITE scores compared to those in Category 5. University residents in Category 1 and Category 5 showed a large mean difference (-3.43; p = 0.01). CONCLUSIONS: DH <60-65 h per week was independently associated with lower resident performance, but more DH did not improve performance. DH of 60-65 h per week may be the optimal balance for a resident's education and well-being.

Validation of the General Medicine in-Training Examination Using the Professional and Linguistic Assessments Board Examination Among Postgraduate Residents in Japan.

PURPOSE: In Japan, the General Medicine In-training Examination (GM-ITE) was developed by a non-profit organization in 2012. The GM-ITE aimed to assess the general clinical knowledge among residents and to improve the training programs; however, it has not been sufficiently validated and is not used for high-stake decision-making. This study examined the association between GM-ITE and another test measure, the Professional and Linguistic Assessments Board (PLAB) 1 examination. METHODS: Ninety-seven residents who completed the GM-ITE in fiscal year 2019 were recruited and took the PLAB 1 examination in Japanese. The association between two tests was assessed using the Pearson product-moment statistics. The discrimination indexes were also assessed for each question. RESULTS: A total of 91 residents at 17 teaching hospitals were finally included in the analysis, of whom 69 (75.8%) were women and 59 (64.8%) were postgraduate second year residents. All the participants were affiliated with community hospitals. Positive correlations were demonstrated between the GM-ITE and the PLAB scores (r = 0.58, p < 0.001). The correlations between the PLAB score and the scores in GM-ITE categories were as follows: symptomatology/clinical reasoning (r = 0.54, p < 0.001), physical examination/procedure (r = 0.38, p < 0.001), medical interview/professionalism (r = 0.25, p < 0.001), and disease knowledge (r = 0.36, p < 0.001). The mean discrimination index of each question of the GM-ITE (mean ± SD; 0.23 ± 0.15) was higher than that of the PLAB (0.16 ± 0.16; p = 0.004). CONCLUSION: This study demonstrates incremental validity evidence of the GM-ITE to assess the clinical knowledge acquisition. The results indicate that GM-ITE can be widely used to improve resident education in Japan.

Difference in the general medicine in-training examination score between community-based hospitals and university hospitals: a cross-sectional study based on 15,188 Japanese resident physicians.

BACKGROUND: The general medicine in-training examination (GM-ITE) is designed to objectively evaluate the postgraduate clinical competencies (PGY) 1 and 2 residents in Japan. Although the total GM-ITE scores tended to be lower in PGY-1 and PGY-2 residents in university hospitals than those in community-based hospitals, the most divergent areas of essential clinical competencies have not yet been revealed. METHODS: We conducted a nationwide, multicenter, cross-sectional study in Japan, using the GM-ITE to compare university and community-based hospitals in the four areas of basic clinical knowledge". Specifically, "medical interview and professionalism," "symptomatology and clinical reasoning," "physical examination and clinical procedures," and "disease knowledge" were assessed. RESULTS: We found no significant difference in "medical interview and professionalism" scores between the community-based and university hospital residents. However, significant differences were found in the remaining three areas. A 1.28-point difference (95% confidence interval: 0.96-1.59) in "physical examination and clinical procedures" in PGY-1 residents was found; this area alone accounts for approximately half of the difference in total score. CONCLUSIONS: The standardization of junior residency programs and the general clinical education programs in Japan should be promoted and will improve the overall training that our residents receive. This is especially needed in categories where university hospitals have low scores, such as "physical examination and clinical procedures."

Impact of general medicine rotation training on the in-training examination scores of 11, 244 Japanese resident physicians: a Nationwide multi-center cross-sectional study.

BACKGROUND: Although general medicine (GM) faculty in Japanese medical schools have an important role in educating medical students, the importance of residents' rotation training in GM in postgraduate education has not been sufficiently recognized in Japan. To evaluate the relationship between the rotation of resident physicians in the GM department and their In-Training Examination score. METHODS: This study is a nationwide multi-center cross-sectional study in Japan. Participants of this study are Japanese junior resident physicians [postgraduate year (PGY)-1 and PGY-2] who took the General Medicine In-Training Examination (GM-ITE) in fiscal years 2016 to 2018 at least once (n = 11,244). The numbers of participating hospitals in the GM-ITE were 381, 459, and 503 in 2016, 2017, and 2018.The GM-ITE score consisted of four categories (medical interview/professionalism, symptomatology/clinical reasoning, physical examination/procedure, and disease knowledge). We evaluated relationship between educational environment (including hospital information) and the GM-ITE score. RESULTS: A total of 4464 (39.7%) residents experienced GM department rotation training. Residents who rotated had higher total scores than residents who did not rotate (38.1 ± 12.1, 36.8 ± 11.7, and 36.5 ± 11.5 for residents who experienced GM rotation training, those who did not experience this training in hospitals with a GM department, and those who did not experience GM rotation training in hospitals without a GM department, p = 0.0038). The association between GM rotation and competency remained after multivariable adjustment in the multilevel model: the score difference between GM rotation training residents and non-GM rotation residents in hospitals without a GM department was estimated as 1.18 (standard error, 0.30, p = 0.0001), which was approximately half of the standard deviation of random effects due to hospital variation (estimated as 2.00). CONCLUSIONS: GM rotation training improved the GM-ITE score of residents and should be considered mandatory for junior residents in Japan.

A Medical Record Peer-Review System to Evaluate Residents' Clinical Competence: Criterion Validity Analysis.

In contrast to input evaluation (education delivered at school) and output evaluation (students' capability at graduation), the methods of outcome evaluation (performance after graduation) of medical education have not been sufficiently established. To establish a method to measure the quality of patient care and conduct outcome evaluation, we have been developing a peer review system of medical records. Here, we undertook a pilot study to evaluate the criterion validity of our system by using "evaluation by program directors (supervisors in the hospitals)" as a criterion standard. We selected 13 senior residents from three teaching hospitals. Five reviewers (general internists working in other hospitals) visited the hospitals independently and evaluated five patients' records for each resident based on the previously established sheet comprising 15 items. Independently, program directors of the senior residents evaluated their clinical performance using an evaluation sheet comprising ten items. Pearson's analysis revealed statistically significant correlation coefficients in three pairs of assessments including clinical reasoning (r = 0.5848, P = 0.0358). Bootstrap analysis revealed statistically significant correlation coefficients in additional 5 pairs including history taking (r = 0.509, 95% confidence interval: 0.034-0.847). In contrast, the correlation coefficients were low in some items: r = 0.132 (-0.393-0.639) for physical examination and r = 0.089 (-0.847-0.472) for attitude toward patients. To the best of our knowledge, this is the first study, albeit a pilot one, that investigates the criterion validity of medical record evaluations conducted by comparing the assessments of medical records with those by program directors.

Skills acquisition for novice learners after a point-of-care ultrasound course: does clinical rank matter?

BACKGROUND: Few studies have compared the effectiveness of brief training courses on point-of-care ultrasound (POCUS) skill acquisition of novice attending physicians vs. trainees. The purpose of this study was to evaluate the change in POCUS image interpretation skills and confidence of novice attending physicians vs. trainees after a 1-day POCUS training course. METHODS: A 1-day POCUS training course was held in March 2017 in Japan. A standardized training curriculum was developed that included online education, live lectures, and hands-on training. The pre-course assessment tools included a written examination to evaluate baseline knowledge and image interpretation skills, and a physician survey to assess confidence in performing specific ultrasound applications. The same assessment tools were administered post-course, along with a course evaluation. All learners were novices and were categorized as trainees or attending physicians. Data were analyzed using two-way analysis of variance. RESULTS: In total, 60 learners attended the course, and 51 learners (85%) completed all tests and surveys. The 51 novice learners included 29 trainees (4 medical students, 9 PGY 1-2 residents, 16 PGY 3-5 residents) and 22 attending physicians (6 PGY 6-10 physicians, and 16 physicians PGY 11 and higher). The mean pre- and post-course test scores of novice trainees improved from 65.5 to 83.9% while novice attending physicians improved from 66.7 to 81.5% (p < 0.001). The post-course physician confidence scores in using ultrasound significantly increased in all skill categories for both groups. Both trainees and attending physicians demonstrated similar improvement in their post-course test scores and confidence with no statistically significant differences between the groups. The course evaluation scores for overall satisfaction and satisfaction with faculty members' teaching skills were 4.5 and 4.6 on a 5-point scale, respectively. CONCLUSIONS: Both novice trainees and attending physicians showed similar improvement in point-of-care ultrasound image interpretation skills and confidence after a brief training course. Although separate training courses have traditionally been developed for attending physicians and trainees, novice learners of point-of-care ultrasound may acquire skills at similar rates, regardless of their ranking as an attending physician or trainee. Future studies are needed to compare the effectiveness of short training courses on image acquisition skills and determine the ideal course design.

Development of culture-sensitive clinical teacher evaluation sheet in the Japanese context.

AIM: Many instruments for evaluating clinical teaching have been developed, albeit most in Western countries. This study aims to develop a validated cultural and local context sensitive instrument for clinical teachers in an East Asian setting (Japan), Japanese Clinical Teacher Evaluation Sheet (JaCTES). METHODS: A multicenter, cross-sectional evaluation study was conducted. We collected a total of 1368 questionnaires on 304 clinical teachers, completed by residents in 16 teaching hospitals. The construct validity was examined by conducting a factor analysis and using structural equation modeling (SEM). We also assessed the reliability using generalizability analysis and decision study. RESULTS: Exploratory factor analysis resulted in three-factor (role model, teaching activities, and accessibility) model including 18 items. Confirmatory factor analysis was performed, using SEM. The comparative fit index was 0.931 and the root mean square error of approximation was 0.087, meaning an acceptable goodness of fit for this model. To obtain a reliable dependability-coefficient of at least 0.70 or higher, 5-8 resident responses are necessary. DISCUSSION AND CONCLUSION: JaCTES is the first reported instrument with validity evidence of content and internal structure and high feasibility in Japan, an East Asian setting. Medical educators should be aware of the local context and cultural aspects in evaluating clinical teachers.

Reliability and acceptability of six station multiple mini-interviews: past-behavioural versus situational questions in postgraduate medical admission.

BACKGROUND: The multiple mini-interview (MMI) is increasingly used for postgraduate medical admissions and in undergraduate settings. MMIs use mostly Situational Questions (SQs) rather than Past-Behavioural Questions (PBQs). A previous study of MMIs in this setting, where PBQs and SQs were asked in the same order, reported that the reliability of PBQs was non-inferior to SQs and that SQs were more acceptable to candidates. The order in which the questions are asked may affect reliability and acceptability of an MMI. This study investigated the reliability of an MMI using both PBQs and SQs, minimising question order bias. Acceptability of PBQs and SQs was also assessed. METHODS: Forty candidates applying for a postgraduate medical admission for 2016-2017 were included; 24 examiners were used. The MMI consisted of six stations with one examiner per station; a PBQ and a SQ were asked at every station, and the order of questions was alternated between stations. Reliability was analysed for scores obtained for PBQs or SQs separately, and for both questions. A post-MMI survey was used to assess the acceptability of PBQs and SQs. RESULTS: The generalisability (G) coefficients for PBQs only, SQs only, and both questions were 0.87, 0.96, and 0.80, respectively. Decision studies suggested that a four-station MMI would also be sufficiently reliable (G-coefficients 0.82 and 0.94 for PBQs and SQs, respectively). In total, 83% of participants were satisfied with the MMI. In terms of face validity, PBQs were more acceptable than SQs for candidates (p = 0.01), but equally acceptable for examiners (88% vs. 83% positive responses for PBQs vs. SQs; p = 0.377). Candidates preferred PBQs to SQs when asked to choose one, though this difference was not significant (p = 0.081); examiners showed a clear preference for PBQs (p = 0.007). CONCLUSIONS: Reliability and acceptability of six-station MMI were good among 40 postgraduate candidates; modelling suggested that four stations would also be reliable. SQs were more reliable than PBQs. Candidates found PBQs more acceptable than SQs and examiners preferred PBQs when they had to choose between the two. Our findings suggest that it is better to ask both PBQs and SQs during an MMI to maximise acceptability.

The Impact of the Hospital Volume on the Performance of Residents on the General Medicine In-Training Examination: A Multicenter Study in Japan.

Objective Although several studies have been conducted worldwide on factors that might improve residents' knowledge, the relationship between the hospital volume and the internal medicine residents' knowledge has not been fully understood. We conducted a cross-sectional study to compare the relationships of the hospital volume and hospital resources with the residents' knowledge assessed by the In-training Examination. Methods We conducted a retrospective survey and a clinical knowledge evaluation of postgraduate year 1 and 2 (PGY-1 and -2) resident physicians in Japan by using the General Medicine In-training Examination (GM-ITE) in 2014. We compared the ITE score and the hospital volume. Results A total of 2,015 participants (70.6% men; age, 27.3±2.9 years old) from 208 hospitals were retrospectively analyzed. Generalized estimating equations were used, and the results revealed that an increasing number of hospitalizations, decreasing staff number, decreasing age and PGY-2 were significantly associated with higher GM-ITE scores. Conclusion The hospital volume, such as the number of hospitalizations, is thus considered to have a positive impact on the GM-ITE scores.

Modeling Viewpoint Shifts in Probabilistic Choice.

A number of mathematical models for overcoming intransitive choice have been proposed and tested in the literature of decision theory. This article presents the development of a new stochastic choice model based on multidimensional scaling. This allows decision-makers to have multiple viewpoints, whereas current multidimensional scaling models are based on the assumption that a subject or group of subjects has only one viewpoint. The implication of our model is that subjects make an intransitive choice because they are able to shift their viewpoint. This paper also presents the maximum likelihood estimation of the proposed model, and reanalyzes Tversky's gamble experiment data.

Development of a peer review system using patient records for outcome evaluation of medical education: reliability analysis.

In addition to input evaluation (education delivered at school) and output evaluation (students' capability at graduation), the methods for outcome evaluation (performance after graduation) of medical education need to be established. One approach is a review of medical records, which, however, has been met with difficulties because of poor inter-rater reliability. Here, we attempted to develop a peer review system of medical records with high inter-rater reliability. We randomly selected 112 patients (and finally selected 110 after removing two ineligible patients) who visited (and were hospitalized in) one of the four general hospitals in the Tohoku region of Japan between 2008 and 2012. Four reviewers, who were well-trained general internists from outside the Tohoku region, visited the hospitals independently and evaluated outpatient medical records based on an evaluation sheet that consisted of 14 items (3-point scale) for record keeping and 15 items (5-point scale) for quality of care. The mean total score was 84.1 ± 7.7. Cronbach's alpha for these items was 0.798. Single measure and average measure intraclass correlations for the reviewers were 0.733 (95% confidence interval: 0.720-0.745) and 0.917 (95% confidence interval: 0.912-0.921), respectively. An exploratory factor analysis revealed six factors: history taking, physical examination, clinical reasoning, management and outcome, rhetoric, and patient relationship. In conclusion, we have developed a peer review system of medical records with high inter-rater reliability, which may enable us, with further validity analysis, to measure quality of patient care as an outcome evaluation of medical education in the future.

High sleep duration variability is an independent risk factor for weight gain.

OBJECTIVE: This study was conducted to evaluate the association between weight gain and variability of sleep duration. METHODS: A retrospective cohort study was conducted involving apparently healthy individuals aged 20 years or older who underwent annual health checkup at the Center for Preventive Medicine, St. Luke's International Hospital, between 2007 and 2010. The body mass index (BMI) of each participant was measured, and the change in BMI during the study period was calculated. The sleep duration was obtained using a questionnaire that was filled out by participants each year, and the variability in the sleep duration was calculated by dividing the standard deviation (SD) of the sleep duration for 3 years by the square root of the number of data points. Multivariate linear regression analysis was used to explore the association between the change in BMI and the variability of the sleep duration, adjusting for age, sex, alcohol consumption, current smoking, baseline sleep duration, past medical history, and level of physical activity. RESULTS: A total of 21,148 participants were included in this study. The mean age (SD) was 51 (12) years, and 10,993 (49.6%) participants were male. The mean baseline BMI was 22.4 (SD 3.2). According to the self-reported data, the mean sleep duration (SD) was 6.2 (1.0) h, and the mean of the SD of sleep duration for each participant was 0.32 (min-max, 0-7). The result of the linear regression analysis showed that greater variability in the sleep duration was independently related to an increase in BMI (ß coefficient = 0.31; 95% CI = 0.01-0.61). CONCLUSION: The variability of sleep duration is related to body weight gain. Maintaining a constant sleep duration may be recommended for controlling body weight.

Optimal cervical cytology mass screening interval for cervical cancer.

OBJECTIVE: To identify the optimal interval for repeat cervical cytology testing for screening of cervical cancer and dysplasia in healthy female adults. DESIGN AND METHODS: A retrospective cohort study was conducted on 3,804 apparently healthy females without known cervical cancer at baseline from 2005 to 2010. Participants underwent annual health checkups, including cervical cytology testing. This data did not contain human papillomavirus status. Participants with cytological abnormality underwent further examination, including biopsy, to check for cervical cancer. The generalized estimating equation (GEE) was performed to analyze the longitudinal data. RESULTS: In the groups <40, 40-49, 50-59 and ≥60 years old, the 5-year cumulative incidences (95 % CI) of cytological abnormality were 11.2 % (8.8-13.9 %), 7.6 % (6.2-9.3 %), 4.4 % (3.3-5.7 %) and 2.8 % (1.8-4.2 %), respectively, and the cumulative incidences of cervical cancer were 0.9 % (0.3-2.0 %), 0.1 % (0.0-0.4 %), 0.1 % (0.0-0.5 %) and 0 %, respectively. The odds ratios of the incidence for cervical cancer and cervical dysplasia per year, with GEE models, were 1.5 (95 % CI:1.1-2.0), 1.2 (95 % CI:0.8-1.9), 2.2 (95 % CI:0.5-10.3) and 0 for cervical cancer, and 1.3 (95 % CI:1.2-1.5), 1.3 (95 % CI:1.2-1.5), 1.3 (95 % CI:1.1-1.5) and 1.4 (95 % CI:0.9-2.0) for cervical dysplasia, respectively. CONCLUSIONS: For patients under 40 years old, the screening for cervical cancer every 2 years should be considered, while for patients of 40-59 years old screening every 2 or 3 years should be considered. Females over 60 years old may only need repeat screening every 5 years.

Introducing the Professionalism Mini-Evaluation Exercise (P-MEX) in Japan: results from a multicenter, cross-sectional study.

PURPOSE: Despite the growing importance of and interest in medical professionalism, there is no standardized tool for its measurement. The authors sought to verify the validity, reliability, and generalizability of the Professionalism Mini-Evaluation Exercise (P-MEX), a previously developed and tested tool, in the context of Japanese hospitals. METHOD: A multicenter, cross-sectional evaluation study was performed to investigate the validity, reliability, and generalizability of the P-MEX in seven Japanese hospitals. In 2009-2010, 378 evaluators (attending physicians, nurses, peers, and junior residents) completed 360-degree assessments of 165 residents and fellows using the P-MEX. The content validity and criterion-related validity were examined, and the construct validity of the P-MEX was investigated by performing confirmatory factor analysis through a structural equation model. The reliability was tested using generalizability analysis. RESULTS: The contents of the P-MEX achieved good acceptance in a preliminary working group, and the poststudy survey revealed that 302 (79.9%) evaluators rated the P-MEX items as appropriate, indicating good content validity. The correlation coefficient between P-MEX scores and external criteria was 0.78 (P < .001), demonstrating good criterion-related validity. Confirmatory factor analysis verified high path coefficient (0.60-0.99) and adequate goodness of fit of the model. The generalizability analysis yielded a high dependability coefficient, suggesting good reliability, except when evaluators were peers or junior residents. CONCLUSIONS: Findings show evidence of adequate validity, reliability, and generalizability of the P-MEX in Japanese hospital settings. The P-MEX is the only evaluation tool for medical professionalism verified in both a Western and East Asian cultural context.

Development and validation of a 15-item Japanese Health Knowledge Test.

BACKGROUND: Health literacy affects the acquisition of health knowledge and is thus linked to health outcomes. However, few scales have been developed to assess the level of health knowledge among the general public. METHODS: The 15-item Japanese Health Knowledge Test (J-HKT) was developed by using item response theory to score an item pool. We examined the construct validity of the J-HKT in relation to health literacy items, and analyzed the sociodemographic and behavioral factors associated with poor health knowledge. RESULTS: We enrolled 1040 adult participants (mean age, 57 years; women, 52%). The 15 items that best identified people with poor health knowledge were selected. For all items on the J-HKT, the information function curves had a peak in the negative spectrum of the latent trait. As compared with participants reporting high levels of income, educational attainment, and literacy, those with low levels of income, education, and literacy had a lower total score on the J-HKT. As compared with non/light drinkers, moderate and heavy drinkers had lower total scores on the J-HKT. CONCLUSIONS: The J-HKT may prove useful in measuring health knowledge among the general public, and in identifying and characterizing those with poor health knowledge.

Population-level preferences for primary care physicians' characteristics in Japan: a structural equation modeling.

OBJECTIVE: Primary care has potential to play a role for improving the patient care in Japanese health care system; however, little information is available about how patients perceive the roles of primary care physicians (PCPs) within the Japanese health care system. We aimed to assess population-level preferences for PCPs and investigated the extent to which preferences vary in relation to different population groups in Japan. METHODS: Data were extracted from a cross-sectional questionnaire survey in October 2003. An 18-item questionnaire was used to measure the preferences for PCPs. Exploratory factor analysis was performed to identify latent factors, while confirmatory factor analysis was used to evaluate the fit of the structure using structural equation modeling (SEM). PATIENTS: Nationally representative sample of the adult Japanese general population was chosen by controlling for age, sex, and the size of cities. RESULTS: A total of 2,453 adults>or=18-years-old were analyzed. SEM provided a 4-factor structural model of the population-level preference for PCPs, such as clinical competence (path coefficient (pc)=0.72), gate-keeping (pc=0.64), communication with patients or specialists (pc=0.49) and high education (pc=0.25) and demonstrated the best goodness-of-fit. Those who were middle aged, have a high family income, and a high level of education, placed more importance on gate-keeping characteristics, and the rural residents emphasized communication rather than clinical competence. CONCLUSION: Our results indicate that the preferences for PCPs are divided into four main factors and underscore the variation among preferences according to different population groups, such as age, socioeconomic and educational status, and places of living. These variations should be considered to improve the primary care system in Japan.

Professionalism Mini-Evaluation Exercise for medical residents in Japan: a pilot study.

CONTEXT: Assessing medical professionalism among medical residents is of great importance. The Professionalism Mini-Evaluation Exercise (P-MEX) is a tool for assessing professionalism that was developed, tested for reliability and validated in Canada. Prior to the present study, no Japanese version of the P-MEX had been tested. METHODS: We modified the P-MEX for use in Japan and tested it on medical residents in a Japanese teaching hospital. For each resident, eight evaluators completed the P-MEX forms. A total of 184 P-MEX forms were completed on 23 senior residents. The construct validity of the P-MEX was analysed by confirmatory factor analysis through structural equation modelling. The reliability of the P-MEX was tested using generalisability theory and a decision study. After performing the assessment and providing feedback to the residents, we conducted a survey on the residents' perceptions of the assessment. RESULTS: Results indicate content and construct validity. A confirmatory factor analysis revealed that factor loadings ranged from 0.58 to 0.96, indicating good construct validity except for one item (P12: Maintained appropriate boundaries with patients and colleagues). Structural equation modelling showed that adding new items developed in Japan to the P-MEX provided adequate factor validity. A decision study showed confidence intervals sufficiently narrow with as few as 10 evaluations, slightly more than the eight forms verified in Canada. Most residents stated that the items were reasonable and appropriate, the results of the assessment were consistent with their own self-evaluation and the assessment enhanced their motivation. CONCLUSIONS: Our study demonstrated good evidence of adequate reliability and validity of the P-MEX for the assessment of professionalism among Japanese residents. Moreover, the addition of new items developed in Japan provided adequate factor validity.

Assessing items on the SF-8 Japanese version for health-related quality of life: a psychometric analysis based on the nominal categories model of item response theory.

OBJECTIVES: The Short Form-8 (SF-8) questionnaire is a commonly used 8-item instrument of health-related quality of life (QOL) and provides a health profile of eight subdimensions. Our aim was to examine the psychometric properties of the Japanese version of the SF-8 instrument using methodology based on nominal categories model. METHODS: Using data from an adjusted random sample from a nationally representative panel, the nominal categories modeling was applied to SF-8 items to characterize coverage of the latent trait (theta). Probabilities for response choices were described as functions on the latent trait. Information functions were generated based on the estimated item parameters. RESULTS: A total of 3344 participants (53%, women; median age, 35 years) provided responses. One factor was retained (eigenvalue, 4.65; variance proportion of 0.58) and used as theta. All item response category characteristic curves satisfied the monotonicity assumption in accurate order with corresponding ordinal responses. Four items (general health, bodily pain, vitality, and mental health) cover most of the spectrum of theta, while the other four items (physical function, role physical [role limitations because of physical health], social functioning, and role emotional [role limitations because of emotional problems] ) cover most of the negative range of theta. Information function for all items combined peaked at -0.7 of theta (information = 18.5) and decreased with increasing theta. CONCLUSION: The SF-8 instrument performs well among those with poor QOL across the continuum of the latent trait and thus can recognize more effectively persons with relatively poorer QOL than those with relatively better QOL.