Background Preconception care aims to improve both maternal and child health in the short as well as long term, along with providing health benefits to adolescents, women, and men, whether or not they plan to become parents. However, there is limited evidence regarding the effectiveness of interventions for improving preconception health in population-based settings. To accumulate evidence in this field, this study focused on the concept of health literacy, and aimed to develop a self-report health literacy scale in Japanese, focusing on preconception care. Methods We conducted a cross-sectional online survey. Participants were recruited from December 2019 to February 2020 from the registered members of a web-based research company. Participants were Japanese men and women aged 16–49 (n = 2000). A factor analysis was conducted to select both factors and items for health-related behavior and skills (33 initial items were generated), along with an item response theory analysis to examine how the 16 items were related to people’s knowledge of preconception care. Results We developed a 6-factor (including “appropriate medical examinations,” “appropriate diet,” “stress coping,” “healthy weight,” “safe living environment,” and “vaccinations”), 25-item behavior and skills scale, as well as a 13-item knowledge scale, to evaluate participants’ health literacy around preconception care. A shortened version, consisting of 17 items, was also prepared from the 25 items. The reliability coefficients of total scores and each factor of the behavior and skills scale were comparatively high, with weak-to-moderate correlation between behavior and skills and knowledge. Conclusions The new scale will, ideally, provide information on the current state of preconception care health literacy of the general population. In addition, this scale, which consists of both behavioral/skills and knowledge dimensions, should help support the effective implementation of risk assessment programs and interventions aimed at promoting behavioral changes using a population-based approach. Future studies using different question/administration formats for diverse populations, and considering respondents’ opinions on health literacy scales should be effective in improving this scale.

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An attempt to evaluate the method to construct multiple domains of IRT-based scales-For the purpose of building item bank for a common achievement test for nursing colleges

Consider the situation when a set of new items are administered as the part of several forms including anchor items. In this case, in order to add the new items to the existing item bank, we could either 1) estimate the item parameters of the items in each form and equate them using the information contained in the anchor items (separate calibration), or 2) combine the new item response data to the old data set and calibrate whole the items again using the multiple group IRT (concurrent calibration). However, as the number of groups becomes large, the existing multiple group IRT calibration program fails to converge due to the lack of available memory. In this study we examined the proper method to merge groups in order to avoid the above problem. Simulation studies showed that the separate calibration estimates were closest to the true value, and the concurrent calibration with reduced groups was similar to the separate calibration if the mean values of latent ability were similar among the merged groups.

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