It is interested in examining treatment effect on a particular category of subjects or in comparing treatment effects among different subgroups as well as overall treatment effect due to heterogeneity of study subjects. Subgroup analyses are exceedingly common, but they are also often misleading. Conclusions based on subgroup analyses can do harm both when a particular category of people is denied effective treatment (a "false-negative" conclusion), and when ineffective or even harmful treatment is given to a subgroup of people (a "false-positive" conclusion). Because of the frequency and the importance of clinical application of subgroup analysis, researchers need to be cautious about doing subgroup analyses. This study presents guidelines to help conducting subgroup analyses correctly.
Population Characteristics

Confounding is the distortion of a disease/exposure association brought about by other factors which are not considered in the study design or the data analysis. These factors are called confounding factors. We should be cautious in data analysis of observational study of association of disease/exposure, since confounding often occurred in observational study. This study examines confounding effect according to data pattern (the ratio of controls to cases, the ratio of exposures to non-exposures for each level of confounding factor), criteria for treating a variable as a confounding variable, and some notes for the analysis in case-control study.
Case-Control Studies* ; Confounding Factors (Epidemiology) ; Observational Study ; Statistics as Topic

Purpose: Here we aimed to examine the association of breastfeeding (BF) with the metabolic syndrome (Mets) and its components among premenopausal parous Korean women. Methods: We conducted a cross-sectional study on 7,116 Korean women by using nationally representa tive data from the Korea National Health and Nutrition Examination Survey, between 2010 and 2016. Mul­tivariate logistic regression analysis was performed for examining the association of BF with Mets and its components. Results: A total 7,116 women were selected for this study. Mets was present in 12.9% of the study parti cipants. The prevalence of Mets in the BF group (12.38%) was lower than that of the non-BF group (14.69 %) (p<0.05). The prevalence of hypertension and hypertriglyceridemia was significantly higher in the non-BF group compared to that of the BF group. For each of Mets components, the total cholestrol level and systolic blood pressure were significantly higher in the non-BF group, compared to those of the BF group (p<0.05). The BF group was associated with a decreased risk of Mets (odds ratio [OR], 0.82; 95% confidence interval [CI], 0.68–0.99). and lower risks of hypo-high-density lipoprotein-cholesterolemia (OR, 0.78; 95% CI, 0.62–0.68), compared to those of the non-BF group. Conclusion BF is an important factor in reducing the risks of Mets. These results provide fundamental evidence for the establishment of policies for promoting BF.

Purpose: We investigated the the effect of wearing a loose mask on tear-film break-up time using cross-sectional and experimental methods. Methods: This was a comparative analysis of non-invasive tear-film break-up time (NIBUT) after wearing no mask, loose mask, and tight mask for 10 minutes each in 60 eyes with or without dry eye syndrome. NIBUT measurements were performed using a keratograph. Results: The NIBUT values were 7.53 ± 0.83 seconds, 6.19 ± 0.78 seconds, and 7.36 ± 0.68 seconds for the no mask, loose mask, and tight mask groups, respectively. There was no significant difference between the no mask and tight mask groups (ρ-value = 0.517), but the loose mask group had a significantly reduced NIBUT compared with the other groups (ρ-value = 0.013 and 0.022, respectively). Conclusions Wearing a loose mask reduced the tear-film break-up time regardless of the presence or absence of dry eyes and may cause or worsen dry eye symptoms.

OBJECTIVES: In observational studies, the methods used to measure medication adherence may affect assessments of the clinical outcomes of drug therapy. This study estimated medication adherence to multidrug therapy in patients with hypertension using different measurement methods and compared their impacts on clinical outcomes. METHODS: This was a retrospective cohort study using the Korean National Health Insurance Service–National Sample Cohort database (2006-2015). Adults diagnosed with hypertension who initiated multidrug antihypertensive therapy in the index year 2007 were included. Adherence was defined as over 80% compliance. Adherence to multidrug antihypertensive therapy was measured in 3 ways using the proportion of days covered (PDC) with 2 approaches to the end-date of the study observations: PDC with at least one drug (PDCwith≥1), PDC with a duration weighted mean (PDCwm), and the daily polypharmacy possession ratio (DPPR). The primary clinical outcome was a composite of cardiovascular and cerebrovascular disease-specific hospitalizations or all-cause mortality. RESULTS: In total, 4,226 patients who initiated multidrug therapy for hypertension were identified. The mean adherence according to the predefined measurements varied from 72.7% to 79.8%. Non-adherence was associated with an increased risk of a primary outcome. The hazard ratios (95% confidence intervals, CIs) primary outcomes varied from 1.38 (95% CI, 1.19 to 1.59) to 1.44 (95% CI, 1.25 to 1.67). CONCLUSIONS Non-adherence to multidrug antihypertensive therapy was significantly associated with an increased risk of a primary clinical outcome. Across the varying estimates based on different methods, medication adherence levels were similar. These findings may provide evidence to support decision-making when assessing medication adherence.

Background: This study was to identify the factors influencing smartphone dependence among late schoolaged children, focusing on grit and family strengths. Methods: A cross-sectional descriptive study was conducted with 218 children in grades 5 and 6 who were recruited from elementary schools in U and Y cities. The data were collected through self-reported questionnaires, including smartphone dependence, grit, family strengths and general characteristics, for the month of December 2019, just before the novel coronavirus pandemic after obtaining approval from IRB. The collected data were analyzed using multiple regression. Results: Smartphone usage time, the main purpose of smartphone usage (game and social networking), and grit were identified as significant factors of smartphone dependence. This model explained 38% of the total variance showing the variable of grit with the greatest variance. Conclusions A strategy to develop grit is needed to reduce smartphone dependence among late school-age children.

This paper examines Hildegard of Bingen’s embryological theory within the intricate landscape of medieval medicine and religion. It situates Hildegard’s understanding of conception within ongoing historical debates surrounding the roles of male and female reproductive substances, particularly the concept of seed or semen. By analyzing her conceptual framework against prevailing classical and medieval reproductive theories, the research illuminates Hildegard’s distinctive contribution to understanding conception as a holistic bodily process.Classical embryological discourse predominantly oscillated between Aristotle’s one-seed theory—which positioned men as sole generative agents—and Galen’s two-seed theory, which marginally acknowledged female reproductive participation. While technically aligning with Aristotelian principles by denying female semen, Hildegard diverged significantly by valorizing women’s reproductive agency. she argued that women produced a foam essential for new life, just as essential as the man’s semen. Also, the female reproductive body played a crucial role in purifying and nurturing the defective male semen, enabling conception. This conceptualization subtly challenged contemporary gender hierarchies, presenting reproduction as a complex, interdependent physiological mechanism with theological resonances, making the parallels of the woman’s reproduction and God’s creation. In conclusion, Hildegard’s embryological theory presents a sophisticated intellectual intervention that reimagined female reproductive potential within medieval scientific and religious frameworks.

This paper examines Hildegard of Bingen’s embryological theory within the intricate landscape of medieval medicine and religion. It situates Hildegard’s understanding of conception within ongoing historical debates surrounding the roles of male and female reproductive substances, particularly the concept of seed or semen. By analyzing her conceptual framework against prevailing classical and medieval reproductive theories, the research illuminates Hildegard’s distinctive contribution to understanding conception as a holistic bodily process.Classical embryological discourse predominantly oscillated between Aristotle’s one-seed theory—which positioned men as sole generative agents—and Galen’s two-seed theory, which marginally acknowledged female reproductive participation. While technically aligning with Aristotelian principles by denying female semen, Hildegard diverged significantly by valorizing women’s reproductive agency. she argued that women produced a foam essential for new life, just as essential as the man’s semen. Also, the female reproductive body played a crucial role in purifying and nurturing the defective male semen, enabling conception. This conceptualization subtly challenged contemporary gender hierarchies, presenting reproduction as a complex, interdependent physiological mechanism with theological resonances, making the parallels of the woman’s reproduction and God’s creation. In conclusion, Hildegard’s embryological theory presents a sophisticated intellectual intervention that reimagined female reproductive potential within medieval scientific and religious frameworks.

This paper examines Hildegard of Bingen’s embryological theory within the intricate landscape of medieval medicine and religion. It situates Hildegard’s understanding of conception within ongoing historical debates surrounding the roles of male and female reproductive substances, particularly the concept of seed or semen. By analyzing her conceptual framework against prevailing classical and medieval reproductive theories, the research illuminates Hildegard’s distinctive contribution to understanding conception as a holistic bodily process.Classical embryological discourse predominantly oscillated between Aristotle’s one-seed theory—which positioned men as sole generative agents—and Galen’s two-seed theory, which marginally acknowledged female reproductive participation. While technically aligning with Aristotelian principles by denying female semen, Hildegard diverged significantly by valorizing women’s reproductive agency. she argued that women produced a foam essential for new life, just as essential as the man’s semen. Also, the female reproductive body played a crucial role in purifying and nurturing the defective male semen, enabling conception. This conceptualization subtly challenged contemporary gender hierarchies, presenting reproduction as a complex, interdependent physiological mechanism with theological resonances, making the parallels of the woman’s reproduction and God’s creation. In conclusion, Hildegard’s embryological theory presents a sophisticated intellectual intervention that reimagined female reproductive potential within medieval scientific and religious frameworks.

This paper examines Hildegard of Bingen’s embryological theory within the intricate landscape of medieval medicine and religion. It situates Hildegard’s understanding of conception within ongoing historical debates surrounding the roles of male and female reproductive substances, particularly the concept of seed or semen. By analyzing her conceptual framework against prevailing classical and medieval reproductive theories, the research illuminates Hildegard’s distinctive contribution to understanding conception as a holistic bodily process.Classical embryological discourse predominantly oscillated between Aristotle’s one-seed theory—which positioned men as sole generative agents—and Galen’s two-seed theory, which marginally acknowledged female reproductive participation. While technically aligning with Aristotelian principles by denying female semen, Hildegard diverged significantly by valorizing women’s reproductive agency. she argued that women produced a foam essential for new life, just as essential as the man’s semen. Also, the female reproductive body played a crucial role in purifying and nurturing the defective male semen, enabling conception. This conceptualization subtly challenged contemporary gender hierarchies, presenting reproduction as a complex, interdependent physiological mechanism with theological resonances, making the parallels of the woman’s reproduction and God’s creation. In conclusion, Hildegard’s embryological theory presents a sophisticated intellectual intervention that reimagined female reproductive potential within medieval scientific and religious frameworks.