Sample size calculations for model validation in linear regression analysis

Is the 5-Minute Time-Trial Cycling Test a Valid Predictor of Maximal Oxygen Uptake? An External Cross-Validation Study

PURPOSE

This study aimed to cross-validate a recently proposed equation for the prediction of maximal oxygen uptake (V˙O2max) in cycling exercise by using the average power output normalized by the body mass from a 5-minute time trial (RPO5-min) as the independent variable. Further, the study aimed to update the predictive equation using Bayesian informative prior distributions and meta-analysis.

METHODS

On different days, 49 male cyclists performed an incremental graded exercise test until exhaustion and a 5-minute time trial on a stationary cycle ergometer. We compared the actual V˙O2max with the predicted value obtained from the RPO5-min, using a modified Bayesian Bland-Altman agreement analysis. In addition, this study updated the data on the linear regression between V˙O2max and RPO5-min, by incorporating information from a previous study as a Bayesian informative prior distribution or via meta-analysis.

RESULTS

On average, the predicted V˙O2max using RPO5-min underestimated the actual V˙O2max by -6.6 mL·kg-1·min-1 (95% credible interval, -8.6 to -4.7 mL·kg-1·min-1). The lower and upper 95% limits of agreement were -17.2 (-22.7 to -12.3) and 3.8 (-1.0 to 9.5) mL·kg-1·min-1, respectively. When the current study's data were analyzed using the previously published data as a Bayesian informative prior distribution, the accuracy of predicting sample means was found to be better when compared with the data combined via meta-analyses.

CONCLUSIONS

The proposed equation presented systematic bias in our sample, in which the prediction underestimated the actual V˙O2max. We provide an updated equation using the previous one as the prior distribution, which could be generalized to a greater audience of cyclists.

Affiliate Stigma among family caregivers of individuals with dementia in China: a cross-sectional study

Background

Affiliate stigma experienced by family caregivers of individuals with dementia may seriously affect home care and prognosis of these patients. This study aimed to explore the levels of perceived affiliate stigma and its influencing factors among family caregivers of patients with dementia in mainland China, which remains a relatively unexplored topic.

Methods

In this cross-sectional study, purposive sampling was used to recruit dementia family caregivers from an online communication group between April and May 2022. A total of 727 eligible caregivers were included and asked to complete the demographic questionnaire, the affiliate stigma scale, and the caregiver burden inventory. Descriptive statistics, independent sample t-test, one-way analysis of variance, Pearson correlation analysis, and multiple linear regression were used to explore the factors that influence perceived affiliate stigma among dementia family caregivers.

Results

The mean score for affiliate stigma of dementia family caregivers was 48.09 ± 16.38 (range: 22-86). Whether there were regular breaks during patient care, time-dependent burden, developmental burden, physical burden, and social burden were significant factors influencing the affiliate stigma of dementia family caregivers.

Conclusion

Dementia family caregivers showed a moderate to high level of affiliate stigma. Those who had regular breaks during patient care, higher time-dependent burden, developmental burden, and physical burden and lower social burden exhibited higher levels of affiliate stigma.

Mental Health Risk and Protective Factors of Nigerian Male Asylum Seekers Hosted in Southern Italy: a Culturally Sensitive Quantitative Investigation

This study provides a culturally sensitive quantitative investigation aimed at assessing the post-traumatic symptomatology, post-migratory difficulties, and resilience of 36 Nigerian male asylum seekers hosted in the province of Caserta, South Italy. A survey composed by the Harvard Trauma Questionnaire-Revised (HTQ-R), the Post-Migratory Checklist (PLMD), and the Connor-Davidson Resilience Scale (CD-RISC) was administered to participants. Descriptive and correlation analyses were made in order to describe the mental health risk and protective factors and understand the relation between these. A linear regression analysis was used to evaluate the influence of post-migratory difficulties and resilience on PTSD. Stratified bivariate analyses were also computed to detect PTSD group and no-PTSD group differences about post-migration difficulties and resilience levels. Regression analysis showed that PMLD numbers significantly increased the risk of having PTSD. No significant effect emerged for the level of resilience. Statistically significant differences between the PTSD group and non-PTSD group in relation to post-migratory difficulties were also found. No differences in the resilience factors emerged. The results offer a glimpse into a specific ethnic group of asylum seekers and its mental health risks and protective factors, taking into consideration the specificities of their past and current life-story experiences. Clinical implications for professionals working in the field of forced migration will be outlined.

Preoperative Fibrinogen Level and Bleeding in Liver Transplantation for End-stage Liver Disease: A Cohort Study

BACKGROUND

Liver transplantation is a high-risk surgery associated with important perioperative bleeding and transfusion needs. Uncertainties remain on the association between preoperative fibrinogen level and bleeding in this population.

METHODS

We conducted a cohort study that included all consecutive adult patients undergoing a liver transplantation for end-stage liver disease in 1 center. We analyzed the association between the preoperative fibrinogen level and bleeding-related outcomes. Our primary outcome was intraoperative blood loss, and our secondary outcomes were estimated perioperative blood loss, intraoperative and perioperative red blood cell transfusions, reinterventions for bleeding and 1-y graft and patient survival. We estimated linear regression models and marginal risk models adjusted for all important potential confounders. We used restricted cubic splines to explore potential nonlinear associations and reported dose-response curves.

RESULTS

We included 613 patients. We observed that a lower fibrinogen level was associated with a higher intraoperative blood loss, a higher estimated perioperative blood loss and a higher risk of intraoperative and perioperative red blood cell transfusions (nonlinear effects). Based on an exploratory analysis of the dose-response curves, these effects were observed below a threshold value of 3 g/L for these outcomes. We did not observe any association between preoperative fibrinogen level and reinterventions, 1-y graft survival or 1-y patient survival.

CONCLUSIONS

This study suggests that a lower fibrinogen level is associated with bleeding in liver transplantation. The present results may help improving the selection of patients for further studies on preoperative fibrinogen administration in liver transplant recipients with end-stage liver disease.

Investigating predictors of self-care behavior among homebound older adults: The role of self-efficacy, eHealth literacy, and perceived social support

PURPOSE

This study aimed to investigate the predictors of self-care behavior among homebound older adults using the Health Empowerment theory as a framework.

DESIGN

This was a cross-sectional, predictive correlational study.

METHODS

Sixty-eight participants were randomly selected from five Hong Kong community centers from May 21, 2020 through July 20, 2020. Self-care behaviors were assessed using the Chinese version of Partners in Health. Self-efficacy, eHealth literacy, and perceived social support were assessed as potential predictors of self-care behaviors. A multiple linear regression analysis was adopted to examine the predictive effects.

RESULTS

The age of the sample ranged from 61 to 85 years (mean = 71.7, SD = 6.0). Participants who reported having sufficient or more than sufficient financial resources had better self-care behaviors than those who claimed to have insufficient financial resources (F = 5.08, p = 0.009). Statistically significant correlations were found between the participants' eHealth literacy (r = 0.54, p < 0.001), perceived social support (r = 0.60, p < 0.001), and self-care behaviors. eHealth literacy (β = 0.13, p = 0.007) and perceived social support (β = 0.13, p < 0.001) were significant predictors of self-care behaviors. Collectively, the three variables accounted for 41% of the variances in self-care behaviors.

CONCLUSIONS

The findings in this study suggest that eHealth literacy and perceived social support are two key factors that predicted the self-care behaviors of this vulnerable population.

CLINICAL RELEVANCE

In this technological era, the use of eHealth, together with enhanced social support, can lead to better self-care among older adults, particularly those who are homebound.