Structural equation modeling: a framework for ocular and other medical sciences research

Exploring the influences of personal attitudes on the intention of continuing online grocery shopping after the COVID-19 pandemic

The unprecedented COVID-19 pandemic has brought drastic changes in our daily activities. One of these essential activities is grocery shopping. In compliance with the recommended social distancing standards, many people have switched to online grocery shopping or curbside pickup to minimize possible contagion. Although the shift to online grocery shopping is substantial, it is not clear whether this change would last in the long term. This study examines the attributes and underlying attitudes that may influence individuals' future decisions on online grocery shopping. An online survey was conducted in May 2020 in South Florida to collect data for this study. The survey contained a comprehensive set of questions related to respondents' sociodemographic attributes, shopping and trip patterns, technology use, as well as attitudes toward telecommuting and online shopping. A structural equation model (SEM) was applied to examine the intervening effects of observed as well as latent attitude variables on the likelihood of online grocery shopping after the outbreak. The results indicated that those with more experience in using online grocery shopping platforms were more likely to continue purchasing their groceries online. Individuals with positive attitudes toward technology and online grocery shopping in terms of convenience, efficiency, usefulness, and easiness were more likely to adopt online grocery shopping in the future. On the other hand, pro- driving individuals were less likely to substitute online grocery shopping for in-store shopping. The results suggested that attitudinal factors could have substantial impacts on the propensity toward online grocery shopping.

Structural equation modelling of work related musculoskeletal disorders among dumper operators

The aim of this study is to investigate the impact of personal factors, habitual factors, and work-related factors on work-related musculoskeletal disorders (WRMSDs) among dumper operators. In total, 248 dumper operators working in an iron ore mine were considered for this study. A questionnaire was developed and administered to collect dumper operators' personal, habitual, and work-related data. The reliability of the questionnaire was cross-checked by Cronbach alpha and the test-retest method. The values of Cronbach alpha for all latent variables were above 0.7, and the correlation coefficient of the questionnaire items at Time 1 and Time 2 was above 0.82. After verifying the validity (i.e., convergent and divergent) of the questionnaire data, the relationship between the factors under consideration was examined by structural equation modeling (SEM). The SEM demonstrated a moderate fit, with [Formula: see text] value of 1.386, comparative fit index (CFI) of 0.86, goodness-of-fit index (GFI) of 0.72, adjusted goodness-of-fit index (AGFI) of 0.69, Tucker-Lewis Index (TLI) of 0.83, normed fit index (NFI) of 0.71 and root mean square error of approximation (RMSEA) of 0.051. The SEM analysis revealed a positive relationship between WRMSDs and personal factors (with path coefficient = 0.313 and p < 0.05) as well as work-related factors (with path coefficient = 0.296 and p < 0.05). However, the relationship between WRMSDs and habitual factors was not statistically significant (with path coefficient = 0.142 and p > 0.05). Overall, this study provides valuable insights into the factors that influence the prevalence of WRMSDs among dumper operators. The findings highlight the significance of personal and work-related factors by which one can make a positive decision to prevent and reduce the incidence of WRMSDs among dumper operators.

Relative impact of red blood cell transfusion and anaemia on 5-year mortality in cardiac surgery

OBJECTIVES

The aim was to compare the relative effects of red blood cell (RBC) transfusion and preoperative anaemia on 5-year mortality following open-heart cardiac surgery using structural equation modelling. We hypothesized that patient risk factors associated with RBC transfusion are of larger importance than transfusion itself.

METHODS

This prospective cohort study, part of the Cardiac Surgery Outcome Study at St. Olavs University Hospital, Trondheim, Norway, included open-heart on-pump cardiac surgery patients operated on from 2000 through 2017 (n = 9315). Structural equation modelling, which allows for intervariable correlations, was used to analyse pathway diagrams between known risk factors and observed mortality between 30 days and 5 years postoperatively. Observation times between 30 days and 1 year, and 1-5 years postoperatively were also compared with the main analysis.

RESULTS

In a simplified model, preoperative anaemia had a larger effect on 5-year mortality than RBC transfusion (standardized coefficients: 0.17 vs 0.09). The complete model including multiple risk factors showed that patient risk factors such as age (0.15), anaemia (0.10), pulmonary disease (0.11) and higher creatinine level (0.12) had larger effects than transfusion (0.03). Results from several sensitivity analyses supported the main findings. The models showed good fit.

CONCLUSIONS

Preoperative anaemia had a larger impact on 5-year mortality than RBC transfusion. Differences in 5-year mortality were mainly associated with patient risk factors.

Methods to Account for Uncertainty in Latent Class Assignments When Using Latent Classes as Predictors in Regression Models, with Application to Acculturation Strategy Measures

Latent class models have become a popular means of summarizing survey questionnaires and other large sets of categorical variables. Often these classes are of primary interest to better understand complex patterns in data. Increasingly, these latent classes are reified into predictors of other outcomes of interests, treating the most likely class as the true class to which an individual belongs even though there is uncertainty in class membership. This uncertainty can be viewed as a form of measurement error in predictors, leading to bias in the estimates of the regression parameters associated with the latent classes. Despite this fact, there is very limited literature treating latent class predictors as measurement error models. Most applications ignore this issue and fit a two-stage model that treats the modal class prediction as truth. Here, we develop two approaches-one likelihood-based, the other Bayesian-to implement a joint model for latent class analysis and outcome prediction. We apply these methods to an analysis of how acculturation behaviors predict depression in South Asian immigrants to the United States. A simulation study gives guidance for when a two-stage model can be safely implemented and when the joint model may be required.

Do Consumers Really Want to Reduce Plastic Usage? Exploring the Determinants of Plastic Avoidance in Food-Related Consumption Decisions

The mass production and use of plastics over the past decades is now posing a threat to the environment due to increasing pollution. The industrial transition towards more sustainable plastic alternatives has already started, but the process will require years to become truly feasible from an industrial and economic standpoint. In the meantime, a significant contribution to limit plastic-related environmental impact could arise from consumers’ daily consumption choices. This study aims at investigating the determinants of consumers’ decision to avoid purchasing single-use plastic eating utensils, food products with multiple plastic packaging, and plastic water bottles while grocery shopping. The results of the Structural Equation Model reveal that environment- and health-related concerns associated with plastics are key drivers of plastic avoidance. Instead, subjective knowledge and the importance attached to the commitment of third parties for tackling the plastic issue only indirectly affect consumer behaviors with regard to plastic avoidance.

Social and physical environmental factors in daily stepping activity in those with chronic stroke

BACKGROUND, PURPOSE/OBJECTIVE

Walking behavior in the chronic stroke population is multi-factorial. Previous work focused on the role of physical and biopsychosocial factors in understanding daily stepping post stroke. However, qualitative evidence suggests that social and physical environmental factors also affect daily stepping in those with stroke. The purpose of this study was to understand the role of social and physical environmental factors in daily stepping after stroke.

METHODS

A total of 249 individuals ≥6 months post stroke were included in this cross-sectional analysis (129 females, mean age 62.98 years, SD 11.94). The social environment included living situation, work status, and marital status. The physical environment included the Area Deprivation Index (ADI) and Walk Score. At least 3 days of stepping was collected using an accelerometry-based device. Predictors were entered sequentially into a regression model: demographic characteristics, social environmental factors, and physical environmental factors.

RESULTS

After adjusting for demographic factors, social environmental factors explained 6.2% (p =.017) of the variance in post stroke daily stepping. The addition of physical environmental factors improved the model (ΔR² =.029, p =.024). The final model explained 9.2% (p =.003) of the variance in daily stepping. Lower area deprivation (ADI β = -0.178, p =.015) and working (working vs. retired β = -0.187, p = .029 and working vs. unemployed β = -0.227, p =.008) were associated with greater daily stepping.

DISCUSSION/CONCLUSION

Social and physical environmental factors predicted daily stepping and should be considered when setting expectations relative to the effects of rehabilitation on daily stepping in individuals poststroke.

Protection motivation theory in predicting cervical cancer screening participation: A longitudinal study in rural Chinese women

OBJECTIVE

To examine factors longitudinally associated with cervical cancer screening uptake among rural Chinese women, guided by protection motivation theory (PMT).

METHODS

A large sample of women (n = 2408, aged 35-65 years old) was randomly selected from a rural county in China in 2015 and followed up for 2 years. Data for demographic factors, knowledge of cervical cancer screening, screening outcome, and six PMT constructs measured at the baseline in 2015 were used to predict cervical cancer screening participation at the follow-up in 2017 using structural equation model method.

RESULTS

Among the 2408 women at the baseline, 1879 (78.03%) participated in the screening services at the follow-up. In addition to significant direct effect of age, social status and baseline screening outcome, and three (perceived severity, fear arousal and response efficacy) of the six PMT subconstructs, four variables (age, social status, knowledge of cervical cancer screening, and baseline screening outcome) at the baseline were indirectly associated with screening participation, mediated by the three significant PMT subconstructs.

CONCLUSIONS

Findings of this study indicate that the rate of participating in cervical cancer screening for rural women needs to be further improved. In addition to the commonly reported influential factors, PMT subconstructs play important roles in encouraging rural women in China to participate in cervical cancer screening. These longitudinal findings provided data much needed for future research to develop evidence-based intervention programs to enhance cervical cancer screening among rural women in China.

The Effect of Gender on Visual Field Sensitivity: The Singapore Chinese Eye Study

PURPOSE

Visual field (VF) sensitivity is known to be age-dependent, but there is a paucity of evidence on whether it is gender-dependent. We therefore investigated the effect of gender on VF sensitivity.

METHODS

An observational study involving 491 adults from the population-based Singapore Chinese Eye Study (SCES). Study participants underwent a comprehensive and standardised ocular examination and VF assessment on the Humphrey Field Analyzer II (Carl Zeiss Meditec, Inc., Dublin, CA, USA). The effect of gender on the mean deviation (MD) and pattern standard deviation (PSD) was analysed with linear regression models.

RESULTS

The mean age was 52.9 ± 5.9 years, and 229 (46.6%) participants were women. A total of 800 reliable VFs from 655 healthy eyes without visual impairment, glaucoma and significant cataract were included. The mean (± standard deviation) MD was -0.45 ± 1.01 dB in men, and -0.84 ± 1.20 dB in women. The MD [95% confidence interval] was 0.28 [-0.44 to -0.12] dB lower in females compared to males (P = 0.001) after adjusting for reliability indices, degree of lens opacity, and other potential confounders. The PSD was not significantly different between the genders.

CONCLUSIONS

In the SCES, the population-average of the central VF sensitivity was significantly lower in women compared to men by a small amount (0.28 dB). This effect was observed in healthy eyes, and was not explained by multiple potential confounders. Hence, this likely represents a physiological gender-based difference that is unaccounted for in standard automated perimetry. Further studies in other populations would be needed to corroborate our findings.

Exploring the Adherence to the Mediterranean Diet and Its Relationship with Individual Lifestyle: The Role of Healthy Behaviors, Pro-Environmental Behaviors, Income, and Education

The reduction of diet-related diseases and the improvement of environmental sustainability represent two of the major 21st century food policy challenges. Sustainable diets could significantly contribute to achieving both of these goals, improving consumer health and reducing the environmental impact of food production and consumption. The Mediterranean diet (MD) represents an excellent example of sustainable diet, however recent evidence indicates that such a dietary pattern is now progressively disappearing in Mediterranean countries. In such a context, this paper explores how individual lifestyle and habits are related to a high/low adherence to the MD model. The goal is to examine whether there is a relationship between individuals' healthy and pro-environmental behaviors and their level of adherence to the MD. The analysis also explores the role of consumer income and education. The study is based on the Italian population (n = 42,000) and uses a structural equation model approach. The results outline that the MD is part of a sustainability-oriented lifestyle and stress the key role of both income and education in affecting adherence to MD. Future policy aimed at contrasting the gradual disappearance of the MD should emphasize the sustainable dimension of the MD, meanwhile reducing socio-economic disparities among different population segments.

Relative Influence of Socioeconomic, Psychological and Sensory Characteristics, Physical Activity and Diet on 5-Year Weight Gain in French Adults

Individual characteristics, dietary intake and physical activity influence weight status; however, the contribution of each factor to weight change has not been studied. The objective was to confirm a conceptual framework by simultaneously assessing the relative influence of socioeconomic, psychological and sensory characteristics, physical activity, and dietary intake on five-year weight gain in French adults. Individual characteristics, physical activity, and dietary data were assessed at baseline in 8014 participants in the NutriNet-Santé cohort. Self-reported anthropometric data were collected at baseline and five years later. Structural equation models, stratified by baseline body mass index (BMI), were used to perform analyses. Dietary restraint was a direct predictor of weight gain, with a stronger effect than age or intake of energy-dense foods, both in non-overweight and overweight participants. In non-overweight individuals only, intake of nutrient-dense foods and physical activity were inversely associated with weight gain. Regarding dietary intake, fat liking was the most important predictor of nutrient-dense food intake and was also related to energy-dense food intake. In these models, dietary restraint appears to be a direct predictor of weight gain and fat liking is a strong determinant of dietary intake. The influence of dietary restraint on weight gain, not explained by diet, warrants further investigation.

Farm-Related Concerns and Mental Health Status Among Norwegian Farmers

The agricultural sector in Norway has undergone structural changes over the past 50 years. The objective of this study was to analyze the distribution of concerns about farm economy, work time, and mental complaints among Norwegian farmers. In a sample of single principal owner-operators (n = 2,676), we calculated the unadjusted and adjusted odd ratios (ORs) for concerns about the farm economy, concerns for insufficient time to complete work, and high symptom load of mental complaints. Structural equation modeling (SEM) was used to explore the associations between farm characteristics, concerns, and mental health. Farmers had a high probability for an increased symptom load of mental complaints. The level of farm income was more strongly associated with economic concerns and mental health concerns when a major part of total household income resulted from farming. The high workload required in farming combined with off-farm supplemental employment was additionally associated with higher levels of time concerns and mental complaints. Norwegian farmers have a relatively high workload both in farming and in off-farm work but are able to make sustainable plans for their individual workload needs. The high individual workload in both these arenas poses a challenge, but was not associated with a greater probability for a high symptom load of mental complaints.