Estimating the Marginal Causal Effect of Fish Consumption during Adolescence on Multiple Sclerosis: A Population-Based Incident Case-Control Study

Comparison of outcomes between off-pump and on-pump coronary artery bypass graft surgery using collaborative targeted maximum likelihood estimation

There are some discrepancies about the superiority of the off-pump coronary artery bypass grafting (CABG) surgery over the conventional cardiopulmonary bypass (on-pump). The aim of this study was estimating risk ratio of mortality in the off-pump coronary bypass compared with the on-pump using a causal model known as collaborative targeted maximum likelihood estimation (C-TMLE). The data of the Tehran Heart Cohort study from 2007 to 2020 was used. A collaborative targeted maximum likelihood estimation and targeted maximum likelihood estimation, and propensity score (PS) adjustment methods were used to estimate causal risk ratio adjusting for the minimum sufficient set of confounders, and the results were compared. Among 24,883 participants (73.6% male), 5566 patients died during an average of 8.2 years of follow-up. The risk ratio estimates (95% confidence intervals) by unadjusted log-binomial regression model, PS adjustment, TMLE, and C-TMLE methods were 0.86 (0.78-0.95), 0.88 (0.80-0.97), 0.88 (0.80-0.97), and 0.87(0.85-0.89), respectively. This study provides evidence for a protective effect of off-pump surgery on mortality risk for up to 8 years in diabetic and non-diabetic patients.

Association between dietary inflammatory index and risk of demyelinating autoimmune diseases

Background: Considering limited data on the association between dietary inflammatory index (DII) and demyelinating autoimmune diseases, here, we studied this issue in the early diagnosed patients [e.g., preceding Multiple Sclerosis (MS) diagnosing level (Clinically Isolated Syndrome (CIS), and Radiologically Isolated Syndrome (RIS), MS, and Neuromyelitis Optica Spectrum Disorder (NMOSD)] using a case-control study among the Iranian population. Methods: A total of 291 subjects were selected as the cases (Patients with demyelinating autoimmune diseases including CIS, RIS, MS, and NMOSD, who were diagnosed less than six months before recruitment) and 297 others as controls. A 117-item semi-quantitative food frequency questionnaire (FFQ) was obtained from all of the participants and DII was calculated. Results: After controlling for potential confounders, adherence to a pro-inflammatory diet was associated with a higher risk of demyelinating autoimmune diseases (OR=2.05, 95% CI: 0.51, 3.58), EDSS (OR=2.02, 95% CI: 0.51, 3.53), active plaque (OR=1.90, 95% CI: 0.08, 3.71), higher lesion load (OR=2.11, 95% CI: 0.58, 3.64), LETM (OR=2.19, 95% CI: 0.27, 4.11), higher number of plaques (OR=2.11, 95% CI: 0.58, 3.64), and brain atrophy (OR=2.12, 95% CI: 0.57, 3.67). Conclusion: Our study suggests a possible link between the inflammatory potential of the diet and demyelinating autoimmune disease; however, further prospective cohort studies are needed to draw a causal link on this issue.

The effect of smoking on latent hazard classes of metabolic syndrome using latent class causal analysis method in the Iranian population

BACKGROUND

The prevalence of metabolic syndrome is increasing worldwide. Clinical guidelines consider metabolic syndrome as an all or none medical condition. One proposed method for classifying metabolic syndrome is latent class analysis (LCA). One approach to causal inference in LCA is using propensity score (PS) methods. The aim of this study was to investigate the causal effect of smoking on latent hazard classes of metabolic syndrome using the method of latent class causal analysis.

METHODS

In this study, we used data from the Tehran Lipid and Glucose Cohort Study (TLGS). 4857 participants aged over 20 years with complete information on exposure (smoking) and confounders in the third phase (2005-2008) were included. Metabolic syndrome was evaluated as outcome and latent variable in LCA in the data of the fifth phase (2014-2015). The step-by-step procedure for conducting causal inference in LCA included: (1) PS estimation and evaluation of overlap, (2) calculation of inverse probability-of-treatment weighting (IPTW), (3) PS matching, (4) evaluating balance of confounding variables between exposure groups, and (5) conducting LCA using the weighted or matched data set.

RESULTS

Based on the results of IPTW which compared the low, medium and high risk classes of metabolic syndrome (compared to a class without metabolic syndrome), no association was found between smoking and the metabolic syndrome latent classes. PS matching which compared low and moderate risk classes compared to class without metabolic syndrome, showed that smoking increases the probability of being in the low-risk class of metabolic syndrome (OR: 2.19; 95% CI: 1.32, 3.63). In the unadjusted analysis, smoking increased the chances of being in the low-risk (OR: 1.45; 95% CI: 1.01, 2.08) and moderate-risk (OR: 1.68; 95% CI: 1.18, 2.40) classes of metabolic syndrome compared to the class without metabolic syndrome.

CONCLUSIONS

Based on the results, the causal effect of smoking on latent hazard classes of metabolic syndrome can be different based on the type of PS method. In adjusted analysis, no relationship was observed between smoking and moderate-risk and high-risk classes of metabolic syndrome.

Impact of Alcohol Consumption on Multiple Sclerosis Using Model-based Standardization and Misclassification Adjustment Via Probabilistic Bias Analysis

BACKGROUND

The etiology of multiple sclerosis (MS) is still not well-demonstrated, and assessment of some risk factors like alcohol consumption has problems like confounding and measurement bias. To determine the causal effect of alcohol consumption on MS after adjusting for alcohol consumption misclassification bias and confounders.

METHODS

In a population-based incident case-control study, 547 patients with MS and 1057 healthy people were recruited. A minimally sufficient adjustment set of confounders was derived using the causal directed acyclic graph. The probabilistic bias analysis method (PBAM) using beta, logit-logistic, and triangular probability distributions for sensitivity/specificity to adjust for misclassification bias in self-reporting alcohol consumption and model-based standardization (MBS) to estimate the causal effect of alcohol consumption were used. Population attributable fraction (PAF) estimates with 95% Monte Carlo sensitivity analysis (MCSA) intervals were calculated using PBAM and MBS analysis. Bootstrap was used to deal with random errors.

RESULTS

The adjusted risk ratio (95% MCSA interval) from the probabilistic bias analysis and MBS between alcohol consumption and MS using the three distribution was in the range of 1.93 (1.07 to 4.07) to 2.02 (1.15 to 4.69). The risk difference (RD) in all three scenarios was 0.0001 (0.0000 to 0.0005) and PAF was in the range of 0.15 (0.010 to 0.50) to 0.17 (0.001 to 0.47).

CONCLUSION

After adjusting for measurement bias, confounding, and random error alcohol consumption had a positive causal effect on the incidence of MS.

The Effects of Smoking on Metabolic Syndrome and Its Components Using Causal Methods in the Iranian Population

Background

The aim of this study was to estimate the effect of smoking on metabolic syndrome (MS) and its components applying inverse probability-of-treatment weighting (IPTW) and propensity score (PS) matching.

Methods

Using data from Tehran Lipid and Glucose Study, 4857 participants aged over 20 years with information on smoking and confounders in the third phase (2005-2008) were included, and the MS was assessed in the fifth phase (2011-2014). IPTW and PS matching were used to adjust for confounders.

Results

Based on average treatment effect (ATE) estimates, smoking decreased the risk of hypertension (RR: 0.62; 95% CI: 0.43, 0.88), but increased the risk of low HDL cholesterol (1.20; 0.98, 1.48). Similarly, the average treatment effect in the treated (ATT) estimates using IPTW and PS matching suggested that smoking decreased the risk of hypertension (0.63; 0.52, 0.76, and 0.68; 0.54, 0.85), and increased the risk of low HDL cholesterol (1.24; 1.07, 1.43, and 1.28; 1.06, 1.54), respectively.

Conclusions

Smoking seems to increase the risk of low HDL cholesterol but decreases the risk of hypertension.

Population attributable fraction in textbooks: Time to revise

Introduction

The population attributable fraction is an important measure for assessing the impact of intervention on the disease risk in populations, but it is frequently misused in the research literature.

Methods

In this study, we review the definition, calculation, interpretation and assumptions of PAF in 43 textbooks and highlight important shortcomings.

Results

While the Levin formula was proposed as a method of calculation in 29 (67%) textbooks, only in 4 (9%) was the Miettinen formula or its generalization for multilevel exposure recommended to calculate a confounding-adjusted population attributable fraction. Other concepts such as generalized impact fraction and prevented and preventable fractions were briefly discussed in few textbooks.

Discussion

We recommend the authors revise the textbooks in light of our proposed framework for teaching the population attributable fraction.

Parental relationship status and age at autism spectrum disorder diagnosis of their child

LAY ABSTRACT

Autism spectrum disorder (ASD) can be diagnosed as early as 18 months of age. However, the average age at diagnosis in the United States is over 2 years later. A lot has been written about the many barriers families face when seeking a diagnosis for their child. One area of research that has received no attention is whether separation between a child's biological parents affects the age at which a child is diagnosed with ASD. This study was conducted among 561 children who were receiving an ASD diagnosis for the first time. On average, these children were 5 years of age. The study took place in an urban, outpatient specialty autism clinic in the United States. Biological parents self-reported their relationship status during the evaluation. This was categorized as either "together" (married or living together but not married) or "not together" (separated, divorced, or never married). At the time of diagnosis, most children's biological parents were together (69%). We found children of parents who were together were diagnosed 1.4 years earlier than those who were not together. These findings have important implications for providing support to families that separate early in a child's life, with the goal of reducing the age at ASD evaluation among single parents and those who have been separated from their child's other biological parent. Providing support to these families is important since earlier age at diagnosis leads to earlier intervention, which can improve long-term outcomes for the child, family, and community as a whole.

Estimating the Marginal Causal Effect and Potential Impact of Waterpipe Smoking on Risk of Multiple Sclerosis Using the Targeted Maximum Likelihood Estimation Method: A Large, Population-Based Incident Case-Control Study

There are few if any reports regarding the role of lifetime waterpipe smoking in the etiology of multiple sclerosis (MS). In a population-based incident case-control study conducted in Tehran, Iran, we investigated the association between waterpipe smoking and MS, adjusted for confounders. Cases (n = 547) were patients aged 15-50 years identified from the Iranian Multiple Sclerosis Society between 2013 and 2015. Population-based controls (n = 1,057) were persons aged 15-50 years recruited through random digit telephone dialing. A doubly robust estimation method, the targeted maximum likelihood estimator (TMLE), was used to estimate the marginal risk ratio and odds ratio for the association between waterpipe smoking and MS. The estimated risk ratio and odds ratio were both 1.70 (95% confidence interval: 1.34, 2.17). The population attributable fraction was 21.4% (95% confidence interval: 4.0, 38.8). Subject to the limitations of case-control studies in interpreting associations causally, these results suggest that waterpipe use, or strongly related but undetermined factors, increases the risk of MS. Further epidemiologic studies, including nested case-control studies, are needed to confirm these findings.

The causal effect and impact of reproductive factors on breast cancer using super learner and targeted maximum likelihood estimation: a case-control study in Fars Province, Iran

OBJECTIVES

The relationship between reproductive factors and breast cancer (BC) risk has been investigated in previous studies. Considering the discrepancies in the results, the aim of this study was to estimate the causal effect of reproductive factors on BC risk in a case-control study using the double robust approach of targeted maximum likelihood estimation.

METHODS

This is a causal reanalysis of a case-control study done between 2005 and 2008 in Shiraz, Iran, in which 787 confirmed BC cases and 928 controls were enrolled. Targeted maximum likelihood estimation along with super Learner were used to analyze the data, and risk ratio (RR), risk difference (RD), andpopulation attributable fraction (PAF) were reported.

RESULTS

Our findings did not support parity and age at the first pregnancy as risk factors for BC. The risk of BC was higher among postmenopausal women (RR = 3.3, 95% confidence interval (CI) = (2.3, 4.6)), women with the age at first marriage ≥20 years (RR = 1.6, 95% CI = (1.3, 2.1)), and the history of oral contraceptive (OC) use (RR = 1.6, 95% CI = (1.3, 2.1)) or breastfeeding duration ≤60 months (RR = 1.8, 95% CI = (1.3, 2.5)). The PAF for menopause status, breastfeeding duration, and OC use were 40.3% (95% CI = 39.5, 40.6), 27.3% (95% CI = 23.1, 30.8) and 24.4% (95% CI = 10.5, 35.5), respectively.

CONCLUSIONS

Postmenopausal women, and women with a higher age at first marriage, shorter duration of breastfeeding, and history of OC use are at the higher risk of BC.

Dietary fish intake and the risk of multiple sclerosis: a systematic review and meta-analysis of observational studies

Objectives: There is some inconclusive evidence for the role of fish consumption in susceptibility to multiple sclerosis (MS). The present study aimed to systematically review and determine the association between dietary fish intake and risk of MS.Methods: A systematic search with related keywords was carried out in PubMed-MEDLIN, Scopus-EMBASE, and OVID-MEDLINE from inception up to September 2019 to find observational studies that evaluated the association between dietary fish intake and the risk of MS. Random effect and subgroup analyses were performed to calculate pooled estimates at 95% CIs.Results: Six articles met the inclusion criteria for systematic review and meta-analysis. The results of this study indicated that the consumption of fish decreases the risk of MS [OR (95% CIs): 0.77 (0.64, 0.92); p-value = 0.004; I² = 54.7%] compared with controls.Discussion: Dietary intake of at least 0.5 servings of fish per week during adolescence and after might reduce the risk of MS; however, further studies are required to prove this preventive effect.

Low fish consumption is associated with a small increased risk of MS

OBJECTIVE

We aimed to investigate the influence of lean and fatty fish consumption on MS risk and to what extent a potential effect may be mediated by vitamin D. We also studied the interplay between fish consumption, sun exposure, DRB1*15:01, and A*02:01.

METHODS

We used 2 population-based case-control studies (6,914 cases and 6,590 controls). Subjects with different fish consumption habits were compared regarding MS risk by calculating ORs with 95% CIs using logistic regression models. The mediation effect of vitamin D on the relationship between fish consumption and MS risk was assessed. Potential interactions between fish consumption, sun exposure, and MS-associated HLA genes were assessed on the additive scale.

RESULTS

Irrespective of sun exposure habits, low fish consumption, including both lean and fatty fish, was associated with increased MS risk (OR 1.2, 95% CI 1.1-1.4) and interacted with the DRB1*15:01 allele (AP 0.3, p < 0.0001). The mediation analysis did not support vitamin D as a mediator of the association between fish consumption and MS risk. There was no interaction between fish consumption and sun exposure habits with regard to MS risk.

CONCLUSIONS

Low fish consumption and low sun exposure seem to be separate risk factors for MS. Our findings suggest that fish consumption predominantly influences MS risk by other means than by effecting vitamin D status, which is of relevance for prevention, in particular for those with a genetic susceptibility to MS.

The role of nutritional factors during adolescence in multiple sclerosis onset: a population-based incident case-control study

OBJECTIVE

The potential role of nutritional factors in multiple sclerosis (MS) etiology is not clearly understood. The authors investigated the association between dietary intake during adolescence with MS.

DESIGN, SETTING AND PARTICIPANTS

This was a population-based incident case-control study in Iran with 547 incident cases and 1057 general population controls (7/8/2013-17/2/2015). Logistic regression was used to test differences in dietary intake between cases and controls adjusted for confounders.

RESULTS

We found that a higher dietary consumption during adolescence of fresh fish, canned tuna, poultry, cheese, yogurt, butter, fruit, vegetables and a number of dietary supplements were associated with a significantly reduced risk of MS, while red meat, shrimp, and margarine were not associated with MS. Fresh fish had a dose-response association of 0.71 (0.58-0.88) per category increase, and consuming >0.5 serves of canned tuna fish per week had an OR of 0.72 (0.56-0.90); fruit intake had an OR of 0.82 (0.71-0.94) per category increase and cheese consumption an OR of 0.78 (0.67-0.91) per category increase.

CONCLUSIONS

We identified that a higher intake of a number of food groups generally viewed as healthy were associated with a reduced risk of MS. A healthier diet during adolescence may be protective of developing MS.

The Implications of Using Lagged and Baseline Exposure Terms in Longitudinal Causal and Regression Models

There are now many published applications of causal (structural) models for estimating effects of time-varying exposures in the presence of confounding by earlier exposures and confounders affected by earlier exposures. Results from these models can be highly sensitive to inclusion of lagged and baseline exposure terms for different visits. This sensitivity is often overlooked in practice; moreover, results from these models are not directly comparable to results from conventional time-dependent regression models, because the latter do not estimate the same causal parameter even when no bias is present. We thus explore the implications of including lagged and baseline exposure terms in causal and regression models, using a public data set (Caerphilly Heart Disease Study in the United Kingdom, 1979-1998) relating smoking to cardiovascular outcomes.

Sociodemographic, environmental and lifestyle risk factors for multiple sclerosis development in the Western region of Saudi Arabia. A matched case control study

Objectives:

To examine the association of exposure to sociodemographic, environmental, and lifestyle risk factors during adolescence with the development of multiple sclerosis (MS).

Methods:

We conducted a case-control study between October 2017 and January 2018 at King Fahd General Hospital (KFH) in Madinah, Saudi Arabia. Data were collected by direct physician-subject interviews. We utilized a questionnaire modified from the environmental risk factors in multiple sclerosis questionnaire (EnvIMS-Q). Chi-square tests were used to examine associations of selected risk factors with the development of MS, a p-value of <0.05 was considered significant.

Results:

A total of 80 cases and 160 controls were enrolled into the study. Smoking during adolescence significantly increased the risk of MS, with an adjusted odds ratio (AOR) of 4.165, and a 95% confidence interval (CI) of 1.449-11.974. Large body size, assessed using a figure rating scale, also increased the risk of MS (AOR=8.970, 95% CI=1.032-77.983), as well as a history of measles infection (AOR=3.758, 95% CI=1.455-9.706). Furthermore, exposure to sunlight during the weekend for more than 4 hours/day decreased the risk of MS (AOR=0.063, 95% CI=0.006-0.654), so did the consumption of fish for more than once per week (AOR=0.206, 95% CI=0.055-0.773).

Conclusion:

The risk of developing MS is significantly increased by exposure during adolescence to smoking, a history of measles infection, and large body size (obesity).

Stress-full life events and multiple sclerosis: A population-based incident case-control study

AIM

While sizeable evidence regarding the association between stressful-life events and multiple sclerosis (MS) disease activity (clinical and/or radiological) was previously documented, their relation to MS risk is controversial. We aimed to investigate the possible association of stressful-life events and multiple sclerosis risk after adjustment for relevant confounders in an Iranian population.

METHOD

This was a population-based incident case-control study that recruited 547 MS cases and 1057 healthy controls between August 2013 and February 2015, Tehran. The patients were identified using the Iranian MS Society based on 2010 McDonald criteria. We used standard random digit dialing protocol for control selection. Logistic regression model was applied to estimate the odds ratios (95% CI) adjusted for physical activity, age, gender, tobacco smoking, waterpipe smoking and passive smoking.

RESULTS

While total life events number was not associated with risk of MS, homeless periods OR 3.85 (1.65-8.90), p = 0.002 as well as divorce OR 2.11 (1.24-3.58), p = 0.005 increased the risk of MS. However, marriage OR 0.59 (0.41-0.86), p = 0.006, death of ones' dear OR 0.60 (0.44-0.82), p = 0.002 and joblessness OR 0.61 (0.41-0.91) reduced the risk of MS.

CONCLUSION

We could not detect a statistically significant role for the total stressful life event during the last 3 years and MS diagnosis. However, there is some evidence confirming the possible role of some individual life events, i.e. divorce and periods of homelessness as potential risk factors for MS and conversely, having married as a protective factor in MS onset.