Ethnic differences of genetic risk and smoking in lung cancer: two prospective cohort studies

BACKGROUND

The role of genetic background underlying the disparity of relative risk of smoking and lung cancer between European populations and East Asians remains unclear.

METHODS

To assess the role of ethnic differences in genetic factors associated with smoking-related risk of lung cancer, we first constructed ethnic-specific polygenic risk scores (PRSs) to quantify individual genetic risk of lung cancer in Chinese and European populations. Then, we compared genetic risk and smoking as well as their interactions on lung cancer between two cohorts, including the China Kadoorie Biobank (CKB) and the UK Biobank (UKB). We also evaluated the absolute risk reduction over a 5-year period.

RESULTS

Differences in compositions and association effects were observed between the Chinese-specific PRSs and European-specific PRSs, especially for smoking-related loci. The PRSs were consistently associated with lung cancer risk, but stronger associations were observed in smokers of the UKB [hazard ratio (HR) 1.26 vs 1.15, P  =  0.028]. A significant interaction between genetic risk and smoking on lung cancer was observed in the UKB (RERI, 11.39 (95% CI, 7.01-17.94)], but not in the CKB. Obvious higher absolute risk was observed in nonsmokers of the CKB, and a greater absolute risk reduction was found in the UKB (10.95 vs 7.12 per 1000 person-years, P <0.001) by comparing heavy smokers with nonsmokers, especially for those at high genetic risk.

CONCLUSIONS

Ethnic differences in genetic factors and the high incidence of lung cancer in nonsmokers of East Asian ethnicity were involved in the disparity of smoking-related risk of lung cancer.

Additive interaction between dietary inflammatory index and some key risk factors of multiple sclerosis: a population-based incident case-control study

BACKGROUND

Recently, dietary inflammatory index (DII) has been introduced as a significant risk factor for MS. We examined the interaction between dietary inflammatory index and some formerly demonstrated key risk factors of multiple sclerosis (MS).

MATERIAL AND METHODS

We conducted a population-based incident case-control study of 547 MS cases and 1057 controls. Multiplicative and additive interaction were assessed using interaction term in the logistic regression model and synergy index (SI), respectively.

RESULTS

Additive interaction was detected between DII and drug abuse (SI = 2.58; 95% CI: 1.14-5.82), gender (SI = 2.00; 95% CI: 1.39-2.87) and history of depression (SI = 1.68; 95% CI: 1.04-2.72) on the risk scale. The risk of MS in drug abusers with DII ≥ 0 was 10.4-times higher than that in non-drug abusers with DII < 0 (OR = 10.4, 95% CI: 5.12-21.02, P < 0.001). We also found that women with DII ≥ 0 had a 9.2 times larger risk compared with the men with DII < 0(OR = 9.2, 95% CI: 6.3-13.5, P < 0.001). Similarly, the risk of MS was remarkably higher in those with a history of depression and DII >0 (OR = 7.6, 95% CI: 5.1-11.5, P < 0.001). There was no evidence of multiplicative interaction between DII and the other risk factors of MS on the risk scale.

CONCLUSIONS

We identified additive interaction between DII and drug abuse, gender and history of depression on MS. Further studies are needed to understand the underlying mechanisms of these detected interactions.

Birthweight, genetic risk, and gastrointestinal cancer incidence: a prospective cohort study

BACKGROUND

The epidemiologic studies investigating the association of birthweight and genetic factors with gastrointestinal cancer remain scarce. The study aimed to prospectively assess the interactions and joint effects of birthweight and genetic risk levels on gastrointestinal cancer incidence in adulthood.

METHODS

A total of 254,997 participants were included in the UK Biobank study. We used multivariate restricted cubic splines and Cox regression models to estimate the hazard ratios (HRs) and 95% confidential intervals (CI) for the association between birthweight and gastrointestinal cancer risk, then constructed a polygenic risk score (PRS) to assess its interaction and joint effect with birthweight on the development of gastrointestinal cancer.

RESULTS

We documented 2512 incident cases during a median follow-up of 8.88 years. Compare with participants reporting a normal birthweight (2.5-4.5 kg), multivariable-adjusted HR of gastrointestinal cancer incidence for participants with high birthweight (≥4.5 kg) was 1.17 (95%CI: 1.01-1.36). Such association was remarkably observed in pancreatic cancer, with an HR of 1.82 (95%CI: 1.26-2.64). No statistically significant association was observed between low birth weight and gastrointestinal cancers. Participants with high birthweight and high PRS had the highest risk of gastrointestinal cancer (HR: 2.95, 95%CI: 2.19-3.96).

CONCLUSION

Our findings highlight that high birthweight is associated with a higher incidence of gastrointestinal cancer, especially for pancreatic cancer. Benefits would be obtained from birthweight control, particularly for individuals with a high genetic risk.KEY MESSAGESThe epidemiologic studies investigating the association of birthweight and genetic factors with gastrointestinal cancer remain scarce.This cohort study of 254,997 adults in the United Kingdom found an association of high birthweight with the incidence of gastrointestinal cancer, especially for pancreatic cancer, and also found that participants with high birthweight and high polygenic risk score had the highest risk of gastrointestinal cancer.Our data suggests a possible effect of in utero or early life exposures on adulthood gastrointestinal cancer, especially for those with a high genetic risk.

Household air pollution and risk of incident lung cancer in urban China: A prospective cohort study

Household air pollution (HAP) is associated with the development of lung cancer, yet few studies investigated the exposure patterns and joint associations with tobacco smoking. In our study, we included 224 189 urban participants from China Kadoorie Biobank (CKB), 3288 of which diagnosed with lung cancer during the follow-up. Exposure to four HAP sources (solid fuels for cooking/heating/stove and environmental tobacco smoke exposure) was assessed at baseline. Distinct HAP patterns and their associations with lung cancer were examined through latent class analysis (LCA) and multivariable Cox regression. A total of 76.1% of the participants reported regular cooking and 52.2% reported winter heating, of which 9% and 24.7% used solid fuels, respectively. Solid fuel heating increased lung cancer risk (Hazards ratio [HR]: 1.25, 95% confidence interval [CI]: 1.08-1.46). LCA identified three HAP patterns; the "clean fuel cooking and solid fuel heating" pattern significantly increased lung cancer risk (HR: 1.25, 95% CI: 1.10-1.41), compared to low HAP pattern. An additive interaction was observed between heavy smoking and "clean fuel cooking and solid fuel heating" (relative excess risk [RERI]: 1.32, 95% CI: 0.29-2.47, attributable proportion [AP]: 0.23, 95% CI: 0.06-0.36). Cases resulting from solid fuel account for ~4% of total cases (population attribute fraction [PAF]overall : 4.31%, 95% CI: 2.16%-6.47%, PAFever smokers : 4.38%, 95% CI: 1.54%-7.23%). Our results suggest that in urban China, solid fuel heating increased the risk of lung cancer, particularly among heavy smokers. The whole population could benefit from cleaner indoor air quality by reducing using solid fuels, especially smokers.

Familial risk of seropositive rheumatoid arthritis and interaction with smoking: a population-based cohort study

OBJECTIVES

We evaluated the familial risk of seropositive rheumatoid arthritis (RA) and examined interactions between family history and smoking.

METHODS

Using the National Health Insurance and Health Screening Program databases, which include information on familial relationships and lifestyle factors, we identified 5 524 403 individuals with first-degree relatives (FDRs) from 2002-2018. We calculated familial risk using hazard ratios (HRs) with 95% CIs which compare the risk of individuals with and without affected FDRs. Interactions between smoking and family history were assessed on an additive scale using the relative excess risk due to interaction (RERI).

RESULTS

Individuals with affected FDR had 4.52-fold (95% CI 3.98, 5.12) increased risk of disease compared with those with unaffected FDR. Familial risk adjusted for lifestyle factors decreased slightly (HR 4.49), suggesting that a genetic contribution is the predominant driver in the familial aggregation of RA. Smoking was associated with an increased risk of disease that was more pronounced among heavy (HR 1.92 95% CI 1.70, 2.18) compared with moderate (HR 1.15 95% CI 1.04, 1.28) smoking. In the interaction analysis, the risk associated with the combined effect of smoking and family history was higher than the sum of their individual effects, though statistically non-significant (RERI 1.30 95% CI ‒0.92, 3.51). Heavy smokers with a positive family history showed a prominent interaction (RERI 4.13 95% CI ‒0.88, 9.13) which exceeded moderate smokers (RERI 0.61 95% CI ‒1.90, 3.13), suggesting a dose-response interaction pattern.

CONCLUSION

Our findings indicate the possibility of an interaction between RA-associated genes and smoking.

Behavioural activity pattern, genetic factors, and the risk of nonalcoholic fatty liver disease: A prospective study in the UK Biobank

BACKGROUND & AIMS

Physical activity, sedentary behaviour, and genetic variants have been associated with the nonalcoholic fatty liver disease (NAFLD). However, whether and how the degree of healthy activity patterns may modify the impact of genetic susceptibility on NAFLD remains unknown.

METHODS

Behaviour activity factors were determined according to total physical activity (TPA) and sedentary time. The polygenic risk score (PRS) was calculated by variants in PNPLA3, TM6SF2, MBOAT7, and GCKR. Cox regression was used to analyse the associations of genetic and behaviour activity factors with incident NAFLD in the UK Biobank (N = 338 087).

RESULTS

During a median follow-up of 12.4 years, 3201 incident NAFLD cases were ascertained. Analyses of TPA and sedentary time simultaneously showed a dose-response association with the risk of NAFLD (ptrend  < .001). The association of behaviour activity patterns with NAFLD varied by genetic variants. Of the subjects with high genetic risk, we observed a null protective effect of moderate or high TPA on NAFLD risk, while sitting less than three hours a day significantly decreased the risk of NAFLD (p = 3.50 × 10-4 ). The high genetic risk of NAFLD can also be offset by the combination of moderate physical activity and shorter sedentary time. Moreover, the high genetic risk group has the greatest reduction of 10-year absolute risk (6.95 per 1000 person-years) if reaching both healthy activities.

CONCLUSIONS

Moderate-to-high physical activity and favourable sedentary behaviour may be lifestyle modifications in preventing NAFLD, which could offset the harmful effect of predisposing genetic factors.

Effect of gestational diabetes mellitus on pregnancy outcomes among younger and older women and its additive interaction with advanced maternal age

Background

The prevalence of gestational diabetes mellitus (GDM) and advanced maternal age (AMA, ≥ 35 years) has shown an increasing trend worldwide. This study aimed to evaluate the risk of pregnancy outcomes among younger (20-34 years) and older (≥ 35 years) women with GDM and further analyze the epidemiologic interaction of GDM and AMA on these outcomes.

Methods

This historical cohort study included 105 683 singleton pregnant women aged 20 years or older between January 2012 and December 2015 in China. Stratified by maternal age, the associations between GDM and pregnancy outcomes were analyzed by performing logistic regression. Epidemiologic interactions were assessed by using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP), and synergy index (SI) with their 95% confidence intervals (95%CIs).

Results

Among younger women, individuals with GDM had a higher risk of all maternal outcomes, preterm birth (relative risk [RR] 1.67, 95%CI 1.50-1.85), low birthweight (RR 1.24, 95%CI 1.09-1.41), large for gestational age (RR 1.51, 95%CI 1.40-1.63), macrosomia (RR 1.54, 95%CI 1.31-1.79), and fetal distress (RR 1.56, 95%CI 1.37-1.77) than those without GDM. Among older women, GDM increased the risk of gestational hypertension (RR 2.17, 95%CI 1.65-2.83), preeclampsia (RR 2.30, 95%CI 1.81-2.93), polyhydramnios (RR 3.46, 95%CI 2.01-5.96), cesarean delivery (RR 1.18, 95%CI 1.10-1.25), preterm birth (RR 1.35, 95%CI 1.14-1.60), large for gestational age (RR 1.40, 95%CI 1.23-1.60), macrosomia (RR 1.65, 95%CI 1.28-2.14) and fetal distress (RR 1.46, 95%CI 1.12-1.90). Additive interactions of GDM and AMA on polyhydramnios and preeclampsia were found, with RERI of 3.11 (95%CI 0.05-6.16) and 1.43 (95%CI 0.09-2.77), AP of 0.51 (95%CI 0.22-0.80) and 0.27 (95%CI 0.07-0.46), and SI of 2.59 (95%CI 1.17-5.77) and 1.49 (95%CI 1.07-2.07), respectively.

Conclusion

GDM is an independent risk factor for multiple adverse pregnancy outcomes, and may exert additive interactions with AMA on the risk of polyhydramnios and preeclampsia.

Interaction between Occupational and Non-Occupational Arsenic Exposure and Tobacco Smoke on Lung Cancerogenesis: A Systematic Review

Although a higher lung cancer risk has been already associated with arsenic exposure, the contribution of arsenic and its compounds to the carcinogenic effects of other agents, such as tobacco smoke, is not well characterized. This systematic review examined the relationship between occupational and non-occupational arsenic exposure and tobacco smoking on lung cancer risk using papers published from 2010 to 2022. Two databases, PUBMED and Scifinder, were used for the searches. Among the sixteen human studies included, four were about occupational exposure, and the others were about arsenic in drinking water. Furthermore, only three case-control studies and two cohort studies evaluated an additive or multiplicative interaction. The interaction between arsenic exposure and tobacco smoke seems to be negligible at low arsenic concentrations (<100 μg/L), while there is a synergistic effect at higher concentrations. Finally, it is not yet possible to assess whether a linear no-threshold (LNT) model for lung cancer risk can be applied to the co-exposure to arsenic and tobacco smoke. Although the methodological quality of the included studies is good, these findings suggest that rigorous and accurate prospective studies on this topic are highly needed.

Familial Risk of Graves' Disease among First-Degree Relatives and Interaction with Smoking: A Population-Based Study

OBJECTIVE

Population-based studies on the familial aggregation of Graves' disease (GD) are scarce and gene-environment interactions are not well-studied. We evaluated the familial aggregation of GD and assessed interactions between family history and smoking.

METHODS

Using the National Health Insurance database, which includes information on familial relationships and lifestyle risk factors, we identified 5,524,403 individuals with first-degree relatives (FDRs). Familial risk was calculated using hazard ratios (HRs), which compare the risk of individuals with and without affected FDRs. Interactions between smoking and family history were assessed on an additive scale using relative excess risk due to interaction (RERI).

RESULTS

The HR among individuals with affected FDRs was 3.39 (95% CI 3.30-3.48) compared to those without affected FDR, and among individuals with affected twin, brother, sister, father and mother the HRs were 36.53 (23.85-53.54), 5.26 (4.89-5.66), 4.12 (3.88-4.38), 3.34 (3.16-3.54), and 2.63 (2.53-2.74), respectively. Individuals with both a positive family history and smoking had an increased risk of disease (HR 4.68) with statistically significant interaction (RERI 0.94 95% CI 0.74-1.19). Heavy smokers with a positive family history showed a nearly 6-fold increased risk, which was higher than moderate smoking, suggesting a dose-response interaction pattern. Current smoking also showed a statistically significant interaction with family history (RERI 0.52 95% CI 0.22-0.82), while this was not observed for former smoking.

CONCLUSION

A gene-environment interaction can be suggested between smoking and GD-associated genetic factors, which diminishes after smoking cessation. Smokers with a positive family history should be considered a high-risk group and smoking cessation should be advised.

Interactive effect of prepregnancy overweight/obesity and GDM history on prevalence of GDM in biparous women

BACKGROUND

Prepregnancy overweight/obesity (OWO) and gestational diabetes mellitus (GDM) history may increase the prevalence of GDM in parous women, but little is known about their potential combined effect on the prevalence of GDM in biparous women.

OBJECTIVE

This study aims to explore the interactive effect of prepregnancy overweight/obesity (OWO) and GDM history on the prevalence of GDM in biparous women.

METHODS

A retrospective study was conducted on 16,282 second-birth women who delivered a single neonate at ≧28 weeks of gestation twice. Logistic regression was used to assess the independent and multiplicative interactions of prepregnancy overweight/obesity (OWO) and GDM history on the risk of GDM in biparous women. Additive interactions were calculated using an Excel sheet that was made by Anderson to calculate relative excess risk.

RESULTS

A total of 14,998 participants were included in this study. Both prepregnancy OWO and GDM history were independently associated with an increased risk of GDM in biparous women (odds ratio (OR) = 19.225, 95% confidence interval (CI) = 17.106, 21.607 and OR = 6.826, 95% CI = 6.085, 7.656, respectively). The coexistence of prepregnancy OWO and GDM history was associated with GDM, with an adjusted OR of 1.754 (95% CI, 1.625, 1.909) compared to pregnant women without either condition. The additive interaction between prepregnancy OWO and GDM history was found to be not significant with regard to GDM in biparous women.

CONCLUSIONS

Prepregnancy OWO and GDM history both increase the risk of GDM in biparous women and have multiplicative interactions but not additive interactions.

The Effects of Multiple Global Change Factors on Soil Nutrients across China: A Meta-Analysis

The quantification of the effects of global changes on soil nutrients is crucial for the prediction of future terrestrial ecosystem changes. Combined with 100 articles and 1129 observations from all over China, the meta-analysis method was applied to explore the effects of various global change factors on soil nutrients, including precipitation change, nitrogen addition, warming, and carbon dioxide (CO₂) concentration rise. Results indicated that among all the individual drivers, soil nutrients are most sensitive to N addition. Significant positive effects of N addition on carbon concentration (+4.6%), nitrogen concentration (+6.1%), organic carbon (+5.0%), and available nitrogen (+74.6%) were observed considering all the land-use types. The results highlighted that the combined and interactive effects of multiple global change factors on soil nutrients were of great significance. The interaction of the two drivers is usually additive, followed by antagonism and synergy. Our findings contribute to better understanding of how soil nutrients will change under future global change.

Maternal periconceptional alcohol consumption and gastroschisis in the National Birth Defects Prevention Study, 1997-2011

BACKGROUND

Gastroschisis is particularly prevalent among offspring of young women and has increased over recent decades. Although previous studies suggest that maternal alcohol consumption is associated with increased gastroschisis risk, none have explored whether maternal age modifies that association.

OBJECTIVE

The objective of the study was to evaluate associations between self-reported maternal periconceptional alcohol consumption (1 month prior through the third month after conception) and risk of gastroschisis among offspring, by maternal age.

METHODS

We used data from the National Birth Defects Prevention Study (NBDPS), a multi-site population-based case-control study. The analysis included 1450 gastroschisis cases and 11,829 unaffected liveborn controls delivered during 1997-2011 in ten US states. We estimated adjusted odds ratios (aOR) and 95% confidence intervals (CI) for the individual and joint effects of alcohol consumption and young maternal age at delivery (<25 years vs ≥25 years) on gastroschisis risk. We estimated the relative excess risk due to interaction (RERI) to quantify additive interaction.

RESULTS

Periconceptional alcohol consumption was common regardless of maternal age (women <25 years: cases 38.8%, controls 29.3%; women ≥25: cases 43.5%, controls 39.5%). Compared with women ≥25 years who did not consume alcohol, we observed increased risk of gastroschisis among women <25 years, with higher estimates among those who consumed alcohol (women <25 years who did not consume alcohol. aOR 5.90, 95% CI 4.89, 7.11; women <25 years who did consume alcohol: aOR 8.21, 95% CI 6.69, 10.07). Alcohol consumption among women ≥25 years was not associated with gastroschisis (aOR 1.12, 95% CI 0.88, 1.42). This suggests super-additive interaction between alcohol consumption and maternal age (RERI -2.19, 95% CI 1.02, 3.36).

CONCLUSIONS

Periconceptional alcohol consumption may disproportionately increase risk of gastroschisis among young mothers. Our findings support public health recommendations to abstain from alcohol consumption during pregnancy.

Independent and interactive effects of eye rubbing and atopy on keratoconus

Purpose

To evaluate the independent and interactive effects of eye rubbing and atopy on keratoconus (KC) in central China.

Methods

A total of 330 KC patients and 330 controls were recruited in the case-control study. Eye rubbing and history of atopy were recorded through face-to-face interviews. The association between KC and eye rubbing, atopy, interactive effects of eye rubbing and atopy were analyzed by logistic regression, and the odds ratios (OR), relative excess risk due to interaction (RERI), attributable proportion (AP), synergy (S) index, and 95% confidence intervals (95% CI) were calculated.

Results

A total of 228 patients (69.09%) had an eye rubbing history, and 53 (16.06%) had an atopy history in the KC group, which were both higher than that in the control group (p<0.001). Eye rubbing and atopy were positively associated with KC in multivariate analysis, with ORs (95% CIs) of 15.11 (10.02, 22.80) and 5.30 (2.59, 10.84), respectively. Compared to non-eye rubbing and non-atopy eyes, the risk for eye rubbing coexisted with atopy was 52.31 (12.25, 223.35). No significant associations were found between KC and multiplicative interaction (p=0.608). The RERI, AP, and S values were 32.89 (-43.35, 109.14), 0.63 (0.05, 1.21), and 2.79 (0.56, 13.96), respectively, with no significant association between additive interaction and KC. No significant associations were found between eye rubbing, atopy and the severity of KC (p>0.05).

Conclusion

Eye rubbing and atopy were separately positively associated with KC, and there was a strong impact of coexistent eye rubbing and atopy on KC in China. Further multi-center and cohort study need to be conducted to explore the role of eye rubbing and atopy in the occurrence and development of KC.

Interaction between occupational radon exposure and tobacco smoke: a systematic review

INTRODUCTION

: The risk of lung cancer from radon exposure was small compared to tobacco smoking (BEIR VI), but the relationship between these two carcinogenic agents has yet to be quantitatively estimated. The objective of this systematic review was to evaluate the last evidences on the role of radon occupational exposures and tobacco smoke on lung cancer risk.

AREAS COVERED

: Thirteen articles were selected using two different databases, PubMed and Scifinder, and were limited to those published from 2010 to 2021. The reference list of selected studies was reviewed to identify other relevant papers.

EXPERT OPINION

: Seven papers included in this systematic review did not deal with the multiplicative or the additive type of interaction between radon exposure and smoking habit. Six papers discussed the nature of this interaction with a prevalence of the sub-multiplicative model compared to the additive one. Altogether, smoking adjustment did not change significantly lung cancer risk. The included studies might constitute a starting point for updating the models for risk assessment in occupational and residential scenarios, promoting concomitantly the exposure reduction to radon and other cofactors, as recently introduced by Italian Legislative Decree number 101 of 31 July 2020, an application of Euratom Directive 59/2013.

Combined application of entomopathogenic nematodes and fungi against fruit flies, Bactrocera zonata and B. dorsalis (Diptera: Tephritidae): laboratory cups to field study

BACKGROUND

The peach fruit fly, Bactrocera zonata, and the Oriental fruit fly, B. dorsalis (Diptera: Tephritidae), are economically important fruit fly species in various regions of the world. We evaluated the effects of separate and combined applications of the entomopathogenic fungi (EPF) Beauveria bassiana (WG-18) and Metarhizium anisopliae (WG-02), and the entomopathogenic nematodes (EPNs) Heterorhabditis bacteriophora (VS strain) and Steinernema carpocapsae (ALL strain) against larvae, pupae and pharate adults, of B. zonata and B. dorsalis under laboratory, glasshouse and field cage conditions.

RESULTS

Combined applications of EPF and EPNs produced greater mortality than individual treatments under all conditions. Against both species, the combination of B. bassiana and H. bacteriophora consistently exerted strong effects that were similar to the combined application of B. bassiana and S. carpocapsae whereas M. anisopliae applied with S. carpocapsae was least effective in all combinations. In a laboratory bioassay, synergistic interactions were detected between B. bassiana and H. bacteriophora applied against larvae and pharate adults of both fly species, between B. bassiana and S. carpocapsae against larvae of both species and pharate adults of B. zonata, and between M. anisopliae and H. bacteriophora against B. zonata larvae. Other combined treatments resulted in additive effects, especially against fly pupae. In a potted soil bioassay, there were only additive interactions in all combinations against different stages of both flies. The 3rd instar of both flies was more susceptible than pharate adult and pupal stages. Additive interactions between EPNs and EPF were detected in the glasshouse against 3rd instars and pupae, and under field conditions against 3rd instars of both fly species.

CONCLUSION

These results indicate how particular combinations of entomopathogenic fungi and nematodes could be deployed in integrated pest management of tephritid fruit flies in orchard agro-ecosystems. © 2022 Society of Chemical Industry.

Joint effect of cognitive decline and walking ability on incidence of wandering behavior in older adults with dementia: A cohort study

OBJECTIVES

Wandering behavior is one of the most troublesome behavioral disturbances in dementia. Inconsistent associations between physical function and wandering behavior were reported, and the effect of cognitive decline may be different according to walking ability. The purposes of this study are to investigate whether high walking ability is a risk factor for wandering behavior and to investigate the interaction of walking ability and cognitive function with wandering behavior in older adults with dementia.

METHODS

This retrospective cohort study included 3979 elderly adults with dementia. The association of cognitive function and walking ability with incidence of wandering behavior during a 5-year follow-up period were examined using a generalized linear model, and relative excess risk due to interaction (RERI) was calculated.

RESULTS

Severe cognitive decline and high walking ability were associated with a higher risk for wandering behavior. Additionally, some joint effects of cognitive decline and walking ability decline were higher than the sum of its individual effects (RERI [95% confidence interval], severe cognitive decline × 'walk with help': 1.58 [0.35, 2.81]; severe cognitive decline × 'independent': 3.09 [1.05, 5.14]).

CONCLUSIONS

Effects of cognitive decline and walking ability on incidence of wandering behavior were observed, and the effects varied depending on their combination.

Association of Body Mass Index and Abdominal Obesity with the Risk of Airflow Obstruction: National Health and Nutrition Examination Survey (NHANES) 2007-2012

This study aimed to explore the relationship between body mass index (BMI) and abdominal obesity and the risk of airflow obstruction, based on the data from the 2007-2012 National Health and Nutrition Survey (NHANES). Logistic regression was applied to assess the relationships between BMI or abdominal obesity and the risk of airflow obstruction by the fixed ratio method and the lower limit of normal (LLN) method. We further used the restricted cubic splines with 3 knots located at the 5th, 50th, and 95th percentiles of the distribution to evaluate the dose-response relationship. A total of 12,865 individuals aged 20-80 years old were included. In the fixed ratio method, underweight was positively correlated with the risk of airflow obstruction, and overweight and obesity were negatively correlated with the risk of airflow obstruction. In the LLN method, the results were consistent with the fixed ratio method. Abdominal obesity was positively associated with the risk of airflow obstruction only in the fixed ratio method (OR: 1.41, 95% CI: 1.04-1.90). There was an additive interaction between underweight and smoking on airflow obstruction in both methods. Abdominal obesity and smoking had additive interactions in the LLN method. Dose-response analysis indicated that there was a non-linear trend between BMI and the risk of airflow obstruction (P_{for nonlinearity} < 0.01). Our study suggested that underweight and abdominal obesity were associated with the increased risk of airflow obstruction, and overweight and general obesity were associated with the decreased risk of airflow obstruction.

Rapid characterisation of xanthine oxidase inhibitors from the flowers of Chrysanthemum morifolium Ramat. Using metabolomics approach

INTRODUCTION

Hyperuricemia is the key risk factor for gout, in which the elevated uric acid is attributed to the oxidation of hypoxanthine and xanthine to uric acid by xanthine oxidase (XO). Adverse effects of the current treatments lead to an urgent need for safer and more effective alternative from natural resources.

OBJECTIVE

To compare the metabolite profile of Chrysanthemum morifolium flower fraction with that of its detannified fraction in relation to XO inhibitory activity using a rapid and effective metabolomics approach.

METHODS

Proton nuclear magnetic resonance (¹ H-NMR)-based metabolomics approach coupled with multivariate data analysis was utilised to characterise the XO inhibitors related to the antioxidant properties, total phenolic, and total flavonoid contents of the C. morifolium dried flowers.

RESULTS

The highest XO inhibitory activity, 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity, total phenolic and flavonoid content with strong positive correlation between them were observed in the ethyl acetate (EtOAc) fraction. Detannified EtOAc showed higher XO inhibitory activity than non-detannified EtOAc fraction. A total of 17 metabolites were tentatively identified, of which three namely kaempferol, 4-hydroxybenzoic acid and apigenin, could be suggested to be responsible for the strong XO inhibitory activity. Additive interaction between 4-hydroxybenzoic acid and apigenin (or kaempferol) in XO inhibition was demonstrated in the interaction assay conducted.

CONCLUSION

Chrysanthemum morifolium dried flower-part could be further explored as a natural XO inhibitor for its anti-hyperuricemic potential. Metabolomics approach served as an effective classification of plant metabolites responsible for XO inhibitory activity, and demonstrated that multiple active compounds can work additively in giving combined inhibitory effects.

Joint effect between bisphenol A and alcohol consumption on benign prostatic hyperplasia: A case-control study in Hong Kong Chinese males

BACKGROUND

Whether bisphenol A (BPA) exposure is a contributing factor to benign prostatic hyperplasia (BPH) remains unclear. This study evaluated the association between chronic BPA exposure and BPH risk, and explored whether this association was modified by alcohol drinking.

METHODS

This study included a total of 650 BPH cases and 650 controls recruited from the same hospital in Hong Kong during 2011-2016. Chronic BPA exposure level was estimated by a validated cumulative BPA exposure index (CBPAI). We performed unconditional logistic regression model to examine the association of BPH risk with potential sources of BPA exposure via oral intake and CBPAI. We further tested the interactions between CBPAI and alcohol consumption habits on BPH risk.

RESULTS

A positive exposure-response relationship was observed between CBPAI and BPH risk. Frequent BPA exposure via oral intake of foods heated in a plastic box/bag (odds ratio [OR] = 3.52, 95% confidence interval [CI]: 1.51-8.22), cooling water in a plastic bottle (OR = 2.65, 95% CI: 1.33-5.27), or using a plastic cup to contain hot water (OR = 4.14, 95% CI: 1.02-16.89), was significantly associated with increased BPH risk. Compared with nonalcohol drinkers, alcohol drinkers was insignificantly associated with BPH risk (OR = 1.10, 95% CI: 0.77-1.57), but it demonstrated a more remarkable positive gradient between CBPAI exposure and BPH risk among alcohol drinkers, indicating an additive interaction between CBPAI and alcohol on BPH risk (synergy index = 4.24, 95% CI: 1.21-14.94).

CONCLUSIONS

Chronic oral BPA exposure increased BPH risk with a positive exposure-response relationship among Hong Kong Chinese, and alcohol drinking amplified the effect of BPA on BPH. Hence, minimizations of containing food or water/beverage in plastic containers and drinking alcohol are recommended in the community to mitigate BPH risk. Future larger and designated studies are warranted.

Air Pollution, Genetic Factors and the Risk of Lung Cancer: A Prospective Study in the UK Biobank

Rationale: Both genetic and environmental factors contribute to lung cancer, but the degree to which air pollution modifies the impact of genetic susceptibility on lung cancer remains unknown. Objectives: To investigate whether air pollution and genetic factors jointly contribute to incident lung cancer. Methods: We analyzed data from 455,974 participants (53% women) without previous cancer at baseline in the UK Biobank. The concentrations of particulate matter (PM_2.5, PM_coarse and PM₁₀), nitrogen dioxide (NO₂), and nitrogen oxides (NO_x) were estimated by land-use regression models, and the association between air pollutants and incident lung cancer was investigated using a Cox proportional hazard model. Furthermore, we constructed a polygenic risk score and evaluated whether air pollutants modified the effect of genetic susceptibility on the development of lung cancer. Measurements and Main Results: The results showed significant associations between the risk of lung cancer and PM_2.5 (hazard ratio [HR]: 1.63, 95% confidence interval [CI]: 1.33-2.01; per 5 μg/m³), PM₁₀ (1.53, 1.20-1.96; per 10 μg/m³), NO₂ (1.10, 1.05-1.15; per 10 μg/m³), and NO_x (1.13, 1.07-1.18; per 20 μg/m³). There were additive interactions between air pollutants and the genetic risk. Compared with participants with low genetic risk and low air pollution, those with high air pollution and high genetic risk had the highest risk of lung cancer (PM_2.5: HR: 1.71, 95% CI:1.45-2.02; PM₁₀: 1.77, 1.50-2.10; NO₂: 1.77, 1.42-2.22; NO_x: 1.67, 1.43-1.95). Conclusion: Long-term exposure to air pollution may increase the risk of lung cancer, especially in those with high genetic risk.

Combined effect of obesity and metabolic profile on glomerular dysfunction in hypertensive subjects

AIM

The aim of this study is to explore the individual and combined effects of obesity and metabolic profile on the impairment of glomerular function among hypertensive subjects.

METHODS

This is a cross-sectional study enrolling 499 hypertensive subjects. Based on body mass index values and metabolic profile, they were assigned to one of four metabolic phenotype groups: MHNO: metabolically healthy non-obese, MHO: metabolically healthy but obese, MUHNO: metabolically unhealthy but non-obese, and MUHO: metabolically unhealthy and obese. The effect of the interaction between obesity and metabolic profile was tested on an additive scale, for both microalbuminuria and reduced estimated glomerular filtration rate (eGFR).

RESULTS

After adjustment for confounding factors, the highest risk of both microalbuminuria and decreased eGFR was found among patients of the MUHO group (OR = 6.0 [2.13], p < 0.0001, OR = 5.4 [1.26], p = 0.03, respectively). Analysis of the additive interaction indicates that 51% and 53% of the risk of microalbuminuria and its combination with low eGFR respectively is explained by the co-occurrence of obesity and metabolic disorder. The mechanism of this interaction is synergistic (synergy index = 2.6, [1.5.3]).

CONCLUSION

The decline of glomerular function in hypertensive subjects is significantly exacerbated by the interaction between obesity and metabolic disorders. The management of such high-risk subjects requires, in addition to the therapeutic regimen, an adequate dietary and physical program in order to preserve glomerular function.

Virulence of Entomopathogenic Fungi to Rhagoletis pomonella (Diptera: Tephritidae) and Interactions With Entomopathogenic Nematodes

The objectives of this study were to quantify the virulence of four entomopathogenic fungal species to pupae of Rhagoletis pomonella (Walsh) (Diptera: Tephritidae) and to determine the potential to combine entomopathogenic fungi (EPFs) and entomopathogenic nematodes (EPNs) for biological control of this pest. The four species of EPFs included Beauveria bassiana (strain GHA), Metarhizium brunneum (strain F52), Isaria javanica (wf GA17), and Isaria fumosorosea (Apopka 97 strain). In laboratory assays, all fungi reduced adult emergence but there were no differences between fungal species. Isaria javanica and M. brunneum were examined further in a EPFs and EPNs bioassay that also included the EPNs Steinernema carpocapsae (ALL strain) and S. riobrave (355 strain). All nematodes and fungi were applied either alone or in combination (fungus + nematode). There were no differences between species within the same entomopathogen group (fungi and nematodes). However, the treatment with S. riobrave resulted in lower R. pomonella emergence than either fungal species. The combination of S. riobrave and I. javanica resulted in the lowest R. pomonella emergence (3%) at fourth-week interval, which was significantly lower than any of the single-agent applications, yet virulence of the other three combination treatments was not different from their respective nematode treatments applied alone. Additive interactions were detected for all fungus-nematode combinations. This study suggests that application of entomopathogenic nematodes and fungi could be an effective option to suppress R. pomonella populations.

Additive and Multiplicative Interactions Between Genetic Risk Score and Family History and Lifestyle in Relation to Risk of Type 2 Diabetes

We examined interactions between lifestyle factors and genetic risk of type 2 diabetes (T2D-GR), captured by genetic risk score (GRS) and family history (FH). Our initial study cohort included 20,524 European-ancestry participants, of whom 1,897 developed incident T2D, in the Nurses' Health Study (1984-2016), Nurses' Health Study II (1989-2016), and Health Professionals Follow-up Study (1986-2016). The analyses were replicated in 19,183 European-ancestry controls and 2,850 incident T2D cases in the Women's Genome Health Study (1992-2016). We defined 2 categories of T2D-GR: high GRS (upper one-third) with FH and low GRS or without FH. Compared with participants with the healthiest lifestyle and low T2D-GR, the relative risk of T2D for participants with the healthiest lifestyle and high T2D-GR was 2.24 (95% confidence interval (CI): 1.76, 2.86); for participants with the least healthy lifestyle and low T2D-GR, it was 4.05 (95% CI: 3.56, 4.62); and for participants with the least healthy lifestyle and high T2D-GR, it was 8.72 (95% CI: 7.46, 10.19). We found a significant departure from an additive risk difference model in both the initial and replication cohorts, suggesting that adherence to a healthy lifestyle could lead to greater absolute risk reduction among those with high T2D-GR. The public health implication is that a healthy lifestyle is important for diabetes prevention, especially for individuals with high GRS and FH of T2D.

Associations of objectively measured sleep characteristics and incident hypertension among police officers: The role of obesity

This study investigated the associations of baseline sleep onset latency, wake after sleep onset, longest wake episode, number of awakenings, sleep efficiency and sleep duration with incident hypertension during a 7-year follow-up (n = 161, 68% men) and the joint effect of insufficient sleep and obesity on incident hypertension. Sleep parameters were derived from 15-day actigraphy data. Relative risks and 95% confidence intervals were estimated using a robust Poisson regression model. Each 10-min increase in sleep onset latency was associated with an 89% higher risk of hypertension (95% confidence interval [CI] = 1.12-3.20). Each 10-min increase in longest wake episode was associated with a 23% higher risk of hypertension (95% CI = 1.01-1.50) and each 10% decrease in sleep efficiency was associated with a 50% higher risk of hypertension (95% CI = 1.02-2.22). These associations were independent of demographic and lifestyle characteristics, depressive symptoms, shift work, sleep duration and body mass index. Having <6 hr of sleep and a body mass index ≥30 kg/m² increased the risk of hypertension (relative risk = 2.81; 95% CI = 1.26-6.25) compared with having ≥6 hr of sleep and a body mass index <30 after controlling for confounders. Relative excess risk due to interaction was 3.49 (95% CI = -1.69-8.68) and ratio of relative risk was 3.21 (95% CI = 0.72-14.26). These results suggest that poor sleep quality is a risk factor for hypertension. Longitudinal studies with larger sample sizes are warranted to examine the joint effect of insufficient sleep and obesity on development of hypertension.

A comprehensive gene-environment interaction analysis in Ovarian Cancer using genome-wide significant common variants

As a follow-up to genome-wide association analysis of common variants associated with ovarian carcinoma (cancer), our study considers seven well-known ovarian cancer risk factors and their interactions with 28 genome-wide significant common genetic variants. The interaction analyses were based on data from 9971 ovarian cancer cases and 15,566 controls from 17 case-control studies. Likelihood ratio and Wald tests for multiplicative interaction and for relative excess risk due to additive interaction were used. The top multiplicative interaction was noted between oral contraceptive pill (OCP) use (ever vs. never) and rs13255292 (p value = 3.48 × 10-4 ). Among women with the TT genotype for this variant, the odds ratio for OCP use was 0.53 (95% CI = 0.46-0.60) compared to 0.71 (95%CI = 0.66-0.77) for women with the CC genotype. When stratified by duration of OCP use, women with 1-5 years of OCP use exhibited differential protective benefit across genotypes. However, no interaction on either the multiplicative or additive scale was found to be statistically significant after multiple testing correction. The results suggest that OCP use may offer increased benefit for women who are carriers of the T allele in rs13255292. On the other hand, for women carrying the C allele in this variant, longer (5+ years) use of OCP may reduce the impact of carrying the risk allele of this SNP. Replication of this finding is needed. The study presents a comprehensive analytic framework for conducting gene-environment analysis in ovarian cancer.

Gastrointestinal bleeding risk of selective serotonin reuptake inhibitors by level of kidney function: A population-based cohort study

Aim

To estimate the risk of gastrointestinal (GI) bleeding associated with serotonin reuptake inhibitors (SSRIs) by level of kidney function.

Methods

We conducted a cohort study using the Clinical Practice Research Datalink linked to Hospital Episode Statistics. We identified patients with chronic kidney disease (CKD; estimated glomerular filtration rate <60 ml min^–1 1.73 m^–2 for ≥3 months), and a comparison group of patients without it. Patients with CKD were further classified as stage 3a (eGFR 45–59 ml min^–1 1.73 m^–2), 3b (30–44 ml min^–1 1.73 m^–2) and 4/5 (<30 ml min^–1 1.73 m^–2). We excluded prevalent SSRI users at cohort entry. Exposure was time‐dependent SSRI prescription and outcome was first hospitalization for GI bleeding. We estimated adjusted rate ratio (aRR) and rate difference (aRD) of GI bleeding comparing periods with and without SSRI prescription at each level of kidney function.

Results

The aRRs and aRDs were: (i) no CKD (n = 202 121) aRR: 1.66 (95%CI 1.37–2.01), aRD: 2.0/1000 person–years (5.5 vs. 3.5/1000 person–years in period with and without SSRIs); (ii) CKD stage 3a (n = 153 316) aRR: 1.86 (1.62–2.15), aRD: 4.2/1000 person–years (8.3 vs. 4.1/1000 person–years); (iii) CKD stage 3b (n = 46 482) aRR: 1.61 (1.27–2.04), aRD: 4.8/1000 person–years (9.9 vs. 5.1/1000 person–years); and (iv) CKD stage 4/5 (n = 11 197) aRR: 1.84 (1.14–2.96), aRD: 7.9/1000 person–years (15.3 vs. 7.4/1000 person–years). While there was no evidence of increase in the aRR (P = 0.922), there was strong evidence that the aRD increased as kidney function deteriorated (P = 0.001).

Conclusions

While the relative risk was constant, the excess risk of GI bleeding associated with SSRIs markedly increased among patients with decreased kidney function.

Predicting the atopic march: Results from the Canadian Healthy Infant Longitudinal Development Study

BACKGROUND

The atopic march describes the progression from atopic dermatitis during infancy to asthma and allergic rhinitis in later childhood. In a Canadian birth cohort we investigated whether concomitant allergic sensitization enhances subsequent development of these allergic diseases at age 3 years.

METHODS

Children completed skin prick testing at age 1 year. Children were considered sensitized if they produced a wheal 2 mm or larger than that elicited by the negative control to any of 10 inhalant or food allergens. Children were also assessed for atopic dermatitis by using the diagnostic criteria of the UK Working Party. At age 3 years, children were assessed for asthma, allergic rhinitis, food allergy, and atopic dermatitis. Data from 2311 children were available.

RESULTS

Atopic dermatitis without allergic sensitization was not associated with an increased risk of asthma at age 3 years after adjusting for common confounders (relative risk [RR], 0.46; 95% CI, 0.11-1.93). Conversely, atopic dermatitis with allergic sensitization increased the risk of asthma more than 7-fold (RR, 7.04; 95% CI, 4.13-11.99). Atopic dermatitis and allergic sensitization had significant interactions on both the additive (relative excess risk due to interaction, 5.06; 95% CI, 1.33-11.04) and multiplicative (ratio of RRs, 5.80; 95% CI, 1.20-27.83) scales in association with asthma risk. There was also a positive additive interaction between atopic dermatitis and allergic sensitization in their effects on food allergy risk (relative excess risk due to interaction, 15.11; 95% CI, 4.19-35.36).

CONCLUSIONS

Atopic dermatitis without concomitant allergic sensitization was not associated with an increased risk of asthma. In combination, atopic dermatitis and allergic sensitization had strong interactive effects on both asthma and food allergy risk at age 3 years.

Additivity vs Synergism: Investigation of the Additive Interaction of Cinnamon Bark Oil and Meropenem in Combinatory Therapy

Combinatory therapies have been commonly applied in the clinical setting to tackle multi-drug resistant bacterial infections and these have frequently proven to be effective. Specifically, combinatory therapies resulting in synergistic interactions between antibiotics and adjuvant have been the main focus due to their effectiveness, sidelining the effects of additivity, which also lowers the minimal effective dosage of either antimicrobial agent. Thus, this study was undertaken to look at the effects of additivity between essential oils and antibiotic, via the use of cinnamon bark essential oil (CBO) and meropenem as a model for additivity. Comparisons between synergistic and additive interaction of CBO were performed in terms of the ability of CBO to disrupt bacterial membrane, via zeta potential measurement, outer membrane permeability assay and scanning electron microscopy. It has been found that the additivity interaction between CBO and meropenem showed similar membrane disruption ability when compared to those synergistic combinations which was previously reported. Hence, results based on our studies strongly suggest that additive interaction acts on a par with synergistic interaction. Therefore, further investigation in additive interaction between antibiotics and adjuvant should be performed for a more in depth understanding of the mechanism and the impacts of such interaction.

Additive Interaction of MTHFR C677T and MTRR A66G Polymorphisms with Being Overweight/Obesity on the Risk of Type 2 Diabetes

Although both methylenetetrahydrofolate reductase (MTHFR) C677T and methionine synthase reductase (MTRR) A66G polymorphisms have been associated with type 2 diabetes (T2D), their interactions with being overweight/obesity on T2D risk remain unclear. To evaluate the associations of the two polymorphisms with T2D and their interactions with being overweight/obesity on T2D risk, a case-control study of 180 T2D patients and 350 healthy controls was conducted in northern China. Additive interaction was estimated using relative excess risk due to interaction (RERI), attributable proportion due to interaction (AP) and synergy index (S). After adjustments for age and gender, borderline significant associations of the MTHFR C677T and MTRR A66G polymorphisms with T2D were observed under recessive (OR = 1.43, 95% CI: 0.98-2.10) and dominant (OR = 1.43, 95% CI: 1.00-2.06) models, respectively. There was a significant interaction between the MTHFR 677TT genotype and being overweight/obesity on T2D risk (AP = 0.404, 95% CI: 0.047-0.761), in addition to the MTRR 66AG/GG genotypes (RERI = 1.703, 95% CI: 0.401-3.004; AP = 0.528, 95% CI: 0.223-0.834). Our findings suggest that individuals with the MTHFR 677TT or MTRR 66AG/GG genotypes are more susceptible to the detrimental effect of being overweight/obesity on T2D. Further large-scale studies are still needed to confirm our findings.

Interactions between cigarette smoking and fine particulate matter in the Risk of Lung Cancer Mortality in Cancer Prevention Study II

The International Agency for Research on Cancer recently classified outdoor air pollution and airborne particulate matter as carcinogenic to humans. However, there are gaps in the epidemiologic literature, including assessment of possible joint effects of cigarette smoking and fine particulate matter (particulate matter less than or equal to 2.5 µm in diameter) on lung cancer risk. We present estimates of interaction on the additive scale between these risk factors from Cancer Prevention Study II, a large prospective US cohort study of nearly 1.2 million participants recruited in 1982. Estimates of the relative excess risk of lung cancer mortality due to interaction, the attributable proportion due to interaction, and the synergy index were 2.19 (95% confidence interval (CI): -0.10, 4.83), 0.14 (95% CI: 0.00, 0.25), and 1.17 (95% CI: 1.00, 1.37), respectively, using the 25th and 75th percentiles as cutpoints for fine particulate matter. This suggests small increases in lung cancer risk among persons with both exposures beyond what would be expected from the sum of the effects of the individual exposures alone. Although reductions in cigarette smoking will achieve the greatest impact on lung cancer rates, these results suggest that attempted reductions in lung cancer risk through both tobacco control and air quality management may exceed expectations based on reducing exposure to either risk factor alone.

Invited commentary: How big is that interaction (in my community)--and in which direction?

In an accompanying article, Turner et al. (Am J Epidemiol. 2014;180(12):1145-1149) compare the joint effects of smoking and air pollution to make inferences about the reduction in lung cancer mortality achieved when reducing each exposure separately and when reducing both together. In this commentary, we use first principles to quantify the difference between the risk or mortality reduction obtained from reducing each of 2 exposures together and the sum of the risk differences obtained from reducing the 2 exposures separately. Metrics of the impact of joint effects or comparisons of joint effects presented in units of absolute risk, such as Rothman's I, can provide more meaningful quantitative measures of public health impact than unitless metrics (e.g., ratios) and standardized metrics (e.g., the population attributable fraction) of potential interventions for reducing smoking and air pollution exposure. In particular, the venerable attributable community risk metric can provide an estimate of the community impact of such interventions in units of absolute risk. A spreadsheet we provide demonstrates the calculation of the various metrics for hypothetical data similar to those reported by Turner et al. Using algebra, graphics, and examples, we show that positive interaction, or synergy, on the additive scale implies that the impact on risk reduction from a program that applies both interventions will be lesser than the sum of the impacts of the separate interventions.

Psychological distress and academic self-perception among international medical students: the role of peer social support

BACKGROUND

Psychological distress among medical students is commonly observed during medical education and is generally related to poor academic self-perception. We evaluated the role of peer social support at medical schools in the association between psychological distress and academic self-perception.

METHODS

An online survey was conducted in a medical degree program for 138 international students educated in English in the Czech Republic. The Medical Student Well-Being Index was used to define the students' psychological distress. Perceived peer social support was investigated with the Multidimensional Scale of Perceived Social Support. Poor academic self-perception was defined as the lowest 30% of a subscale score of the Dundee Ready Education Environment Measure. Analyses evaluated the presence of additive interactions between psychological distress and peer social support on poor academic self-perception, adjusted for possible confounders.

RESULTS

Both psychological distress and low peer social support were negatively associated with poor academic self-perception, adjusted for local language proficiency and social support from family. Students with psychological distress and low peer social support had an odds ratio of 11.0 (95% confidence interval (CI): 2.1-56.6) for poor academic self-perception as compared with those without distress who had high peer social support. The presence of an additive interaction was confirmed in that the joint association was four times as large as what would have been expected to be on summing the individual risks of psychological distress and low peer social support (synergy index = 4.5, 95% CI: 1.3-14.9).

CONCLUSIONS

Psychological distress and low peer social support may synergistically increase the probability of poor academic self-perception among international medical students. Promoting peer social relationships at medical school may interrupt the vicious cycle of psychological distress and poor academic performance.

Renin angiotensin system inhibitors may attenuate low LDL cholesterol-related cancer risk in type 2 diabetes

BACKGROUND

In type 2 diabetes (T2D), copresence of low-density lipoprotein cholesterol (LDL-C) < 2.8 mmol/L with triglyceride < 1.7 mmol/L or with albuminuria synergistically increased cancer risk. We tested whether use of renin angiotensin system inhibitors attenuated the increased cancer risk associated with these two risk subphenotypes.

METHODS

A prospective cohort of 4307 patients with T2D enrolled from December 1996 to January 2005 was analysed using a new user cohort design. Cox model analysis was used to obtain hazard ratios and 95% confidence intervals. The study measured additive interactions between nonuse of renin angiotensin system inhibitors and low LDL-C plus low triglyceride or albuminuria for the risk of cancer. A positive interaction suggests a specific drug effect on the low LDL-C-related cancer risk.

RESULTS

During 18 769 person years of follow-up (median follow-up years: 4.44), 4.48% (n = 193) of patients developed cancer. Use of renin angiotensin system inhibitors was associated with reduced cancer risk among patients with copresence of low LDL-C plus low triglyceride or low LDL-C plus albuminuria but not in patients without these subphenotypes. In multivariable analysis, renin angiotensin system inhibitor usage attenuated the hazard ratio of copresence of low LDL-C plus low triglyceride versus lack of this subphenotype for cancer from 2.08 (95% CI: 1.25-3.47) to 1.13 (0.61-2.11) with significant additive interaction (p = 0.0225). Similarly, RAS inhibitor usage attenuated the hazard ratio of copresence of low LDL-C plus albuminuria versus lack of this subphenotype for cancer from 1.99 (95% CI: 1.12-3.56) to 0.82 (0.43-1.54) with significant additive interaction (p = 0.0009).

CONCLUSION

In T2D, renin angiotensin system inhibitor usage may specifically attenuate the low LDL-C-related cancer risk.

Invited commentary: Some advantages of the relative excess risk due to interaction (RERI)--towards better estimators of additive interaction

In the accompanying commentary, Rose and van der Laan (Am J Epidemiol. 2014;179(6):663-669) criticize the relative excess risk due to interaction (RERI) measure, the use of additive interaction, and the weighting approach we developed to assess RERI with case-control data. In this commentary, we note some of the advantages of using additive measures of interaction, such as RERI, in making decisions about targeting interventions toward certain subgroups and in assessing mechanistic interaction. We discuss the relationship between Rose and van der Laan's estimator for case-control data and the one we had previously proposed. We also develop a new doubly robust estimator for determining the RERI with case-control data when the prevalence or incidence of the outcome is known.

Effect modification of body mass index and body fat percentage on fatty liver disease in a Japanese population

BACKGROUND AND AIM

No previous study has performed multivariate analysis of the risk factors of fatty liver disease (FL), focusing on the effect of weight gain of ≥ 10 kg since the age of 20, and no analysis model exists that simultaneously evaluates body mass index (BMI) and body fat percentage (BFP) as adjustment variables.

METHODS

To investigate these, we collected anthropometric data from health checkups, and conducted a cross-sectional study (targeting 1851 males and 1259 females aged 30 years or over).

RESULTS

Regardless of sex, weight gain of ≥10 kg since the age of 20 was positively associated with FL. Our stratified analysis of BFP into two categories, to evaluate the interaction between BMI and BFP in FL, indicated an approximately fivefold increase in the odds ratio in the male group with high BMI and BFP values compared to those with low BMI and BFP values, with a synergy index of 1.77 > 1. On the other hand, females demonstrated no significant additive interaction, with a synergy index of 0.49 < 1.

CONCLUSIONS

We revealed that weight gain ≥ 10 kg since the age of 20 is significantly associated with FL regardless of sex. In addition, by performing a synergy index (S), we showed that the additive interaction between BMI and BFP in FL differs according to gender.

Association of low to moderate levels of arsenic exposure with risk of type 2 diabetes in Bangladesh

Chronic exposure to high levels of arsenic in drinking water is associated with increased risk of type 2 diabetes mellitus (T2DM), but the association between lower levels of arsenic and T2DM is more controversial. Therefore, this study evaluated the association between low to moderate arsenic exposure and T2DM. In 2009-2011, we conducted a study of 957 Bangladeshi adults who participated in a case-control study of skin lesions in 2001-2003. The odds ratio of T2DM was evaluated in relationship to arsenic exposure measured in drinking water and in subjects' toenails (in 2001-2003) prior to the diagnosis of T2DM (in 2009-2011). Compared with those exposed to the lowest quartile of arsenic in water (≤ 1.7 µg/L), the adjusted odds ratio for T2DM was 1.92 (95% confidence interval (CI): 0.82, 4.35) for those in the second quartile, 3.07 (95% CI: 1.38, 6.85) for those in the third quartile, and 4.51 (95% CI: 2.01, 10.09) for those in the fourth quartile. The relative excess risk of T2DM was 4.78 for individuals who smoked and 8.93 for people who had a body mass index (weight (kg)/height (m)(2)) greater than 25. These findings suggest that exposure to modest levels of arsenic in drinking water was associated with increased risk of T2DM in Bangladesh. Being overweight or smoking was also associated with increased risk of T2DM.

The interaction between ethanol and pregnanolone at induction of anaesthesia investigated with a threshold method in male rats

1. An anaesthesia threshold was used to investigate the pharmacodynamic and pharmacokinetic interactions between ethanol and pregnanolone in male rats. 2. The criterion to determine threshold doses of pregnanolone was the first burst suppression of 1 s in the EEG. 3. Ethanol (0.5, 1.0, 1.5 and 2.0 g kg(-1)) was injected i.p. 15 min before pregnanolone infusion. Trunk blood, serum, cortex, cerebellum, hippocampus, striatum, brain stem, fat and muscle tissues obtained at criterion were used to determine ethanol (blood) and pregnanolone. Ethanol reduced threshold doses in a dose dependent linear manner. A similar reduction of pregnanolone tissue concentrations was only found in brain stem and striatum. Deviations consisted of larger decreases in serum, cerebellum and hippocampus after 0.5 g kg(-1) ethanol and in cerebellum, cortex and hippocampus after 2.0 g kg(-1) of ethanol. Positive correlations between dose and concentration of pregnanolone was recorded in brain stem, hippocampus, cerebellum and cortex. A kinetic component influenced the concentration in cortex. There was a correlation between dose and serum concentration of pregnanolone only after ethanol. In the muscle 0.5 g kg(-1) ethanol had no influence on pregnanolone concentration. 4. The linear, additive pharmacodynamic interaction could involve the GABA ionophore. A pharmacokinetic interaction was found in cortex. The retained high uptake of pregnanolone in muscle (after 0.5 g kg(-1)) corresponded to losses in other tissues (including serum). The reduced uptake of pregnanolone in cerebellum, cortex and hippocampus (after 2.0 g kg(-1)) was not due to a corresponding change in serum concentration. It was probably due to a reduced blood flow.