Ecological Study Of The Relationship Between Solar Ultraviolet Radiation And Global RA Disease Burden

Objective:Rheumatoid arthritis(RA)is a chronic autoimmune inflammatory disease,which can lead to serious disease burden.There are many factors affecting RA,such as genetic factors,age and gender,obesity,smoking and drinking.Vitamin D deficiency is also considered to be a risk factor for RA.Some epidemiological studies support that vitamin D is one of the factors in the pathogenesis and progression of RA;some studies have not found a close relationship between vitamin D and RA.However,no matter whether it is supporting or negative research results,these studies are mostly the results of epidemiological investigations in some regions of some countries,and they have limitations in global representativeness and dose-response intervals.Therefore,it is necessary to study the relationship between vitamin D deficiency and RA on a global scale,so as to observe the impact of vitamin D on the disease burden of RA in different countries.This study takes the global distribution of solar ultraviolet erythema exposure as the main factor representing the vitamin D levels of various countries population,combined with the risk factors closely related to RA and the indicators of the socio-economic development level of each country,to carry out its impact on the burden of RA disease in 181 countries around the world.The ecological epidemiological study on the impact of gender and age-specific disease burden has clarified the impact of differences in the distribution of influencing factors such as ultraviolet erythema exposure on the disease burden of RA in various countries.Methods:1.Data source:Global Burden of Disease(GBD)datas of RA were downloaded from The Institute for Health Metrics and Evaluation(IHME)website of the University of Washington,which includes Disability Adjusted of Life(DALY),incidence,prevalence,Years Lived with Disability(YLD)and Years of Life Lost(YLL)of RA.The UV erythema exposure datas of various countries in 2004 were from the World Health Organization(WHO)website,and the global UV erythema exposure datas in 2015 were from NASA database website.The UV erythema exposure datas of National Aeronautics and Space Administration(NASA)were calculated by us.We obtained the datas of smoking rate,daily average grams of alcohol consumption and Body Mass Index(BMI)from WHO,as well as the datas of Human Development Index(HDI),annual per capita fish consumption,urbanization rate,and latitude of each country from United Nations Development Programme(UNDP),food and Agriculture Organization of the United Nations(FAO),World Bank and other websites.2.Statistical analysis:We took the country as the sample unit,and first carried out a normality test on the disease burden datas of 181 countrys,and performed a logarithmic transformation on the datas that did not meet the normality assumption.Secondly,we characterized the disease burden and related influencing factors obtained from 181 country,and compared the disease burden of RA by layering the exposure to ultraviolet erythema and BMI.Then bivariate correlation analysis was performed between vitamin D-related factors(exposure to ultraviolet erythema,latitude,annual per capita fish consumption and urbanization rate),RA-related risk factors(smoking,drinking and BMI)and socio-economic development index(HDI)and RA.Highly correlated influencing factors were included as independent variables of RA disease burden into multiple linear regression analysis.Finally,the statistically significant ultraviolet erythema exposure and BMI were obtained from the multiple linear regression analysis,and then the interaction analysis was performed.Results:1.In 2004,the UV erythema exposures in various countries were divided by quartiles.The average values of Q1?Q4 were 2.03±0.42 KJ/m~2,3.80±0.51 KJ/m~2,4.93±1.82 KJ/m~2and 5.60±0.75 KJ/m~2;the average values of Q1?Q4 in 2015 were1.30±0.28 KJ/m~2,2.7±0.41 KJ/m~2,3.62±0.15 KJ/m~2and 4.23±0.25 KJ/m~2.2.With the UV erythema exposure of Q1?Q4 group Increased,DALYs,incidence,prevalence and YLDs of each group showed a gradient decline in the Q1?Q4 group;YLLs showed a gradient increase on the contrary.3.Except for YLLs,the average values of DALYs,incidence,prevalence,and YLDs of RA in 2015 were higher than those of 2004.Per capita alcohol consumption per day,BMI,annual per capita fish consumption,and urbanization rate and the average value of HDI were also higher than in 2004,only the average value of ultraviolet erythema exposure and smoking rate were lower than in 2004.4.Correlation analysis between the burden of RA disease and the influencing factors in2004 and 2015 showed that UV erythema exposure,latitude,urbanization rate,daily per capita alcohol consumption in grams,BMI,HDI were mostly correlated with DALYs,incidence,prevalence,YLDs and YLLs.5.The results of multiple linear regression analysis in 2004 showed that DALYs,incidence,prevalence,YLDs and YLLs were all significantly different from those of UVB exposure,smoking rate and sex;prevalence,YLDs and YLLs were also significantly different from BMI.DALYs,incidence,prevalence,YLDs and YLLs in 2015 were also statistically significant with ultraviolet erythema exposure,smoking rate and gender;incidence,prevalence and YLDs were also statistically significant with BMI.6.In 2004 and 2015,the average value of YLLs in women was nearly twice as high as that of men;DALYs,incidence and prevalence were more than two times higher in women than in men,while YLDs were more than three times higher in women than men.In terms of influencing factors,in addition to the significant decrease in UV erythema exposure and a slight decrease in smoking rate and daily per capita consumption of alcohol,urbanization rate,BMI,HDI and annual per capita consumption of fish in 2015 were higher than those in 2004.7.Analysis of the correlation between the burden of RA disease and the influencing factors in 2004 and2015 showed that they were mainly related to ultraviolet erythema exposure,smoking rate,daily per capita alcohol consumption in grams,BMI and HDI in males,and were mainly related to ultraviolet erythema exposure,latitude,urbanization rate,BMI and HDI in females.8.Multiple linear regression analysis showed that smoking rate,BMI and UV erythema exposure were the influencing factors of disease burden of RA in men in 2004and 2015,while only UV erythema exposure and BMI were found in women.9.There was no interaction between UV erythema exposure and BMI in 2004 and 2015 on the burden of RA disease in men,however,there was an interaction effect on the incidence and YLDs of RA in women.The contribution of the interaction to the incidence and YLDs of RA was 0.048*(UV*BMI)?0.058*(UV*BMI)and 0.068*(UV*BMI)?0.083*(UV*BMI),respectively.10.In 2004 and 2015,both the higher and lower ultraviolet erythema exposure groups and the higher and lower BMI groups,the age-specific peaks of DALYs and YLLs appeared in the age group 75-79.The peak incidence of lower ultraviolet erythema exposure group and higher BMI group were 5years old earlier than their counterparts of the same factors,and women were 5 years old earlier than men.The peaks prevalence of two factors were the same,women than men over 5 years old earlier.YLDs peak level there was no difference in ultraviolet erythema exposure between higher and lower groups,and women were 5 years old earlier than men;the higher BMI group in men was 5 years old earlier than the lower BMI group,while the for women was same in both group.The peaks in age-specific of RA disease burden in2004 and 2015 have the same basic trend.11.We compared the age-specific disease burden of RA between the higher and lower ultraviolet erythema exposure groups and the same BMI groups in 2004 and 2015.The results showed that incidence,prevalence,and YLDs of the lower ultraviolet erythema exposure group for most of the age groups of men reached the same level of the higher ultraviolet erythema exposure group over 5years old earlier,and the three indicators of women were in the lower ultraviolet erythema exposure group for most age groups 5-10 years old earlier than the high UV exposure group.In most age groups,the genders in the high BMI group of the above indicators also reached 5 years old earlier than the lower BMI group.The change trend of YLLs was opposite to the above indicators.12.For men,the distribution of the unstandardized regression coefficient B of ultraviolet erythema exposure and BMI in age-specific disease burden in 2004 and 2015 showed that DALYs 50 years old,the incidence 46 years old,and the prevalence and YLDs 60 were as the boundary,after these ages the exposure to ultraviolet erythema was statistically significant,and before it was statistically significant with BMI.The non-standardized regression coefficient B of ultraviolet erythema exposure and BMI in female showed that it was statistically significant that ultraviolet erythema exposure covers most of the age groups,BMI was mostly statistically significant in the 15-69 age group.13.The standard regression coefficient Beta absolute value of UV erythema exposure age-specific in males increased with age only in the elderly;Beta absolute value of BMI decreased with age.Beta absolute value of ultraviolet erythema exposure in women increased first and decreased slightly in old age;BMI Beta absolute value also decreased with increasing age in absolute value.14.The contribution of exposure to ultraviolet erythema to the reduction of the incidence of RA was 8.6%in men;8.0%-13.2%in women.The contribution of BMI to the increase in the incidence of RA was 3.4%-4.4%in women.Conclusion:1.The disease burden of RA in women is about 2-3 times higher than that in men.2.Global ultraviolet erythema exposure is negatively correlated with DALYs,incidence,prevalence,and YLDs of RA in various countries.3.Ultraviolet erythema exposure and BMI are the main factors influencing the differences in the burden of RA in different countries.4.Ultraviolet erythema exposure and BMI have antagonistic interactions on the burden of RA disease.5.The incidence of both sexes in the low ultraviolet erythema exposure group and the high BMI group reached the incidence level of the high ultraviolet erythema exposure group and the low BMI group by 5 or 10 years old earlier,and the peak age of onset was 5 years old earlier.6.Male BMI has a significant impact on the disease burden of RA in the young and middle ages,while the ultraviolet erythema exposure has a more prominent impact in the middle-aged age;basically,the two factors run through most age groups in women.