| Background Psoriasis is an inflammatory skin disease with a complex pathogenesis,and previous experimental studies have shown that environmental factors can significantly influence the recurrence and exacerbation of psoriasis.However,evidence from population studies on the effects of climate,air pollutants and greenness space on the recurrence and exacerbation of psoriasis remains insufficient,and the effects of air pollutants and greenness space on psoriasis and the pattern of effects remain unclear.The aim of this study was to analyse the exposure-response relationships between climate,air pollutants,greenness space and psoriasis outpatient visits in Guangzhou.This study aims to elucidate the environmental factors that trigger the recurrence and exacerbation of psoriasis,so as to provide a scientific basis for clinical guidance on the health management of psoriasis patients.Methods A time-series research design was used for this study.Data on outpatient visits for psoriasis in Guangzhou were collected through the outpatient visit data system of Guangdong Dermatology Hospital for the period 2016-1-1 to 2020-12-31,and variables collected included:gender,age,first diagnosis,visit time,and permanent address information.Patients with an outpatient first diagnosis of psoriasis(International Classification of Diseases 10th revision,ICD-10:L40)were included on the basis of the visit data set.Patients with 1.incomplete information,2.patients whose usual place of residence was not Guangzhou,and 3.patients who were prescribed medication only on a regular basis were excluded.Climate data were obtained from the Guangzhou National Meteorological Monitoring Station,air pollution data from the Guangzhou Station of the National Air Quality Control Centre,and greenness space data from the US National Geological Survey Global Satellite Data.Climate variables include:daily average values of air temperature,air pressure,relative humidity,and sunshine hours.Air pollutant variables include:daily average values of PM2.5,PM10,SO2,NO2,CO,O3.The variables for greenness space data are monthly averages of Fractional Vegetation Cover(FVC)satellite remote sensing data.The data analysis is divided into three stages.In the first step,descriptive analysis,seasonal decomposition and Spelman correlation analysis were used to explore the relationship between environmental factors and psoriasis outpatient visits.In the second step,the distributed lag nonlinear model was used to analyze the exposure-response relationship,lag effect and cumulative effect of climate,air pollution and green space on the number of psoriasis outpatients.After screening,the factors included in the climate model are average atmospheric temperature,average air pressure and average relative humidity,with a lag of 7 days.Included covariates include:long-term trends,days of the week,holidays.Using the adjusted relative risk degree(RR)as the reference index,the best model is determined according to the Akaike information criterion(AIC).In the air pollution model,the included factors were PM10,SO2 and NO2,and the lag days were 7 days.The included covariates include:average atmospheric temperature,average air pressure,average relative humidity,long-term trend,day of the week,holiday data.The third step is to use subgroup analysis to identify vulnerable groups.Through the stratification of sex,age and season,the effects of different levels of population under different environmental factors were compared.By grading NDVI and fitting different levels of pollutant factors into models,the modification effects of NDVI on psoriasis were further compared.The differences between layers were compared by I~2 test.Results(1)In this study,a total of 124158 patient data(average age 42±16.2years)and satellite data of climate,air pollutants and greenness space were collected from Guangdong Dermatology Hospital from 2016-1-1 to 2020-12-31.(2)The results showed that the environment of low temperature and low relative humidity was obviously dangerous to psoriasis,and the risk of outpatient visits at low temperature on the day of exposure was higher than that at high temperature,,and the proportion was 30.74%(RR=1.290,95%CI:22.82%～39.86%).The risk of outpatient visits in low humidity environment increased by 66.40%compared with high humidity environment(RR=1.577,95%CI:54.71%～79.38%),and had a similar effect after a lag of 4 days.However,the changes of temperature and relative humidity have no cumulative effect.The effect of air pressure on psoriasis outpatient service is lagging and has a cumulative effect.High air pressure will significantly increase the risk of psoriasis 5 and 6 days later,and the risk of outpatient visits increases by 14.45%(RR=1.007,95%CI:12.91%～16.08%)and 16.44%(RR=1.045,95%CI:12.35%～21.15%),respectively.After 7 days of accumulation,the risk of outpatient visits in high-pressure environment increased by 26.13%(RR=1.084,95%CI:18.78%～35.09%).(3)Exposure of air pollutants to high concentrations of PM10 and NO2 increased the risk of psoriasis clinics at lower concentrations by 31.27%(RR=1.199,95%CI:22.51%～41.06%)and 5.87%(RR=1.188,95%CI:11.65%～20.27%),respectively.The obvious trend for SO2 occurred in 1-day lag and 6-day lag(lag1/6).With the increase of SO2 concentration,the risk of psoriasis clinic decreased.The outpatient risk of psoriasis at a high concentration of SO2 was lower than that at a low concentration,with a ratio of 11.4%(RR=0.887,95%CI:6.28%～16.24%).After the establishment of multi-pollutant factor model analysis,it is found that there is an interaction among the three pollutants,and the common impact on psoriasis outpatient risk is different from that of a single pollutant.Specifically,RR significantly decreased after NO2 was included in the PM10 model,which was 0.969(95%CI:0.960-0.978).RR decreased significantly after PM10 and NO2 were included in SO2 model,which were 0.887(95%CI:0.839-0.938)and 0.782(95%CI:0.745-0.821)respectively.(4)In the subgroup analysis,we divided the years into cold and warm seasons,and the population was divided into groups by sex and age.It was found that the risk of environmental factors in cold season(May to October)was significantly higher than that in warm season(November to April),eespecially when the temperature,relative humidity and SO2 changed.The relative risk of temperature decrease in cold and warm seasons was 1.096(95%CI:1.027～1.169)vs 0.883(95%CI:0.766～1.017).The relative risk of humidity reduction was 0.981(95%CI:0.752～1.280)vs 0.351(95%CI:0.189～0.653)in cold and warm seasons and 1.104(95%CI:1.047～1.164)vs 0.858(95%CI:0.782～0.943)in warm and cold seasons,respectively.These results suggest the risk of psoriasis in cold season.For both sexes,there were no significant differences between men and women in their effects when facing changes in each climate and air pollution concentration in this study(differences were not statistically significant).However,among the different age groups,those aged 0-17 years were more sensitive to temperature change,RR=1.137(95%CI:1.009～1.281),while they were significantly more tolerant to atmospheric pressure change,RR=0.854(95%CI:0.766～0.952).Individuals over 60 years of age may be more sensitive to changes in RH,RR=1.086(95%CI:1.046～1.127),while tolerance to changes in NO2 and SO2 concentrations was greater than the rest of the population,RR=1.055(95%CI:1.030～1.082)and0.934(95%CI:0.847～1.031),respectively,with no significant differences in susceptibility to changes in PM10 concentrations across all age groups.(5)Finally,we found that green space had a significant modifying effect on the risk of outpatient visits among patients with psoriasis.Increasing concentrations of all three air pollutants showed a risk for psoriasis in the low vegetation cover zone,while interestingly none of the three pollutants showed such a risk in the high vegetation cover zone.The RR of increased PM10 concentrations on psoriasis was 1.005(95%CI:0.987-1.025)vs 1.038(95%CI:1.031-1.046)at high and low vegetation cover,respectively.The RR of increased SO2 concentrations on psoriasis was 0.859(95%CI:0.745-0.989)vs 1.091(95%CI:1.040-1.145)respectively.While the RR for increasing NO2 concentration was 1.006(95%CI:0.979-1.034)vs 1.109(95%CI:1.099-1.120)respectively.Discussion In our study,we found that the changes of temperature,humidity,PM10and NO2 significantly affect the risk of psoriasis outpatients in the short term,while the effect of air pressure change is long-term and cumulative.SO2 shows a protective effect on psoriasis,and the specific mechanism needs to be further studied.In addition,various pollutants may interact with each other to change the impact of a single pollutant on psoriasis.The risk of psoriasis caused by the changes of environmental factors in the cold season is significantly higher than that in the warm season,suggesting the importance of psoriasis protection in the cold season.In terms of vulnerable groups,there are no significant differences between men and women,and young and old people show their own susceptibility to different environmental factors.Greeness factor has a strong modification effect on psoriasis,which changes the influence trend of pollutants on psoriasis clinic.In general,this study investigated the effects of climate,pollutants and greeness on psoriasis outpatients,and analyzed the differences in different seasons and populations.At present,there are few studies on the pathogenesis of psoriasis caused by environmental factors.This study is of reference value to further explore the impact of environmental factors on psoriasis. |
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