Association Between Shift Work And Risk Of Lower Extremity Osteoarthritis

Osteoarthritis is a common disabling disease,involving cartilage,subchondral bone,synovium,ligaments,and surrounding muscles.Lower extremity joints(knee and hip joint)are the most common sites of osteoarthritis.According to the Global Burden of Disease Study 2016,osteoarthritis caused 16.28 million years lived with disability.In addition to causing serious burden of disease,osteoarthritis also caused high direct medical costs and indirect economic costs.Previous studies already showed that increasing age,female,obesity,strain,etc.were risk factors for osteoarthritis.Shift work,as a common labor mode among professional groups,referred to encompasses work time arrangements outside of conventional daytime hours.With the rapid development of our country’s secondary and tertiary industries,our country’s demand for shift work has increased year by year.Shift work could disrupt normal circadian rhythms,disrupt metabolic homeostasis and lead to metabolic diseases.In addition,some studies showed that circadian rhythm could regulate musculoskeletal homeostasis and function.Disruption of the circadian rhythm may cause musculoskeletal diseases.However,the impact of shift work on osteoarthritis is currently unclear.In this study,13365 retired workers in the Dongfeng-Tongji Cohort who completed the supplemental survey on osteoarthritis information in 2013 were enrolled as the participants.Demographic characteristics and history of osteoarthritis were collected with questionnaire.Physical examination checked the health of lower extremity joints.The objectives were:(1)To analyze the distribution and influence factors of lower extremity osteoarthritis among retired workers;(2)To analyze the association between shift work and risk of lower extremity osteoarthritis.This study was divided into the following two parts.Part 1:Distribution and influence factors of lower extremity osteoarthritis among retired workersObjective:To evaluate the distribution and influence factors of lower extremity osteoarthritis among retired workers.Methods:A total of 13365 retired workers in the Dongfeng-Tongji Cohort who completed the osteoarthritis survey in 2013 were enrolled in this study.Demographic characteristics,lifestyle,occupational history and history of lower extremity joints were collected through questionnaires.Height,weight and related information of lower extremity joints were measured by professional physicians.Body mass index(BMI)was calculated by weight(kg)/square height(m~2).According to World Health Organization BMI reference standard,the participants were divided into normal or low weight group(BMI<24 kg/m~2)and overweight and obesity group(BMI≥24 kg/m~2).The lower extremity osteoarthritis in this study included knee osteoarthritis and hip osteoarthritis.Participants who met both of the following criteria were diagnosed knee or hip osteoarthritis:(1)knee or hip pain or stiffness for at least 1 month during one year,or persistent pain for at least 1 week;(2)meeting the imaging diagnostic criteria for knee or hip osteoarthritis.Chi-square test was used to compare the prevalence of lower extremity osteoarthritis among groups of different characteristics.Logistic regression models were used to analyze the influence factors of lower extremity osteoarthritis.This study was approved by the ethics committee,and all the participants filled out the informed consent form.During the investigation,random inspections and data verification were conducted through the quality control system.Results:Finally,a total of 13365 participants were included in this study with a mean age of 64.7(standard deviation 8.2)years old.And there were 7337(54.9%)females among retired workers.The number(prevalence)of lower extremity osteoarthritis,knee osteoarthritis,and hip osteoarthritis were 946(7.1%),897(6.7%),and 92(0.7%),respectively.The prevalence of lower extremity osteoarthritis,knee osteoarthritis,and hip osteoarthritis in female(8.9%,8.6%,and 0.8%,respectively)were significantly higher than those in male(4.8%,4.5%,and 0.5%,respectively)(P<0.05).The prevalence of lower extremity osteoarthritis and knee osteoarthritis in male≥65 years old(5.3%and4.9%,respectively)were significantly higher than those in male<65 years old(3.9%and3.6%,respectively)(P<0.05).The prevalence of lower extremity osteoarthritis and knee osteoarthritis in female≥60 years old(10.8%and 10.4%,respectively)were significantly higher than those in female<60 years old(6.4%and 6.0%,respectively)(P<0.05).The prevalence of lower extremity osteoarthritis and knee osteoarthritis in overweight and obese participants(BMI≥24 kg/m~2)(8.6%and 8.2%,respectively)were significantly higher than those in people with normal or low weight(BMI<24 kg/m~2)(5.6%and 5.2%,respectively)(P<0.05).The prevalence of lower extremity osteoarthritis and knee osteoarthritis in drinking male(5.6%and 5.2%,respectively)were significantly higher than those in male who had never drink(3.9%and 3.6%,respectively)(P<0.05).There were no significant differences in the prevalence of lower extremity osteoarthritis,knee osteoarthritis,and hip osteoarthritis among different workload groups,different work posture groups,whether exposed to occupational chemicals groups,different working years groups,and whether early retirement groups(P>0.05).The results of multivariate logistic regression analysis showed that female(OR 2.72,95%CI 2.20-3.36),increasing age(OR 1.04,95%CI 1.03-1.05),increasing BMI(OR1.09,95%CI 1.06-1.11),and drinking(OR 1.34,95%CI 1.13-1.60)were risk factors for lower extremity osteoarthritis.Female(OR 2.80,95%CI 2.26-3.48),increasing age(OR1.04,95%CI 1.03-1.05),increasing BMI(OR 1.09,95%CI 1.07-1.11),and drinking(OR1.32,95%CI 1.11-1.59)were risk factors for knee osteoarthritis.Female(OR 2.48,95%CI 1.32-4.67)and increasing age(OR 1.05,95%CI 1.03-1.08)were risk factors for hip osteoarthritis.The results of multiple stepwise logistic regression analyses were similar.Conclusions:The prevalence of lower extremity osteoarthritis and knee osteoarthritis were higher in female,the elderly,overweight and obese people,and drinking male.The prevalence of hip osteoarthritis was higher in female than in male.Female,increasing age,increasing BMI,and drinking were risk factors for lower extremity osteoarthritis and knee osteoarthritis.Female,increasing age were risk factors for hip osteoarthritis.Part 2:Association between shift work and risk of lower extremity osteoarthritisObjective:To explore the relationship between shift work and risk of lower extremity osteoarthritis.Methods:The participants and diagnostic criteria for lower extremity osteoarthritis were the same as the first part.Shift work referred to engaging in regular rotation work outside of normal daytime working hours(8:00-17:00)for 1 year and above.There were two common types of shift work for the participants.Two-shifts were defined as workers alternately rotating between day work(08:00–20:00)and night work(20:00–8:00).And three-shifts were defined as workers alternately rotating at 08:00,16:00,and 00:00.Shift work duration referred to the number of years from the beginning of shift work to the end of shift work.The duration after leaving shift work referred to the number of years from leaving the shift position to retirement.The logistic regression models were used to analyze the relationship between shift work,shift work types,shift work duration and risk of lower extremity osteoarthritis.Further stratified analyses were carried out for sociodemographic characteristics,lifestyle and occupational factors.And the effect modification P values were calculated.After the participants were grouped according to the shift work duration,the logistic regression models were used in each group to analyze the association between the duration after leaving shift work and risk of lower extremity osteoarthritis.Results:Among the participants,there were 5332 shift workers with a mean age of63.7(standard deviation 8.2)years old.And there were 2947(55.3%)females among shift workers.Compared with daytime workers,the risks of lower extremity osteoarthritis,knee osteoarthritis,and hip osteoarthritis for shift workers were increased by 21%(OR 1.21,95%CI 1.06-1.40)and 16%(OR 1.16,95%CI 1.00-1.34),and 57%(OR 1.57,95%CI1.02-2.41).Occupational chemical exposure had an effect modification on the association between shift work and risk of lower extremity osteoarthritis(effect modification P=0.039).In the group with occupational chemical exposure,compared with daytime workers,the OR(95%CI)for lower extremity osteoarthritis among shift workers was1.50(1.13-1.99).In the group without occupational chemical exposure,compared with daytime workers,the OR(95%CI)for lower extremity osteoarthritis among shift workers was 1.13(0.96-1.33).Compared with daytime workers,the ORs(95%CIs)of two-shift and three-shift workers were 1.21(1.04-1.41),1.22(0.97-1.53)for lower extremity osteoarthritis,respectively.The ORs(95%CIs)of two-shift and three-shift workers were 1.18(1.01-1.38),1.09(0.86-1.39)for knee osteoarthritis,respectively.And the ORs(95%CIs)of two-shift and three-shift workers were 1.28(0.79-2.09),2.50(1.41-4.44)for hip osteoarthritis,respectively.Occupational chemical exposure had effect modification on the associations between shift work types and risks of lower extremity osteoarthritis and knee osteoarthritis(effect modification P<0.05).In the group with occupational chemicals exposure,compared with daytime work,three-shift work increased the risks of lower extremity osteoarthritis(OR 2.01,95%CI 1.35-3.00)and knee osteoarthritis(OR1.75,95%CI 1.15-2.67).In the group without occupational chemicals exposure,compared with daytime work,two-shift and three-shift work did not increase the risk of lower extremity osteoarthritis,and the ORs(95%CIs)were 1.19(0.99-1.41)and 0.97(0.73-1.30),respectively.And two-shift and three-shift work did not increase the risk of knee osteoarthritis,and the ORs(95%CIs)were 1.15(0.96-1.38)and 0.88(0.65-1.19),respectively.Work posture had an effect modification on the association between shift work types and risk of lower extremity osteoarthritis(effect modification P=0.034).In the standing posture group,compared with daytime work,two-shift work increased the risk of lower extremity osteoarthritis(OR 1.32,95%CI 1.07-1.64);in the bending,squatting or kneeling posture group,compared with daytime work,three-shift work increased the risk of lower extremity osteoarthritis(OR 2.08,95%CI 1.32-3.26).In the sitting posture group,compared with daytime work,two-shift and three-shift work did not increase the risk of lower extremity osteoarthritis.The ORs(95%CIs)were 1.07(0.80-1.43)and 0.97(0.60-1.57),respectively.Compared with daytime workers,the ORs(95%CIs)of shift work for 1-9 years and≥10 years were 1.14(0.94-1.39)and 1.26(1.07-1.48)for lower extremity osteoarthritis,respectively.And P value for trend was 0.006.Each 5-year increase in the duration of shift work was associated with a 4%increase in the risk of lower extremity osteoarthritis(OR 1.04,95%CI 1.01-1.08).There were also similar associations between shift work duration and risk of knee osteoarthritis.The results suggested that increasing the duration of shift work increased the risk of lower limb osteoarthritis.Among participants with 1-9 years shift work history,there was no statistically significant difference in the risk of lower extremity osteoarthritis in the group who left shift work for 1-14 years compared with daytime workers(OR 1.13,95%CI 0.88-1.45).Among participants with≥10 years shift work history,the risk of lower extremity osteoarthritis in the group who left shift work for 1-4 years and the group who left shift work for 5-14 years were still significantly higher than those in daytime workers.The ORs(95%CIs)were 1.26(1.04-1.54)and 1.39(1.06-1.83),respectively.There was no significant difference in the risk of lower extremity osteoarthritis in the group who left shift work for≥15 years and daytime workers(OR 1.18,95%CI 0.84-1.67).In each shift work duration group,the relationships between the duration after leaving shift work and risk of knee osteoarthritis were similarly related.The results suggested that leaving shift work can partially alleviate the risk of lower limb osteoarthritis.Conclusions:Shift work could increase the risks of lower extremity osteoarthritis,knee osteoarthritis,and hip osteoarthritis.There were exposure-response relationships between duration of shift work and risks of lower extremity osteoarthritis and knee osteoarthritis.Occupational chemical exposure and bad work postures could strengthen the effect of shift work on lower extremity osteoarthritis.Leaving shift work could reduce the impact of shift work on the risk of lower extremity osteoarthritis to a certain extent.As the duration of leaving shift work increased,the impact of shift work on the risk of lower extremity osteoarthritis gradually decreased.