Growth Mixture Model In The Motivation Of Oral Pre-exposure Prophylaxis Among Men Who Have Sex With Men

ObjectiveTo identify the latent class of protection motivation to oral PrEP among MSM with longitudinal PrEP use,and to analyze the development trend of the latent class,and to explore the relationship between the latent class and the compliance of PrEP,and to put forward the suggestions on enhancing the motivation and improving the compliance.It provides theoretical reference for subsequent PrEP research and the application of PrEP.MethodsMSM who participated in the clinical trial of oral PrEP to prevent HIV infection were recruited in four regions of western China(Xinjiang,Guangxi,Chongqing and Sichuan)by non-probability sampling method from April 2013 to October 2014.After the baseline survey,the eligible MSM were included clinical trial and they were randomly divided into the daily medication group,the before and after sex medication group and the blank control group.The protection motivation,adherence evaluation,and sexual behavior were followed up every 12 weeks.The subjects of this study were the daily medication group(one TDF taken orally every day).GMM with 1,2,3and 4 latent classes were estimated by linear estimation,second estimation and free estimation to explore the development trend and the number of latent class of PrEP motivation.Generalized estimating equations was uesd to explore the relationship between latent class and adherence to PrEP.Logistic regression was used to exploreeffect factors of latent class.Results1.A total of 338 MSM were included in the study.2.GMM of 2 latent classes estimated by free estimation had the minimum AIC,BIC and aBIC,and maximum Entropy(0.890),and was found to best fit the observed data.One of the 2 latent classes included 78.70% of MSM and was described as well protection motivation group that protection motivation was relatively high and increased slowly over time,the other included 21.30% of MSM and was described as descending protection motivation group that protection motivation was high at baseline but dropped rapidly after 12 weeks and increased slowly after 48 weeks.3.The average score of threat perception,response effectiveness,and self-efficacy reduced by 2,2,2 points respectively in descending protection motivation group,those points were respectively higher than 0,0,1 points in well protection motivation group,all P<0.05.The average score of response cost increased by 11 points in descending protection motivation group,this point was higher than-3point in well protection motivation group,all P<0.05.4.At the first follow-up 84.85% of MSM in descending protection motivation group thought the drug was difficult to swallow,71.21% thought the drug was uncomfortable,83.33% disliked the dosage form of the drug,60.61% of MSM felt the side effects of the drug and 59.09% felt the drug made them uncomfortable,which was higher than the 34.22%,38.22%,33.78%,33.33% and 32.00% in well protection motivation group.5.Multivariate logistic regression analysis showed that the average monthly income(3001~5000 yuan vs ≤1000 yuan,OR=2.890,95%CI=1.056~7.909;≥5001yuan vs ≤1000 yuan,OR=4.050,95%CI=1.364~12.02),and minority(OR=2.753,95%CI=1.18~6.425)were risk factors for descending protection motivation group.6.After adjusting for age,household registration,nationality,employment status,education level,marital status,average monthly personal income,knowledge of AIDS,in descending protection motivation group,the rate of missed medication inthe last 2 weeks at 12 weeks,24 weeks,36 weeks and 48 weeks were 93.94%,95.65%,91.55% and 94.20%,respectively,which were higher than 69.64%,73.46%,74.58%,and 74.45% in well protection motivation group,P<0.01.The rate of high medication adherence at 12 weeks,24 weeks and 36 weeks were 5.71%,8.70%,and 19.05%,in descending protection motivation group,respectively,which were lower than 40.38%,41.26% and 42.33% in well protection motivation group,P<0.01.7.The HIV infection rate was 6.94% after 60 weeks of follow-up in the descending protection motivation group,which was higher than 1.50% in descending protection motivation group.Conclusion1.There exists group heterogeneity in protection motivation change among MSM with longitudinal PrEP use.MSM can be divided into two potential subgroups:well protection motivation group and descending protection motivation group.2.There is a positive correlation between the motivation of PrEP and medication adherence,focusing on MSM with decreased motivation to protect after taking the drug3.In future PrEP studies among MSM,researhers should take measures to improve motivation of taking PrEP,and adherence and to increase the protective effect of PrEP,sunch as,improving objective factors of the drug(such as taste and dosage form),strengthening publicity and education on safety and effectiveness of PrEP.