Effect of laboratory referencing on data analysis of community viral load in HIV positive MSM from 15 cities, China / 中华流行病学杂志

Objective To compare the community viral load (CVL) among MSM in 15 cities in China using standardized national reference sources.Methods The study analyzed the existing database of National Major Science and Technology Project of China.The database was established with serial random survey of MSM HIV CVL among MSM in 15 cities from 2013 to 2015.VL tests were conducted in 15 laboratories with different equipment and methods,including RT-PCR,nucleic acid sequence based amplification (NASBA),branched DNA testing (bDNA) and Abbott M2000 RealTime system (M2000).Based on proficiency test for 15 laboratories conducted by National HIV Reference Laboratory,VL test values detected with EasyQ,bDNA and M2000 were converted and standardized into resultant values of TaqMan 2.0.Software SPSS 17.0 was used to produce descriptive statistics for the dataset.Results From 2014 to 2015,the 15 testing sites were found to use a number of different viral load detection techniques.In 2014,the community viral load values were (2.38 ±1.47) and (2.99 ± 1.31) in 15 testing sites,while in 2015 these values were found to be (2.07± 1.34) and (2.72± 1.19).The measurement of community VL was done using standard benchmarks of ≤200 copies/ml,≤400 copies/ml and ≤1 000 copies/ml,that were used for reference for now.Conclusion It is necessary to use standard detection method to improve the comparability of annual results.Using a standardized rate of ≤400 copies/ml or ≤ 1 000 copies/ml for successful control of VL was found with high stability for the result comparison among different areas.

Comparison of different methods in dealing with HIV viral load data with diversified missing value mechanism on HIV positive MSM / 中华流行病学杂志

Objective To compare results of different methods in organizing HIV viral load (VL) data with missing values mechanism. Methods We used software SPSS 17.0 to simulate complete and missing data with different missing value mechanism from HIV viral loading data collected from MSM in 16 cities in China in 2013. Maximum Likelihood Methods Using the Expectation and Maximization Algorithm (EM), regressive method, mean imputation, delete method, and Markov Chain Monte Carlo (MCMC) were used to supplement missing data respectively. The results of different methods were compared according to distribution characteristics, accuracy and precision. Results HIV VL data could not be transferred into a normal distribution. All the methods showed good results in iterating data which is Missing Completely at Random Mechanism (MCAR). For the other types of missing data, regressive and MCMC methods were used to keep the main characteristic of the original data. The means of iterating database with different methods were all close to the original one. The EM, regressive method, mean imputation, and delete method under-estimate VL while MCMC overestimates it. Conclusion MCMC can be used as the main imputation method for HIV virus loading missing data. The iterated data can be used as a reference for mean HIV VL estimation among the investigated population.

Data distribution and transformation in population based sampling survey of viral load in HIV positive men who have sex with men in China / 中华流行病学杂志

Objective To understand the distribution of population viral load (PVL) data in HIV infected men who have sex with men (MSM), fit distribution function and explore the appropriate estimating parameter of PVL. Methods The detection limit of viral load (VL) was ≤ 50 copies/ml. Box-Cox transformation and normal distribution tests were used to describe the general distribution characteristics of the original and transformed data of PVL, then the stable distribution function was fitted with test of goodness of fit. Results The original PVL data fitted a skewed distribution with the variation coefficient of 622.24%, and had a multimodal distribution after Box-Cox transformation with optimal parameter (λ) of-0.11. The distribution of PVL data over the detection limit was skewed and heavy tailed when transformed by Box-Cox with optimal λ=0. By fitting the distribution function of the transformed data over the detection limit, it matched the stable distribution (SD) function (α=1.70, β=-1.00, γ=0.78, δ=4.03). Conclusions The original PVL data had some censored data below the detection limit, and the data over the detection limit had abnormal distribution with large degree of variation. When proportion of the censored data was large, it was inappropriate to use half-value of detection limit to replace the censored ones. The log-transformed data over the detection limit fitted the SD. The median (M) and inter-quartile ranger (IQR) of log-transformed data can be used to describe the centralized tendency and dispersion tendency of the data over the detection limit.

Development of HIV infection risk assessment tool for men who have sex with men based on Delphi method / 中华流行病学杂志

Objective To develop a HIV infection risk assessment tool for men who have sex with men (MSM) based on Delphi method.Methods After an exhaustive literature review,we used Delphi method to determine the specific items and relative risk scores of the assessment tool through two rounds of specialist consultation and overall consideration of the opinions and suggestions of 17 specialists.Results The positivity coefficient through first and second round specialist consultation was 100.0％ and 94.1％,respectively.The mean of authority coefficients (Cr) was 0.86.Kendall's W coefficient of the specialist consultation was 0.55 for the first round consultation (x2=84.426,P＜0.001) and 0.46 for the second round consultation (x2=65.734,P＜0.001),respectively,suggesting that the specialists had similar opinions.The final HIV infection risk assessment tool for MSM has 8 items.Conclusions The HIV infection risk assessment tool for MSM,developed under the Delphi method,can be used in the evaluation of HIV infection risk in MSM and individualized prevention and intervention.However,the reliability and validity of this risk assessment tool need to be further evaluated.

Effect of data missing on population based viral load survey in HIV infected men who have sex with men sampled in 16 large cities, China / 中华流行病学杂志

Objective To analyze the effect of missing data in population based viral load (PVL) survey in HIV infected men who have sex with men (MSM) sampled in 16 cities in China.Methods The database of 3 virus load sampling survey conducted consecutively in HIV infected MSM population in 16 large cities (Beijing,Shanghai,Nanjing,Hangzhou,Wuhan,Chongqing,Kunming,Xi' an,Guangzhou,Shenzhen,Narning,Urumuqi,Harbin,Changchun,Chengdu and Tianjin) during 2013-2015 was used.SPSS 17.0 software was used to describe distribution of the missing data and analyze associated factors.Results A total of 12 150 HIV infected MSM were randomly selected for the surveys,in whom,9 141 (75.2％) received virus load tests,while 3 009 (24.8％) received no virus load tests,whose virus load data missed.The virus load data missing rates in MSM with or without access to antiretroviral therapy (ART) were 11.5％ (765/6 675) and 39.4％ (2 060/5 223) respectively,and the virus load data missing rates were 21.9％ (1 866/8 523) and 28.4％ (959/3 374),respectively,in local residents and non-local residents (migrants).Conclusions The analysis indicated that the data missing occurred in the virus load survey in HIV infected MSM population.ART status and census registering status were the main influencing factors.Data missing could influence the accurate evaluation of community viral load (CVL) and population viral load (PVL) levels in HIV infected MSM in China.

Effect of laboratory referencing on data analysis of community viral load in HIV positive MSM from 15 cities, China / 中华流行病学杂志

Objective To compare the community viral load (CVL) among MSM in 15 cities in China using standardized national reference sources.Methods The study analyzed the existing database of National Major Science and Technology Project of China.The database was established with serial random survey of MSM HIV CVL among MSM in 15 cities from 2013 to 2015.VL tests were conducted in 15 laboratories with different equipment and methods,including RT-PCR,nucleic acid sequence based amplification (NASBA),branched DNA testing (bDNA) and Abbott M2000 RealTime system (M2000).Based on proficiency test for 15 laboratories conducted by National HIV Reference Laboratory,VL test values detected with EasyQ,bDNA and M2000 were converted and standardized into resultant values of TaqMan 2.0.Software SPSS 17.0 was used to produce descriptive statistics for the dataset.Results From 2014 to 2015,the 15 testing sites were found to use a number of different viral load detection techniques.In 2014,the community viral load values were (2.38 ±1.47) and (2.99 ± 1.31) in 15 testing sites,while in 2015 these values were found to be (2.07± 1.34) and (2.72± 1.19).The measurement of community VL was done using standard benchmarks of ≤200 copies/ml,≤400 copies/ml and ≤1 000 copies/ml,that were used for reference for now.Conclusion It is necessary to use standard detection method to improve the comparability of annual results.Using a standardized rate of ≤400 copies/ml or ≤ 1 000 copies/ml for successful control of VL was found with high stability for the result comparison among different areas.

Comparison of different methods in dealing with HIV viral load data with diversified missing value mechanism on HIV positive MSM / 中华流行病学杂志

Objective To compare results of different methods in organizing HIV viral load (VL) data with missing values mechanism. Methods We used software SPSS 17.0 to simulate complete and missing data with different missing value mechanism from HIV viral loading data collected from MSM in 16 cities in China in 2013. Maximum Likelihood Methods Using the Expectation and Maximization Algorithm (EM), regressive method, mean imputation, delete method, and Markov Chain Monte Carlo (MCMC) were used to supplement missing data respectively. The results of different methods were compared according to distribution characteristics, accuracy and precision. Results HIV VL data could not be transferred into a normal distribution. All the methods showed good results in iterating data which is Missing Completely at Random Mechanism (MCAR). For the other types of missing data, regressive and MCMC methods were used to keep the main characteristic of the original data. The means of iterating database with different methods were all close to the original one. The EM, regressive method, mean imputation, and delete method under-estimate VL while MCMC overestimates it. Conclusion MCMC can be used as the main imputation method for HIV virus loading missing data. The iterated data can be used as a reference for mean HIV VL estimation among the investigated population.

Data distribution and transformation in population based sampling survey of viral load in HIV positive men who have sex with men in China / 中华流行病学杂志

Objective To understand the distribution of population viral load (PVL) data in HIV infected men who have sex with men (MSM), fit distribution function and explore the appropriate estimating parameter of PVL. Methods The detection limit of viral load (VL) was ≤ 50 copies/ml. Box-Cox transformation and normal distribution tests were used to describe the general distribution characteristics of the original and transformed data of PVL, then the stable distribution function was fitted with test of goodness of fit. Results The original PVL data fitted a skewed distribution with the variation coefficient of 622.24%, and had a multimodal distribution after Box-Cox transformation with optimal parameter (λ) of-0.11. The distribution of PVL data over the detection limit was skewed and heavy tailed when transformed by Box-Cox with optimal λ=0. By fitting the distribution function of the transformed data over the detection limit, it matched the stable distribution (SD) function (α=1.70, β=-1.00, γ=0.78, δ=4.03). Conclusions The original PVL data had some censored data below the detection limit, and the data over the detection limit had abnormal distribution with large degree of variation. When proportion of the censored data was large, it was inappropriate to use half-value of detection limit to replace the censored ones. The log-transformed data over the detection limit fitted the SD. The median (M) and inter-quartile ranger (IQR) of log-transformed data can be used to describe the centralized tendency and dispersion tendency of the data over the detection limit.

Development of HIV infection risk assessment tool for men who have sex with men based on Delphi method / 中华流行病学杂志

Objective To develop a HIV infection risk assessment tool for men who have sex with men (MSM) based on Delphi method.Methods After an exhaustive literature review,we used Delphi method to determine the specific items and relative risk scores of the assessment tool through two rounds of specialist consultation and overall consideration of the opinions and suggestions of 17 specialists.Results The positivity coefficient through first and second round specialist consultation was 100.0％ and 94.1％,respectively.The mean of authority coefficients (Cr) was 0.86.Kendall's W coefficient of the specialist consultation was 0.55 for the first round consultation (x2=84.426,P＜0.001) and 0.46 for the second round consultation (x2=65.734,P＜0.001),respectively,suggesting that the specialists had similar opinions.The final HIV infection risk assessment tool for MSM has 8 items.Conclusions The HIV infection risk assessment tool for MSM,developed under the Delphi method,can be used in the evaluation of HIV infection risk in MSM and individualized prevention and intervention.However,the reliability and validity of this risk assessment tool need to be further evaluated.

Effect of data missing on population based viral load survey in HIV infected men who have sex with men sampled in 16 large cities, China / 中华流行病学杂志

Objective To analyze the effect of missing data in population based viral load (PVL) survey in HIV infected men who have sex with men (MSM) sampled in 16 cities in China.Methods The database of 3 virus load sampling survey conducted consecutively in HIV infected MSM population in 16 large cities (Beijing,Shanghai,Nanjing,Hangzhou,Wuhan,Chongqing,Kunming,Xi' an,Guangzhou,Shenzhen,Narning,Urumuqi,Harbin,Changchun,Chengdu and Tianjin) during 2013-2015 was used.SPSS 17.0 software was used to describe distribution of the missing data and analyze associated factors.Results A total of 12 150 HIV infected MSM were randomly selected for the surveys,in whom,9 141 (75.2％) received virus load tests,while 3 009 (24.8％) received no virus load tests,whose virus load data missed.The virus load data missing rates in MSM with or without access to antiretroviral therapy (ART) were 11.5％ (765/6 675) and 39.4％ (2 060/5 223) respectively,and the virus load data missing rates were 21.9％ (1 866/8 523) and 28.4％ (959/3 374),respectively,in local residents and non-local residents (migrants).Conclusions The analysis indicated that the data missing occurred in the virus load survey in HIV infected MSM population.ART status and census registering status were the main influencing factors.Data missing could influence the accurate evaluation of community viral load (CVL) and population viral load (PVL) levels in HIV infected MSM in China.