Sexual Mixing in Shanghai Are Heterosexual Contac

Authors: M Giovanna Merli James Moody Joshua Mendelsohn Robin Gauthier

Publish Date: 2015/04/23

Volume: 52, Issue: 3, Pages: 919-942

PDF Link

Abstract

China’s HIV prevalence is low mainly concentrated among female sex workers FSWs their clients men who have sex with men and the stable partners of members of these highrisk groups We evaluate the contribution to the spread of HIV of China’s regime of heterosexual relations of the structure of heterosexual networks and of the attributes of key population groups with simulations driven by data from a crosssectional survey of egocentric sexual networks of the general population of Shanghai and from a concurrent respondentdriven sample of FSWs We find that the heterosexual network generated by our empirically calibrated simulations has low levels of partner change strong constraints on partner selection by age and education and a very small connected core mainly comprising FSWs and their clients and characterized by a fragile transmission structure This network has a small HIV epidemic potential but is compatible with the transmission of bacterial sexually transmitted infections STIs such as syphilis which are less susceptible to structural breaks in transmission of infection Our results suggest that policies that force commercial sex underground could have an adverse effect on the spread of HIV and other STIsCollection of the survey data analyzed here was undertaken by the first author in collaboration with Ersheng Gao and Xiaowen Tu at Fudan University School of Public Health and Anan Shen at the Shanghai Academy of Social Sciences The Shanghai Sexual Network Survey SSNS was funded by NICHD/NIDA Grant R21HD047521 supplemented by two smaller grants from NICHD Merli PI The Shanghai Womens Health Survey SWHS was funded by a Ford Foundation grant to Ersheng Gao The SSNS sample was designed in consultation with William Kalsbeek Data analyses were funded in part by NICHD Grants R01 HD068523 Merli PI and R01 HD075712 Moody PI We thank the seminar participants of the Center for Studies in Demography and Ecology at the University of Washington and of the Population Research Center at the University of Texas at Austin Ashton Verdery and two anonymous reviewers for constructive commentsThe samples of Shanghai registered residents and migrants were selected as random subsamples of Shanghai registered residents and migrants from a stratified multistage clusters sample screened by the Shanghai Statistical Bureau for the 2005 3 intercensal survey of the Shanghai populationThe design of the 3 sample produced a stratified twostage sample of persons where 963 neighborhood committees NCs consisting of 2000–5000 persons were selected as primary sampling units PSUs with probabilities proportional to their estimated number of residents and migrants Explicit stratification of NCs was done by the 19 districts/counties 18 urban districts and 1 rural county NC selection in the first stage was also implicitly stratified within each district/county by the estimated ratio of resident population to migrant population in sorting the NCs for probability proportional to size PPS systematic selection within each district/county Allocation of the 963 NCs among districts/county was proportionate to the population of the stratified subsample of NCs In the second sampling stage all persons and households were included within 2151 small groups SGs approximately 100 persons each that were chosen within each sample NC by unstratified simple random samplingThe subsamples of residents and migrants for the SSNS was selected from the 3 sample to yield a stratified fourstage sample of Shanghai residents and migrants aged 18–49 In Stage 1 for both subsamples 50 NCs were first subsampled from the 963 NCs selected for the 3 sample This was accomplished by simple random sampling without replacement within each of the following three groups of the 19 districts/counties used for the 3 sample central city inner suburbs and outer suburbs Allocation in the stratified subsample of NCs was proportionate In Stage 2 exactly two of the two or three SGs that were selected for the second stage of the 3 sample were retained for the SSNS subsample yielding 100 SGs subsampled Separate subsamples of 18 to 49yearold residents and migrants were then subsampled in the two remaining subsampling stages In Stage 3 for the resident subsample 12 registered households were recruited within each selected SG using a currently updated list of household addresses in the SG as the sampling frame In Stage 4 one 18 to 49yearold household resident was randomly chosen from among those living in each participating household using a conventional Kish table For the migrant subsample a similar procedure was used with five migrant households recruited per SG using a currently updated list of household addresses with at least one migrant presentAmong the 1200 Shanghai registered residents and 500 migrants identified in the samples participation rates were 56 for Shanghai registered residents and 61 for migrants 177 of Shanghai registered residents and 178 of migrants refused to be interviewed 14 and 12 did not participate because of failure to reach them and 31 and 3 did not participate for other reasons No reason was provided for nonparticipation for the remaining 97 and 52 of the samples To prevent unit nonresponse from affecting the size of the samples of Shanghai residents and migrants field substitution Chapman 1983 was used to compensate for unit nonresponse In the third sampling stage within each SG assigned and reserved samples of potential respondent households were selected according to random procedures Respondents drawn from the assigned samples who did not participate in the survey were replaced with respondents drawn from reserve samples Because substitution can easily be abused and the statistical integrity of the final sample can be compromised we developed and rigorously enforced strict rules for replacing assigned addresses for example establishing when to call what to say and do and how many attempts to make before substitution These were emphasized to both interviewers and supervisors at field training A comparison of basic demographic characteristics of initial nonrespondents with those of respondents drawn from reserve samples and of participating respondents initially assigned for recruitment revealed no significant difference with respect to age and gender This adjustment procedure yielded a total sample size adjusted for nonresponse of 1192 Shanghai registered residents and 496 migrants

Keywords: