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Environ Health ; 19(1): 46, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-32357874


BACKGROUND: The shape of the exposure-response curve describing the effects of air pollution on population health has crucial regulatory implications, and it is important in assessing causal impacts of hypothetical policies of air pollution reduction. METHODS: After having reformulated the problem of assessing the short-term impact of air pollution on health within the potential outcome approach to causal inference, we developed a method based on the generalized propensity score (GPS) to estimate the average dose-response function (aDRF) and quantify attributable deaths under different counterfactual scenarios of air pollution reduction. We applied the proposed approach to assess the impact of airborne particles with a diameter less than or equal to 10 µm (PM10) on deaths from natural, cardiovascular and respiratory causes in the city of Milan, Italy (2003-2006). RESULTS: As opposed to what is commonly assumed, the estimated aDRFs were not linear, being steeper for low-moderate values of exposure. In the case of natural mortality, the curve became flatter for higher levels; this behavior was less pronounced for cause-specific mortality. The effect was larger in days characterized by higher temperature. According to the curves, we estimated that a hypothetical intervention able to set the daily exposure levels exceeding 40 µg/m3 to exactly 40 would have avoided 1157 deaths (90%CI: 689, 1645) in the whole study period, 312 of which for respiratory causes and 771 for cardiovascular causes. These impacts were higher than those obtained previously from regression-based methods. CONCLUSION: This novel method based on the GPS allowed estimating the average dose-response function and calculating attributable deaths, without requiring strong assumptions about the shape of the relationship. Its potential as a tool for investigating effect modification by temperature and its use in other environmental epidemiology contexts deserve further investigation.

BMC Public Health ; 20(1): 616, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32366241


BACKGROUND: Men who have sex with men (MSM) globally have a high burden of curable sexually transmitted infections (STIs). MSM do not frequently receive rectal STI testing because of several barriers, such as not being out (disclosure of sexual behavior). We evaluate whether Chinese MSM select an STI test (rectal vs urethral) appropriate for their sexual behavior (insertive and/or receptive), and the interactions with being out. METHODS: This was a secondary analysis of data from a cross sectional MSM survey conducted at a multisite randomized controlled trial (RCT) (December 2018 to January 2019) around uptake of gonorrhea and chlamydia testing among Chinese MSM (N = 431). We collected socio demographics, relevant medical and sexual history, and disclosure of sexual behavior (outness). We estimated the decision to test and test choice, and the extent to which disclosure plays a role in decision making. RESULTS: Among 431 MSM, mean age was 28 years (SD = 7.10) and 65% were out to someone. MSM who indicated versatile sexual behavior and were out to someone had a 26.8% (95%CI = 6.1, 47.5) increased likelihood for selecting the rectal test vs the ure thral test, compared to those versatile and not out. Versatile MSM out to their health provider outside of the study context had a 29.4% (95%CI = 6.3, 52.6) greater likelihood for selecting the rectal STI test vs the urethral test, compared to versatile MSM not out to their health provider. CONCLUSIONS: Sexual behavior and outness may affect gonorrhea and chlamydia testing provision. Apart from clinicians, community based efforts may reduce stigma based barriers to testing.

Sex Transm Dis ; 47(6): 395-401, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32149952


BACKGROUND: Gonorrhea and chlamydia are common among Chinese men who have sex with men (MSM), but testing rates are low. We developed a pay-it-forward program where men receive a free gonorrhea/chlamydia test and can then donate toward future participants' tests. This study aims to investigate drivers of testing uptake and donation using a mixed methods approach. METHODS: We used a sequential explanatory design to explore drivers of testing uptake and donation unique to pay-it-forward through a quantitative cross-sectional survey and a qualitative thematic analysis of semistructured interviews. We collected data on sociodemographics and perceived benefits of pay-it-forward among men offered the pay-it-forward interventionand analyzed testing uptake and donations using descriptive statistics and logistic regression. We then conducted 30 semistructured interviews with men and coded interview data to identify themes. RESULTS: Three hundred and one MSM were offered pay-it-forward and 55% (165/301) received gonorrhea/chlamydia testing. Ninety-one percent (150 of 165) donated any amount with a mean of 58.31 ± 53.39 RMB (US $8.61 ± 7.88), or 39% of the standard price of gonorrhea/chlamydia testing. Getting tested was not associated with income, but donations were higher in the highest income bracket (adjusted odds ratio, 7.12; 95% confidence interval, 1.61-31.52). Fifty-eight percent (94 of 162) selected "more MSM can get tested," and 54% (88 of 162) selected "I can help someone else" as benefits of pay-it-forward. Qualitative themes for drivers of testing and donation included flexible pricing, generosity and reciprocity, and MSM community identity. CONCLUSIONS: Quantitative and qualitative results suggest that this pay-it-forward program may increase gonorrhea/chlamydia testing by reducing cost barriers, leveraging generosity and reciprocity, and mobilizing community altruism.

Infect Dis Poverty ; 8(1): 76, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31426869


BACKGROUND: Gonorrhea and chlamydia testing rates are poor among Chinese men who have sex with men (MSM). A quasi-experimental study suggested that a pay-it-forward strategy increased dual gonorrhea/chlamydia testing among MSM. Pay-it-forward offers an individual a gift (e.g., a free test) and then asks the same person if they would like to give a gift to another person. This article reports the protocol of a randomized controlled trial to evaluate dual gonorrhea/chlamydia test uptake and other outcomes among MSM in three arms - a pay-it-forward arm, a pay-what-you-want arm, and a standard of care arm. METHODS: Three hundred MSM will be recruited at three HIV testing sites in Guangzhou and Beijing. Testing sites include two hospital-based MSM sexually transmitted diseases clinics and one MSM community-based organization. Eligible participants will be born biologically male, aged 16 years or older, reporting previous anal sex with another man, having never participated in the pay-it-forward program, without previous gonorrhea and chlamydia testing in the past 12 months, and residing in China. Following a cluster randomized design, every cluster of ten participants will be randomly allocated into one of three arms: (1) a pay-it-forward arm in which men are offered free gonorrhea and chlamydia testing and then asked whether they would like to donate ("pay it forward") toward testing for future testers; (2) a pay-what-you-want arm in which men are offered free testing and told to decide how much to pay after receiving the test; (3) a standard of care arm in which men can pay the full price for dual gonorrhoea and chlamydia testing. The primary outcome is dual gonorrhoea/chlamydia testing as verified by administrative records. Secondary outcomes include incremental cost per test, incremental cost per diagnosis, community connectedness, and social cohesion. Primary outcome will be calculated for each arm using intention-to-treat and compared using one-sided 95% confidence intervals with a margin of 20% increase defined as superiority. DISCUSSION: This study will examine the pay-it-forward strategy in comparison to the standard of care in improving test uptake for gonorrhea and chlamydia. We will leverage the cluster randomized controlled trial to provide scientific evidence on the potential effect of pay-it-forward. Findings from this study will shed light on novel intervention methods for increasing preventive health service utilization and innovate ways to finance it among communities. TRIAL REGISTRATION:, NCT03741725 . Registered on 12 November 2018.

Infecções por Chlamydia/diagnóstico , Gonorreia/diagnóstico , Promoção da Saúde/métodos , Programas de Rastreamento/economia , Pessoa de Meia-Idade , Ensaios Clínicos Controlados Aleatórios como Assunto/métodos , Minorias Sexuais e de Gênero , Adolescente , Adulto , Idoso , Pequim , China , Análise por Conglomerados , Testes Diagnósticos de Rotina/economia , Homossexualidade Masculina , Humanos , Masculino , Adulto Jovem
J Am Stat Assoc ; 111(514): 510-525, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-28008210


Exploration of causal mechanisms is often important for researchers and policymakers to understand how an intervention works and how it can be improved. This task can be crucial in clustered encouragement designs (CED). Encouragement design studies arise frequently when the treatment cannot be enforced because of ethical or practical constrains and an encouragement intervention (information campaigns, incentives, etc) is conceived with the purpose of increasing the uptake of the treatment of interest. By design, encouragements always entail the complication of non-compliance. Encouragements can also give rise to a variety of mechanisms, particularly when encouragement is assigned at cluster level. Social interactions among units within the same cluster can result in spillover effects. Disentangling the effect of encouragement through spillover effects from that through the enhancement of the treatment would give better insight into the intervention and it could be compelling for planning the scaling-up phase of the program. Building on previous works on CEDs and non-compliance, we use the principal stratification framework to define stratum-specific causal effects, that is, effects for specific latent subpopulations, defined by the joint potential compliance statuses under both encouragement conditions. We show how the latter stratum-specific causal effects are related to the decomposition commonly used in the literature and provide flexible homogeneity assumptions under which an extrapolation across principal strata allows one to disentangle the effects. Estimation of causal estimands can be performed with Bayesian inferential methods using hierarchical models to account for clustering. We illustrate the proposed methodology by analyzing a cluster randomized experiment implemented in Zambia and designed to evaluate the impact on malaria prevalence of an agricultural loan program intended to increase the bed net coverage. Farmer households assigned to the program could take advantage of a deferred payment and a discount in the purchase of new bed nets. Our analysis shows a lack of evidence of an effect of the offering of the program to a cluster of households through spillover effects, that is through a greater bed net coverage in the neighborhood.