Semiparametric Sensitivity Analysis: Unmeasured Confounding In Observational Studies

Establishing cause-effect relationships from observational data often relies on untestable assumptions. It is crucial to know whether, and to what extent, the conclusions drawn from non-experimental studies are robust to potential unmeasured confounding. In this paper, we focus on the average causal effect (ACE) as our target of inference. We generalize the sensitivity analysis approach developed by Robins et al. (2000), Franks et al. (2020) and Zhou and Yao (2023. We use semiparametric theory to derive the non-parametric efficient influence function of the ACE, for fixed sensitivity parameters. We use this influence function to construct a one-step bias-corrected estimator of the ACE. Our estimator depends on semiparametric models for the distribution of the observed data; importantly, these models do not impose any restrictions on the values of sensitivity analysis parameters. We establish sufficient conditions ensuring that our estimator has root-n asymptotics. We use our methodology to evaluate the causal effect of smoking during pregnancy on birth weight. We also evaluate the performance of estimation procedure in a simulation study

Dosage of Sulfadoxine–Pyrimethamine and Risk of Low Birth Weight in a Cohort of Zambian Pregnant Women in a Low Malaria Prevalence Region

In Lusaka, Zambia, where malaria prevalence is low, national guidelines continue to recommend that all pregnant women receive sulfadoxine–pyrimethamine (SP) for malaria prophylaxis monthly at every scheduled antenatal care visit after 16 weeks of gestation. Human immunodeficiency virus (HIV)–positive women should receive co-trimoxazole prophylaxis for HIV and not SP, but many still receive SP. We sought to determine whether increased dosage of SP is still associated with a reduced risk of low birth weight (LBW) in an area where malaria transmission is low. Our secondary objective was to determine whether any association between SP and LBW is modified by receipt of antiretroviral therapy (ART). We analyzed data routinely collected from a cohort of HIV-positive pregnant women with singleton births in Lusaka, Zambia, between February 2006 and December 2012. We used a log-Poisson model to estimate the risk of LBW by dosage of SP and to determine whether the association between SP and LBW varied by receipt of ART. Risk of LBW declined as the number of doses increased and appeared lowest among women who received three doses (adjusted risk ratio [ARR] = 0.78; 95% confidence interval [CI] = 0.64–0.95). In addition, women receiving combination ART had a higher risk of delivering an LBW infant compared with women receiving no treatment or prophylaxis (ARR = 1.18; 95% CI = 1.09–1.28), but this risk was attenuated among women who were receiving SP (risk ratio = 1.09; 95% CI = 0.99–1.21). SP was associated with a reduced risk of LBW in HIV-positive women, including those receiving ART, in a low malaria prevalence region

A retrospective study of HIV, antiretroviral therapy, and pregnancy-associated hypertension among women in Lusaka, Zambia

To investigate the association between HIV, antiretroviral therapy (ART), and pregnancy-associated hypertension (PAH) in an HIV-endemic setting

Predictors and outcomes of low birth weight in Lusaka, Zambia

To determine factors associated with low birth weight (LBW) in an urban Zambian cohort and investigate risk of adverse outcomes for LBW neonates

Prospective acceptability of digital phenotyping among pregnant and parenting people with opioid use disorder: A multisite qualitative study

BackgroundWhile medications for opioid use disorder (MOUD) effectively treat OUD during pregnancy and the postpartum period, poor treatment retention is common. Digital phenotyping, or passive sensing data captured from personal mobile devices, namely smartphones, provides an opportunity to understand behaviors, psychological states, and social influences contributing to perinatal MOUD non-retention. Given this novel area of investigation, we conducted a qualitative study to determine the acceptability of digital phenotyping among pregnant and parenting people with opioid use disorder (PPP-OUD).MethodsThis study was guided by the Theoretical Framework of Acceptability (TFA). Within a clinical trial testing a behavioral health intervention for PPP-OUD, we used purposeful criterion sampling to recruit 11 participants who delivered a child in the past 12  months and received OUD treatment during pregnancy or the postpartum period. Data were collected through phone interviews using a structured interview guide based on four TFA constructs (affective attitude, burden, ethicality, self-efficacy). We used framework analysis to code, chart, and identify key patterns within the data.ResultsParticipants generally expressed positive attitudes about digital phenotyping and high self-efficacy and low anticipated burden to participate in studies that collect smartphone-based passive sensing data. Nonetheless, concerns were noted related to data privacy/security and sharing location information. Differences in participant assessments of burden were related to length of time required and level of remuneration to participate in a study. Interviewees voiced broad support for participating in a digital phenotyping study with known/trusted individuals but expressed concerns about third-party data sharing and government monitoring.ConclusionDigital phenotyping methods were acceptable to PPP-OUD. Enhancements in acceptability include allowing participants to maintain control over which data are shared, limiting frequency of research contacts, aligning compensation with participant burden, and outlining data privacy/security protections on study materials

The impact of SARS-CoV-2 in dementia across Latin America : A call for an urgent regional plan and coordinated response

The SARS-CoV-2 global pandemic will disproportionately impact countries with weak economies and vulnerable populations including people with dementia. Latin American and Caribbean countries (LACs) are burdened with unstable economic development, fragile health systems, massive economic disparities, and a high prevalence of dementia. Here, we underscore the selective impact of SARS-CoV-2 on dementia among LACs, the specific strain on health systems devoted to dementia, and the subsequent effect of increasing inequalities among those with dementia in the region. Implementation of best practices for mitigation and containment faces particularly steep challenges in LACs. Based upon our consideration of these issues, we urgently call for a coordinated action plan, including the development of inexpensive mass testing and multilevel regional coordination for dementia care and related actions. Brain health diplomacy should lead to a shared and escalated response across the region, coordinating leadership, and triangulation between governments and international multilateral networks