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The main goal of this paper is to suggest a combination of data analyses -- notably generalized additive models, time-series clustering methodology, visual methods for significance testing and qualitative analyses -- that relate to Complex Dynamic Systems Theory (CDST). To this end, we report on findings from a larger project conducted in a bilingual (pre)primary school in Switzerland, aiming to elucidate the complex ways that L2 English development emerges over time in 45 children who received German/English bilingual instruction over a period of eight years (age 5-12) in combination with emerging extracurricular exposure to English. The results reveal that increased extracurricular activities in English are particularly noticeable during periods of rapid development, but the effects seem temporally limited to the end stages of testing and strongly hinge on the cluster in question (i.e., learners with trajectorial similarities). We relate the findings to the "authenticity gap" between English inside and outside of school, as clusters who perceive a discrepancy between in- and out-of-school encounters with English also show rapid development that is characterized by increased English exposure during extracurricular activities. Methodological implications of adopting non-linear models, which can model complex dynamic relationships in order to better reconcile generalizability, variability, and individuality, are discussed.

This study is the first to explore microdevelopment in sociolinguistic evaluative judgments of standard German and Austro-Bavarian dialect by adult second language learners of German by using dense time serial measurements. Intensive longitudinal data (10 observations per participant) were collected from four learners at approximately weekly intervals over 3 months. We employed generalized additive models with superimposed periods of significant change to identify rapid developmental phases in individual developmental trajectories. By triangulating these models with qualitative introspective and retrodictive interview data, we identified environmental and psychological stimuli for change. Learners evinced increasing and decreasing periods of significant change, independent of length of residence. Dynamic constellations of identity- and agency-related variables alongside more intensive social interaction with target-variety speakers contributed to significant changes. We discuss findings from a complexity perspective and advocate for microlongitudinal studies in variationist second language acquisition to better capture stimuli for change in learners' emerging multivarietal repertoires.

BackgroundThe HIV epidemic disproportionately impacts transgender women in the United States. Cohort studies identify unique risks for affected populations, but use of facility-based methods may bias findings towards individuals living in research catchment areas, more engaged in health services, or, in the case of transgender populations, those who are open about their transgender identity. Digital clinical trials and other online research methods are increasingly common, providing opportunity to reach those not commonly engaged in research. Simultaneously, there is a need to understand potential biases associated with digital research, how these methods perform, and whether they are accepted across populations. ObjectiveThis study aims to assess the feasibility of developing and implementing an online cohort of transgender women to assess risks for HIV acquisition and other health experiences. Further, this study aims to evaluate how an online cohort compares to a site-based, technology-enhanced cohort for epidemiologic research. The overarching goal is to estimate incidence of HIV and other health outcomes among transgender women in eastern and southern United States. MethodsThis substudy is part of a larger multisite prospective cohort (LITE) conducted among transgender women, which also includes a site-based, technology-enhanced cohort in 6 eastern and southern US cities. The online cohort was launched to enroll and follow participants across 72 cities in the same region and with similar demographic characteristics as the site-based cohort. Participants are followed for 24 months. Adult transgender women are recruited via convenience sampling (eg, peer referrals, social media, and dating apps). Participants reporting negative or unknown HIV status are enrolled in a baseline study visit, complete a sociobehavioral survey, and provide oral fluid specimens to test for HIV. Participants not living with HIV (lab-confirmed) at baseline are offered enrollment into the cohort; follow-up assessments occur every 6 months. ResultsEnrollment into the online cohort launched in January 2019. Active recruitment stopped in May 2019, and enrollment officially closed in August 2020. A total of 580 participants enrolled into and are followed in the cohort. A recruitment-enrollment cascade was observed across screening, consent, and completion of study activities. Implementation experiences with HIV test kits highlight the need for heavy staff engagement to support participant engagement, visit completion, and retention, even with automated digital procedures. ConclusionsThis study is responsive to increasing research interest in digital observational and intervention research, particularly for populations who are most affected by the HIV epidemic and for those who may otherwise not participate in person. The progression across stages of the recruitment-enrollment cascade provides useful insight for implementation of cohort studies in the online environment. International Registered Report Identifier (IRRID)DERR1-10.2196/29152

BackgroundThe US National HIV/AIDS Strategy 2020 calls for increasing access to care, improving outcomes of people living with HIV, and targeting biomedical prevention efforts, including access to pre-exposure prophylaxis (PrEP) in communities where HIV is most heavily concentrated. The cities of Baltimore, Maryland (MD); Washington, DC; and Philadelphia, Pennsylvania (PA) are disproportionately burdened by high rates of new cases of HIV infection, with high prevalence among young Black and Latinx men who have sex with men (YBLMSM) and young Black and Latinx transgender women (YBLTW) aged 15-24 years. ObjectiveThis study aims (1) to identify and recruit YBLMSM and YBLTW who are at risk or living with HIV in Baltimore, MD; Philadelphia, PA; and Washington, DC, using respondent-driven sampling (RDS) with targeted seed selection, and (2) to assess the efficacy of a coach-based mobile-enhanced intervention (MEI) compared with standard of care (SOC) to increase successful engagement and retention into HIV, PrEP, and substance use treatment care across the HIV care and prevention continua in 3 Mid-Atlantic cities. This paper describes the protocol and progress as of October 20, 2019. MethodsThis study uses a multiphase mixed methods design. The first phase is a formative, qualitative research with focus group discussions and key informant interviews. The second phase consists of evaluating the ability of RDS with targeted seed selection. The third phase includes 2 embedded randomized controlled trials (RCTs), where participants complete a baseline sociobehavioral survey, rapid HIV testing, and eligible youth enroll in parallel status-dependent RCTs that randomize the participant to 1 of 2 study arms: MEI with coach or SOC. Participants are asked to complete a web-based survey and provide biologic specimens—HIV-1 RNA (viral load) or HIV-1 antibody test and urine drug screen—at baseline and at 3, 6, and 12 months, and an exit interview at 18 months. ResultsA formative qualitative research was conducted in February 2017 and May 2018, and this led to further refinement of recruitment and study methods. Aim 1 recruitment began in September 2017 with subsequent enrollment into the RCTs. Recruitment is ongoing with 520 participants screened and 402 (77.3%) enrolled in aim 1 by October 2020. Of these, 159 are enrolled in the 2 randomized trials: 36 (22.6%) HIV-positive not virally suppressed (aim 2) and 123 (77.4%) high-risk HIV-negative (aim 3). ConclusionsThis study has the potential to significantly impact the medical and substance use services provided to YBLMSM and YBLTW in the United States by providing rigorous scientific evidence outlining approaches and strategies that improve the uptake and engagement of YBLMSM and YBLTW in the HIV treatment and prevention continuum. Trial RegistrationClinicalTrials.gov NCT03194477; https://clinicaltrials.gov/ct2/show/NCT03194477 International Registered Report Identifier (IRRID)DERR1-10.2196/17269

BackgroundBlack and Latina transgender women (TW) experience a disparate burden of HIV and related comorbidities, including poor mental health and cardiovascular disease (CVD) risks. Pervasive multilevel stigma and discrimination operate as psychosocial stressors for TW living with HIV and shape health disparities for this population. Gender-affirming hormone therapy (GAHT) is commonly used by TW to facilitate alignment of the body with gender identity; in the context of stigma, GAHT may both improve mental health and increase CVD risks. ObjectiveThis study aims to quantify the longitudinal relationship between stigma and chronic stress among black and Latina TW living with HIV. Secondary objectives include identifying pathways linking chronic stress to HIV comorbidities and exploring chronic stress as a mediator in the pathway linking stigma and GAHT to CVD comorbidities. MethodsThis US-based mixed methods longitudinal study will enroll a prospective cohort of 200 black and Latina TW living with HIV, collecting quantitative survey data, qualitative interviews, and biomarkers of chronic stress. Interviewer-administered surveys will include validated psychosocial measures of self-reported stigma and discrimination, perceived stress, CVD risk factors, mental health, access to gender-affirming care, coping, and social support. Medical record abstraction will collect data on GAHT use, CD4 count, HIV viral load, antiretroviral therapy, treatment, and comorbid conditions. Clinical measures will include physiological biomarkers as well as salivary and blood-based biomarkers of chronic stress. Survey data will be collected every 6 months (baseline, and 6, 12, 18, and 24 months), and biospecimens will be collected at baseline and at 12 and 24 months. A purposive subsample (stratified by use of GAHT and presence of depressive symptoms) of 20 to 30 TW living with HIV will be invited to participate in in-depth interviews at 6 and 18 months to explore experiences of intersectional stigma, chronic stress, and the role of GAHT in their lives. ResultsThis study was funded by the National Institute on Minority Health and Health Disparities in December 2018. The study community advisory board and scientific advisors provided critical input on study design. Recruitment began in October 2019 (n=29 participants as of submission) and data collection will continue through 2022, with publication of baseline results anticipated summer 2021. ConclusionsThis study will focus on black and Latina TW living with HIV, an understudied health disparities population, advance both stigma and intersectionality research, and move chronic stress physiology research toward a more nuanced understanding of sex and gender. The comprehensive methodology will support the exploration of the role of exogenous estrogen in the pathways between stress and HIV comorbidities, elucidating the role of GAHT in the stress-health relationship. Finally, this study will provide longitudinal evidence of the impact of stigma-related chronic stress on the lives of black and Latina TW living with HIV integrating qualitative and quantitative data with psychosocial, clinical, and biological measures. International Registered Report Identifier (IRRID)DERR1-10.2196/17076

BackgroundPre-exposure prophylaxis (PrEP) is highly effective in the prevention of HIV acquisition, particularly for men who have sex with men (MSM). Questions remain on the benefits of PrEP and implementation strategies for those at occupational risk of HIV acquisition in sex work, as well as on methods to support adherence among young people who initiate PrEP. ObjectiveThe Combination Prevention Effectiveness study for young cisgender MSM and transgender women (TGW) aims to assess the effectiveness and cost-effectiveness of a combination intervention among HIV-uninfected young MSM and TGW engaged in sex work in Thailand. MethodsThis open-label, nonrandomized assessment compares the relative effectiveness of a combination prevention intervention with and without daily oral emtricitabine and tenofovir disoproxil fumarate (Truvada) PrEP with SMS-based adherence support. HIV-uninfected young MSM and TGW aged 18 to 26 years in Bangkok and Pattaya who self-report selling/exchanging sex at least once in the previous 12 months are recruited by convenience sampling and peer referral and are eligible regardless of their intent to initiate PrEP. At baseline, participants complete a standard assessment for PrEP eligibility and may initiate PrEP then or at any time during study participation. All participants complete a survey and HIV testing at baseline and every 3 months. Participants who initiate PrEP complete monthly pill pickups and may opt-in to SMS reminders. All participants are sent brief weekly SMS surveys to assess behavior with additional adherence questions for those who initiated PrEP. Adherence is defined as use of 4 or more pills within the last 7 days. The analytic plan uses a person-time approach to assess HIV incidence, comparing participant time on oral PrEP to participant time off oral PrEP for 12 to 24 months of follow-up, using a propensity score to control for confounders. Enrollment is based on the goal of observing 620 person-years (PY) on PrEP and 620 PY off PrEP. ResultsAs of February 2019, 445 participants (417 MSM and 28 TGW) have contributed approximately 168 PY with 95% (73/77) retention at 12 months. 74.2% (330/445) of enrolled participants initiated PrEP at baseline, contributing to 134 PY of PrEP adherence, 1 PY nonadherence, and 33 PY PrEP nonuse/noninitiation. Some social harms, predominantly related to unintentional participant disclosure of PrEP use and peer stigmatization of PrEP and HIV, have been identified. ConclusionsThe majority of cisgender MSM and TGW who exchange sex and participate in this study are interested in PrEP, report taking sufficient PrEP, and stay on PrEP, though additional efforts are needed to address community misinformation and stigma. This novel multilevel, open-label study design and person-time approach will allow evaluation of the effectiveness and cost-effectiveness of combination prevention intervention in the contexts of both organized sex work and exchanged sex. International Registered Report Identifier (IRRID)RR1-10.2196/15354

This cross-sectional study addresses for the first time the non/linear association between individual learner differences of social, proficiency-related, and socioaffective nature (length of residence [LoR], varietal proficiency, exposure, and socioaffect) and differential outcomes in L2 sociolinguistic repertoires against the backdrop of the Austro-Bavarian naturalistic context. Forty adult migrant L2 German learners participated in a virtual reality experiment involving interactions with dialect-speaking and standard German-speaking interlocutors. The goal was to explore differences in participants' interpersonal varietal behavior, that is, their addressee-relational variable use of standard German, Austro-Bavarian dialect, and mixture varieties. The results of Bayesian multinomial modeling indicated that LoR, dialect exposure, and proficiency, as well as reduced anxiety when speaking dialect, predicted differences in interpersonal varietal behavior. That said, a visual-quantitative analysis revealed critical thresholds concerning when, within these predictors, changes in sociolinguistic behavior manifested, indicating a rapid change in sociolinguistic development at the inter-individual level and ultimately facilitating initial insights as to how advanced one needs to be in order to engage in sociolinguistic variation in the Austro-Bavarian naturalistic context.

Abstract Gasdermin C is one of the least studied members of the gasdermin family of proteins, known for their critical involvement in pyroptosis and host defense. Furthermore, evidence for the role of Gasdermin C in the intestine is scarce and partly controversial. Here, we tested the functional role of Gasdermin C in intestinal homeostasis, inflammation and tumorigenesis. : We studied Gasdermin C in response to cytokines in intestinal organoids. We evaluated epithelial differentiation, cell death and immune infiltration under steady state conditions in a new mouse line deficient in Gasdermin C. The role of Gasdermin C was analyzed in acute colitis, infection and colitis-associated cancer. Gasdemin C is highly expressed in the intestinal epithelium and strongly induced by the type 2 cytokines IL-4 and IL-13 in a STAT6-dependent manner. Gasdermin C-deficient mice show no changes in tissue architecture and epithelial homeostasis. Epithelial organoids deficient in Gasdermin C develop normally and show no alterations in proliferation or cell death. No changes were found in models of acute colitis, type 2 intestinal infection and colitis-associated cancer. Gasdermin C genes are upregulated by type 2 immunity, yet appear dispensable for the development of intestinal inflammation, infection and colitis-associated cancer.

Abstract Age-related cognitive decline has become an increasingly relevant public health issue. However, risk and protective factors of cognitive decline have yet to be investigated prospectively taking into account genetic, lifestyle, physical and mental health factors. Population-based data from middle-aged (40 to 59 years; N = 2,764) and older individuals (60 to 80 years; N = 1,254) were drawn from a prospective community cohort study using the Tower of London (TOL) planning task. Assessments were repeated at a 5-year interval to investigate age-related changes in planning performance and to determine the impact of risk and protective factors. Planning performance improved in middle-aged, but declined in older participants over 5 years. SNPs affecting the dopamine system (COMT, DRD2) and APOE polymorphisms differentially predicted cognitive performance in older vs. middle-aged individuals. For older individuals, high alcohol consumption, antidepressant medication and living without a partner had additional negative predictive power on cognition. In contrast, undiagnosed hypertension, no obstructive lung disease, and fewer years of education predicted cognitive decline in the middle-aged group. The results inform screening for individuals particularly vulnerable to cognitive decline and interventions (e.g., focusing on lifestyle factors) to help maintain cognitive performance into old age.

Abstract Nerve tumors in the retroperitoneal space are a rarity. Radical surgery according to soft tissue tumors can lead to persistent pain and neurological deficits. This study aims to evaluate clinical outcomes of patients treated by a visceral- / neurosurgical approach. 33 patients with a retroperitoneal nerve tumor underwent surgery between 01/2002 and 12/2022 at our department. A visceral surgeon provided access to the retroperitoneal space, followed by micro-neurosurgical tumor preparation under neuromonitoring. Clinical examination and MRI were performed 12 weeks after surgery and further 3 months (WHO grade > 1) or 12 months (WHO grade 1). Further examinations were based on MRI findings and residual symptoms with median follow-up time of 24 months. One patient was treated for two distinct masses resulting in a total of 34 histological findings. Schwannomas (n = 15; 44.1%) and neurofibromas (n = 10; 29.4%) were the most common tumors. Long-term improvements were noted in radicular pain (15/18 patients; 83.3%), motor deficits (7/16 patients; 43.8%), abdominal discomfort and pain (5/7 patients; 71.4%). Recurrences were observed in 3/33 (9,1%) patients. This study represents the largest series of retroperitoneal BPNSTs treated with microsurgical techniques. Prospective multicenter studies are warranted to establish standardized treatment guidelines.

Abstract Background Allergic diseases are among the most common chronic diseases in childhood. Early childhood allergy prevention (ECAP) behaviors of those caring for the infant during pregnancy and the first months of life may influence the risk of allergy development over the life course. Motivation and intention to use appropriate primary ECAP measures are thus of critical importance. Aims To characterize parental ECAP motivation, (a) valid indicators will be developed and (b) typical parental characteristics will be identified. (c) According to socio-cognitive models, the predictive value of parental risk perception, control belief and self-efficacy for parental ECAP motivation shall be determined. Method A sample of N = 343 (expectant) mothers of infants completed a questionnaire on self-reported ECAP motivation, risk perception, control belief, and self-efficacy. The cross-sectional data were analyzed using latent class analysis and structural equation modelling including nominal regression models. Results Four typical maternal response profiles (motivated to a customary degree, 70%; motivated to use primary preventive measures, 17.8%; reluctant towards new prevention measures, 6.4%; highly motivated to apply preventive measures in case of an existing allergy, 5.8%) could be identified for the items on ECAP motivation. After splitting the model variables “risk perception” (allergy vs. allergy-associated general health problems) and “self-efficacy” (trust vs. insecurity) a satisfactory model-fit was achieved (CFI = .939; RMSEA = .064). Particularly, increased “risk perception-allergy” (OR = 1.655) and “self-efficacy-insecurity” (OR = 2.013) as well as lower “risk perception-general health” (OR = 0.555) and “control belief” (OR = 0.217), respectively, are associated with higher ECAP motivation. Conclusion The use of ECAP-measures by parents to protect their newborns from allergies is important, but there are deficiencies in their implementation. Based on a social cognitive model approach, predictive characteristics could be identified, which are associated with increased motivation to implement ECAP-measures. For public health our findings provide a promising basis for conception of behavioral and environmental ECAP prevention measures and their motivated implementation by parents.

Ischiomysis proincisa sp. nov. is described from a comparatively large, semi-dark marine cave in sublittoral waters off the small island Ilhéu das Rolas, directly south of São Tomé Island in the Gulf of Guinea. As striking features, the new species is distinguished from both its congeners by an anteriorly incised rostrum in both sexes and by two versus only one modified flagellate spine on the ischium of the eighth thoracic endopod in males. The new species is sympatric yet ecologically remote from the congener I. telmatactiphila, which is associated with the sea anemone Telmatactis cricoides in brighter habitats. New records and morphological notes are given for I. telmatactiphila and I. peterwirtzi. An updated definition of the genus Ischiomysis and a key to its three species are given.

Abstract Objectives To assess the prognostic value of cardiac MRI (CMR) parameters for the occurrence of major adverse cardiac events (MACE) in patients with infarct-like myocarditis. Methods In this retrospective single-center study, patients with CMR-confirmed acute myocarditis with infarct-like presentation were identified (2007–2020). Functional and structural parameters were analyzed including late gadolinium enhancement (LGE). The primary endpoint was the occurrence of MACE up to 5 years after discharge. Results In total, 130 patients (mean age, 40 ± 19 years; 97 men, 75%) with infarct-like myocarditis were included. CMR was conducted a median of 3 days (interquartile range [IQR], 1–5) after symptom onset. MACE occurred in 18/130 patients (14%) during a median follow-up of 19.3 months (IQR, 4.5–53). The median extent of LGE was 7% (IQR, 4–10). LGE affected the subepicardium in 111/130 patients (85%), the midwall in 45/130 patients (35%), and both the subepicardium and midwall in 27/130 patients (21%). Transmural extension of non-ischemic LGE lesions was observed in 15/130 patients (12%) and septal LGE in 42/130 patients (32%). In univariable Cox regression analysis, a significant association was found between the occurrence of MACE and both, quantified LGE extent and transmural LGE pattern. In multivariable analysis, transmural extension of LGE was an independent predictor for MACE (hazard ratio, 6.34; 95% confidence interval: 2.29–17.49; p

As an important source of sub-micrometer particles, atmospheric new particle formation (NPF) has been observed in various environments. However, most studies provide little more than snapshots of the NPF process due to their underlying observations being limited in space and time. To obtain statistically relevant evidence on NPF across various environments, we investigated the characteristics of NPF based on a 5-year dataset of the German Ultrafine Aerosol Network (GUAN). The results were also compared with observations in previous studies, with the aim to depict a relatively complete picture of NPF in central Europe. The highest NPF occurrence frequency was observed in regional background sites, with an average of about 19 %, followed by urban background (15 %), low-mountain-range (7 %), and high Alpine (3 %) sites. The annual mean growth rate between 10 and 25 nm varied from 3.7–4.7 nm h−1, while the formation rate with same size range 10–25 nm from 0.4 to 2.9 cm−3 s−1. The contribution of NPF to ultrafine particles (UFPs) was about 13 %, 21 %, and 7 % for the urban background, regional background, and low mountain range, respectively. The influence of NPF on cloud condensation nuclei (CCN) number concentration and the aerosol extinction coefficient for NPF days was the highest in mountainous areas. These findings underscore the importance of local environments when assessing the potential impact of NPF on regional climate in models, and they also emphasize the usefulness of a long-term aerosol measurement network for understanding the variation in NPF features and their influencing factors over a regional scale.

The present study takes a variationist perspective to explore the varietal repertoires of adult learners of German as a second language (L2), that is, their variable use of standard German, Austro-Bavarian dialect, and mixture varieties. Forty L2 learners completed a virtual reality task involving interactions with dialect-speaking and standard-German-speaking interlocutors. Using Bayesian multilevel modeling, the goal was to explore differential outcomes in the acquisition of sociolinguistic competence by determining whether participants adjusted their varietal behavior to match that of the interlocutor (i.e., varietal convergence). The results show that there were no interindividual addressee-dependent convergence tendencies. A holistic person-centered analysis of individual learners' intraspeaker variation revealed that only select L2 learners adjusted their usage patterns but did not entirely invert their usage of dialect and standard language as a function of the variety of the interlocutor. Introspective qualitative data speak to potential drivers behind the differential development of L2 (multi)varietal repertoires.

This study is the first to investigate subject-level variability in sociolinguistic evaluative judgements by 30 adult L2 German learners and explore whether the observed variability is characterizable as a function of individual differences in proficiency, exposure, and motivation. Because group-level estimates did not paint an accurate picture of the individual, we propose methods capable of integrating population-level estimates with person- and ensemble-centered approaches so as to reconcile generalizability and individuality. Using random effects from Bayesian mixed-effects models, we found that global subject-level variability in evaluative judgements was not predicted by individual differences. By building homogeneous ensembles (i.e., subgroups of individuals with similar evaluative judgements), however, it was possible to assess whether ensembles were characteristic of certain levels of individual differences. This ensemble-centered approach presents an innovative way to address the "group-to-individual generalizability" issue in cross-sectional data and transcend individual variability in order to make tentative generalizations of individual cases to wider populations.

BACKGROUND: Post-COVID-19 condition (also known as long COVID) is an emerging chronic illness potentially affecting millions of people. We aimed to evaluate whether outpatient COVID-19 treatment with metformin, ivermectin, or fluvoxamine soon after SARS-CoV-2 infection could reduce the risk of long COVID. METHODS: We conducted a decentralised, randomised, quadruple-blind, parallel-group, phase 3 trial (COVID-OUT) at six sites in the USA. We included adults aged 30-85 years with overweight or obesity who had COVID-19 symptoms for fewer than 7 days and a documented SARS-CoV-2 positive PCR or antigen test within 3 days before enrolment. Participants were randomly assigned via 2 × 3 parallel factorial randomisation (1:1:1:1:1:1) to receive metformin plus ivermectin, metformin plus fluvoxamine, metformin plus placebo, ivermectin plus placebo, fluvoxamine plus placebo, or placebo plus placebo. Participants, investigators, care providers, and outcomes assessors were masked to study group assignment. The primary outcome was severe COVID-19 by day 14, and those data have been published previously. Because the trial was delivered remotely nationwide, the a priori primary sample was a modified intention-to-treat sample, meaning that participants who did not receive any dose of study treatment were excluded. Long COVID diagnosis by a medical provider was a prespecified, long-term secondary outcome. This trial is complete and is registered with ClinicalTrials.gov, NCT04510194. FINDINGS: Between Dec 30, 2020, and Jan 28, 2022, 6602 people were assessed for eligibility and 1431 were enrolled and randomly assigned. Of 1323 participants who received a dose of study treatment and were included in the modified intention-to-treat population, 1126 consented for long-term follow-up and completed at least one survey after the assessment for long COVID at day 180 (564 received metformin and 562 received matched placebo; a subset of participants in the metformin vs placebo trial were also randomly assigned to receive ivermectin or fluvoxamine). 1074 (95%) of 1126 participants completed at least 9 months of follow-up. 632 (56·1%) of 1126 participants were female and 494 (43·9%) were male; 44 (7·0%) of 632 women were pregnant. The median age was 45 years (IQR 37-54) and median BMI was 29·8 kg/m2 (IQR 27·0-34·2). Overall, 93 (8·3%) of 1126 participants reported receipt of a long COVID diagnosis by day 300. The cumulative incidence of long COVID by day 300 was 6·3% (95% CI 4·2-8·2) in participants who received metformin and 10·4% (7·8-12·9) in those who received identical metformin placebo (hazard ratio [HR] 0·59, 95% CI 0·39-0·89; p=0·012). The metformin beneficial effect was consistent across prespecified subgroups. When metformin was started within 3 days of symptom onset, the HR was 0·37 (95% CI 0·15-0·95). There was no effect on cumulative incidence of long COVID with ivermectin (HR 0·99, 95% CI 0·59-1·64) or fluvoxamine (1·36, 0·78-2·34) compared with placebo. INTERPRETATION: Outpatient treatment with metformin reduced long COVID incidence by about 41%, with an absolute reduction of 4·1%, compared with placebo. Metformin has clinical benefits when used as outpatient treatment for COVID-19 and is globally available, low-cost, and safe. FUNDING: Parsemus Foundation; Rainwater Charitable Foundation; Fast Grants; UnitedHealth Group Foundation; National Institute of Diabetes, Digestive and Kidney Diseases; National Institutes of Health; and National Center for Advancing Translational Sciences.