Browsing by Author "Yiannoutsos, Constantin"
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Item A qualitative study of the barriers and enhancers to retention in care for pregnant and postpartum women living with HIV(Public Library of Science, 2021-10-13) Humphrey, John; Alera, Marsha; Kipchumba, Bett; Pfeiffer, Elizabeth J.; Songok, Julia; Mwangi, Winfred; Musick, Beverly; Yiannoutsos, Constantin; Wachira, Juddy; Wools-Kaloustian, Kara; Medicine, School of MedicineRetention in care is a major challenge for pregnant and postpartum women living with HIV (PPHIV) in the prevention of mother-to-child HIV transmission (PMTCT) continuum. However, the factors influencing retention from the perspectives of women who have become lost to follow-up (LTFU) are not well described. We explored these factors within an enhanced sub-cohort of the East Africa International Epidemiology Databases to Evaluate AIDS Consortium. From 2018-2019, a purposeful sample of PPHIV ≥18 years of age were recruited from five maternal and child health clinics providing integrated PMTCT services in Kenya. Women retained in care were recruited at the facility; women who had become LTFU (last visit >90 days) were recruited through community tracking. Interview transcripts were analyzed thematically using a social-ecological framework. Forty-one PPHIV were interviewed. The median age was 27 years, 71% were pregnant, and 39% had become LTFU. In the individual domain, prior PMTCT experience and desires to safeguard infants' health enhanced retention but were offset by perceived lack of value in PMTCT services following infants' immunizations. In the peer/family domain, male-partner financial and motivational support enhanced retention. In the community/society domain, some women perceived social pressure to attend clinic while others perceived pressure to utilize traditional birth attendants. In the healthcare environment, long queues and negative provider attitudes were prominent barriers. HIV-related stigma and fear of disclosure crossed multiple domains, particularly for LTFU women, and were driven by perceptions of HIV as a fatal disease and fear of partner abandonment and abuse. Both retained and LTFU women perceived that integrated HIV services increased the risk of disclosure. Retention was influenced by multiple factors for PPHIV. Stigma and fear of disclosure were prominent barriers for LTFU women. Multicomponent interventions and refining the structure and efficiency of PMTCT services may enhance retention for PPHIV.Item The Academic Model Providing Access To Healthcare (AMPATH) in Kenya(Global Livestock CRSP, UC Davis, 2008-11) Nyandiko, Winstone; Siika, Abraham; Ernst, Judith A.; Ettyang, Grace; Neumann, Charlotte; Yiannoutsos, ConstantinIn sub-Saharan Africa, an estimated 28 million people are living with the human immunodeficiency virus (HIV) and acquired immunodeficiency syndrome (AIDS). In 2001, Moi University in Eldoret, Kenya joined with Kenya’s second national referral hospital, Moi Teaching and Referral Hospital (MTRH) and Indiana University (IU) to establish the Academic Model Providing Access To Healthcare (AMPATH). AMPATH’s missions were to (1) provide high-quality patient care; (2) educate patients and health care providers; and (3) establish a laboratory for clinical research in HIV/AIDS (http://medicine.iupui.edu/kenya/hiv.aids.html). Leveraging the power of an academic medical partnership, AMPATH has quickly become one of the largest and most comprehensive HIV/AIDS control systems in sub-Saharan Africa, providing a comprehensive system of care that has been described as a model of sustainable development (Tobias, 2006). Delivery of services occurs in the public sector through hospitals and health centers run by Kenya’s Ministry of Health. AMPATH currently implements prevention activities that touch the lives of millions of persons in a wide geographic area. The research arm of AMPATH, created to facilitate and manage the international research agenda being generated by Kenyan and US faculty, includes the Global Livestock CRSP’s HIV Nutrition Project (HNP), “Increasing Animal Source Foods in Diets of HIV-infected Kenyan Women and Their Children,” which is a collaborative initiative between AMPATH and faculty from Moi University, Indiana University and the University of California, Los Angeles.Item Adjusting Mortality for Loss to Follow-Up: Analysis of Five ART Programmes in Sub-Saharan Africa(Public Library of Science, 2010-11-30) Brinkhof, Martin W. G.; Spycher, Ben D.; Yiannoutsos, Constantin; Weigel, Ralf; Wood, Robin; Messou, Eugène; Boulle, Andrew; Egger, Matthias; Sterne, Jonathan A. C.; Biostatistics, School of Public HealthEvaluation of antiretroviral treatment (ART) programmes in sub-Saharan Africa is difficult because many patients are lost to follow-up. Outcomes in these patients are generally unknown but studies tracing patients have shown mortality to be high. We adjusted programme-level mortality in the first year of antiretroviral treatment (ART) for excess mortality in patients lost to follow-up. Methods and Findings Treatment-naïve patients starting combination ART in five programmes in Côte d'Ivoire, Kenya, Malawi and South Africa were eligible. Patients whose last visit was at least nine months before the closure of the database were considered lost to follow-up. We filled missing survival times in these patients by multiple imputation, using estimates of mortality from studies that traced patients lost to follow-up. Data were analyzed using Weibull models, adjusting for age, sex, ART regimen, CD4 cell count, clinical stage and treatment programme. A total of 15,915 HIV-infected patients (median CD4 cell count 110 cells/µL, median age 35 years, 68% female) were included; 1,001 (6.3%) were known to have died and 1,285 (14.3%) were lost to follow-up in the first year of ART. Crude estimates of mortality at one year ranged from 5.7% (95% CI 4.9–6.5%) to 10.9% (9.6–12.4%) across the five programmes. Estimated mortality hazard ratios comparing patients lost to follow-up with those remaining in care ranged from 6 to 23. Adjusted estimates based on these hazard ratios ranged from 10.2% (8.9–11.6%) to 16.9% (15.0–19.1%), with relative increases in mortality ranging from 27% to 73% across programmes. Conclusions Naïve survival analysis ignoring excess mortality in patients lost to follow-up may greatly underestimate overall mortality, and bias ART programme evaluations. Adjusted mortality estimates can be obtained based on excess mortality rates in patients lost to follow-up.Item An Analysis of Survival Data when Hazards are not Proportional: Application to a Cancer Treatment Study(2021-12) White, John Benjamin; Yiannoutsos, Constantin; Bakoyannis, Giorgos; Fadel, WilliamThe crossing of Kaplan-Meier survival curves presents a challenge when conducting survival analysis studies, making it unclear whether any of the study groups involved present any significant difference in survival. An approach involving the determination of maximum vertical distance between the curves is considered here as a method to assess whether a survival advantage exists between different groups of patients. The method is illustrated on a dataset containing survival times of patients treated with two cancer treatment regimes, one involving treatment by chemotherapy alone, and the other by treatment with both chemotherapy and radiotherapy.Item Association of Health Status and Nicotine Consumption with SARS-CoV-2 positivity rates(BMC, 2021-10) Duszynski, Thomas J.; Fadel, William; Wools-Kaloustian, Kara K.; Dixon, Brian E.; Yiannoutsos, Constantin; Halverson, Paul K.; Menachemi, Nir; Epidemiology, School of Public HealthBACKGROUND: Much of what is known about COVID-19 risk factors comes from patients with serious symptoms who test positive. While risk factors for hospitalization or death include chronic conditions and smoking; less is known about how health status or nicotine consumption is associated with risk of SARS-CoV-2 infection among individuals who do not present clinically. METHODS: Two community-based population samples (including individuals randomly and nonrandomly selected for statewide testing, n = 8214) underwent SARS-CoV-2 testing in nonclinical settings. Each participant was tested for current (viral PCR) and past (antibody) infection in either April or June of 2020. Before testing, participants provided demographic information and self-reported health status and nicotine and tobacco behaviors (smoking, chewing, vaping/e-cigarettes). Using descriptive statistics and a bivariate logistic regression model, we examined the association between health status and use of tobacco or nicotine with SARS-CoV-2 positivity on either PCR or antibody tests. RESULTS: Compared to people with self-identified "excellent" or very good health status, those reporting "good" or "fair" health status had a higher risk of past or current infections. Positive smoking status was inversely associated with SARS-CoV-2 infection. Chewing tobacco was associated with infection and the use of vaping/e-cigarettes was not associated with infection. CONCLUSIONS: In a statewide, community-based population drawn for SARS-CoV-2 testing, we find that overall health status was associated with infection rates. Unlike in studies of COVID-19 patients, smoking status was inversely associated with SARS-CoV-2 positivity. More research is needed to further understand the nature of this relationship.Item Building Prediction Models for Dementia: The Need to Account for Interval Censoring and the Competing Risk of Death(2019-08) Marchetti, Arika L.; Bakoyannis, Giorgos; Li, Xiaochun; Gao, Sujuan; Yiannoutsos, ConstantinContext. Prediction models for dementia are crucial for informing clinical decision making in older adults. Previous models have used genotype and age to obtain risk scores to determine risk of Alzheimer’s Disease, one of the most common forms of dementia (Desikan et al., 2017). However, previous prediction models do not account for the fact that the time to dementia onset is unknown, lying between the last negative and the first positive dementia diagnosis time (interval censoring). Instead, these models use time to diagnosis, which is greater than or equal to the true dementia onset time. Furthermore, these models do not account for the competing risk of death which is quite frequent among elder adults. Objectives. To develop a prediction model for dementia that accounts for interval censoring and the competing risk of death. To compare the predictions from this model with the predictions from a naïve analysis that ignores interval censoring and the competing risk of death. Methods. We apply the semiparametric sieve maximum likelihood (SML) approach to simultaneously model the cumulative incidence function (CIF) of dementia and death while accounting for interval censoring (Bakoyannis, Yu, & Yiannoutsos, 2017). The SML is implemented using the R package intccr. The CIF curves of dementia are compared for the SML and the naïve approach using a dataset from the Indianapolis Ibadan Dementia Project. Results. The CIF from the SML and the naïve approach illustrated that for healthier individuals at baseline, the naïve approach underestimated the incidence of dementia compared to the SML, as a result of interval censoring. Individuals with a poorer health condition at baseline have a CIF that appears to be overestimated in the naïve approach. This is due to older individuals with poor health conditions having an elevated risk of death. Conclusions. The SML method that accounts for the competing risk of death along with interval censoring should be used for fitting prediction/prognostic models of dementia to inform clinical decision making in older adults. Without controlling for the competing risk of death and interval censoring, the current models can provide invalid predictions of the CIF of dementia.Item Contemporary Outcomes of Distal Lower Extremity Bypass for Chronic Limb Threatening Ischemia and a Model Based Comparison with Non-surgical Therapies(2021-03) Leckie, Katherin; Bakoyannis, Giorgos; Yiannoutsos, Constantin; Murphy, MichaelObjective: Gold standard therapy for chronic limb threatening ischemia (CLTI) is revascularization but in patients in whom below-the-knee bypass is indicated autologous vein conduit may not be available. Contemporary outcomes of distal bypass with suboptimal conduits have not been well described and recent advances in non-surgical therapies raise the question of whether in some cases there is evidence that these should be considered. Methods: Data was obtained from the Vascular Quality Initiative (VQI) registry as well as from a multi-center, randomized clinical trial of cell therapy. Incidence of major amputation after distal bypass was estimated for the VQI cohort by conduit type using non-parametric survival analysis with death as a competing risk. A cox proportional hazards model was then fit to the pooled data in a stepwise fashion with death as a competing risk, including evaluations for appropriate transformation, time dependency and interactions for each included covariate, and hazard ratios were estimated for the risk of major amputation by treatment. Results: At 365 days, the estimated cumulative incidence of major amputation with death as a competing risk is 25% after distal bypass with non-autologous biologic conduit (0.2499, 95% CI 0.2242 - 0.2785), 13% for prosthetic (0.1276, 95% CI 0.1172 - 0.1389) and 9% for GSV (0.0900, 95% CI 0.0848 - 0.0956). The cox proportional hazards model found a significant interaction between age and treatment. Compared to bypass with non-autogenous biologic, the hazard ratios for bypass with GSV were 0.41 (p<0.0001), 0.41 (p<0.0001), 0.42 (p<0.0001) and 0.42 (p<0.0001) respectively at ages 55, 60, 65 and 70 and for bypass with prosthetic were 0.68 (p=0.0043), 0.67 (p=0.0004), 0.65 (p<0.0001) and 0.64 (p<0.0001) respectively and for autologous cell therapy 0.22 (p=0.0005), 0.34 (p=0.0011), 0.52 (p=0.0196) and 0.76 (p=0.3677) respectively. No significant differences were found between best medical management and distal bypass with non-autologous biologic. Conclusion: The risk of major amputation after distal bypass is lowest in patients with GSV conduit and highest following bypass with non-autologous biologic. Using a semi-parametric model, cell therapy was estimated to significantly decrease the risk of amputation compared to distal bypass with non-autologous biologic conduit in younger patients.Item Delayed presentation of HIV among older individuals: a growing problem(Elsevier, 2022) Justice, Amy C.; Goetz, Matthew B.; Stewart, Cameron N.; Hogan, Brenna C.; Humes, Elizabeth; Luz, Paula M.; Castilho, Jessica L.; Nash, Denis; Brazier, Ellen; Musick, Beverly; Yiannoutsos, Constantin; Malateste, Karen; Jaquet, Antoine; Cornell, Morna; Shamu, Tinei; Rajasuriar, Reena; Jiamsakul, Awachana; Althoff, Keri N.; Biostatistics and Health Data Science, Richard M. Fairbanks School of Public HealthLate presentation for care is a major impediment to the prevention and effective treatment of HIV infection. Older individuals are at increased risk of late presentation, represent a growing proportion of people with late presentation, and might require interventions tailored to their age group. We provide a summary of the literature published globally between 2016-21 (reporting data from 1984-2018) and quantify the association of age with delayed presentation. Using the most common definitions of late presentation and older age from these earlier studies, we update this work with data from the International Epidemiology Databases to Evaluate AIDS (IeDEA) consortium, focusing on data from 2000-19, encompassing four continents. Finally, we consider how late presentation among older individuals might be more effectively addressed as electronic medical records become widely adopted.Item Development, Assessment, and Outcomes of a Community-Based Model of Antiretroviral Care in Western Kenya Through a Cluster-Randomized Control Trial(Wolters Kluwer, 2021-06-01) Goodrich, Suzanne; Siika, Abraham; Mwangi, Ann; Nyambura, Monicah; Naanyu, Violet; Yiannoutsos, Constantin; Spira, Thomas; Bateganya, Moses; Toroitich-Ruto, Cathy; Otieno-Nyunya, Boaz; Wools-Kaloustian, Kara; Medicine, School of MedicineObjective: To develop and assess an alternative care model using community-based groups for people living with HIV and facilitate by lay personnel. Methods: Geographic locations in the Academic Model Providing Access to Healthcare Kitale clinic catchment were randomized to standard of care versus a community-based care group (ART Co-op). Adults stable on antiretroviral therapy and virally suppressed were eligible. Research Assistant-led ART Co-ops met in the community every 3 months. Participants were seen in the HIV clinic only if referred. CD4 count and viral load were measured in clinic at enrollment and after 12 months. Retention, viral suppression, and clinic utilization were compared between groups using χ2, Fisher exact, and Wilcoxon rank sum tests. Results: At 12 months, there were no significant differences in mean CD4 count or viral load suppression. There was a significant difference in patient retention in assigned study group between the intervention and control group (81.6% vs 98.6%; P < 0.001), with a number of intervention patients withdrawing because of stigma, relocation, pregnancy, and work conflicts. All participants, however, were retained in an HIV care program for the study duration. The median number of clinic visits was lower for the intervention group than that for the control group (0 vs 3; P < 0.001). Conclusions: Individuals retained in a community-based HIV care model had clinical outcomes equivalent to those receiving clinic-based care. This innovative model of HIV care addresses the problems of insufficient health care personnel and patient retention barriers, including time, distance, and cost to attend clinic, and has the potential for wider implementation.Item Effects of Alcohol Use on Patient Retention in HIV Care in East Africa(Springer, 2024) Monroy, Alexa; Goodrich, Suzanne; Brown, Steven A.; Balanos, Theofanis; Bakoyannis, Giorgos; Diero, Lameck; Byakwaga, Helen; Muyindike, Winnie; Kanyesigye, Michael; Aluda, Maurice; Lewis‑Kulzer, Jayne; Yiannoutsos, Constantin; Wools‑Kaloustian, Kara; East Africa International Epidemiologic Databases to Evaluate AIDS (EA-IeDEA) Consortium; Medicine, School of MedicineWe sought to investigate the association between hazardous alcohol use and gaps in care for people living with HIV over a long-term follow-up period. Adults who had participated in our previously published Phase I study of hazardous alcohol use at HIV programs in Kenya and Uganda were eligible at their 42 to 48 month follow-up visit. Those who re-enrolled were followed for an additional ~ 12 months. Hazardous alcohol use behavior was measured using the Alcohol Use Disorders Identification Test (AUDIT) tool. Deidentified clinical data were used to assess gaps in care (defined as failure to return to clinic within 60 days after a missed visit). The proportion of patients experiencing a gap in care at a specific time point was based on a nonparametric moment-based estimator. A semiparametric Cox proportional hazard model was used to determine the association between hazardous alcohol use at enrollment in Phase I (AUDIT score ≥ 8) and gaps in care. Of the 731 study-eligible participants from Phase I, 5.5% had died, 10.1% were lost to follow-up, 39.5% transferred, 7.5% declined/not approached, and 37.3% were enrolled. Phase II participants were older, had less hazardous drinking and had a lower WHO clinical stage than those not re-enrolled. Hazardous drinking in the re-enrolled was associated with a Hazard Ratio (HR) of 1.88 [p-value = 0.016] for a gap in care. Thus, hazardous alcohol use at baseline was associated with an increased risk of experiencing a gap in care and presents an early target for intervention.