Person: Parker, Robert
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Publication Predictors of HIV infection: a prospective HIV screening study in a Ugandan refugee settlement
(BioMed Central, 2016) O’Laughlin, Kelli N.; Rabideau, Dustin; Kasozi, Julius; Parker, Robert; Bustamante, Nirma D.; Faustin, Zikama M.; Greenwald, Kelsy; Walensky, Rochelle; Bassett, IngridBackground: The instability faced by refugees may place them at increased risk of exposure to HIV infection. Nakivale Refugee Settlement in southwestern Uganda hosts 68,000 refugees from 11 countries, many with high HIV prevalence. We implemented an HIV screening program in Nakivale and examined factors associated with new HIV diagnosis. Methods: From March 2013-November 2014, we offered free HIV screening to all clients in the Nakivale Health Center while they waited for their outpatient clinic visit. Clients included refugees and Ugandan nationals accessing services in the settlement. Prior to receiving the HIV test result, participants were surveyed to obtain demographic information including gender, marital status, travel time to reach clinic, refugee status, and history of prior HIV testing. We compared variables for HIV-infected and non-infected clients using Pearson’s chi-square test, and used multivariable binomial regression models to identify predictors of HIV infection. Results: During the HIV screening intervention period, 330 (4%) of 7766 individuals tested were identified as HIV-infected. Refugees were one quarter as likely as Ugandan nationals to be HIV-infected (aRR 0.27 [0.21, 0.34], p < 0.0001). Additionally, being female (aRR 1.43 [1.14, 1.80], p = 0.002) and traveling more than 1 h to the clinic (aRR 1.39 [1.11, 1.74], p = 0.003) increased the likelihood of being HIV-infected. Compared to individuals who were married or in a stable relationship, being divorced/separated/widowed increased the risk of being HIV-infected (aRR 2.41 [1.88, 3.08], p < 0.0001), while being single reduced the risk (aRR 0.60 [0.41, 0.86], p < 0.0001). Having been previously tested for HIV (aRR 0.59 [0.47, 0.74], p < 0.0001) also lowered the likelihood of being HIV-infected. Conclusions: In an HIV screening program in a refugee settlement in Uganda, Ugandan nationals are at higher risk of having HIV than refugees. The high HIV prevalence among clients seeking outpatient care, including Ugandan nationals and refugees, warrants enhanced HIV screening services in Nakivale and in the surrounding region. Findings from this research may be relevant for other refugee settlements in Sub-Saharan Africa hosting populations with similar demographics, including the 9 other refugee settlements in Uganda.
Publication Potential Clinical and Economic Value of Long-Acting Preexposure Prophylaxis for South African Women at High-Risk for HIV Infection
(Oxford University Press, 2015) Walensky, Rochelle; Jacobsen, Margo M.; Bekker, Linda-Gail; Parker, Robert; Wood, Robin; Resch, Stephen C.; Horstman, N. Kaye; Freedberg, Kenneth; Paltiel, A. DavidBackground. For young South African women at risk for human immunodeficiency virus (HIV) infection, preexposure prophylaxis (PrEP) is one of the few effective prevention options available. Long-acting injectable PrEP, which is in development, may be associated with greater adherence, compared with that for existing standard oral PrEP formulations, but its likely clinical benefits and additional costs are unknown. Methods. Using a computer simulation, we compared the following 3 PrEP strategies: no PrEP, standard PrEP (effectiveness, 62%; cost per patient, $150/year), and long-acting PrEP (effectiveness, 75%; cost per patient, $220/year) in South African women at high risk for HIV infection (incidence of HIV infection, 5%/year). We examined the sensitivity of the strategies to changes in key input parameters among several outcome measures, including deaths averted and program cost over a 5-year period; lifetime HIV infection risk, survival rate, and program cost and cost-effectiveness; and budget impact. Results. Compared with no PrEP, standard PrEP and long-acting PrEP cost $580 and $870 more per woman, respectively, and averted 15 and 16 deaths per 1000 women at high risk for infection, respectively, over 5 years. Measured on a lifetime basis, both standard PrEP and long-acting PrEP were cost saving, compared with no PrEP. Compared with standard PrEP, long-acting PrEP was very cost-effective ($150/life-year saved) except under the most pessimistic assumptions. Over 5 years, long-acting PrEP cost $1.6 billion when provided to 50% of eligible women. Conclusions. Currently available standard PrEP is a cost-saving intervention whose delivery should be expanded and optimized. Long-acting PrEP will likely be a very cost-effective improvement over standard PrEP but may require novel financing mechanisms that bring short-term fiscal planning efforts into closer alignment with longer-term societal objectives.
Publication Survival benefits of antiretroviral therapy in Brazil: a model-based analysis
(International AIDS Society, 2016) Luz, Paula M; Girouard, Michael; Grinsztejn, Beatriz; Freedberg, Kenneth; Veloso, Valdilea G; Losina, Elena; Struchiner, Claudio J; MacLean, Rachel L; Parker, Robert; Paltiel, A David; Walensky, RochelleObjective: In Brazil, universal provision of antiretroviral therapy (ART) has been guaranteed free of charge to eligible HIV-positive patients since December 1996. We sought to quantify the survival benefits of ART attributable to this programme. Methods: We used a previously published microsimulation model of HIV disease and treatment (CEPAC-International) and data from Brazil to estimate life expectancy increase for HIV-positive patients initiating ART in Brazil. We divided the period of 1997 to 2014 into six eras reflecting increased drug regimen efficacy, regimen availability and era-specific mean CD4 count at ART initiation. Patients were simulated first without ART and then with ART. The 2014-censored and lifetime survival benefits attributable to ART in each era were calculated as the product of the number of patients initiating ART in a given era and the increase in life expectancy attributable to ART in that era. Results: In total, we estimated that 598,741 individuals initiated ART. Projected life expectancy increased from 2.7, 3.3, 4.1, 4.9, 5.5 and 7.1 years without ART to 11.0, 17.5, 20.7, 23.0, 25.3, and 27.0 years with ART in Eras 1 through 6, respectively. Of the total projected lifetime survival benefit of 9.3 million life-years, 16% (or 1.5 million life-years) has been realized as of December 2014. Conclusions: Provision of ART through a national programme has led to dramatic survival benefits in Brazil, the majority of which are still to be realized. Improvements in initial and subsequent ART regimens and higher CD4 counts at ART initiation have contributed to these increasing benefits.
Publication Relationship Between Upper Respiratory Tract Influenza Test Result and Clinical Outcomes Among Critically Ill Influenza Patients
(Oxford University Press, 2016) Reddy, Krishna; Bajwa, Ednan; Parker, Robert; Onderdonk, Andrew; Walensky, RochelleAmong critically ill patients with lower respiratory tract (LRT)-confirmed influenza, we retrospectively observed worse 28-day clinical outcomes in upper respiratory tract (URT)-negative versus URT-positive subjects. This finding may reflect disease progression and highlights the need for influenza testing of both URT and LRT specimens to improve diagnostic yield and possibly inform prognosis.
Publication Impact of Medication Adherence on Virologic Failure in A5202: A Randomized, Partially Blinded, Phase 3B Study
(Oxford University Press, 2017) Parker, Robert; Rabideau, Dustin J.; Sax, Paul; Tierney, Camlin; Daar, Eric S.; Collier, Ann C.; Losina, Elena; Freedberg, KennethAbstract In AIDS Clinical Trials Group A5202, participants who reported missing their medication within the past month or not providing adherence reports at both 8 and 24 weeks had 5 times the hazard of virological failure compared to more adherent participants. Adherence interventions should focus on such patients.
Publication Age- and Gender-Related Differences in Ischemia/Reperfusion Injury and Cardioprotection: Effects of Diazoxide
(Elsevier BV, 2006) McCully, James; Toyoda, Yoshiya; Wakiyama, Hidetaka; Rousou, Anthony J.; Parker, Robert; Levitsky, SidneyBackground
Recent studies have demonstrated that aging is associated with reduced tolerance to ischemia and that the aged (not senescent) female heart has greater susceptibility to ischemia as compared with the aged male heart. Previously, we have shown that ischemia can be modulated with cardioplegia in the male heart; however, efficacy in the female heart was unknown.
Methods
In this study, male and female mature (15 to 20 weeks) aged (>32 months) rabbit hearts (n = 134) were subjected to Langendorff perfusion. Control hearts were perfused for 180 minutes. Global ischemia hearts received 30 minutes of equilibrium, 30 minutes of global ischemia, and 120 minutes of reperfusion. Cardioplegia ± diazoxide was infused separately, 5 minutes before global ischemia.
Results
Global ischemia significantly decreased post-ischemic functional recovery and significantly increased infarct size in the mature and aged male and female heart (p < 0.05 versus control). The effects of global ischemia were significantly exacerbated (p < 0.05) in the aged heart as compared with the mature heart. Cardioplegia ± diazoxide significantly increased postischemic functional recovery and significantly decreased infarct size in mature male and female hearts, but these effects were significantly decreased in the aged heart (p < 0.05) and in the aged female as compared with the aged male heart.
Conclusions
Postischemic functional recovery and infarct size are affected by age but not by gender. The cardioprotection afforded by cardioplegia is affected by age and gender with a strong age-by-gender interaction for end-diastolic pressure and infarct size. Our results indicate that currently optimized cardioplegia protocols effective in the male heart are not as efficacious in the aged female heart.
Publication Diazoxide amelioration of myocardial injury and mitochondrial damage during cardiac surgery
(Elsevier BV, 2002) McCully, James; Wakiyama, Hidetaka; Cowan, Douglas; Federman, Micheline; Parker, Robert; Levitsky, SidneyBackground Recently, we have shown that the selective opening of mitochondrial ATP-sensitive potassium channels with diazoxide significantly decreases myocardial injury. The purpose of this study was to determine the effects of diazoxide on apoptosis and the mechanisms modulating apoptosis and myocardial injury in a blood-perfused model of acute myocardial infarction.
Methods Pigs (32 to 42 kg) undergoing total cardiopulmonary bypass underwent left anterior descending coronary artery occlusion for 30 minutes. The aorta was cross-clamped and magnesium-supplemented potassium cold-blood cardioplegia (DSA; n = 6) or magnesium-supplemented potassium cardioplegia containing 50 μmol/L diazoxide (DZX; n = 6) was administered, followed by 30 minutes of global ischemia and 120 minutes of reperfusion. Left ventricular tissue samples from DSA and DZX hearts were obtained after reperfusion. Apoptosis was determined by TUNEL, caspase-3 and PARP cleavage, and caspase-3 activity. Bax and bcl-2 levels were determined and tissue morphology was examined by light and transmission electron microscopy.
Results Apoptosis, as estimated by TUNEL-positive nuclei/3,000 myocardial cells, was 120.3 ± 48.8 in DSA hearts and was significantly decreased to 21.4 ± 5.3 in DZX hearts (p < 0.05 vs control). Caspase-3 and poly-ADP-ribose polymerase cleavage and pro-apoptotic bax protein levels were significantly decreased with diazoxide (p < 0.05 vs DSA). Light and transmission electron microscopy indicated severe disruption of tissue with capillary dilatation, mitochondrial cristae damage, and evidence of increased presence of mitochondrial granules in DSA as compared with DZX hearts.
Conclusions The addition of diazoxide (50 μmol/L) to cardioplegia significantly decreases regional myocardial apoptosis and mitochondrial damage, and provides an additional modality for achieving myocardial protection.
Publication Age- and Gender-Related Differences in Mitochondrial Oxygen Consumption and Calcium With Cardioplegia and Diazoxide
(Elsevier BV, 2007) McCully, James; Rousou, Anthony J.; Parker, Robert; Levitsky, SidneyBackground
We have recently shown that the cardioprotection afforded by cardioplegia is affected by age and gender and is less effective in the aged female rabbit heart compared with the aged male rabbit heart. We hypothesized that these differences were due to age and gender-specific modulation of mitochondrial oxygen consumption and mitochondrial free matrix calcium ([Ca2+]Mito) content occurring during early reperfusion.
Methods
To test this hypothesis, 104 male and female rabbit hearts, mature (15 to 20 weeks) and aged (>32 months), were subjected to Langendorff perfusion. Control hearts were perfused for 75 minutes. Global ischemia hearts were underwent 30 minutes of equilibrium, 30 minutes of global ischemia, and 15 minutes of reperfusion. Cardioplegia (potassium/magnesium) ± diazoxide was infused 5 minutes before global ischemia. Mitochondria were isolated from left ventricular tissue and used for the measurement of oxygen consumption and [Ca2+]Mito.
Results
Mitochondrial oxygen consumption was significantly increased in the mature and aged female hearts in all treatment groups (p < 0.001 versus male). Cardioplegia ± diazoxide modulated mitochondrial oxygen consumption, but these effects were significantly decreased in the aged heart and in the female heart (p < 0.001 each versus male). Cardioplegia (potassium/magnesium) significantly decreased [Ca2+]Mito (p < 0.001 versus global ischemia) in aged but not mature hearts. The addition of diazoxide to potassium/magnesium significantly decreased [Ca2+]Mito in mature and aged males (p < 0.001 versus potassium/magnesium) but not in females.
Conclusions
These results demonstrate that mitochondrial oxygen consumption and [Ca2+]Mito are modulated by age and gender and play an important role in the differences observed between mature and aged male and female response to global ischemia and the cardioprotection afforded by cardioplegia ± diazoxide.
Publication Adolescent Linkage to Care After a Large-scale Transfer From a Hospital-based HIV Clinic to the Public Sector in South Africa
(Williams & Wilkins, 2017) Ramirez-Avila, Lynn; Regan, Susan; Cloete, Christie; Crankshaw, Tamaryn; Rabideau, Dustin; Freedberg, Kenneth; Parker, Robert; Walensky, Rochelle; Losina, Elena; Bassett, IngridHIV clinics formerly supported by the President’s Emergency Plan for AIDS Relief are transferring patients to public-sector clinics. We evaluated adolescent linkage to care after a large-scale transfer from a President’s Emergency Plan for AIDS Relief-subsidized pediatric HIV clinic in Durban, South Africa. All adolescents (11–18 years) in care at a pediatric state-subsidized, hospital-based clinic (HBC) were transferred, from May to June 2012, to government sites [primary health care (PHC) clinic; community health center (CHC); and HBCs] or private clinics. Caregivers were surveyed 7–8 months after transfer to assess their adolescents’ linkage to care and their reports were validated by clinic record audits in a subset of randomly selected clinics. Of the 309 (91%) caregivers reached, only 5 (2%) reported that their adolescent did not link. Of the 304 adolescents who linked, 105 (35%) were referred to a PHC, 73 (24%) to a CHC and 106 (35%) to a HBC. A total of 146 (48%) linked adolescents attended a different clinic than that assigned. Thirty-five (20%) of the 178 who linked and were assigned to a PHC or CHC ultimately attended a HBC. Based on clinic validation, the estimated transfer success was 88% (95% confidence interval: 77%–97%). The large majority of adolescents successfully transferred to a new HIV clinic, although nearly half attended a clinic other than that assigned.
Publication The Impact of Reporting a Prior Penicillin Allergy on the Treatment of Methicillin-Sensitive Staphylococcus aureus Bacteremia
(Public Library of Science, 2016) Blumenthal, Kimberly; Seiguer Shenoy, Erica; Huang, Mingshu; Kuhlen, James L.; Ware, Winston A.; Parker, Robert; Walensky, RochelleBackground: Methicillin-sensitive Staphylococcus aureus (MSSA) bacteremia is a morbid infection with mortality benefit from receipt of parenteral β-lactam therapy. A substantial portion of MSSA bacteremia patients report penicillin allergy, but infrequently have true allergy. Objective: To determine the frequency and predictors of optimal and adequate therapy in patients with MSSA bacteremia. Design: Retrospective cohort. Participants: Adult inpatients with MSSA bacteremia, January 2009 through October 2013. Main Measures The primary measure was a trial of optimal therapy (OT), defined as ≥3 inpatient days or discharge on any first-line agents (nafcillin, oxacillin, cefazolin, or penicillin G, if susceptible). The secondary measure was completion of adequate therapy (AT), defined as ≥10 inpatient days or discharge on an agent appropriate for MSSA bacteremia. Data were electronically gathered with key variables manually validated through chart review. Log-binomial regression models were used to determine the frequency and predictors of outcomes. Key Results Of 456 patients, 346 (76%) received a trial of OT. Patients reporting penicillin allergy (13%) were less likely to receive OT trial than those without penicillin allergy (47% vs. 80%, p <0.001). Adjusting for other factors, penicillin allergy was the largest negative predictor of OT trial (RR 0.64 [0.49, 0.83]). Infectious Disease (ID) consultation was the largest positive predictor of OT trial across all patients (RR 1.34 [1.14, 1.57]). Allergy/Immunology consultation was the single most important predictor of OT trial among patients reporting penicillin allergy (RR 2.33 [1.44, 3.77]). Of 440 patients, 391 (89%) completed AT, with ID consultation the largest positive predictor of the outcome (RR 1.28 [1.15, 1.43]). Conclusions: Nearly 25% of patients with MSSA bacteremia did not receive OT trial and about 10% did not receive AT completion. Reported penicillin allergy reduced, and ID consult increased, the likelihood of OT. Allergy evaluation, coupled with ID consultation, may improve outcomes in MSSA bacteremic patients.