Papers by Pinar Keskinocak
BACKGROUNDThe essential components of a vaccine delivery system are well-documented, but robust e... more BACKGROUNDThe essential components of a vaccine delivery system are well-documented, but robust evidence is lacking on how policies and implementation strategies are operationalized to drive catalytic improvements in coverage. To address this gap, we identified success factors that supported improvements in routine immunization coverage in Senegal, especially from 2000 to 2019.METHODSWe identified Senegal as an exemplar in the delivery of childhood vaccines through analysis of DTP1 and DTP3 coverage data. Through interviews and focus group discussions at the national, regional, district, health facility, and community-level, we investigated factors that contributed to high and sustained vaccination coverage. We conducted a thematic analysis through application of implementation science frameworks to determine critical success factors. We triangulated these findings with quantitative analyses using publicly available data.RESULTSThe following success factors emerged: 1) Strong politi...
IntroductionThe essential components of a vaccine delivery system are well-documented, but robust... more IntroductionThe essential components of a vaccine delivery system are well-documented, but robust evidence on how and why the related processes and implementation strategies prove effective at driving coverage is not well-established. To address this gap, we identified critical success factors associated with advancing key policies and programs that may have led to the substantial changes in routine childhood immunization coverage in Zambia between 2000 and 2018.MethodsWe conducted mixed-methods research based on an evidence-based conceptual framework of core vaccine system requirements. Additional facilitators and barriers were explored at the national and subnational levels in Zambia. We conducted a thematic analysis grounded in implementation science frameworks to determine the critical success factors for improved vaccine coverage.ResultsThe following success factors emerged: 1) the Inter-agency Coordinating Committee was strengthened for long-term engagement which, complemented...
SSRN Electronic Journal, 2020
Background Routine childhood immunization is a cost-effective way to save lives and protect peopl... more Background Routine childhood immunization is a cost-effective way to save lives and protect people from disease. Some low-income countries (LIC) have achieved remarkable success in childhood immunization, despite lower levels of gross national income or health spending compared to other countries. We investigated the impact of financing and health spending on vaccination coverage across LIC and lower-middle income countries (LMIC). Methods Among LIC, we identified countries with high-performing vaccination coverage (LIC+) and compared their economic and health spending trends with other LIC (LIC-) and LMIC. We used crosscountry multi-year linear regressions with mixed-effects to test financial indicators over time. We conducted three different statistical tests to verify if financial trends of LIC+ were significantly different from LIC-and LMIC; p-values were calculated with an asymptotic χ 2 test, a Kenward-Roger approximation for F tests, and a parametric bootstrap method. Findings During 2014-18, LIC+ had a mean vaccination coverage between 91-96% in routine vaccines, outperforming LIC-(67-80%) and LMIC (83-89%). During 2000-18, gross national income and development assistance for health (DAH) per capita were not significantly different between LIC+ and LIC-(p > 0•13, p > 0•65) while LIC+ had a significant lower total health spending per capita than LIC-(p < 0•0001). Government health spending per capita per year increased by US$0•42 for LIC+ and decreased by US$0•24 for LIC-(p < 0•0001). LIC+ had a significantly lower private health spending per capita than LIC-(p < 0•012).
Journal of Heuristics, 2021
The multiple knapsack problem with grouped items aims to maximize rewards by assigning groups of ... more The multiple knapsack problem with grouped items aims to maximize rewards by assigning groups of items among multiple knapsacks, considering knapsack capacities. Either all items in a group are assigned or none at all. We propose algorithms which guarantee that rewards are not less than the optimal solution, with a bound on exceeded knapsack capacities. To obtain capacityfeasible solutions, we propose a binary-search heuristic combined with these algorithms. We test the performance of the algorithms and heuristics in an extensive set of experiments on randomly generated instances and show they are efficient and effective, i.e., they run reasonably fast and generate good quality solutions.
Presented on November 9, 2018, at 1:00 p.m. in the Roger A. and Helen B. Krone Engineered Biosyst... more Presented on November 9, 2018, at 1:00 p.m. in the Roger A. and Helen B. Krone Engineered Biosystems Building (EBB Krone), Children's Healthcare of Atlanta (CHOA) Seminar Room, Georgia Tech, Atlanta, GA.
Transplant Infectious Disease, 2019
Background: Between 2002 and 2013, the organs of thirteen deceased donors with infectious encepha... more Background: Between 2002 and 2013, the organs of thirteen deceased donors with infectious encephalitis were transplanted, causing infections in 23 recipients. As a consequence, organs from donors showing symptoms of encephalitis (increased probability of infectious encephalitis (IPIE) organs) might be declined. We had previously characterized the risk of IPIE organs using data available to most transplant teams and not requiring special diagnostic tests. If the probability of infection is low, the benefits of a transplant from a donor with suspected infectious encephalitis might outweigh the risk and could be lifesaving for some transplant candidates. Methods: Using organ transplant data and Cox Proportional Hazards models, we determined liver donor and recipient characteristics predictive of post-transplant or waitlist survival and generated 5-year survival probability curves. We also calculated expected waiting times for an organ offer based on transplant candidate characteristics. Using a limited set of actual cases of infectious encephalitis transmission via transplant, we estimated post-transplant survival curves given an organ from an IPIE donor. Results: 54% (1,256) of patients registered from 2002-2006 who died or were removed from the waiting list due to deteriorated condition within 1 year could have had an at least marginal estimated benefit by accepting an IPIE liver with some probability of infection, with the odds increasing to 86% of patients if the probability of infection was low (5% or less). Additionally, 54% (1,252) were removed from the waiting list prior to their estimated waiting time for a non-IPIE liver and could have benefited from an IPIE liver.
Thousands of school systems have been struggling with the decisions about how to safely and effec... more Thousands of school systems have been struggling with the decisions about how to safely and effectively deliver education during the fall semester of 2020, amid the COVID19 pandemic. The objective of this study is to evaluate the public health impact of reopening schools on the spread of COVID19. An agent-based simulation model was adapted and used to project the number of infections and deaths under multiple school reopening dates and scenarios, including different cohorts receiving in-person instruction on alternating days, only younger children returning to in-person instruction, regular schedule (all students receiving in-person instruction), and school closure (all students receiving online instruction). The study period was February 18th-November 24th, 2020 and the state of Georgia was used as a case study. Across all scenarios, the number of COVID19-related deaths ranged from approximately 17 to 22 thousand during the study period, and on the peak day, the number of new infec...
Prenatal Diagnosis, 2020
Screening for Down Syndrome (DS) includes traditional ultrasound and serum‐based and cell‐free DN... more Screening for Down Syndrome (DS) includes traditional ultrasound and serum‐based and cell‐free DNA (cfDNA) testing. While cfDNA testing usually has superior performance, it is significantly more costly. As an alternative, a hybrid strategy combining contingent cfDNA with traditional testing is recommended when universal cfDNA screening is not feasible. This study compares the efficacy of traditional, contingent cfDNA, and universal cfDNA screening strategies at various cut‐offs based on maternal age and parents' preferences, which may improve testing outcomes and patients' satisfaction.
Vaccine, 2020
Background: Despite high vaccine coverage rates in children and efficacy of pneumococcal conjugat... more Background: Despite high vaccine coverage rates in children and efficacy of pneumococcal conjugate vaccines, invasive pneumococcal disease (IPD) episodes due to serotypes included in the vaccine following completion of the recommended course of immunisation (i.e. vaccine failure) have been reported. Methods: We used data gathered from a population-based enhanced passive surveillance for IPD in children under 18 years of age in Massachusetts and an ensemble model composed of three machinelearning algorithms to predict probability of 13-valent pneumococcal conjugated vaccine (PCV13) failure and to evaluate potential associated features including age, underlying comorbidity, clinical presentation, and vaccine schedule. Vaccine failure was defined as diagnosis of IPD due to vaccine serotype (VST), in a child who received age recommended doses recommended by Advisory Committee of Immunization Practices. Results: During the 7-year study period, between April 01, 2010 and March 31, 2017, we identified 296 IPD cases. There were 107 (36%) IPD cases caused by VST, mostly serotype 19A (49, 17%), 7F (21, 7%), and 3 (18, 6%). Thirty-seven (34%) were in children who were completely vaccinated representing 13% of all IPD cases. Vaccine failure was more likely among children older than 60 months (predicted probability 0.40, observed prevalence 0.37, model prediction accuracy 79%), children presenting with pneumonia (predicted probability 0.27, observed prevalence 0.31, model accuracy 77%), and children with underlying comorbidity (predicted probability 0.24, observed prevalence 0.23, model accuracy 96%). Vaccine failure probability for those >60 months of age and had an underlying risk factor was 45% (observed prevalence 0.33, model accuracy 82%). The likelihood of vaccine failure was lowest among children who had completed 3 primary doses plus one booster dose PCV13 (predicted probability 0.14, observed prevalence 0.14, model prediction accuracy 100%). Conclusion: PCV13 vaccine failure is more frequent among older children with underlying comorbidity, and among those who present with pneumococcal pneumonia. Our study provides a preliminary framework to predict the patterns of vaccine failures and may contribute to decision-making processes to optimize PCV immunization schedules.
Transplant Infectious Disease, 2019
In 1994, the Centers for Disease Control and Prevention (CDC) and the Public Health Service (PHS)... more In 1994, the Centers for Disease Control and Prevention (CDC) and the Public Health Service (PHS) released guidelines classifying donors at risk of transmitting human immunodeficiency virus (HIV) through organ transplantation. 1 In 2013, the guidelines were updated to include donors at risk of transmitting hepatitis B (HBV) and hepatitis C (HCV). 2 These donors are known as increased risk for disease transmission donors (IRD). Even though donors are now universally screened for HIV, HBV, and HCV by nucleic acid testing (NAT), NAT can be negative during the eclipse phase (the time during early infection when a virus is not detectable in blood). In part due
Prenatal Diagnosis, 2020
Screening for Down Syndrome (DS) includes traditional ultrasound and serum‐based and cell‐free DN... more Screening for Down Syndrome (DS) includes traditional ultrasound and serum‐based and cell‐free DNA (cfDNA) testing. While cfDNA testing usually has superior performance, it is significantly more costly. As an alternative, a hybrid strategy combining contingent cfDNA with traditional testing is recommended when universal cfDNA screening is not feasible. This study compares the efficacy of traditional, contingent cfDNA, and universal cfDNA screening strategies at various cut‐offs based on maternal age and parents' preferences, which may improve testing outcomes and patients' satisfaction.
Vaccine, 2020
Background: Despite high vaccine coverage rates in children and efficacy of pneumococcal conjugat... more Background: Despite high vaccine coverage rates in children and efficacy of pneumococcal conjugate vaccines, invasive pneumococcal disease (IPD) episodes due to serotypes included in the vaccine following completion of the recommended course of immunisation (i.e. vaccine failure) have been reported. Methods: We used data gathered from a population-based enhanced passive surveillance for IPD in children under 18 years of age in Massachusetts and an ensemble model composed of three machinelearning algorithms to predict probability of 13-valent pneumococcal conjugated vaccine (PCV13) failure and to evaluate potential associated features including age, underlying comorbidity, clinical presentation, and vaccine schedule. Vaccine failure was defined as diagnosis of IPD due to vaccine serotype (VST), in a child who received age recommended doses recommended by Advisory Committee of Immunization Practices. Results: During the 7-year study period, between April 01, 2010 and March 31, 2017, we identified 296 IPD cases. There were 107 (36%) IPD cases caused by VST, mostly serotype 19A (49, 17%), 7F (21, 7%), and 3 (18, 6%). Thirty-seven (34%) were in children who were completely vaccinated representing 13% of all IPD cases. Vaccine failure was more likely among children older than 60 months (predicted probability 0.40, observed prevalence 0.37, model prediction accuracy 79%), children presenting with pneumonia (predicted probability 0.27, observed prevalence 0.31, model accuracy 77%), and children with underlying comorbidity (predicted probability 0.24, observed prevalence 0.23, model accuracy 96%). Vaccine failure probability for those >60 months of age and had an underlying risk factor was 45% (observed prevalence 0.33, model accuracy 82%). The likelihood of vaccine failure was lowest among children who had completed 3 primary doses plus one booster dose PCV13 (predicted probability 0.14, observed prevalence 0.14, model prediction accuracy 100%). Conclusion: PCV13 vaccine failure is more frequent among older children with underlying comorbidity, and among those who present with pneumococcal pneumonia. Our study provides a preliminary framework to predict the patterns of vaccine failures and may contribute to decision-making processes to optimize PCV immunization schedules.
Transplant Infectious Disease, 2019
In 1994, the Centers for Disease Control and Prevention (CDC) and the Public Health Service (PHS)... more In 1994, the Centers for Disease Control and Prevention (CDC) and the Public Health Service (PHS) released guidelines classifying donors at risk of transmitting human immunodeficiency virus (HIV) through organ transplantation. 1 In 2013, the guidelines were updated to include donors at risk of transmitting hepatitis B (HBV) and hepatitis C (HCV). 2 These donors are known as increased risk for disease transmission donors (IRD). Even though donors are now universally screened for HIV, HBV, and HCV by nucleic acid testing (NAT), NAT can be negative during the eclipse phase (the time during early infection when a virus is not detectable in blood). In part due
Open Forum Infectious Diseases, 2018
Background Thirteen-valent-pneumococcal conjugate vaccine (PCV13) replaced PCV7 in the childhood ... more Background Thirteen-valent-pneumococcal conjugate vaccine (PCV13) replaced PCV7 in the childhood immunization schedule in Massachusetts beginning in April 2010. We evaluated the predictors of vaccine-type (VT) invasive pneumococcal infection (IPD) occurrence despite vaccination. Methods Cases of IPD in children <18 years of age were detected through an enhanced surveillance system in MA since 2001. All cases and Streptococcus pneumoniae (SP) isolates are submitted to Department of Public Health (MDPH) and parents/physicians are interviewed for confirmation of demographic and clinical data. All available isolates are serotyped by Quellung reaction. Children who received any dose of PCV7 were excluded from this study. We used 4-layer, feed-forward, neural network with backpropagation learning algorithm, random forest algorithm with 150 classification trees, and extreme gradient boosting (XGBoost) algorithm based on boosted trees with over than 200 iterations to make prediction abou...
Open Forum Infectious Diseases, 2018
Background Thirteen-valent-pneumococcal conjugate vaccine (PCV13) replaced PCV7 in the childhood ... more Background Thirteen-valent-pneumococcal conjugate vaccine (PCV13) replaced PCV7 in the childhood immunization schedule in Massachusetts beginning in April 2010. We evaluated the predictors of vaccine-type (VT) invasive pneumococcal infection (IPD) occurrence despite vaccination. Methods Cases of IPD in children <18 years of age were detected through an enhanced surveillance system in MA since 2001. All cases and Streptococcus pneumoniae (SP) isolates are submitted to Department of Public Health (MDPH) and parents/physicians are interviewed for confirmation of demographic and clinical data. All available isolates are serotyped by Quellung reaction. Children who received any dose of PCV7 were excluded from this study. We used 4-layer, feed-forward, neural network with backpropagation learning algorithm, random forest algorithm with 150 classification trees, and extreme gradient boosting (XGBoost) algorithm based on boosted trees with over than 200 iterations to make prediction abou...
International Series in Operations Research & Management Science, 2011
At the end of this volume, several years in the making, it is worth reflecting upon the objective... more At the end of this volume, several years in the making, it is worth reflecting upon the objectives the editorial team had in mind when we started this project. We were motivated by the disturbing observation that although academia seemed to view the problems of planning production and inventories as a largely solved problem, with basic formulations established and agreed upon, there was broad consensus among our industrial colleagues that the available models and solution techniques were a long way from representing the full richness and complexity of the task as they encountered it in their daily operations. Our objective with these volumes was to address this situation by bringing together a leading group of researchers and practitioners to delineate the broader boundaries of the problem and present the state of the art in various related areas. A representative sample of leading-edge industrial contributions illustrates the state of the art in industrial practice, while a selection of research contributions with a more academic bent explores specific aspects of new areas.
Dedicated clinics can be established in an influenza pandemic to isolate people and potentially r... more Dedicated clinics can be established in an influenza pandemic to isolate people and potentially reduce opportunities for influenza transmission. However, their operation requires resources and their existence may attract the worried-well. In this study, we quantify the impact of opening dedicated influenza clinics during a pandemic based on an agent-based simulation model across a time-varying social network of households, workplaces, schools, community locations, and health facilities in the state of Georgia. We calculate performance measures, including peak prevalence and total attack rate, while accounting for clinic operations, including timing and location. We find that opening clinics can reduce disease spread and hospitalizations even when visited by the worried-well, open for limited weeks, or open in limited locations, and especially when the clinics are in operation during times of highest prevalence. Specifically, peak prevalence, total attack rate, and hospitalization re...
Production and Operations Management, 2019
Nella formazione delle decisioni, noi scegliamo quelle alternative che consideriamo mezzi adatti ... more Nella formazione delle decisioni, noi scegliamo quelle alternative che consideriamo mezzi adatti al raggiungimento dei fini voluti. I fini stessi, però, hanno spesso un mero valore strumentale rispetto ad obiettivi più lontani. Siamo così condotti alla concezione di una serie, o gerarchia, di fini. La razionalità ha a che fare con la costruzione di catene mezzi fini di questo tipo.
Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies, Jan 20, 2017
As a result of a workshop to identify common causes of unplanned extubation, Children's Healt... more As a result of a workshop to identify common causes of unplanned extubation, Children's Healthcare of Atlanta developed a scoring tool (Risk Assessment Score) to stratify patients into groups of low, moderate, high, and extreme risk. This tool could be used to institute appropriate monitoring or interventions for patients with high risks of unplanned extubation to enhance safety. The objective of this study is to test the hypothesis that the Risk Assessment Score will correlate with the occurrence rate of unplanned extubation in pediatric patients. Retrospective review of 2,811 patients at five ICUs conducted between December 2012 and July 2014. Five ICUs at two freestanding pediatric hospitals within a large children's healthcare system in the United States. All intubated pediatric patients. Data of intubations and Risk Assessment Score were collected. Extubation outcomes and severity levels were compared across demographic groups and with the maximum Risk Assessment Score ...
Service Science, 2015
We develop a mathematical model for planning and scheduling staff and demand, considering a time ... more We develop a mathematical model for planning and scheduling staff and demand, considering a time window for on-time demand fulfillment, as well as individual staff characteristics, preferences, and availability. We also discuss a version where the staff schedule is fixed. The model can be applied in many service settings, such as warehouses, fulfillment centers, and back-office services. We develop a user-friendly decision-support tool that employs the model and the solution methodology, and we implement it in a healthcare back-office services provider, considering additional operational practices of this company, such as team leader scheduling. We conduct a computational study to develop insights regarding the trade-offs between the on-time demand fulfillment and the quality of the staff schedule, the effect of a change in the demand fulfillment time window, the impact of client behavior e.g., batch arrivals of demand, and the consequences of considering additional preferences and operational constraints. We also evaluate the robustness of the staff schedule generated by the model under different demand scenarios. Finally, we present a heuristic to set high-quality staff schedules quickly. After the implementation, the company reported a 25% increase in staff productivity.
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Papers by Pinar Keskinocak