A pinboard by
Nasser Sharareh

Research Assistant - Ph.D. Candidate, Binghamton University


I develop simulation models for public health issues in order to propose policies and interventios

The burden of health issues and associated costs of population-level health problems, including the infectious diseases are significant and require a considerable amount of prevention efforts and involvement of various stakeholders to alleviate the consequences of those diseases. Therefore, I devoted my Ph.D. dissertation to designing processes and systems for patient care using system dynamics methodology and GIS mapping, and it comprises three different essays. In the first essay, I looked at a population-level health issue, Lyme disease infection, to design effective and efficient public health interventions. In this research, I developed a risk assessment tool for Lyme disease, by using demographic, environmental, and behavioral data and proposed interventions to alleviate the burden of the disease. The dynamical simulation tool captures the public’s awareness and how the awareness of people is evolving over time by observing the growth of infection throughout the community. During this research, I found that quite a few determinants of health including behavioral and environmental factors, and socioeconomic status had a significant role in the spread of Lyme disease throughout the society. In the second essay of my dissertation, I developed a simulation model for HPV infection which is the most common Sexually Transmitted Infection in the United States. The purpose of this modeling project was to design impactful policies to increase vaccination uptake for HPV prevention among adolescent boys. In this research, I applied the word-of-mouth (WOM) phenomenon and health belief model constructs, such as perceived barriers and benefits, into simulation modeling. In my final dissertation essay, I am working on GIS mapping to study the Medicaid access to primary care. In this essay, I am using spatial analysis to investigate the primary care utilization among Medicaid patients by taking into account the spatial and demographic characteristics of the area, the distance between patients and primary care providers, the location of primary care facilities, and the median household income. In developing these models and tools, I have collaborated with experts in the field including anthropologists, nurses, engineers, and primary care providers to validate the models and transform the simulation results into practical public health interventions.


Inequitable Access to Health Care by the Poor in Community-Based Health Insurance Programs: A Review of Studies From Low- and Middle-Income Countries.

Abstract: Out-of-pocket payments for health care services lead to decreased use of health services and catastrophic health expenditures. To reduce out-of-pocket payments and improve access to health care services, some countries have introduced community-based health insurance (CBHI) schemes, especially for those in rural communities or who work in the informal sector. However, there has been little focus on equity in access to health care services in CBHI schemes.We searched PubMed, Web of Science, African Journals OnLine, and Africa-Wide Information for studies published in English between 2000 and August 2014 that examined the effect of socioeconomic status on willingness to join and pay for CBHI, actual enrollment, use of health care services, and drop-out from CBHI. Our search yielded 755 articles. After excluding duplicates and articles that did not meet our inclusion criteria (conducted in low- and middle-income countries and involved analysis based on socioeconomic status), 49 articles remained that were included in this review. Data were extracted by one author, and the second author reviewed the extracted data. Disagreements were mutually resolved between the 2 authors. The findings of the studies were analyzed to identify their similarities and differences and to identify any methodological differences that could account for contradictory findings.Generally, the rich were more willing to pay for CBHI than the poor and actual enrollment in CBHI was directly associated with socioeconomic status. Enrollment in CBHI was price-elastic-as premiums decreased, enrollment increased. There were mixed results on the effect of socioeconomic status on use of health care services among those enrolled in CBHI. We found a high drop-out rate from CBHI schemes that was not related to socioeconomic status, although the most common reason for dropping out of CBHI was lack of money to pay the premium.The effectiveness of CBHI schemes in achieving universal health coverage in low- and middle-income countries is questionable. A flexible payment plan where the poor can pay in installments, subsidized premiums for the poor, and removal of co-pays are measures that can increase enrollment and use of CBHI by the poor.

Pub.: 29 Jun '17, Pinned: 29 Jun '17

Practices of Lyme disease diagnosis and treatment by general practitioners in Quebec, 2008-2015.

Abstract: Lyme disease (LD), a multisystem infection caused by the spirochete Borrelia burgdorferi sensu stricto (B. burgdorferi), is the most reported vector-borne disease in North America, and by 2020, 80% of the population in central and eastern Canada could live in LD risk areas. Among the key factors for minimising the impact of LD are the accurate diagnosis and appropriate management of patients bitten by ticks. In this study, the practices of Quebec general practitioners (GPs) on LD diagnosis and management of patients bitten by infected ticks are described.Eight years (2008 to 2015) of retrospective demographic and clinical data on patients bitten by infected Ixodes scapularis (I. scapularis) ticks and on the management of suspected and confirmed LD cases by Quebec GPs were analysed.Among 50 patients, all the antimicrobial treatments of LD clinical cases were appropriate according to current guidelines. However, more than half (62.8%) of erythema migrans (EM) were possibly misdiagnosed, 55.6%, (n = 27) of requested serologic tests were possibly unnecessary and the majority (96.5%, n = 57) of prophylactic antimicrobial treatments were not justified according to current guidelines.These observations underline the importance for public health to enhance the knowledge of GPs where LD is emerging, to minimise the impact of the disease on patients and the financial burden on the health system.

Pub.: 24 May '17, Pinned: 29 Jun '17

Cost-effectiveness of HPV-based cervical cancer screening in the public health system in Nicaragua.

Abstract: To evaluate the cost-effectiveness of human papillomavirus (HPV) DNA testing (versus Papanicolaou (Pap)-based screening) for cervical cancer screening in Nicaragua.A previously developed Monte Carlo simulation model of the natural history of HPV infection and cervical cancer was calibrated to epidemiological data from Nicaragua. Cost data inputs were derived using a micro-costing approach in Carazo, Chontales and Chinandega departments; test performance data were from a demonstration project in Masaya department.Nicaragua's public health sector facilities.Women aged 30-59 years.Screening strategies included (1) Pap testing every 3 years, with referral to colposcopy for women with an atypical squamous cells of undetermined significance or worse result ('Pap'); (2) HPV testing every 5 years, with referral to cryotherapy for HPV-positive eligible women (HPV cryotherapy or 'HPV-Cryo'); (3) HPV testing every 5 years, with referral to triage with visual inspection with acetic acid (VIA) for HPV-positive women ('HPV-VIA'); and (4) HPV testing every 5 years, with referral to Pap testing for HPV-positive women ('HPV-Pap').Reduction in lifetime risk of cancer and incremental cost-effectiveness ratios (ICER; 2015 US$ per year of life saved (YLS)).HPV-based screening strategies were more effective than Pap testing. HPV-Cryo was the least costly and most effective strategy, reducing lifetime cancer risk by 29.5% and outperforming HPV-VIA, HPV-Pap and Pap only, which reduced cancer risk by 19.4%, 12.2% and 10.8%, respectively. With an ICER of US$320/YLS, HPV-Cryo every 5 years would be very cost-effective using a threshold based on Nicaragua's per capita gross domestic product of US$2090. Findings were robust across sensitivity analyses on test performance, coverage, compliance and cost parameters.HPV testing is very cost-effective compared with Pap testing in Nicaragua, due to higher test sensitivity and the relatively lower number of visits required. Increasing compliance with recommended follow-up will further improve the health benefits and value for public health dollars.

Pub.: 18 Jun '17, Pinned: 29 Jun '17

Prevalence of Human Papillomavirus Infection and Cervical Cancer Screening among Riverside Women of the Brazilian Amazon.

Abstract: Purpose The aim of this study was to evaluate the overall and type-specific prevalence of human papillomavirus (HPV) infection among females living in riverside communities in the state of Pará, in the Eastern Brazilian Amazon. These communities are inhabited by low-income people, and are accessible only by small boats. Cervical cytology and risk factors for HPV infection were also assessed. Methods Cervical samples from 353 women of selected communities were collected both for Papanicolau (Pap) test and HPV detection. Conventional polymerase chain reaction (PCR) and real-time PCR were used to assess the overall and type-specific prevalence of HPV-16 and HPV-18, the main oncogenic types worldwide. Epidemiological questionnaires were used for the assessment of the risk factors for HPV infection. Results The mean age of the participants was 37 years (standard deviation [SD] ± 13.7). Most were married or with a fixed sexual partner (79%), and had a low educational level (80%) and family monthly income (< U$ 250; 53%). Overall, HPV prevalence was 16.4% (n = 58), with 8 cases of HPV-16 (2.3%) and 5 of HPV-18 (1.4%). Almost 70% of the women surveyed had never undergone the Pap test. Abnormal cytology results were found in 27.5% (n = 97) of the samples, with higher rates of HPV infection according to the severity of the lesions (p = 0.026). Conclusions The infections by HPV-16 and HPV-18 were not predominant in our study, despite the high prevalence of overall HPV infection. Nevertheless, the oncogenic potential of these types and the low coverage of the Pap test among women from riverside communities demonstrate a potential risk for the development of cervical lesions and their progression to cervical cancer, since the access to these communities is difficult and, in most cases, these women do not have access to primary care and public health services.

Pub.: 29 Jun '17, Pinned: 29 Jun '17

COPEWELL: A Conceptual Framework and System Dynamics Model for Predicting Community Functioning and Resilience After Disasters.

Abstract: Policy-makers and practitioners have a need to assess community resilience in disasters. Prior efforts conflated resilience with community functioning, combined resistance and recovery (the components of resilience), and relied on a static model for what is inherently a dynamic process. We sought to develop linked conceptual and computational models of community functioning and resilience after a disaster.We developed a system dynamics computational model that predicts community functioning after a disaster. The computational model outputted the time course of community functioning before, during, and after a disaster, which was used to calculate resistance, recovery, and resilience for all US counties.The conceptual model explicitly separated resilience from community functioning and identified all key components for each, which were translated into a system dynamics computational model with connections and feedbacks. The components were represented by publicly available measures at the county level. Baseline community functioning, resistance, recovery, and resilience evidenced a range of values and geographic clustering, consistent with hypotheses based on the disaster literature.The work is transparent, motivates ongoing refinements, and identifies areas for improved measurements. After validation, such a model can be used to identify effective investments to enhance community resilience.(Disaster Med Public Health Preparedness. 2017;page 1 of 11).

Pub.: 22 Jun '17, Pinned: 29 Jun '17