Ali Hajjar joined the MGH Institute for Technology Assessment (ITA) in August 2020 as a Postdoctoral Research Fellow within the Radiology Department. He received his Ph.D. in Industrial and Systems Engineering from the University of Wisconsin-Madison, M.S. in Industrial Engineering from the University of Pittsburgh, and B.S. in Industrial Engineering and Operations Research from King Fahd University of Petroleum and Minerals (KFUPM), Saudi Arabia.
Dr. Hajjar’s research lies in the area of medical decision making and operational efficiency in healthcare delivery systems. His primary methodological and computational research interest is stochastic optimization, in particular completely and partially observable Markov decision processes (MDPs). During his graduate studies, his research focused on personalizing the screening decisions for patients with multiple chronic conditions (MCC).
At ITA, he is working with Dr. Jagpreet Chhatwal on research projects related to nonalcoholic fatty liver disease (NAFLD) and screening for Hepatocellular Carcinoma (HCC).
Selected Publications
2024
Chhatwal, Jagpreet; Hajjar, Ali; Mueller, Peter P; Nemutlu, Gizem; Kulkarni, Neeti; Peters, Mary Linton B; Kanwal, Fasiha
Hepatocellular Carcinoma Incidence Threshold for Surveillance in Virologically Cured Hepatitis C Individuals Journal Article
In: Clin Gastroenterol Hepatol, vol. 22, iss. 1, pp. 91-101, 2024, ISSN: 1542-7714.
@article{pmid37302445,
title = {Hepatocellular Carcinoma Incidence Threshold for Surveillance in Virologically Cured Hepatitis C Individuals},
author = {Jagpreet Chhatwal and Ali Hajjar and Peter P Mueller and Gizem Nemutlu and Neeti Kulkarni and Mary Linton B Peters and Fasiha Kanwal},
doi = {10.1016/j.cgh.2023.05.024},
issn = {1542-7714},
year = {2024},
date = {2024-01-01},
urldate = {2024-01-01},
journal = {Clin Gastroenterol Hepatol},
volume = {22},
issue = {1},
pages = {91-101},
abstract = {BACKGROUND \& AIMS: Guidelines recommend biannual surveillance for hepatocellular carcinoma (HCC) in hepatitis C individuals with cirrhosis if the HCC incidence rate is above 1.5 per 100 person-years (PY). However, the incidence threshold for surveillance in individuals who achieve a virologic cure is unknown. We estimated the HCC incidence rate above which routine HCC surveillance is cost-effective in this growing population of virologically cured hepatitis C individuals with cirrhosis or advanced fibrosis.nnMETHODS: We developed a Markov-based microsimulation model of the natural history of HCC in individuals with hepatitis C who achieved virologic cure with oral direct-acting antivirals. We used published data on the natural history of hepatitis C, competing risk post virologic cure, HCC tumor progression, real-world HCC surveillance adherence, contemporary HCC treatment options and associated costs, and utilities of different health states. We estimated the HCC incidence above which biannual HCC surveillance using ultrasound and alpha-fetoprotein would be cost-effective.nnRESULTS: In virologically cured hepatitis C individuals with cirrhosis or advanced fibrosis, HCC surveillance is cost-effective if HCC incidence exceeds 0.7 per 100 PY using $100,000 per quality-adjusted life year willingness-to-pay. At this HCC incidence, routine HCC surveillance would result in 2650 and 5700 additional life years per 100,000 cirrhosis and advanced fibrosis persons, respectively, compared with no surveillance. At $150,000 willingness-to-pay, surveillance is cost-effective if HCC incidence exceeds 0.4 per 100 PY. Sensitivity analysis showed that the threshold mostly remained below 1.5 per 100 PY.nnCONCLUSIONS: The contemporary HCC incidence threshold is much lower than the previous 1.5% incidence value used to guide HCC surveillance decisions. Updating clinical guidelines could improve the early diagnosis of HCC.},
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BACKGROUND & AIMS: Guidelines recommend biannual surveillance for hepatocellular carcinoma (HCC) in hepatitis C individuals with cirrhosis if the HCC incidence rate is above 1.5 per 100 person-years (PY). However, the incidence threshold for surveillance in individuals who achieve a virologic cure is unknown. We estimated the HCC incidence rate above which routine HCC surveillance is cost-effective in this growing population of virologically cured hepatitis C individuals with cirrhosis or advanced fibrosis.nnMETHODS: We developed a Markov-based microsimulation model of the natural history of HCC in individuals with hepatitis C who achieved virologic cure with oral direct-acting antivirals. We used published data on the natural history of hepatitis C, competing risk post virologic cure, HCC tumor progression, real-world HCC surveillance adherence, contemporary HCC treatment options and associated costs, and utilities of different health states. We estimated the HCC incidence above which biannual HCC surveillance using ultrasound and alpha-fetoprotein would be cost-effective.nnRESULTS: In virologically cured hepatitis C individuals with cirrhosis or advanced fibrosis, HCC surveillance is cost-effective if HCC incidence exceeds 0.7 per 100 PY using $100,000 per quality-adjusted life year willingness-to-pay. At this HCC incidence, routine HCC surveillance would result in 2650 and 5700 additional life years per 100,000 cirrhosis and advanced fibrosis persons, respectively, compared with no surveillance. At $150,000 willingness-to-pay, surveillance is cost-effective if HCC incidence exceeds 0.4 per 100 PY. Sensitivity analysis showed that the threshold mostly remained below 1.5 per 100 PY.nnCONCLUSIONS: The contemporary HCC incidence threshold is much lower than the previous 1.5% incidence value used to guide HCC surveillance decisions. Updating clinical guidelines could improve the early diagnosis of HCC.
2023
Lu, Yifan; Hajjar, Ali; Cryns, Vincent L; Trentham-Dietz, Amy; Gangnon, Ronald E; Heckman-Stoddard, Brandy M; Alagoz, Oguzhan
Breast cancer risk for women with diabetes and the impact of metformin: A meta-analysis Journal Article
In: Cancer Med, vol. 12, no. 10, pp. 11703–11718, 2023, ISSN: 2045-7634.
@article{pmid36533539,
title = {Breast cancer risk for women with diabetes and the impact of metformin: A meta-analysis},
author = {Yifan Lu and Ali Hajjar and Vincent L Cryns and Amy Trentham-Dietz and Ronald E Gangnon and Brandy M Heckman-Stoddard and Oguzhan Alagoz},
doi = {10.1002/cam4.5545},
issn = {2045-7634},
year = {2023},
date = {2023-05-01},
journal = {Cancer Med},
volume = {12},
number = {10},
pages = {11703--11718},
abstract = {BACKGROUND: Diabetes mellitus has been associated with increased breast cancer (BC) risk; however, the magnitude of this effect is uncertain. This study focused on BC risk for women with type 2 diabetes mellitus (T2DM).nnMETHODS: Two separate meta-analyses were conducted (1) to estimate the relative risk (RR) of BC for women with T2DM and (2) to evaluate the risk of BC for women with T2DM associated with the use of metformin, a common diabetes treatment. In addition, subgroup analyses adjusting for obesity as measured by body mass index (BMI) and menopausal status were also performed. Studies were identified via PubMed/Scopus database and manual search through April 2021.nnRESULTS: A total of 30 and 15 studies were included in the first and second meta-analyses, respectively. The summary RR of BC for women with T2DM was 1.15 (95% confidence interval [CI], 1.09-1.21). The subgroup analyses adjusting BMI and adjusting BMI and menopause resulted in a summary RR of 1.22 (95% CI, 1.15-1.30) and 1.20 (95% CI, 1.05-1.36), respectively. For women with T2DM, the summary RR of BC was 0.82 (95% CI, 0.60-1.12) for metformin users compared with nonmetformin users.nnCONCLUSIONS: Women with T2DM were more likely to be diagnosed with BC and this association was strengthened by adjusting for BMI and menopausal status. No statistically significant reduction of BC risk was observed among metformin users.nnIMPACT: These two meta-analyses can inform decision-making for women with type 2 diabetes regarding their use of metformin and the use of screening mammography for early detection of breast cancer.},
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BACKGROUND: Diabetes mellitus has been associated with increased breast cancer (BC) risk; however, the magnitude of this effect is uncertain. This study focused on BC risk for women with type 2 diabetes mellitus (T2DM).nnMETHODS: Two separate meta-analyses were conducted (1) to estimate the relative risk (RR) of BC for women with T2DM and (2) to evaluate the risk of BC for women with T2DM associated with the use of metformin, a common diabetes treatment. In addition, subgroup analyses adjusting for obesity as measured by body mass index (BMI) and menopausal status were also performed. Studies were identified via PubMed/Scopus database and manual search through April 2021.nnRESULTS: A total of 30 and 15 studies were included in the first and second meta-analyses, respectively. The summary RR of BC for women with T2DM was 1.15 (95% confidence interval [CI], 1.09-1.21). The subgroup analyses adjusting BMI and adjusting BMI and menopause resulted in a summary RR of 1.22 (95% CI, 1.15-1.30) and 1.20 (95% CI, 1.05-1.36), respectively. For women with T2DM, the summary RR of BC was 0.82 (95% CI, 0.60-1.12) for metformin users compared with nonmetformin users.nnCONCLUSIONS: Women with T2DM were more likely to be diagnosed with BC and this association was strengthened by adjusting for BMI and menopausal status. No statistically significant reduction of BC risk was observed among metformin users.nnIMPACT: These two meta-analyses can inform decision-making for women with type 2 diabetes regarding their use of metformin and the use of screening mammography for early detection of breast cancer.
2022
Mueller, Peter P.; Chen, Qiushi; Ayer, Turgay; Nemutlu, Gizem; Hajjar, Ali; Bethea, Emily D.; Peters, Mary Linton B.; Lee, Brian P.; Janjua, Naveed Z.; Kanwal, Fasiha; Chhatwal, Jagpreet
Duration and cost-effectiveness of hepatocellular carcinoma surveillance in hepatitis C patients after viral eradication. Journal Article
In: Journal of hepatology, vol. 77, iss. 1, pp. 55-62, 2022, ISSN: 1600-0641.
@article{Mueller2022,
title = {Duration and cost-effectiveness of hepatocellular carcinoma surveillance in hepatitis C patients after viral eradication.},
author = {Peter P. Mueller and Qiushi Chen and Turgay Ayer and Gizem Nemutlu and Ali Hajjar and Emily D. Bethea and Mary Linton B. Peters and Brian P. Lee and Naveed Z. Janjua and Fasiha Kanwal and Jagpreet Chhatwal},
url = {https://pubmed.ncbi.nlm.nih.gov/35157959/},
doi = {10.1016/j.jhep.2022.01.027},
issn = {1600-0641},
year = {2022},
date = {2022-07-01},
urldate = {2022-02-01},
journal = {Journal of hepatology},
volume = {77},
issue = {1},
pages = {55-62},
abstract = {Successful treatment of chronic hepatitis C with oral direct-acting antiviral (DAA) leads to virological cure, however, the subsequent risk of hepatocellular carcinoma (HCC) persists. Our objective was to evaluate the cost-effectiveness of biannual surveillance for HCC in patients cured of hepatitis C and the optimal age to stop surveillance. We developed a microsimulation model of the natural history of HCC in hepatitis C individuals with advanced fibrosis or cirrhosis who achieved virological cure with oral DAAs. We used published data on HCC incidence, tumor progression, real-world HCC surveillance adherence, and costs and utilities of different health states. We compared biannual HCC surveillance using ultrasound and alpha-fetoprotein for varying durations of surveillance (from 5 years to lifetime) versus no surveillance. In virologically-cured patients with cirrhosis, the ICER of biannual surveillance remained below $150,000 per additional quality-adjusted life year (QALY) (range: $79,500-$94,800) when surveillance was stopped at age 70, irrespective of the start age (40-65). Compared with no surveillance, surveillance per 1000 cirrhosis patients detected 130 additional HCCs in 'very early'/early stage and yielded 51 additional QALYs. In virologically-cured patients with advanced fibrosis, the ICER of biannual surveillance remained below $150,000/QALY (range: $124,600-$129,800) when surveillance was stopped at age 60, irrespective of the start age (40-50). Compared with no surveillance, surveillance per 1000 advanced fibrosis patients detected 24 additional HCCs in 'very early'/early stage and yielded 12 additional QALYs. Biannual surveillance for HCC in virologically-cured hepatitis C patients is cost-effective until the age of 70 for cirrhosis patients, and until the age of 60 for patients with stable advanced fibrosis. Individuals who are cured of hepatitis C using oral antiviral drugs remain at risk of developing liver cancer. The value of lifelong screening for liver cancer in these individuals is not known. By simulating the life course of hepatitis C cured individuals, we found that ultrasound-based bi-annual screening for liver cancer is cost-effective up to age 70 in those having cirrhosis and up to age 60 in those having stable advanced fibrosis.},
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pubstate = {published},
tppubtype = {article}
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Successful treatment of chronic hepatitis C with oral direct-acting antiviral (DAA) leads to virological cure, however, the subsequent risk of hepatocellular carcinoma (HCC) persists. Our objective was to evaluate the cost-effectiveness of biannual surveillance for HCC in patients cured of hepatitis C and the optimal age to stop surveillance. We developed a microsimulation model of the natural history of HCC in hepatitis C individuals with advanced fibrosis or cirrhosis who achieved virological cure with oral DAAs. We used published data on HCC incidence, tumor progression, real-world HCC surveillance adherence, and costs and utilities of different health states. We compared biannual HCC surveillance using ultrasound and alpha-fetoprotein for varying durations of surveillance (from 5 years to lifetime) versus no surveillance. In virologically-cured patients with cirrhosis, the ICER of biannual surveillance remained below $150,000 per additional quality-adjusted life year (QALY) (range: $79,500-$94,800) when surveillance was stopped at age 70, irrespective of the start age (40-65). Compared with no surveillance, surveillance per 1000 cirrhosis patients detected 130 additional HCCs in 'very early'/early stage and yielded 51 additional QALYs. In virologically-cured patients with advanced fibrosis, the ICER of biannual surveillance remained below $150,000/QALY (range: $124,600-$129,800) when surveillance was stopped at age 60, irrespective of the start age (40-50). Compared with no surveillance, surveillance per 1000 advanced fibrosis patients detected 24 additional HCCs in 'very early'/early stage and yielded 12 additional QALYs. Biannual surveillance for HCC in virologically-cured hepatitis C patients is cost-effective until the age of 70 for cirrhosis patients, and until the age of 60 for patients with stable advanced fibrosis. Individuals who are cured of hepatitis C using oral antiviral drugs remain at risk of developing liver cancer. The value of lifelong screening for liver cancer in these individuals is not known. By simulating the life course of hepatitis C cured individuals, we found that ultrasound-based bi-annual screening for liver cancer is cost-effective up to age 70 in those having cirrhosis and up to age 60 in those having stable advanced fibrosis.
Ergun, Mehmet A; Hajjar, Ali; Alagoz, Oguzhan; Rampurwala, Murtuza
Optimal breast cancer risk reduction policies tailored to personal risk level Journal Article
In: Health Care Manag Sci, 2022, ISSN: 1386-9620.
@article{pmid35687269,
title = {Optimal breast cancer risk reduction policies tailored to personal risk level},
author = {Mehmet A Ergun and Ali Hajjar and Oguzhan Alagoz and Murtuza Rampurwala},
doi = {10.1007/s10729-022-09596-2},
issn = {1386-9620},
year = {2022},
date = {2022-06-01},
journal = {Health Care Manag Sci},
abstract = {Depending on personal and hereditary factors, each woman has a different risk of developing breast cancer, one of the leading causes of death for women. For women with a high-risk of breast cancer, their risk can be reduced by two main therapeutic approaches: 1) preventive treatments such as hormonal therapies (i.e., tamoxifen, raloxifene, exemestane); or 2) a risk reduction surgery (i.e., mastectomy). Existing national clinical guidelines either fail to incorporate or have limited use of the personal risk of developing breast cancer in their proposed risk reduction strategies. As a result, they do not provide enough resolution on the benefit-risk trade-off of an intervention policy as personal risk changes. In addressing this problem, we develop a discrete-time, finite-horizon Markov decision process (MDP) model with the objective of maximizing the patient's total expected quality-adjusted life years. We find several useful insights some of which contradict the existing national breast cancer risk reduction recommendations. For example, we find that mastectomy is the optimal choice for the border-line high-risk women who are between ages 22 and 38. Additionally, in contrast to the National Comprehensive Cancer Network recommendations, we find that exemestane is a plausible, in fact, the best, option for high-risk postmenopausal women.},
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Depending on personal and hereditary factors, each woman has a different risk of developing breast cancer, one of the leading causes of death for women. For women with a high-risk of breast cancer, their risk can be reduced by two main therapeutic approaches: 1) preventive treatments such as hormonal therapies (i.e., tamoxifen, raloxifene, exemestane); or 2) a risk reduction surgery (i.e., mastectomy). Existing national clinical guidelines either fail to incorporate or have limited use of the personal risk of developing breast cancer in their proposed risk reduction strategies. As a result, they do not provide enough resolution on the benefit-risk trade-off of an intervention policy as personal risk changes. In addressing this problem, we develop a discrete-time, finite-horizon Markov decision process (MDP) model with the objective of maximizing the patient's total expected quality-adjusted life years. We find several useful insights some of which contradict the existing national breast cancer risk reduction recommendations. For example, we find that mastectomy is the optimal choice for the border-line high-risk women who are between ages 22 and 38. Additionally, in contrast to the National Comprehensive Cancer Network recommendations, we find that exemestane is a plausible, in fact, the best, option for high-risk postmenopausal women.
2019
Hajjar, Ali; Alagoz, Oguzhan
Ëffective Preventive Care Management of Multiple Chronic Conditions" Journal Article
In: SSRN, 2019, ().
@article{hajjar_effective_2019,
title = {\"{E}ffective Preventive Care Management of Multiple Chronic Conditions"},
author = {Ali Hajjar and Oguzhan Alagoz},
url = {https://papers.ssrn.com/sol3/papers.cfm?abstract_id=3398415},
year = {2019},
date = {2019-06-01},
journal = {SSRN},
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Alagoz, Oguzhan; Hajjar, Ali; Chootipongchaivat, Sarocha; Ravesteyn, Nicolien T.; Yeh, Jennifer; Ergun, Mehmet Ali; Koning, Harry J.; Chicoine, Brian; Martin, Barry
Benefits and harms of mammography screening for women with Down syndrome: a collaborative modeling study Journal Article
In: Journal of General Internal Medicine, vol. 34, no. 11, pp. 2374–2381, 2019, ().
@article{alagoz_benefits_2019,
title = {Benefits and harms of mammography screening for women with Down syndrome: a collaborative modeling study},
author = {Oguzhan Alagoz and Ali Hajjar and Sarocha Chootipongchaivat and Nicolien T. Ravesteyn and Jennifer Yeh and Mehmet Ali Ergun and Harry J. Koning and Brian Chicoine and Barry Martin},
url = {https://pubmed.ncbi.nlm.nih.gov/31385214/},
year = {2019},
date = {2019-01-01},
urldate = {2019-01-01},
journal = {Journal of General Internal Medicine},
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Hajjar, Ali; Ergun, Mehmet A.; Alagoz, Oguzhan; Rampurwala, Murtuza
Cost-effectiveness of adjuvant paclitaxel and trastuzumab for early-stage node-negative, HER2-positive breast cancer Journal Article
In: PloS one, vol. 14, no. 6, pp. e0217778, 2019, ().
@article{hajjar_cost-effectiveness_2019,
title = {Cost-effectiveness of adjuvant paclitaxel and trastuzumab for early-stage node-negative, HER2-positive breast cancer},
author = {Ali Hajjar and Mehmet A. Ergun and Oguzhan Alagoz and Murtuza Rampurwala},
url = {https://pubmed.ncbi.nlm.nih.gov/31166995/},
year = {2019},
date = {2019-01-01},
urldate = {2019-01-01},
journal = {PloS one},
volume = {14},
number = {6},
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