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Dr. M. Ehsan Karim is an Assistant Professor at the UBC School of Population and Public Health, a Scientist at the Centre for Health Evaluation and Outcome Sciences (CHÉOS), and a Michael Smith Foundation for Health Research (MSFHR) Scholar. He obtained his PhD in Statistics from UBC. He completed his postgraduate training in the Department of Epidemiology, Biostatistics, and Occupational Health at McGill University, and was also a trainee at the Canadian Network for Observational Drug Effect Studies (CNODES). His current research focuses on causal inference and real-world observational data analyses, in both cross-sectional and longitudinal settings; applications of machine learning approaches in the context of electronic healthcare databases; patient-oriented research and survey sampling methodologies in epidemiologic studies.
I am currently looking for multiple graduate students/postdocs for the following two projects (with methodologic focuses within epidemiologic contexts): (1) Improving Causal Inference Methods in Statistics for Analyzing High-dimensional / Big Data. (2) Developing and Evaluating Causal Inference Methods for Pragmatic Trials to address nonadherence. Graduate students in statistics, biostatistics, epidemiology, economics or computer science with some methodological expertise in statistics and statistical software are encouraged to contact me directly (particularly those with some of the following skills: making data requests, extracting analytic data from administrative / survey databases, running statistical analyses, coding statistical estimators, conducting simulation studies, excellent scientific writing, ability to work on a multidisciplinary team). Interested candidates should email me (at my UBC email address) their complete CV and a cover letter. Only candidates shortlisted will be contacted.
Graduate students in statistics, biostatistics, epidemiology, economics or computer science with somewhat strong methodological expertise in statistics (as well as statistical computing) are encouraged to contact me directly; particularly those with some of the following skills:
- making data requests,
- extracting analytic data from administrative (e.g., health admin) and survey databases (e.g., DHS, NHANES, BRFSS or CCHS),
- running statistical analyses using standard software (e.g., SAS, R or python),
- coding statistical estimators (via SAS macro/IML, R, python or stata mata),
- conducting simulation studies (e.g., in servers, parallel computing, High Performance Computing),
- excellent scientific writing (e.g., demonstrated via peer-reviewed publications),
- ability to work on a multidisciplinary team (e.g., work within biostatistics groups).
See details of instructions to apply here.
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Graduate Student Supervision
Doctoral Student Supervision (Jan 2008 - April 2022)
BACKGROUND: Improvements in and expansion of tuberculosis (TB) diagnosis and treatment have yielded a growing population of TB survivors, with an estimated 155 million alive in 2020. While TB is preventable and curable, there is accumulating evidence of elevated chronic disease risk among survivors. Research objectives: (1) estimate the relative risk of non-TB mortality among TB survivors compared with controls, (2) systematically review the literature on cardiovascular disease (CVD) in TB and latent TB infection, (3) estimate the relative risk of airway disease among respiratory TB survivors compared with controls, and (4) estimate the relative risk of depression among TB survivors compared with controls, mediated by hospital length of stay (LOS).METHODS: A cohort of immigrants to British Columbia, Canada, 1985-2015, with linked health administrative and TB registry data was used for retrospective cohort studies of TB survivor health. Cox proportional hazards (PH) and time-varying models were used in statistical analyses. Causal mediation analysis of depression, mediated by hospital LOS, estimated depression risk. A prospectively registered systematic review and random-effects meta-analysis of TB and CVD was performed. RESULTS: In a time-varying Cox regression of non-TB mortality, an adjusted hazard ratio (aHR) of 1.69 (95% CI:1.50-1.91) was observed between TB exposed and non-TB exposed time. In the systematic review and meta-analysis, we found increased risk of major adverse cardiovascular events (MACE) among TB patients compared with non-TB controls (pooled RR = 1.51; 95% CI: 1.16-1.97). A higher risk of airway disease among respiratory TB survivors compared with non-TB controls was observed in our Cox PH regression (aHR=2.08; 95% CI: 1.91-2.28). In the causal mediation analysis of depression, TB survivors had aHR=1.24 (95% CI: 1.14-1.34) for depression by TB, decomposed into a natural direct effect of aHR=1.11 (95% CI: 1.02-1.21) and indirect effect of aHR=1.11 (95% CI: 1.10-1.12), indicating 50% (95% CI: 35-82%) mediation through hospital LOS.CONCLUSION: TB survivors face higher mortality from non-TB causes, and higher risk of airway disease, CVD, and depression, compared with non-TB controls. Chronic disease screening and models of care development are needed to support TB survivors’ health-related quality of life, during and after TB treatment.
Master's Student Supervision (2010 - 2021)
Participants in pragmatic clinical trials often partially adhere to treatment. In the presence of partial adherence, simple statistical analyses of binary adherence (receiving either full or no treatment) introduce biases. We developed a framework which expands the principal strati cation approach to allow partial adherers to have their own principal stratum and treatment level. We derived consistent estimates for bounds on population values of interest. A Monte Carlo posterior sampling method was derived that is computationally faster than Markov Chain Monte Carlo sampling, with con firmed equivalent results. Simulations indicate that the two methods agree with each other and are superior in most cases to the biased estimators created through standard principal strati cation. The results suggest that these new methods may lead to increased accuracy of inference in settings where study participants only partially adhere to assigned treatment.
- Accurate classification of carotid endarterectomy indication using physician claims and hospital discharge data (2022)
BMC Health Services Research, 22 (1)
- An E-value analysis of potential unmeasured or residual confounding in systematic reviews of post-tuberculosis mortality, respiratory disease, and cardiovascular disease (2022)
Annals of Epidemiology, 68, 24--31
- Considerations for choosing an imputation method for addressing sparse measurement issues dictated by the study design - An illustration from per-protocol analysis in pragmatic trials (2022)
Research Methods in Medicine & Health Sciences,
- Determining the optimal SARS-CoV-2 mRNA vaccine dosing interval for maximum immunogenicity (2022)
- Recommendations for the use of propensity score methods in multiple sclerosis research (2022)
Multiple Sclerosis Journal, , 135245852210857
- The association between diabetes and excessive daytime sleepiness among American adults aged 20–79 years: findings from the 2015–2018 National Health and Nutrition Examination Surveys (2022)
Annals of Epidemiology, 68, 54--63
- The association between rheumatoid arthritis and cardiovascular disease among adults in the United States during 1999–2018, and age-related effect modification in relative and absolute scales (2022)
Annals of Epidemiology, 71, 23--30
- CRTpowerdist: An R package to calculate attained power and construct the power distribution for cross-sectional stepped-wedge and parallel cluster randomized trials (2021)
Computer Methods and Programs in Biomedicine, 208, 106255
- Incorporating partial adherence into the principal stratification analysis framework (2021)
Statistics in Medicine,
- Is Regular Access to Internet Services Associated with Comprehensive Correct HIV/AIDS Knowledge among People Aged 15–49 Years in Nigeria? Findings from the 2018 Demographic Health Survey (2021)
Journal of Consumer Health on the Internet,
- Post-tuberculosis mortality risk among immigrants to British Columbia, Canada, 1985–2015: a time-dependent Cox regression analysis of linked immigration, public health, and vital statistics data (2021)
Canadian Journal of Public Health, 112 (1), 132-141
- Sodium intake and high blood pressure among adults on caloric deficit: a multi-year cross-sectional analysis of the U.S. population, 2007-2018. (2021)
Journal of human hypertension,
- Sodium intake and high blood pressure among adults on caloric restriction: a multi-year cross-sectional analysis of the U.S. Population, 2007-2018 (2021)
- Understanding subjective quality of life in homeless and vulnerably housed individuals: The role of housing, health, substance use, and social support (2021)
SSM - Mental Health, 1, 100021
- When does the use of individual patient data in network meta-analysis make a difference? A simulation study (2021)
BMC Medical Research Methodology, 21 (1)
- A pragmatic randomized controlled trial testing the effects of the international scientific SCI exercise guidelines on SCI chronic pain: protocol for the EPIC-SCI trial (2020)
Spinal Cord, 58 (7), 746--754
- A Propensity Score Analysis of the Effect of a Single Dose Vitamin A Supplementation on Child Hemoglobin Status in Bangladesh (2020)
Child Care in Practice, , 1--15
- Application of decision tree-based techniques to veneer processing (2020)
Journal of Wood Science, 66 (1)
- Are perceived barriers to accessing health care associated with inadequate antenatal care visits among women of reproductive age in Rwanda? (2020)
BMC Pregnancy and Childbirth, 20 (1)
- Association between human papillomavirus vaccine status and sexually transmitted infection outcomes among females aged 18-35 with a history of sexual activity in the United States: A population survey-based cross-sectional analysis (2020)
Vaccine, 38 (52), 8396-8404
- Comparative efficacy, tolerability and safety of dolutegravir and efavirenz 400mg among antiretroviral therapies for first-line HIV treatment: A systematic literature review and network meta-analysis (2020)
- Correction: A pragmatic randomized controlled trial testing the effects of the international scientific SCI exercise guidelines on SCI chronic pain: protocol for the EPIC-SCI trial (2020)
Spinal Cord, 58 (9), 1046--1046
- Explaining the variation in the attained power of a stepped-wedge trial with unequal cluster sizes (2020)
BMC Medical Research Methodology, 20 (1)
- Reply (2020)
Arthritis & Rheumatology, 72 (9), 1583--1584
- The Association of Residential Instability and Hospitalizations among Homeless and Vulnerably Housed Individuals: Results from a Prospective Cohort Study (2020)
Journal of Urban Health, 97 (2), 239-249
- The relationship between mood disorder diagnosis and experiencing an unmet health-care need in Canada: findings from the 2014 Canadian Community Health Survey (2020)
Journal of Mental Health, , 1--13
- The use and quality of reporting of propensity score methods in multiple sclerosis literature: A review (2020)
Multiple Sclerosis Journal,
- Longitudinal associations between perceived quality of living spaces and health-related quality of life among homeless and vulnerably housed individuals living in three canadian cities (2019)
International Journal of Environmental Research and Public Health, 16 (23)
- Multimorbidity prevalence in Canada: a comparison of Northern Territories with Provinces, 2013/14 (2019)
International Journal of Circumpolar Health, 78 (1), 1607703
- Nephrology consultation and mortality in people with stage 4 chronic kidney disease: A population-based study (2019)
CMAJ, 191 (10), E274-E282
- Nurses "Seeing Forest for the Trees" in the Age of Machine Learning: Using Nursing Knowledge to Improve Relevance and Performance. (2019)
Computers, informatics, nursing : CIN,
- Role of Nonsteroidal Antiinflammatory Drugs in the Association Between Osteoarthritis and Cardiovascular Diseases: A Longitudinal Study (2019)
Arthritis & Rheumatology, 71 (11), 1835--1843
- The Effect of Serious Offending on Health: A Marginal Structural Model (2019)
Society and Mental Health, 9 (1), 18-32
- The randomization-induced risk of a trial failing to attain its target power: Assessment and mitigation (2019)
Trials, 20 (1)
- When exposure is subject to nondifferential misclassification, are validation data helpful in testing for an exposure–disease association? (2019)
Canadian Journal of Statistics, 47 (2), 222-237
- Authors' reply: Letter to the Editor: Comparison of statistical approaches dealing with time-dependent confounding in drug effectiveness studies (SMMR, Vol 27, Issue 6, 2018). (2018)
Statistical methods in medical research,
- Can We Train Machine Learning Methods to Outperform the High-dimensional Propensity Score Algorithm? (2018)
Epidemiology (Cambridge, Mass.),
- Comparison of statistical approaches dealing with time-dependent confounding in drug effectiveness studies (2018)
Statistical Methods in Medical Research, 27 (6), 1709-1722
- Effectiveness of contrast-associated acute kidney injury prevention methods; A systematic review and network meta-analysis (2018)
BMC Nephrology, 19 (1)
- Estimating the effect of referral for nephrology care on the survival of adults with advanced chronic kidney disease in a real-world clinical setting (2018)
- Determinants of Antibiotic Tailoring in Pediatric Intensive Care: A National Survey. (2017)
Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies,
- Estimating inverse probability weights using super learner when weight-model specification is unknown in a marginal structural Cox model context (2017)
Statistics in Medicine,
- On the application of statistical learning approaches to construct inverse probability weights in marginal structural Cox models: Hedging against weight-model misspecification (2017)
Communications in Statistics - Simulation and Computation,
- Comparison of Statistical Approaches for Dealing with Immortal Time Bias in Drug Effectiveness Studies (2016)
American Journal of Epidemiology, 184 (4), 325-335
- Hypothesis Testing for an Exposure–Disease Association in Case–Control Studies Under Nondifferential Exposure Misclassification in the Presence of Validation Data: Bayesian and Frequentist Adjustments (2016)
Statistics in Biosciences, 8 (2), 234-252
- THE AUTHORS REPLY. (2016)
American journal of epidemiology,
- Antibody dissociation rates are predictive of neutralizing antibody (NAb) course: A comparison of interferon beta-1b-treated Multiple Sclerosis (MS) patients with transient versus sustained NAbs (2015)
Clinical Immunology, 157 (1), 91-101
- Beta-interferon exposure and onset of secondary progressive multiple sclerosis (2015)
European Journal of Neurology, 22 (6), 990-1000
- Directed Acyclic Graphs to Identify Confounders: A Case Study Exploring the Impact of Hunger on Virologic Suppression Among HIV-Positive Illicit Drug Users Receiving HIV Treatment (2015)
Health of HIV Infected People: Food, Nutrition and Lifestyle with Antiretroviral Drugs, 1, 275-290
- Multiple sclerosis in older adults: The clinical profile and impact of interferon beta treatment (2015)
BioMed Research International, 2015
- Investigation of heterogeneity in the association between interferon beta and disability progression in multiple sclerosis: An observational study (2014)
European Journal of Neurology, 21 (6), 835-844
- Marginal structural cox models for estimating the association between β-interferon exposure and disease progression in a multiple sclerosis cohort (2014)
American Journal of Epidemiology, 180 (2), 160-171
- Can joint replacement reduce cardiovascular risk? (2013)
BMJ (Online), 347
- Interferon beta and long-term disability in multiple sclerosis (2013)
JAMA Neurology, 70 (5), 651-652
- Association between use of interferon beta and progression of disability in patients with relapsing-remitting multiple sclerosis (2012)
JAMA - Journal of the American Medical Association, 308 (3), 247-256