Jeff Brennan

data engineer

I’m a data engineer with a background in public health, motivated by better care for underserved communities. I build reliable data platforms, improve performance, and make working with data easier through thoughtful tooling and mentorship.

At Astrana Health, my work spans a shared Databricks platform, patient matching at a scale of eight million patients, and APIs that bring claims and quality data to care teams. I also contribute to open source and build developer tools, including sparkparse, a parser that helps diagnose Spark performance problems.

Skills

  • Python
  • SQL
  • R
  • Databricks
  • PySpark
  • Polars
  • dbt
  • Azure
  • AWS
  • Databricks Workflows
  • Azure Data Factory
  • Dagster
  • Docker
  • pytest
  • Pydantic
  • Azure DevOps
  • PostgreSQL
  • GraphQL
  • SQL Server
  • Power BI
  • Tableau
  • Plotly Dash

Experience

Data Engineer III at Astrana Health
Jul 2025 - Present

Build healthcare data infrastructure that supports clinicians, clinic managers, and a team of 20+ engineers, data scientists, and analysts.

  • Built a Databricks platform with configuration-driven source onboarding and centralized data-quality management
  • Led delivery of incremental sync and major GraphQL API components over PostgreSQL, bringing claims and quality scores to clinicians and outreach priorities to clinic managers
  • Built an enterprise master patient index for 8M patients as sole engineer, using Splink, deterministic matching constraints, match review, and replayable match history
  • Mentor six engineers on CI/CD and software design, and coach analysts and data scientists daily on platform usage and software engineering practices
  • Lead incident response and root-cause analysis, turning findings into regression tests and platform fixes
  • Co-developed a clinical NLP pipeline with the lead data scientist, using OCR and third-party models to extract diagnoses, procedures, and labs from encounter PDFs for clinician review
Data Engineer at Medisolv
Jul 2023 - Jul 2025

Owned patient-data ingestion and transformation for hundreds of hospital clients, processing 10B+ records weekly into a 150TB+ data lake.

  • Migrated 1,500+ Azure Data Factory pipelines from the portal to source control, adding code review, rollback, one-button deployments, and Pydantic/pytest validation
  • Automated client onboarding with Python and the Azure SDK, reducing setup from over a day of manual work to a five-minute deployment
  • Open sourced sparkparse to expose exploding joins and memory pressure; guided rewrites cut tasks from hours to 10–20 minutes on the same compute
  • Built monitoring with Azure Event Hubs and Power BI that correlated task start/stop events to detect stalled tasks during execution rather than hours later
Data Analyst at NewYork-Presbyterian
Dec 2020 - Jul 2023

Built analytics and quality-reporting workflows for NewYork Quality Care, the accountable care organization of NewYork-Presbyterian, Weill Cornell, and Columbia.

  • Cut Tableau load times from 2–3 minutes to under 10 seconds with pre-aggregated summary tables and a restructured star schema
  • Built the ELT pipeline behind dashboards and measure reporting, processing 100M+ records a week for 35,000 Medicare patients
  • Built address-cleaning and geocoding workflows that prioritized free Census matches and routed low-quality results to paid Esri ArcGIS matching for patient-population mapping
  • Modeled CMS quality scores against sample size to determine reporting depth within the ranked patient sample for a Medicare shared-savings program
Data Engineer (contract) at UTHealth
May 2020 - Sep 2023
Operated the daily data pipeline for UTHealth’s Texas COVID-19 dashboard, integrating state and third-party sources with unit tests and Slack monitoring for data-quality issues.
Research Coordinator I at Baylor College of Medicine
June 2017 - Nov 2019
  • Authored thesis (100+ citations) on biomarkers of traumatic brain injury (TBI) and provided data support for other research efforts
  • Applied variable selection on hundreds of biomarker combinations to identify TBI predictors
  • Built analysis pipelines and created publication-ready data visualization in R

Education

2018 - 2020
Master of Science in Epidemiology
UTHealth Houston
GPA: 3.8
  • Minored in biostatistics, with a thesis on biomarkers of traumatic brain injury (TBI)
  • Coursework included biostatistics, applied machine learning, and study design
2014 - 2018
Bachelor of Science in Public Health
University of Texas at Austin
GPA: 3.7

Studied public health, with coursework spanning biostatistics, infectious disease microbiology, and global health.

Extracurricular Activities

  • President of SURGe - a student-led organization connecting STEM faculty with students needing research experience

Projects

Spark metrics parser that exposes exploding joins and memory pressure to guide performance improvements
Combat sports database and dashboard
Small data cleaning project to create a personalized movie database for my friend
PySpark helper library downloaded 600k+ times per month
Collection of epidemiology data powering the UTHealth COVID-19 dashboard