Our Story

At Quotient Health, we believe great medicine starts with knowing you, not just your symptoms, but your complete health story.

Take Charge of Your Health

We go beyond traditional primary care with longevity as our mission.

Clarity Starts Here.

Dr. Justin Greiwe, MD

Dr. Ryan Collar, MD, MBA

Our Team of Experts

Dr. Justin Greiwe, MD

Co-Founder & Head of Longevity Medicine

An immunologist and longevity specialist dedicated to advancing proactive, data-driven care.

Renowned for his work with the Cleveland Clinic and Bernstein Allergy Group.

Dr. Ryan Collar, MD, MBA

Co-Founder & CEO

A distinguished plastic surgeon, healthcare innovator, and entrepreneur.

Previously Co-Founder & CSO at Invisible Ink (now Removery).

Dr. Katie Sheridan, MD, MSCP

Head of Primary Care & Menopause Specialist
Family medicine physician committed to personalized, prevention-focused care. Expert in menopause and midlife hormonal health.

With a distinguished background at The Ohio State University College of Medicine and TriHealth.

John Zerbe, MD

Internal Medicine & Primary Care

Board-certified internal medicine physician dedicated to optimizing wellness.

Former Global Medical Director at GE Aviation, CEO of The Zerbe Wellness Center, and former team physician for the Cincinnati Reds and Cincinnati Bengals.

Jack McDonnell, MD, MS

Immunologist
& Data Scientist

Expert in translating complex health data into actionable insights.

Having held key positions at Cleveland Clinic and Case Western Reserve University.

Jason Harbin

Head of Fitness & Wellness

Health & performance coach known for results-driven, data-informed programs.

Extensive experience as a personal trainer, coach, and fitness expert.

Quotient Cares

Quotient Health champions our community by partnering with local artists, chefs, and creators to elevate wellness through connection and culture.