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What is Cohort Definition Builder?

Atlas is a web-based tool developed by OHDSI for exploring and visualizing health data. Atlas allows users to define cohorts of patients based on specific criteria, such as age, gender, clinical conditions, and medications

The problem: 

The overall user interface of the cohort definition builder is complex and lacks user-friendly features, making it more challenging for users, especially those new to the platform, to navigate and understand.

The goal: 

Simplify the user interface to make it more intuitive for users at all skill levels. Streamline the cohort definition process to reduce the time and effort required from users.

Design Methodology

Research Questions

I conducted user research by interviewing pharmacists to understand their workflow and challenges. The insights gathered will help inform the design and usability improvements of the cohort definition tool.

Competitive Analysis

Empathy Map

User Persona

Brainstorming

Participants: Designers, developers, pharmacists, product managers

Typography & Colors

UX Audit

UI Elements

Comparing Old and New Design

Impact on Me

• Improved my ability to think critically about complex healthcare workflows and translate them into user-friendly interfaces.

• Strengthened my decision-making and problem-solving skills by balancing usability with technical constraints.

• Enhanced my portfolio with a high-fidelity redesign of a domain-specific, data-heavy product.

• Learned to create and maintain a design system, ensuring consistency across complex UI components.

• Gained deeper knowledge of cohort-building logic (single criteria, group criteria, temporal logic), which broadened my understanding of healthcare analytics tools.

Impact on the User

• Reduced cognitive load by presenting a cleaner, more intuitive interface for creating cohorts.

• Increased efficiency by simplifying drag-and-drop interactions and criteria grouping, enabling faster cohort creation.

• Minimized errors in defining cohorts with clearer visual cues, guidance, and consistency across steps.

• Improved accessibility and usability for both new and experienced users, making the tool more approachable.

Impact on the Business

• Enhanced adoption of the product by making it easier for healthcare professionals to define cohorts accurately.

• Reduced training time and support costs because the redesigned interface is more intuitive.

• Increased trust and credibility of the platform by delivering a professional, user-centered experience.

• Supported better data-driven decision-making in healthcare research, strengthening the company’s value proposition in the competitive market.