The document compares the waterfall and agile models for software development. The waterfall model follows sequential phases from requirements to deployment, while agile uses iterative development and allows changes throughout. For medical device software, the FDA has protocols for waterfall but agile requires design controls and reviews. Design controls include updating documentation at each stage. Reviews involve verifying code meets requirements through testing at each sprint. Agile is suitable when requirements are unclear, but both models require FDA compliance for medical software.

1. Agile vs. Waterfall Model
By: Govind Pramod Yatnalkar
One of the widely accepted software design patterns is the Waterfall model in which all
activities, starting from requirement gathering until the deployment are followed sequentially. It
uses clear structures, transforms information well, and targets concrete goals. Even though it is
popular, it does have several shortcomings:
 No room for incorporating new changes until the current phase is completed.
 No involvement of clients and end-users throughout all phases.
 Delay in testing and deployment phases (as major changes cannot be included).
Considering these limitations, the Agile design pattern was created. It uses the iterative
software development method in which software might receive new requirements or may
undergo design changes in any phase of development1. Also, elements like Sprint and
Continuous Integration with Continuous Deployment (CICD) facilitate the involvement of
product owners or clients along with their feedback in all phases.
Software developed for a medical device must be compliant with the FDA regulations at a
minimum. FDA defines standard protocols for software developed using the Waterfall model.
But, in the case of Agile, in which the changes given by the clients or by the design team are
implemented at any software life cycle stages, what factors play key roles in FDA regulatory
processes?
The two significant parameters considered are Design Controls and Reviews. In the
following context, Story is defined as a feature discussed from a user perspective. Also, Sprint is
a period of 2 or 3 weeks where the product owners along with the development and testing team
reviews the current state of the software. The following are Design Controls activities for
regulating Agile-based software:
 Requirement gathering and planning – Update project plan and forecast document.
 Architecture and Story design – Update system architecture, SRS, traceability
documents, and verification protocols.
 Risk evaluation of Stories – Update risk document.
 Programming and testing with CICD – Update SDS and traceability document.
 Demo phase – Document design review.
 User testing – Update usability summary and risk management documents.
 Risk evaluation – Update risk document.
1
Neetu Yadav (December 2016), FDA Perspective on AgileMethodology: HealthcareEnvironment, Retrieved on
08/12/2020 from https://www.linkedin.com/pulse/fda-perspective-agile-methodology-healthcare-neetu-yadav/.

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 Testing (System, Acceptance) – Update test reports.
 Retrospect/ Working on past software activities – Update software development plan.
Moreover, Design Review is constituted by the Software Verification and Validation. In Agile,
software verification is conducted right from the very first User Story which results in the
following activity mapping: User Story  Code/ Programs  Unit level testing  System
testing. Validation is carried out by clients or end-users in which they test the overall
functionality along with the data flow via product demos or reviews conducted at the end of
every Sprint.2
To sum up, for software that possesses a complex design and requirements are not clear,
Agile is a perfect design pattern. Additionally, it is essential that software developed with
Waterfall or the Agile model and running in a medical setting needs to be FDA compliant. Do
you need help ensuring your medical device software is compliant with FDA’s requirements?
Our regulatory experts at EMMA International can help your software product become
compliant. Contact us at 248-987-4497 or info@emmainternational.com for additional
information.
2
Bernhard Kappe (2013),Ebook: Agilein an FDA Regulated Environment. Retrieved on 08/12/2020 from
https://orthogonal.io/insights/ebook-agile-in-an-fda-regulated-environment/.