Dear Bahar,

Although the two methods are looking backwards for the past collected data (e.g Medical Records), still there is a huge difference between the two. for example, the Retrospective chart review (RCR) aims to Identify patterns or trends, while Retrospectives cohort study (RCS) is to compare outcomes between exposed and unexposed groups. the RCR is cross-sectional explanatory, and the RCS is a follow up over time. Therefore, RCR is quick and relatively inexpensive, unlike the RCS which might take more time and cost and can provide stronger evidence of causality.

Hi Dear Izzeldin,

Thank you so much for your answer. I have the protocol from Resecker in which they mentioned:

"This study will be a comparison between before and after implementation of a program using data collected through a retrospective chart review.

The program was implemented at their clinic site in 2023.

The study will compare data collected 1-year prior to (2022), the transitional period of implementation (2023) and 1-year post (2024) implementation."

so they considered looking at 3 time periods

1. Pre implementation (1 year)

2. Implementation (1 year) or “transition”

3. Post implementation (1 year).

I was thinking of suggesting them to exclude the transitional period, as the goal is to compare some outcome variables pre and post-implementation

I would appreciate it if you have any insight on this.

Bahar

It really seems to make sense to exclude the transition period, as the idea is to compare two periods, before and after, that is, 2022 and 2024. 2023 is just the implementation period.