#52601 | AsPredicted

As Predicted:UPDATE_47510 BCFG Flu Shot Mega-Study - Penn/Geisinger (#52601)


Created:       11/19/2020 08:55 AM (PT)

This is an anonymized version of the pre-registration.  It was created by the author(s) to use during peer-review.
A non-anonymized version (containing author names) should be made availble by the authors when the work it supports is made public.

1) Have any data been collected for this study already?
It's complicated. We have already collected some data but explain in Question 8 why readers may consider this a valid pre-registration nevertheless.

2) What's the main question being asked or hypothesis being tested in this study?
See AsPredicted #47510.

3) Describe the key dependent variable(s) specifying how they will be measured.
See AsPredicted #47510.

4) How many and which conditions will participants be assigned to?
See AsPredicted #47510.

5) Specify exactly which analyses you will conduct to examine the main question/hypothesis.
See AsPredicted #47510.

6) Describe exactly how outliers will be defined and handled, and your precise rule(s) for excluding observations.
See AsPredicted #47510.

7) How many observations will be collected or what will determine sample size?
No need to justify decision, but be precise about exactly how the number will be determined.

We will recruit as many patients as possible with new or routine (non-sick) primary care appointments at Penn Medicine and Geisinger Health starting in September 2020. Participants will be enrolled in one of several studies launching in parallel if they meet the following criteria:
1. They have a cell phone number recorded in the Penn Medicine database or the Geisinger Health database
2. They have not opted out of receiving SMS appointment reminders
3. They do not have a documented allergy or adverse reaction to the flu vaccine
4. They have not already had a flu vaccination in 2020, as documented in their electronic health records.

We will stop enrolling participants with appointments scheduled to occur after December 31, 2020 if we have reached 4,000 participants per condition. If we do not have 4,000 participants per condition by December 31, 2020, we will continue enrolling participants until we have reached 4,000 per condition, or until March 31, 2021 (discontinuing enrollment at whichever milestone arrives sooner – 4,000 people enrolled or 3/31/21). A sample size of 4,000 participants per condition will give us 80% power to detect a 3% difference in flu shot uptake between conditions.

8) Anything else you would like to pre-register?
(e.g., secondary analyses, variables collected for exploratory purposes, unusual analyses planned?)

This pre-registration is an update to pre-registration #47510. We are updating the stopping rule (question 7). Rather than enrolling participants through the end of March 2021 if we do not reach 4,000 per condition by December 31, 2020, we will continue enrolling participants until we have reached 4,000 per condition, or until March 31, 2021 (discontinuing enrollment at whichever milestone arrives sooner – 4,000 people enrolled or 3/31/21). The study launched in September 2020, but no outcome data has been analyzed.