Nudging High-acuity Emergency Department Patients to Schedule a Follow-up Visit With a Primary Care Provider or Specialist Following Discharge to Decrease Emergency Department Utilization
Phase: NA
Conditions: Emergency Service, Hospital
Sponsor: Geisinger Clinic

 
Nudging High-acuity Emergency Department Patients to Schedule a Follow-up Visit 
(NCT06535347) 
 
Study Protocol with Statistical Analysis Plan 
 
 
August 9, 2024 
 
 
 
 

 
Study Protocol 
 
Background 
 
The goal of this campaign is to reduce unnecessary emergency department (ED) 
visits/encourage patients with high acuity visits who have a Geisinger primary care provider 
(PCP) in the Community Medicine Service Line (CMSL) assigned to follow up with an 
appropriate provider (their PCP or a specialist) in the future. In this campaign, patients will be 
assigned to receive or not receive outreach following ED discharge that is aligned with this goal. 
Outreach will occur via a text message, as well as information added to the patient's after visit 
summary (AVS), and will include a call to action for the patient to schedule a follow-up 
appointment with their PCP or a specialist. The SMS messages and AVS will include a phone 
number to call to schedule an appointment. The SMS messages will also include a hyperlink to 
self-schedule an appointment. The study will assess whether ED use differs across patients in 
different outreach conditions. It will also examine whether patients followed through on the 
message-specific calls to action in the messages differently across conditions. 
 
Objectives 
 
The study will involve randomized assignment of patients to different versions of outreach, 
including a treatment arm that encourages patients in non-emergent situations to call their 
PCP’s office or a specialist. Patients will also be provided a number to call through which they 
can schedule an appointment with a provider. SMS messages will include a hyperlink to self-
schedule an appointment with a provider. Both SMS text messages (at 1 day, or 1 day and 8 
days, post-discharge) and AVS (printed or available via patient portal upon discharge) will be 
used for active outreach. The control arm will receive the current standard system outreach and 
AVS. Data will be analyzed to determine which version is most effective at reducing ED use. 
 
Design  
 
This study is a randomized controlled trial with three study arms. Patients will be randomized to 
receive or not receive SMS texts (at 1 day or 1 and 8 days post discharge) and a modified AVS 
upon ED discharge. 
 
Methods 
 
At the time of an eligible patient’s discharge from the ED, that patient will be assigned to one of 
the following study arms, based on which of several ranges of randomized numbers that patient 
was originally assigned in their electronic chart: 
 
1. Current standard practice (control arm): Patients in this arm will receive the current 
standard AVS and whatever typical system outreach occurs. 
2. Follow-up scheduling single notice (treatment arm): Patients in this arm will receive 
suggestions for non-ED follow-up care with their PCP or a specialist via SMS messages 
at 1 day post discharge and in their AVS. The outreach will include a scheduling phone 
number to call. SMS messages will include a hyperlink to self-schedule with a Geisinger 
provider. 
3. Follow-up scheduling notice plus reminder (treatment arm): Patients in this arm will 
receive suggestions for non-ED follow-up care with their PCP or a specialist via SMS 
messages at 1 and 8 days post discharge and in their AVS. The outreach will include a 

 
scheduling phone number to call. SMS messages will include a hyperlink to self-
schedule with a Geisinger provider. 
 
 
Power Analysis 
 
With 7,500 patients, we would have 80% power to detect a 3.0% absolute decrease in ED visits 
between each active arm and the control arm, with two-tailed alpha of .15, assuming a 33% 
baseline rate of subsequent ED visits within 120 days. The target effect size and number of 
patients are largely informed by practical considerations regarding the acceptable duration of 
the intervention (maximum of 6 months, regardless of whether the full sample is achieved), with 
an effect deemed useful if achieved. 
 
 
Project Status 
 
As of August 9, 2024, when this document was uploaded, no messages have been sent or data 
collected or analyzed. 
 
Statistical Analysis Plan 
 
Planned Analyses 
 
Primary Outcome: ED visit [Time Frame: within 120 days following day of discharge] 
 
Question: Does outreach decrease ED visits when including information about follow-up care? 
 
Analysis (Confirmatory): We will test the hypothesis that SMS text plus AVS outreach (with or 
without reminder) decreases the likelihood patients will visit the ED in the 120 days following 
day of discharge.  We will run an OLS regression including a categorical predictor variable 
coding for experimental arm (0 = control arm, 1 = single message arm, 2 = message plus 
reminder arm).  
 
Other Pre-specified Outcomes 
 
We will run the analysis described above on the following additional outcomes: 
 
1. PCP/specialist appointment scheduled 
 
PCP/specialist appointment scheduled (yes/no) 
 
[Time Frame: within 7 days following day of discharge] 
 
2. PCP/specialist visit attended 
 
PCP/specialist appointment attended (yes/no) 
 
[Time Frame: within 7 days following day of discharge] 
 

 
3. PCP/specialist appointment scheduled 
 
PCP/specialist appointment scheduled (yes/no) 
 
[Time Frame: within 14 days following day of discharge] 
 
4. PCP/specialist visit attended 
 
PCP/specialist appointment attended (yes/no) 
 
[Time Frame: within 14 days following day of discharge] 
 
5. PCP/specialist appointment scheduled 
 
PCP/specialist appointment scheduled (yes/no) 
 
[Time Frame: within 30 days following day of discharge] 
 
6. PCP/specialist visit attended 
 
PCP/specialist appointment attended (yes/no) 
 
[Time Frame: within 30 days following day of discharge] 
 
7. PCP/specialist appointment scheduled 
 
PCP/specialist appointment scheduled (yes/no) 
 
[Time Frame: within 60 days following day of discharge] 
 
8. PCP/specialist visit attended 
 
PCP/specialist appointment attended (yes/no) 
 
[Time Frame: within 60 days following day of discharge] 
 
 
 
Analysis Notes 
 
Recent work suggests that OLS regressions are appropriate in randomized experiments with 
binary outcome variables such as ours (Gomila, 2021).  
 
 
 

 
Reference 
 
Gomila, R. (2021). Logistic or linear? Estimating causal effects of experimental treatments on 
binary outcomes using regression analysis. Journal of Experimental Psychology: 
General, 150(4), 700-709. https://doi.org/10.1037/xge0000920