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Encouraging Flu Vaccination Among High-Risk Patients Identified by ML

Encouraging Flu Vaccination Among High-Risk Patients Identified by a Machine-Learning Model of Flu Complication Risk

Status
Completed
Phases
NA
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT04323137
Enrollment
117649
Registered
2020-03-26
Start date
2020-09-21
Completion date
2021-09-21
Last updated
2024-12-30

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Health Behavior, Health Promotion, Influenza, Risk Reduction, Vaccination

Keywords

Flu Vaccine, Choice Architecture, Machine Learning, Perceived Credibility

Brief summary

The purpose of the current study is to test different interventions to determine the most effective way to promote flu vaccine uptake in a high-risk population identified by an artificial intelligence (AI) or machine learning (ML) algorithm. The specific aims are: 1. Evaluate the effect on flu vaccination rates of informing health-system patients who are identified by an ML analysis of EHR data to be at high risk for flu complications that they are at high risk with either (a) no additional explanation, (b) an explanation that this determination comes from an analysis of their medical records, and (c) the additional explanation that an AI or ML algorithm made this determination. 2. Evaluate the effects of the same three interventions on diagnoses of flu in the same patients.

Detailed description

Background On average, 8% of the US population gets sick from flu each flu season (Tokars et al. 2018). Since 2010, the annual disease burden of influenza has included 9-45 million illnesses, 140,000-810,000 hospitalizations, and 12,000-61,000 deaths (CDC 2020). The CDC recommends the flu vaccination to everyone aged 6+ months, with rare exception; almost anyone can benefit from the vaccine, which can reduce illnesses, missed work, hospitalizations, and death (CDC 2019a). Flu vaccination will be especially important for high-risk patients during the COVID-19 pandemic so that flu cases are reduced and resources conserved. While most recover from influenza without treatment, the elderly, those with comorbidities, and other high-risk individuals can experience complications such as pneumonia, other respiratory illness, and death. Geisinger, a large health system in Pennsylvania and New Jersey, has partnered with Medial EarlySign (Medial; www.earlysign.com) to develop a machine learning (ML) algorithm to identify patients at risk for serious (moderate to severe) flu-associated complications on the basis of their existing electronic health record (EHR) data. Geisinger will deploy this system during the 2020-21 flu season and contact the identified patients with special messages (in addition to standard efforts made by the health system every flu season) to encourage vaccination. Flu vaccination will be especially important for high-risk patients during the COVID-19 pandemic so that flu cases are reduced and resources conserved. Published results suggest Medial's ML systems identify high-risk patients in other contexts (Goshen et al., 2018; Zack et al., 2019). However, there is little evidence about (a) whether informing patients they are at high risk makes them more likely to receive vaccination; (b) how patients react to being told their risk status is the result of an analysis of their health records; and (c) whether informing patients their risk status has been determined by an algorithm, by machine learning, and/or by artificial intelligence will increase or decrease their likelihood of getting vaccinated. This study will address these gaps in the literature, which are especially important in light of the anticipated future growth of AI/ML system use throughout healthcare. Medial's algorithm is an example of how interoperable health information exchange (HIE)-the ability for health information technology to share patient data-can improve the efficiency and effectiveness of healthcare. However, patients may not appreciate these benefits or the fact that healthcare has become substantially more integrated and collaborative. A systematic review of patient privacy concerns about HIE found that 15-74% of patients expressed privacy concerns, depending on the study, and concluded that patient perspectives remain poorly understood. A flu outreach message that explicitly references a review of patient medical records might backfire as patients react badly to a sense they have lost control of their health records. There is conflicting evidence on how people respond to advice or information that comes from an algorithm or machine. Dietvorst et al. (2015) documented a pattern of algorithm aversion, in which people choose inferior human over superior algorithmic forecasts, especially after they observed the algorithm make an error. In contrast, Logg et al. (2018) described algorithm appreciation, in which people followed advice more when they thought it came from algorithms than when they thought it came from human beings. Finally, Bigman and Gray (2019) found aversion to algorithms that make moral decisions, including a (fictitious) medical decision of choosing whether or not to operate on a high-risk patient. In the current setting, the algorithm is merely advising patients on taking an action (an annual flu shot) that is already the standard of care, and there is no opportunity to observe an erroneous recommendation, so the hypothesis is that algorithm appreciation will cause people to react positively to being informed of the algorithm's role. Thus, this study will address two important research questions: 1. Does informing patients that they are at high risk for flu complications (a) increase the likelihood that they will receive flu vaccine; and (b) decrease the likelihood that they receive diagnoses of flu and/or flu-like symptoms in the ensuing flu season? 2. Does informing patients that their high-risk status was determined (a) by analyzing their medical records (vs. by no specified method); and (b) by an AI/ML algorithm\* analyzing their medical records (as opposed to via unspecified methods or human medical records analysis) affect the likelihood that they receive the flu vaccine and/or diagnoses of flu and/or flu-like symptoms in the ensuing flu season? Our specific aims are: 1. Evaluate the effect on flu vaccination rates of informing health-system patients who are identified by an ML analysis of EHR data to be at high-risk for flu complications that they are at high risk with either (a) no additional explanation, (b) an explanation that this determination comes from an analysis of their medical records, and (c) the additional explanation that an AI or ML algorithm made this determination. 2. Evaluate the effects of the same three interventions on diagnoses of flu in the same patients. Research Strategy Included in the study will be current Geisinger patients 17+ years of age with one or more visits to a Geisinger primary care physician (PCP) between January 1, 2008 and January 30, 2020 and no contraindications for flu vaccine. Medial will provide flu-complication risk scores from their ML algorithm (based on coded EHR data), on the basis of which the top 10% of patients at highest risk will be included. Based on prior behavior and other predictors in a second ML model, Medial will also provide the likelihood each patient will get vaccinated during the study flu season; these values and the primary risk scores will be used as covariates in exploratory data analyses. The anticipated number of patients in the top 10% of risk is 56,000. On average in the last 3 flu seasons, 55% of Geisinger patients aged 65+ are vaccinated each season, so we will use this as a proxy base rate for a control condition in our power analysis. The study will have 92% power to detect a 2% absolute difference or greater in the vaccination outcome between conditions (55% vs 57%, two-tailed alpha of .05), on the assumption that each condition will have 56,000/4=14,000 patients. For the rarer outcome of flu diagnosis, we have 95% power to detect a 0.8% absolute difference or greater-from an estimated 3.9% rate in this high-risk population (based on the CDC estimate for people age 65+ \[Tokars et al., 2018\]) to a 3.1% rate. The primary study outcomes will be the rates of flu vaccination and flu diagnoses during the 2020-21 season (September-March) by targeted patients. Secondary, exploratory outcomes will also be measured: Rates of flu vaccination and diagnoses by fellow household members of targeted patients; rates of flu vaccination and diagnoses by non-targeted patients who were assigned a risk score that fell just below the cutoff of targeted patients (sub-threshold risk); rates of flu complications and flu-like symptoms among targeted patients, household members, and those at sub-threshold risk; and rates of other relevant healthcare utilization outcomes such as ER visits and hospitalizations. Generalized linear mixed models (GLMMs) will examine the primary study outcomes as a function of the study arms (between-subjects), with patient-visited PCPs and/or clinics included as random effects variables, assuming high intraclass correlation coefficients. GLMMs will specify a binary distribution and log-link function in the case of dichotomous outcome variables (e.g., flu vaccination, flu diagnosis), and a negative binomial distribution and log-link function in the case of any highly positively skewed count variables such as ER visits and hospitalizations (where over-dispersion typically remains in the case of a Poisson distribution model). For these exploratory analyses, within-patient change (from the same period one year earlier) will also be analyzed. Also, each patient will receive the same type of communication (a/b/c/d) via up to three modalities-printed letter to their mailing address, SMS to their mobile phone, and/or secure message via Geisinger's patient portal-depending on what information is on file for each patient. The communication channels used for each patient will be covariates in later analyses. \*Note: The study will not necessarily use the terms AI, ML, or algorithm in the messages to groups b, c, and d; instead, these messages will be designed to be readable and comprehensible by the patient audience while still including the key concepts that differentiate the interventions from one another.

Interventions

BEHAVIORALRisk reduction

Mailed letter, SMS, and/or patient portal message

Mailed letter, SMS, and/or patient portal message

Mailed letter, SMS, and/or patient portal message

Sponsors

National Institute on Aging (NIA)
CollaboratorNIH
Geisinger Clinic
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
DOUBLE (Subject, Caregiver)

Masking description

Participants (i.e., patients) will not be informed specifically of their assignment to different arms throughout the study. Providers who prescribe vaccination and diagnose conditions will not be randomized to study arms or informed of patient assignment.

Intervention model description

Patients from the high-risk sample will be randomly assigned to one of 4 groups: 1. Control: group that receives no additional pro-vaccination intervention beyond Geisinger's normal efforts. 2. High Risk Only: group that receives messages telling them they have been identified to be at high risk for flu complications without specifying how/why Geisinger believes this to be the case 3. High Risk Based on Medical Records: group that receives messages telling them they have been identified to be at high risk for flu complications via analysis of their medical records 4. High Risk Based on Algorithm: group that receives messages telling them they have been identified to be at high risk for flu complications via analysis of their medical records by AI/ML Two additional groups will be monitored for outcome data: 5. Sub-threshold patients: patients who are in the top 11-20% of risk 6. Household members: patients who share an address with target patients

Eligibility

Sex/Gender
ALL
Age
17 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Current Geisinger patient at the time of study * Falls in the top 10% of patients at highest risk, as identified by the flu-complication risk scores of Medial's machine learning algorithm (which operates on coded EHR data) * May limit inclusion to patients that are under Geisinger primary care, depending on algorithm performance of patients who have non-Geisinger PCPs

Exclusion criteria

* Has contraindications for flu vaccination * Has opted out of receiving communications from Geisinger via all of the modalities being tested

Design outcomes

Primary

MeasureTime frameDescription
Flu Vaccination RateThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationPatient received a flu vaccination
Flu Vaccination Rate by Risk LevelThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationPatient received a flu vaccination Note: For patients who received risk communications, those in the top 3% were always told they were in the top 3% of risk. Those in the top 4-10% of risk were randomized to be told that they were in the top 10% of risk or high risk. Control patients in the top 3% and top 4-10% of risk were allocated to the top 3% and randomized to either top 10% or high risk groups, respectively, at the same time as those in the patient contact groups, even though these control patients were not contacted.
High Confidence Flu Diagnosis RateThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationPatient received a flu diagnosis via a positive PCR/antigen/molecular test

Secondary

MeasureTime frameDescription
Change in Hospitalizations From Pre- to Post-interventionWithin 12 months pre-intervention (Time 1) and within 12 months post-intervention (Time 2)Number of patient hospital visits, examining relative rate of visits across Time 1 and 2
Flu Vaccination Among Fellow Household MembersThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationNon-targeted fellow household members of targeted patients received a flu vaccination
High Confidence Flu Diagnosis Among Fellow Household MembersThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationNon-targeted fellow household members of targeted patients received a flu diagnosis (via a positive PCR/antigen/molecular test)
Likely Flu Diagnosis Among Fellow Household MembersThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationNon-targeted fellow household members of targeted patients received a diagnosis that was likely flu (as assessed via ICD codes or Tamiflu administration or positive PCR/antigen/molecular test)
Likely Flu Diagnosis RateThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationPatient received a diagnosis that was likely flu, as assessed via ICD codes or Tamiflu administration or positive PCR/antigen/molecular test. Note that this outcome is a superset of the high confidence flu diagnosis rate outcome.
Flu Vaccination Among Those at Sub-threshold RiskThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationNon-targeted sub-threshold risk patients received a flu vaccination
High Confidence Flu Diagnosis Among Those at Sub-threshold RiskThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationNon-targeted sub-threshold risk patients received a flu diagnosis (via a positive PCR/antigen/molecular test)
Likely Flu Diagnosis Among Those at Sub-threshold RiskThrough the the end of the flu season (May 31st 2021), approximately 9 months assessment durationNon-targeted sub-threshold risk patients received a diagnosis that was likely flu (as assessed via ICD codes or Tamiflu administration or positive PCR/antigen/molecular test)
Flu Complications Among Those at Sub-threshold RiskThrough 3 months after the end of the flu season (August 31st 2021), approximately 12 months assessment durationNon-targeted sub-threshold risk patients were diagnosed with flu-related complications
Flu Complications Among Fellow Household MembersThrough 3 months after the end of the flu season (August 31st 2021), approximately 12 months assessment durationNon-targeted fellow household members of targeted patients were diagnosed with flu-related complications
Flu Complications RateThrough 3 months after the end of the flu season (August 31st 2021), approximately 12 months assessment durationPatient was diagnosed with flu-related complications
Change in ER Visits From Pre- to Post-interventionWithin 12 months pre-intervention (Time 1) and within 12 months post-intervention (Time 2)Number of patient visits to the ER, examining relative rate of visits across Time 1 and 2

Countries

United States

Participant flow

Participants by arm

ArmCount
Control
This group receives no additional pro-vaccination intervention beyond the health system's normal efforts. Although some patients are currently targeted for flu vaccination encouragement due to a non-ML assessment that they are at high risk for complications, these patients are not told that they are at high risk or that they have been targeted.
11,667
High Risk Only
This group receives messages telling them they have been identified to be at high risk for flu complications without specifying how or why the health system believes this to be the case. Risk reduction: Mailed letter, SMS, and/or patient portal message
11,639
High Risk Based on Medical Records
This group receives messages telling them they have been identified to be at high risk for flu complications via analysis of their medical records. Risk reduction: Mailed letter, SMS, and/or patient portal message Medical records-based recommendation: Mailed letter, SMS, and/or patient portal message
11,652
High Risk Based on Algorithm
This group receives messages telling them they have been identified to be at high risk for flu complications via analysis of their medical records by an AI/ML system. Risk reduction: Mailed letter, SMS, and/or patient portal message Medical records-based recommendation: Mailed letter, SMS, and/or patient portal message Algorithm-based recommendation: Mailed letter, SMS, and/or patient portal message
11,644
Sub-threshold Patients
Patients in this group are in the top 11-20% of risk for flu and complications, slightly lower risk than those included in the intervention, who are in the top 10% of risk for flu and complications. This group of patients does not receive an intervention, but is monitored for flu shots as a comparison to target patients.
46,898
Household Members
This group of patients share an address with target high-risk patients (in arms 1-4). This group does not receive an intervention but is monitored for spillover effects of the intervention. Note that some household members of target patients were also sub-threshold risk. Additionally, some of these patients were household members of more than one target patient. The numbers reported here reflect unique household members who were not also sub-threshold risk patients.
24,149
Total117,649

Baseline characteristics

CharacteristicHousehold MembersTotalControlHigh Risk OnlyHigh Risk Based on Medical RecordsHigh Risk Based on AlgorithmSub-threshold Patients
Age, Continuous47.1 years
STANDARD_DEVIATION 20
54.8 years
STANDARD_DEVIATION 19.9
58.0 years
STANDARD_DEVIATION 19.3
57.9 years
STANDARD_DEVIATION 19.3
57.9 years
STANDARD_DEVIATION 19.2
57.6 years
STANDARD_DEVIATION 19.4
55.7 years
STANDARD_DEVIATION 19.5
Ethnicity (NIH/OMB)
Hispanic or Latino
1113 Participants4464 Participants402 Participants457 Participants395 Participants413 Participants1684 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
22777 Participants112756 Participants11253 Participants11159 Participants11240 Participants11207 Participants45120 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
259 Participants429 Participants12 Participants23 Participants17 Participants24 Participants94 Participants
Race/Ethnicity, Customized
American Indian or Alaska Native
32 Participants159 Participants22 Participants21 Participants15 Participants22 Participants47 Participants
Race/Ethnicity, Customized
Asian
124 Participants441 Participants32 Participants37 Participants28 Participants31 Participants189 Participants
Race/Ethnicity, Customized
Black or African American
1116 Participants4268 Participants362 Participants382 Participants389 Participants416 Participants1603 Participants
Race/Ethnicity, Customized
Native Hawaiian or Other Pacific Islander
129 Participants345 Participants18 Participants26 Participants20 Participants26 Participants126 Participants
Race/Ethnicity, Customized
Unknown or Not Reported
72 Participants189 Participants10 Participants14 Participants6 Participants13 Participants74 Participants
Race/Ethnicity, Customized
White
22674 Participants112245 Participants11223 Participants11159 Participants11194 Participants11136 Participants44859 Participants
Region of Enrollment
United States
24149 participants44602 participants11667 participants11639 participants11652 participants11644 participants46898 participants
Sex: Female, Male
Female
10744 Participants69990 Participants7535 Participants7514 Participants7533 Participants7438 Participants29226 Participants
Sex: Female, Male
Male
13405 Participants47659 Participants4132 Participants4125 Participants4119 Participants4206 Participants17672 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
EG002
affected / at risk
EG003
affected / at risk
deaths
Total, all-cause mortality
0 / 00 / 00 / 00 / 0
other
Total, other adverse events
0 / 00 / 00 / 00 / 0
serious
Total, serious adverse events
0 / 00 / 00 / 00 / 0

Outcome results

Primary

Flu Vaccination Rate

Patient received a flu vaccination

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Participants were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Rate4901 Participants
High Risk OnlyFlu Vaccination Rate5042 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate5087 Participants
High Risk Based on AlgorithmFlu Vaccination Rate5090 Participants
Comparison: This analysis compared all groups that were informed they were high risk (High risk only, High risk based on medical records, High risk based on algorithm) to control patients who were not sent a message.~Null hypothesis: informing patients they are high risk for flu and flu-related complications does not increase flu vaccination rate; Alternative hypothesis: informing patients they are high risk for flu and flu-related complications increases flu vaccination ratep-value: 0.0035Regression, Logistic
Comparison: Null hypothesis: the High risk only and High risk based on medical records messages are equally effective at promoting flu vaccinations; Alternative hypothesis: there is a difference in effectiveness between High risk only and High risk based on medical records. Separate regressions were run to assess pairwise differences between the high-risk arms (analyses 2, 3, and 4). The Holm method was used to test whether each comparison reached significance.p-value: 0.613Regression, Logistic
Comparison: Null hypothesis: the High risk only and High risk based on algorithm messages are equally effective at promoting flu vaccinations; Alternative hypothesis: there is a difference in effectiveness between High risk only and High risk based on algorithm messages. Separate regressions were run to assess pairwise differences between the high-risk arms (analyses 2, 3, and 4). The Holm method was used to test whether each comparison reached significance.p-value: 0.889Regression, Logistic
Comparison: Null hypothesis: the High risk based on medical records and High risk based on algorithm messages are equally effective at promoting flu vaccinations; Alternative hypothesis: there is a difference in effectiveness between High risk based on medical records and High risk based on algorithm messages. Separate regressions were run to assess pairwise differences between the high-risk arms (analyses 2, 3, and 4). The Holm method was used to test whether each comparison reached significance.p-value: 0.714Regression, Logistic
Primary

Flu Vaccination Rate by Risk Level

Patient received a flu vaccination Note: For patients who received risk communications, those in the top 3% were always told they were in the top 3% of risk. Those in the top 4-10% of risk were randomized to be told that they were in the top 10% of risk or high risk. Control patients in the top 3% and top 4-10% of risk were allocated to the top 3% and randomized to either top 10% or high risk groups, respectively, at the same time as those in the patient contact groups, even though these control patients were not contacted.

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Participants were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Rate by Risk LevelTop 3%1485 Participants
ControlFlu Vaccination Rate by Risk LevelHigh risk1758 Participants
ControlFlu Vaccination Rate by Risk LevelTop 10%1658 Participants
High Risk OnlyFlu Vaccination Rate by Risk LevelTop 3%1536 Participants
High Risk OnlyFlu Vaccination Rate by Risk LevelHigh risk1757 Participants
High Risk OnlyFlu Vaccination Rate by Risk LevelTop 10%1749 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by Risk LevelTop 10%1795 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by Risk LevelTop 3%1513 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by Risk LevelHigh risk1779 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by Risk LevelTop 3%1537 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by Risk LevelHigh risk1754 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by Risk LevelTop 10%1799 Participants
Comparison: This analysis tested whether vaccination differed in patients with the same risk level who were sent messages with a vague verbal (high risk) vs. specific numeric (top 10%) risk framing.~This analysis was limited to those informed they were high risk (High risk only, High risk based on medical records, High risk based on algorithm).p-value: 0.181Regression, Logistic
Comparison: This analysis tested whether vaccination differed in patients with the same numeric risk phrasing are differentially affected due to different specific risk levels (3% vs. 10%).~This analysis was limited to those informed they were high risk (High risk only, High risk based on medical records, High risk based on algorithm).p-value: 0.301Regression, Logistic
Primary

High Confidence Flu Diagnosis Rate

Patient received a flu diagnosis via a positive PCR/antigen/molecular test

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Change in ER Visits From Pre- to Post-intervention

Number of patient visits to the ER, examining relative rate of visits across Time 1 and 2

Time frame: Within 12 months pre-intervention (Time 1) and within 12 months post-intervention (Time 2)

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Change in Hospitalizations From Pre- to Post-intervention

Number of patient hospital visits, examining relative rate of visits across Time 1 and 2

Time frame: Within 12 months pre-intervention (Time 1) and within 12 months post-intervention (Time 2)

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Flu Complications Among Fellow Household Members

Non-targeted fellow household members of targeted patients were diagnosed with flu-related complications

Time frame: Through 3 months after the end of the flu season (August 31st 2021), approximately 12 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Flu Complications Among Those at Sub-threshold Risk

Non-targeted sub-threshold risk patients were diagnosed with flu-related complications

Time frame: Through 3 months after the end of the flu season (August 31st 2021), approximately 12 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Flu Complications Rate

Patient was diagnosed with flu-related complications

Time frame: Through 3 months after the end of the flu season (August 31st 2021), approximately 12 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Flu Vaccination Among Fellow Household Members

Non-targeted fellow household members of targeted patients received a flu vaccination

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Household members were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine. Household members who shared an address with multiple patients in the intervention were counted in this outcome once for every eligible target participant who shared their address.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Among Fellow Household Members2136 Participants
High Risk OnlyFlu Vaccination Among Fellow Household Members2207 Participants
High Risk Based on Medical RecordsFlu Vaccination Among Fellow Household Members2165 Participants
High Risk Based on AlgorithmFlu Vaccination Among Fellow Household Members2175 Participants
Secondary

Flu Vaccination Among Those at Sub-threshold Risk

Non-targeted sub-threshold risk patients received a flu vaccination

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Participants were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine.

ArmMeasureValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Among Those at Sub-threshold Risk18268 Participants
Secondary

High Confidence Flu Diagnosis Among Fellow Household Members

Non-targeted fellow household members of targeted patients received a flu diagnosis (via a positive PCR/antigen/molecular test)

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

High Confidence Flu Diagnosis Among Those at Sub-threshold Risk

Non-targeted sub-threshold risk patients received a flu diagnosis (via a positive PCR/antigen/molecular test)

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Likely Flu Diagnosis Among Fellow Household Members

Non-targeted fellow household members of targeted patients received a diagnosis that was likely flu (as assessed via ICD codes or Tamiflu administration or positive PCR/antigen/molecular test)

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Likely Flu Diagnosis Among Those at Sub-threshold Risk

Non-targeted sub-threshold risk patients received a diagnosis that was likely flu (as assessed via ICD codes or Tamiflu administration or positive PCR/antigen/molecular test)

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Secondary

Likely Flu Diagnosis Rate

Patient received a diagnosis that was likely flu, as assessed via ICD codes or Tamiflu administration or positive PCR/antigen/molecular test. Note that this outcome is a superset of the high confidence flu diagnosis rate outcome.

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Flu cases and other related outcomes (flu complications, ER visits for flu, hospitalizations for flu) in the 2020-2021 flu season were too low to detect any meaningful differences across study arms. Therefore, the study team did not collect data for this outcome.

Post Hoc

Flu Vaccination Rate by Ethnicity

Patient received a flu vaccination

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Participants were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Rate by EthnicityUnable to obtain5 Participants
ControlFlu Vaccination Rate by EthnicityHispanic or Latino118 Participants
ControlFlu Vaccination Rate by EthnicityNot Hispanic or Latino4778 Participants
High Risk OnlyFlu Vaccination Rate by EthnicityUnable to obtain9 Participants
High Risk OnlyFlu Vaccination Rate by EthnicityHispanic or Latino173 Participants
High Risk OnlyFlu Vaccination Rate by EthnicityNot Hispanic or Latino4860 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by EthnicityNot Hispanic or Latino4943 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by EthnicityHispanic or Latino136 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by EthnicityUnable to obtain8 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by EthnicityHispanic or Latino146 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by EthnicityUnable to obtain6 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by EthnicityNot Hispanic or Latino4938 Participants
Post Hoc

Flu Vaccination Rate by Gender

Patient received a flu vaccination

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Participants were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Rate by GenderFemale3118 Participants
ControlFlu Vaccination Rate by GenderMale1783 Participants
High Risk OnlyFlu Vaccination Rate by GenderMale1797 Participants
High Risk OnlyFlu Vaccination Rate by GenderFemale3245 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by GenderFemale3235 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by GenderMale1852 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by GenderFemale3197 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by GenderMale1893 Participants
Post Hoc

Flu Vaccination Rate by Race

Patient received a flu vaccination

Time frame: Through the the end of the flu season (May 31st 2021), approximately 9 months assessment duration

Population: Participants were excluded from analysis if they were vaccinated prior to the study start date or if they were contraindicated for flu vaccine.

ArmMeasureGroupValue (COUNT_OF_PARTICIPANTS)
ControlFlu Vaccination Rate by RaceAmerican Indian or Alaska Native6 Participants
ControlFlu Vaccination Rate by RaceAsian19 Participants
ControlFlu Vaccination Rate by RaceBlack or African American115 Participants
ControlFlu Vaccination Rate by RaceNative Hawaiian or Other Pacific Islander5 Participants
ControlFlu Vaccination Rate by RaceWhite4751 Participants
ControlFlu Vaccination Rate by RaceUnknown5 Participants
High Risk OnlyFlu Vaccination Rate by RaceUnknown5 Participants
High Risk OnlyFlu Vaccination Rate by RaceNative Hawaiian or Other Pacific Islander9 Participants
High Risk OnlyFlu Vaccination Rate by RaceAmerican Indian or Alaska Native9 Participants
High Risk OnlyFlu Vaccination Rate by RaceBlack or African American134 Participants
High Risk OnlyFlu Vaccination Rate by RaceAsian14 Participants
High Risk OnlyFlu Vaccination Rate by RaceWhite4871 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by RaceAsian15 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by RaceBlack or African American143 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by RaceNative Hawaiian or Other Pacific Islander7 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by RaceUnknown0 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by RaceWhite4916 Participants
High Risk Based on Medical RecordsFlu Vaccination Rate by RaceAmerican Indian or Alaska Native6 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by RaceWhite4914 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by RaceUnknown7 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by RaceAsian13 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by RaceNative Hawaiian or Other Pacific Islander7 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by RaceAmerican Indian or Alaska Native7 Participants
High Risk Based on AlgorithmFlu Vaccination Rate by RaceBlack or African American142 Participants

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026