Results Summary

What was the research about?

Asthma is a health problem that can make it hard for people to breathe. People who have low incomes and who are African American or Hispanic are more likely to have asthma than other adults. Removing or reducing things that can trigger asthma symptoms at patients’ homes, like pollen or dust, can help control symptoms.

In this study, the research team wanted to learn if home visits helped patients manage asthma. The team compared patients who received home visits from a community health worker, or CHW, with patients who didn’t receive home visits. CHWs teach patients about health and link patients with health and social services in their community.

What were the results?

Compared with patients who didn’t receive home visits, patients who did had

  • More days without asthma symptoms
  • Fewer nights when they woke up because of asthma
  • Fewer missed work or school days

Patients who did or didn’t receive home visits were similar in

  • How well they were able to manage their asthma symptoms
  • How asthma affected their quality of life
  • The number of unplanned clinic visits
  • The amount of asthma medicines patients took

Who was in the study?

The study included 551 patients with asthma that was not well controlled or very poorly controlled. Patients received care at one of 13 clinics. Of these patients, 63 percent were female. Also, 34 percent were black, 23 percent were white, and 15 percent were other races; 28 percent were Hispanic. Patients were ages 5–75; 53 percent were over age 18. All patients lived in King County, Washington, and had Medicaid insurance.

What did the research team do?

The research team assigned patients by chance to get home visits or not. During home visits, patients learned about asthma and created a plan to manage it. Patients also learned to remove things in their homes that might cause asthma symptoms. After their first home visit, patients received visits again 2, 6, and 14 weeks later. Home visits were in English, Spanish, or Somali.

At study start and one year later, patients completed a survey about their symptoms and how asthma affected their life.

During the study, the research team also explored ways to improve asthma care in clinics. For improved asthma care, the team gave staff extra training about current, recommended asthma care. When the team compared patients who did and didn’t receive home visits, they took into account whether their clinic provided usual or improved asthma care.

Patients with asthma, asthma doctors, and clinic staff gave input during the study.

What were the limits of the study?

Asthma symptoms can vary based on the season. Some patients had their final study visit in a different season than their first visit, which may have affected their results. CHWs in this study had many years of experience providing home visits; CHWs with less experience may not have the same results.

Future research could look at more ways to support the asthma care that patients receive in clinics.

How can people use the results?

Clinics can use the results when considering ways to help patients improve asthma control.

How this project fits under PCORI’s Research Priorities
PCORI identified asthma in African American and Hispanic/Latino populations as an important research topic. Patients, clinicians, and others wanted to learn how to encourage care that follows national asthma guidelines and improves patient-centered outcomes for African American and Hispanic/Latino populations. In 2013, PCORI launched an initiative on Treatment Options for African Americans and Hispanics/Latinos with Uncontrolled Asthma. The initiative funded this research project and others.

Final Research Report

View this project's final research report.


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Peer-Review Summary

Peer review of PCORI-funded research helps make sure the report presents complete, balanced, and useful information about the research. It also assesses how the project addressed PCORI’s Methodology Standards. During peer review, experts read a draft report of the research and provide comments about the report. These experts may include a scientist focused on the research topic, a specialist in research methods, a patient or caregiver, and a healthcare professional. These reviewers cannot have conflicts of interest with the study.

The peer reviewers point out where the draft report may need revision. For example, they may suggest ways to improve descriptions of the conduct of the study or to clarify the connection between results and conclusions. Sometimes, awardees revise their draft reports twice or more to address all of the reviewers’ comments. 

Peer reviewers commented and the researchers made changes or provided responses. Those comments and responses included the following:

  • The reviewers asked the researchers to acknowledge in the report that they had sufficient power to test the success of the community health worker (CHW) intervention but not the enhanced clinical care intervention. The researchers acknowledged that their study was originally conceptualized as a Two-by-Two factorial design where they could determine the interaction between the enhanced clinical care and CHW interventions. However, because patients were not randomized for enhanced clinical care the project could not really be considered a factorial design. In addition, the enhanced clinical care implementation was not successful in most of the targeted clinics. The researchers, therefore, reconceptualized their study as a randomized controlled trial of the CHW intervention compared to no intervention, overlaid onto a feasibility study of the clinic-level intervention. 
  • The reviewers asked for clarification about the timeframe of the clinic-level intervention in relation to the CHW intervention. The researchers explained that the clinic-level intervention began before they enrolled the first study participant in the CHW intervention.
  • The reviewers noted that most people likely think that community health workers (CHWs) focus on education and support rather than physical changes to homes and asked what is known about the benefit of ongoing engagement by CHWs for medical education as compared with single home visits to reduce environmental triggers of asthma. The researchers explained that in 20 years of research studies on the impact of CHWs, trials initially focused on workers helping with living spaces.  However, their roles expanded later to add medication management and chronic disease self-management. The researchers said that at this point the standard of care is for CHWs to provide both advice on the physical environment and medical management.
  • The reviewers commented on the small number of patients or patients’ parents, six in all, who participated in shaping the study in a focus group meeting. The reviewers noted that this low number of patients and patients’ parents may not have been a representative sample or likely to address the range of issues that could have been raised. The researchers acknowledged this was a limitation of the study and said they found it challenging to induce more low-income people to attend a stakeholder meeting. They agreed that ideally, they would have been able to speak with a larger number of patients and parents. Also, they said they would be grateful to learn from others who have had better success.
  • The reviewers asked whether the study tracked whether the study participants used the dust mite bed covers, vacuum cleaners, and air filters supplied to them.  The researchers said they did not systematically assess if participants used these resources. They said that previous trials suggest that providing a full package of such tools is most helpful, allowing participants to use the tools most suited to their needs, but this study did not try to address which of the tools were most effective. 

Conflict of Interest Disclosures

Project Information

James Stout, MD, MPH^
Seattle-King County Public Health Department
Guidelines to Practice (G2P): Reducing Asthma Health Disparities through Guideline Implementation

Key Dates

December 2013
June 2020

Study Registration Information

^James W. Krieger, MD, MPH, was the original principal investigator for this project.


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Last updated: March 14, 2024