Asthma: Home-Based Multi-Trigger, Multicomponent Environmental Interventions – Adults with Asthma

The Task Force finding is based on evidence from a systematic review of 3 studies (search period 1966 - February 2008). The systematic review was conducted on behalf of the Task Force by a team of specialists in systematic review methods, and in research, practice, and policy related to asthma control.

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Three intervention studies reported one or more outcome measurements in adults. Although two studies observed improvements in quality of life or symptom scores, the results for health care utilization, and productivity outcomes showed borderline or no improvement. No studies in adults reported any physiologic outcomes.

An economic review of this intervention was not conducted because the Task Force did not have enough information to determine if the intervention works.

Applicability of this intervention across different settings and populations was not assessed because the Task Force did not have enough information to determine if the intervention works.

Each Community Preventive Services Task Force (Task Force) review identifies critical evidence gaps—areas where information is lacking. Evidence gaps can exist whether or not a recommendation is made. In cases when the Task Force finds insufficient evidence to determine whether an intervention strategy works, evidence gaps encourage researchers and program evaluators to conduct more effectiveness studies. When the Task Force recommends an intervention, evidence gaps highlight missing information that would help users determine if the intervention could meet their particular needs. For example, evidence may be needed to determine where the intervention will work, with which populations, how much it will cost to implement, whether it will provide adequate return on investment, or how users should structure or deliver the intervention to ensure effectiveness. Finally, evidence may be missing for outcomes different from those on which the Task Force recommendation is based.

Identified Evidence Gaps

The following outlines evidence gaps for home-based multi-trigger, multicomponent environmental interventions for adults and for children and adolescents.

Effectiveness. The effectiveness of home-based multi-trigger, multi-component interventions has been established. Important questions still remain regarding the intervention composition and intensity as well as effectiveness in different settings and populations. Some of these questions include:

• What are the independent contributions of particular intervention components to overall intervention effectiveness? Which components are the most important for inclusion in this intervention?
• What is the required intensity (number of home visits, intensity of remediation, intensity of education) needed for an effective home intervention program?
• How does household member smoking impact the effects of this intervention? Should smoking cessation counseling be a necessary component of all home-based environmental interventions for asthma?

Applicability. This intervention has been studied most in low-income, urban minority populations but is most likely effective in most settings and populations. The following questions remain about the applicability of this intervention in various settings and populations:

• How effective is this intervention in adult populations?
• Are there differences in intervention effectiveness between children and adolescents?
• How effective is this intervention in rural populations?
• Is this intervention more effective in participants with more severe asthma symptoms?
• How does the type of dwelling (apartment, duplex, single family home) impact the effectiveness of the intervention?

Implementation. This intervention has been implemented in a variety of ways. However, questions still remain as to what is the most effective and cost-effective way to implement this intervention in a “real-world setting.” These questions include:

• How should this intervention be integrated in the health care system to insure appropriate access and sustainability?
• Which asthma patients should this intervention target?
• Who are the most effective intervention implementers (CHW, nurses respiratory therapist, etc.) and does this change depending on intervention setting?

The following characteristics describe studies used in systematic reviews of home-based multi-trigger, multicomponent environmental interventions for adults and for children and adolescents.

• Of the 23 included studies, 20 studies evaluated interventions targeting homes in which only children or adolescents had asthma; one study exclusively targeted adults; and two studies targeted children and adults (results of these last two studies were included both in the child and adult analyses).
• The number of participants in the studies ranged from 18 to 1033, with a median number of 104 participants (interquartile interval [IQI]: 64–274).
• Follow-up periods ranged from 1 month to 48 months, with a median follow-up period of 12 months (IQI: 12–18 months).
• Education focus ranged from primarily environmental education to primarily asthma self-management education, including monitoring asthma symptoms and the use of asthma management plans.
• Most studies focused equally on both environmental and self-management education.
• Two studies (9%) focused only on remediation and did not have an educational component.
• Fourteen studies were tailored based on exposure to asthma triggers in the home; of these, seven also included specific allergen sensitivities in tailoring the intervention.
• Number of home visits was one (3 studies), two to seven (15 studies), and eight or more (5 studies).
• Home visits were made exclusively by community health workers (6 studies), nurses (5 studies), respiratory therapists (2 studies), physicians (2 studies), social workers (1 study), housing officers (1 study), environmental educators (1 study), and trained sanitarians (1 study). Or they were conducted by mixed teams of community health workers and nurses (2 studies), social worker, nurse, and respiratory therapist (1 study), and research assistant and pest control professional (1 study).