Asthma: Scope of Literature


This review sought to collect and interpret the evidence on home-based telehealth for management of asthma. We looked at 3 areas:

  • Patients: How is home telehealth used in treating asthma patients?  Do patients like it?  How clinically effective is it?
  • Providers: What is the impact of home telehealth on health human resources?  What are the roles of nurses, general practitioners, and specialists in its delivery?  How do providers characterize their experiences with home telehealth?
  • System: How is home telehealth incorporated into the care continuum?  What is the economic impact of incorporating home telehealth into asthma care?  What policies need to be in place for home telehealth to be successful?

In order to answer these questions, we conducted a systematic search for literature published from 2005 to 2010.  This search retrieved 5 studies that met our inclusion criteria.  The quality of the evidence was strong.  A final search for publications from 2011 to 2012 found 2 additional studies.  Though findings from these studies were incorporated into the review, be aware that material from the 2011-2012 period was screened and analyzed in a slightly different way than the studies retrieved in our original search.


Number and Location

A search of literature published from 2005-2010 located 5 studies of home telehealth for asthma management (Prabhakaran et al., 2010; Rasmussen et al., 2005; Strandbygaard et al., 2009; van der Meer et al., 2009, 2010; Willems et al., 2007, 2008). Two of these were multi-part studies, yielding 2 publications each (van der Meer et al., 2009, 2010; Willems et al., 2007, 2008).

Of these studies, 2 took place in Copenhagen, Denmark (Rasmussen et al., 2005; Strandbygaard et al., 2009), 2 in the Netherlands (van der Meer et al., 2009, 2010; Willems et al., 2007, 2008), and 1 in Singapore (Prabhakaran et al., 2010). No Canadian studies met our inclusion criteria.

A final search for material published from 2011-2012 found 2 additional studies that met our inclusion criteria and filled gaps left by the first rounds of searching (Ryan et al., 2012; van der Meer et al., 2011). These studies were analyzed in a slightly different way than the studies retrieved in our original search, and their findings were incorporated into this review in a limited fashion. For more details, please see Methods.


Study Design

The Oxford 2011 Levels of Evidence were used to assess the strength of the evidence base.[1] Studies were placed on a scale running from Level 1,[2] considered the highest level of evidence, through to Level 5.[3] 

Levels are based primarily on study design. Studies were also assigned scores for quality of execution and reporting. Low execution/reporting scores resulted in downgrading.

The Oxford 2011 Levels of Evidence are intended to provide guidance rather than absolute judgments, and do not obviate the need for careful appraisal of local needs and context. The quality of studies within a given level can vary, as can their applicability to select populations. Furthermore, this system is not suitable for all forms of assessment. In the text that follows, the Oxford 2011 Levels of Evidence are used only when discussing clinical outcomes.

The evidence base for home telehealth in asthma management was strong. All 5 studies retrieved qualified as Level 2 evidence. These studies made use of concurrent comparison groups, randomization, and prospective measurement of exposure and outcomes. Execution/reporting scores tended to be high, although reporting of significance levels was inconsistent. No studies were downgraded. Rasmussen et al. (2005), a 6-month study comparing 3 models of asthma management, was particularly strong.

Sample sizes varied widely, with the number of study completers ranging from 22 (Strandbygaard et al., 2009) to 253 (Rasmussen et al., 2005). Rasmussen et al. (2005) was unique in its use of a 3-group design.

Length of study varied, but did not exceed 12 months in any case. Strandbygaard et al. (2009) and Prabhakaran et al. (2010) followed patients for 3 months. Van der Meer et al. (2009, 2010) and Willems et al. (2007, 2008) carried out 12-month interventions, while Rasmussen et al. (2005) fell at the midpoint with a 6-month study.

And on the qualitative side . . .Only 1 qualitative article of relevance to asthma was retrieved. Pinnock et al. (2007) took place in England and focused on the role of mobile technology in 4 phases of asthma self-management: pre-treatment, gaining control of asthma, maintenance, and stepping down dosage. Data collection took place before and after the 4-week intervention. A total of 6 focus groups and 9 interviews were conducted.
Population Characteristics: Demographics

The mean age in all studies was in the 30-45 range. Several studies excluded patients over 45 or 50 (Rasmussen et al., 2005; Strandbygaard et al., 2009; van der Meer et al., 2009, 2010). Willems et al. (2007, 2008) accepted patients aged 7 or older. Approximately half of their total sample was children or adolescents.

Sex distribution was roughly even in 2 studies (Prabhakaran et al., 2010; Strandbygaard et al., 2009). Samples in Rasmussen et al. (2005) and van der Meer et al. (2009, 2010) skewed strongly female (>65%). This may be partly due to the prevalence of asthma is the general population, which is higher among females than males (9.8% vs. 7.1%). In Willems et al. (2007, 2008), in which participants were stratified by age and sex, approximately 38%[4] of adult participants and 64% of pediatric participants were male. The authors attribute this discrepancy to differing self-selection patterns at the recruitment stage.

None of the 4 European studies provided race or ethnicity data. The sole non-European study reported that its Singapore participants were 45% Malay, 37% Indian, and 18% Chinese (Prabhakaran et al., 2010). None of the studies reported on the socioeconomic status of participants. Nor did they report on whether participants resided in rural or urban communities, although recruitment sites in all 5 studies appear to be located in urban areas. Technological literacy was not reported directly, but 2 studies required a certain level of technological competence in their inclusion criteria (Prabhakaran et al., 2010; Willems et al., 2007, 2008).

Population Characteristics: Clinical Characteristics

Participants in all studies had physician-diagnosed asthma. Prabhakaran et al. (2010) required a certain level of severity; the researchers focused on patients recently admitted to the study hospital with an acute exacerbation, and excluded those with a diagnosis of mild intermittent asthma.

All studies save 1 (Rasmussen et al., 2005) explicitly excluded patients with significant co-morbidities. Van der Meer (2009, 2010) also excluded patients who were receiving continuous oral glucocorticosteroids or omalizumab.


[1]For a comprehensive overview of this system, please refer to Jeremy Howick, Iain Chalmers, Paul Glasziou, Trish Greenhalgh, Carl Heneghan, Alessandro Liberati, Ivan Moschetti, Bob Phillips, and Hazel Thornton. “Explanation of the 2011 Oxford Centre for Evidence-Based Medicine (OCEBM) Levels of Evidence (Background Document)”.

Oxford Centre for Evidence-Based Medicine.

[2] Systematic reviews of randomized trials; n-of-1 trials.

[3] Mechanism-based reasoning.

[4] Statistics Canada. Source: Canadian Community Health Survey, 2010. Accessed at

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