Abstract: We found 18 studies including 2268 participants: 12 in adults, 5 in children and one in individuals from both age groups. Studies generally recruited people with mild to moderate persistent asthma and followed them for between three and 12 months. People in the intervention group were given one of a variety of technologies to record and share their symptoms (text messaging, Web systems or phone calls), compared with a group of people who received usual care or a control intervention. Evidence from these studies did not show clearly whether asthma telemonitoring with feedback from a healthcare professional increases or decreases the odds of exacerbations that require a course of oral steroids (OR 0.93, 95% confidence Interval (CI) 0.60 to 1.44; 466 participants; four studies), a visit to the emergency department (OR 0.75, 95% CI 0.36 to 1.58; 1018 participants; eight studies) or a stay in hospital (OR 0.56, 95% CI 0.21 to 1.49; 1042 participants; 10 studies) compared with usual care. Our confidence was limited by imprecision in all three primary outcomes. Evidence quality ratings ranged from moderate to very low. None of the studies recorded serious or non-serious adverse events separately from asthma exacerbations. Evidence for measures of asthma control was imprecise and inconsistent, revealing possible benefit over usual care for quality of life (MD 0.23, 95% CI 0.01 to 0.45; 796 participants; six studies; I2 = 54%), but the effect was small and study results varied. Telemonitoring interventions may provide additional benefit for two measures of lung function. Current evidence does not support the widespread implementation of telemonitoring with healthcare provider feedback between asthma clinic visits. Studies have not yet proven that additional telemonitoring strategies lead to better symptom control or reduced need for oral steroids over usual asthma care, nor have they ruled out unintended harms. Investigators noted small benefits for quality of life, but these are subject to risk of bias, as the studies were unblinded. Similarly, some benefits for lung function are uncertain owing to possible attrition bias. Larger pragmatic studies in children and adults could better determine the real-world benefits of these interventions for preventing exacerbations and avoiding harms; it is difficult to generalise results from this review because benefits may be explained at least in part by the increased attention participants receive by taking part in clinical trials. Qualitative studies could inform future research by focusing on patient and provider preferences, or by identifying subgroups of patients who are more likely to attain benefit from closer monitoring, such as those who have frequent asthma attacks.

Plain-language summary: We found 18 studies including a total of 2268 people: 12 included adults, five included children and one included individuals from both age groups. Most people included in the studies had mild to moderate persistent asthma, and studies generally lasted between three and 12 months. People in the intervention group were given one of a variety of technologies to record and share their symptoms (text messaging, Web systems or phone calls) and were compared with a group of people who received usual care, or a control group. We could not tell whether people in the telemonitoring groups had a higher or lower chance than people in the control group of having attacks that would require a course of oral steroids, a visit to the emergency department or a hospital stay. No reports described other potential harms of home telemonitoring. Studies used lots of different types of technology, and we couldn't tell whether some were better than others. Our confidence in the results ranged from moderate to very low, meaning that additional studies are likely to change some of these results and may influence how much we believe them. Using technology to monitor people with asthma from home may offer benefits over usual care for overall quality of life, but the effect was small, and studies did not agree with each other. These interventions may provide benefits for lung function, but lots of people dropped out of the studies, so we couldn't be sure.