Cognitive behavioural therapy (CBT) for adults and adolescents with asthma

Background
People with asthma have a higher prevalence of anxiety and depression than the general population. This is associated with poorer
asthma control, medication adherence, and health outcomes. Cognitive behavioural therapy (CBT) may be a way to improve the quality
of life of people with asthma by addressing associated psychological issues, which may lead to a lower risk of exacerbations and better
asthma control.
Objectives
To assess the efficacy of CBT for asthma compared with usual care.
Search methods
We searched the Cochrane Airways Group Specialised Register, ClinicalTrials.gov, and the World Health Organization International
Clinical Trials Registry Platform (WHO ICTRP). We also searched reference lists of all primary studies and review articles and contacted
authors for unpublished data. The most recent searches were conducted in August 2016.
Selection criteria
We included parallel randomised controlled trials (RCTs) comparing any cognitive behavioural intervention to usual care or no
intervention. We included studies of adults or adolescents with asthma, with or without comorbid anxiety or depression. We included
studies reported as full text, those published as abstract only, and unpublished data.
Data collection and analysis
Two or more review authors independently screened the search results, extracted data, and assessed included studies for risk of bias.
We analysed dichotomous data as odds ratios (ORs) and continuous data as mean differences (MDs) or standardised mean differences
(SMD) where scales varied across studies, all using a random-effects model. The primary outcomes were asthma-related quality of life
and exacerbations requiring at least a course of oral steroids. We rated all outcomes using GRADE and presented our confidence in the
results in a ’Summary of findings’ table.
Main results
We included nine RCTs involving 407 adults with asthma in this review; no studies included adolescents under 18. Study size ranged
from 10 to 94 (median 40), and mean age ranged from 39 to 53. Study populations generally had persistent asthma, but severity and
diagnostic measures varied. Three studies recruited participants with psychological symptomatology, although with different criteria.
Interventions ranged from 4 to 15 sessions, and primary measurements were taken at a mean of 3 months (range 1.2 to 12 months).
Participants given CBT had improved scores on the Asthma Quality of Life Questionnaire (AQLQ) (MD 0.55, 95% confidence interval
(CI) 0.17 to 0.93; participants = 214; studies = 6; I2 = 53%) and on measures of asthma control (SMD -0.98, 95% CI -1.76 to -0.20;
participants = 95; studies = 3; I2 = 68%) compared to people getting usual care. The AQLQ effect appeared to be sustained up to a
year after treatment, but due to its low quality this evidence must be interpreted with caution. As asthma exacerbations requiring at
least a course of oral steroids were not consistently reported, we could not perform a meta-analysis.
Anxiety scores were difficult to pool but showed a benefit of CBT compared with usual care (SMD -0.38, 95% CI -0.73 to -0.03),
although this depended on the analysis used. The confidence intervals for the effect on depression scales included no difference between
CBT and usual care when measured as change from baseline (SMD -0.33, 95% CI -0.70 to 0.05) or endpoint scores (SMD -0.41,
95% CI -0.87 to 0.05); the same was true for medication adherence (MD -1.40, 95% CI -2.94 to 0.14; participants = 23; studies = 1;
I
2 = 0%).
Subgroup analyses conducted on the AQLQ outcome did not suggest a clear difference between individual and group CBT, baseline
psychological status, or CBT model. The small number of studies and the variation between their designs, populations, and other
intervention characteristics limited the conclusions that could be drawn about these possibly moderating factors.
The inability to blind participants and investigators to group allocation introduced significant potential bias, and overall we had low
confidence in the evidence.
Authors’ conclusions
For adults with persistent asthma, CBT may improve quality of life, asthma control, and anxiety levels compared with usual care. Risks
of bias, imprecision of effects, and inconsistency between results reduced our confidence in the results to low, and evidence was lacking
regarding the effect of CBT on asthma exacerbations, unscheduled contacts, depression, and medication adherence. There was much
variation between studies in how CBT was delivered and what constituted usual care, meaning the most optimal method of CBT
delivery, format, and target population requires further investigation. There is currently no evidence for the use of CBT in adolescents
with asthma.