Clinically relevant effects of Mindfulness-Based Stress Reduction in individuals with asthma

Abstract

Background: Psychological distress and comorbid psychopathology contribute to exacerbation risk in patients with asthma. Thus, interventions designed to reduce stress and improve emotion regulation, such as Mindfulness-Based Stress Reduction (MBSR), may augment standard care. Few studies have addressed this question and a paucity of data exists to determine the ability of MBSR to impact clinical outcomes in asthma.

Methods: This randomized controlled trial investigated effects of MBSR training on asthma control and airway inflammation, in relation to psychological symptoms, in adults with asthma. Participants were randomized to an 8-week MBSR training (n = 35) or wait-list control group (n = 34). Clinically relevant asthma assessments, including Asthma Control Questionnaire and inflammatory biomarkers, were collected at baseline and six approximately-monthly follow-ups. Self-reported mindfulness, distress, depression, and anxiety symptoms were assessed at baseline, post-intervention, and study completion. Chronic stress level was determined at baseline only.

Results: Asthma control improved significantly in individuals randomized to MBSR, relative to wait-list controls (p = .01; effect size d = 0.76), which was maintained at 4mo post-intervention. 32% of MBSR participants achieved a clinically significant improvement, based on the ACQ6 Minimally Important Difference, relative to 12% of wait-list participants. Moreover, MBSR-related improvement in asthma control was associated with a reduction in distress (p = .043) and the intervention was most efficacious for those with the highest baseline depressive symptoms (p = .023). Importantly, MBSR also reduced levels of exhaled nitric oxide, a biomarker of airway inflammation, relative to wait-list controls (p < .05).

Conclusion: Supporting and extending extant evidence of mind-body relationships in asthma and the benefits of stress reduction for these patients, this is, to the best of our knowledge, the first RCT to demonstrate that training in MBSR improves clinically relevant asthma outcomes. MBSR may thus be a valuable addition to optimal asthma management, particularly for those with comorbid psychopathology.

Clinical trial registration: NCT02157766.

Keywords: Asthma control; Depression; Inflammation; Mindfulness; Psychological distress.

Fig. 1

(A) CONSORT diagram of participants' progress through screening, enrollment, initial visit, randomization, and follow-up visits. MNP-A: Meditation-Naive Participants with Asthma; MBSR: Mindfulness-Based Stress Reduction; WL: Wait-List. (B) Experimental design: baseline psychological measures, inflammatory markers, self-report asthma control and severity, and self-assessed mindfulness were collected prior to randomization to MBSR (n = 38) or wait-list (n = 34) groups. Follow-up visits all included ACQ6, CASI, and inflammatory marker assessment; visits at baseline, post-intervention, and 4mo post-intervention also included FFMQ, SCL-90R, BDI, and BAI assessments.

Fig. 2

Predicted Five-Facet Mindfulness Questionnaire scores over time. FFMQ scores improved significantly in those randomized to the MBSR intervention, but not wait-list controls (p = .022). 95% confidence bars are based on predicted mean estimate ± 1.96 times the standard error.

Fig. 3

Predicted Positive Symptom Distress Index (PSDI) scores over time. Distress (PSDI scores) decreased significantly over time in those randomized to the MBSR intervention, relative to wait-list controls (p = .021). 95% confidence bars are based on predicted mean estimate ± 1.96 times the standard error.

Fig. 4

(A,B,C,D) Relationship between asthma control and psychological symptoms at baseline, adjusted for age and sex. Asthma control (ACQ6 score) is positively associated with A) global severity index (GSI; B = 0.66, p = .009), B) positive symptom distress index (PSDI; B = 1.11, p < .001), C) depression (BDI; B = 0.026, p = .013), and D) chronic stress (B = 0.164, p < .001) at baseline. All models were assessed for influential outliers using cook's d with a cutoff of >20% of the f-distribution, and all final models and plots exclude influential outliers where applicable. Lower ACQ6 scores reflect better asthma control.

Fig. 5

(A) Predicted asthma control (ACQ6 scores). Asthma control improved significantly in participants assigned to the intervention, but not wait-list controls (group × visit interaction p = .01, main effect of visit p = .001). (B) Predicted association between change in global symptoms (GSI scores) and asthma control (ACQ6 scores) over time. Greater intervention-related improvement in asthma control was associated with greater decreases in global symptoms, relative to wait-list controls (GSI x group × visit interaction p = .043). (C) Predicted association between baseline depressive symptoms (BDI) and asthma control (ACQ6 scores) over time. For participants with higher baseline depressive symptoms, asthma control improved with participation in the intervention, but not for wait-list controls (baseline BDI x group × visit interaction p = .0226). 95% confidence bars are based on predicted mean estimate ± 1.96 times the standard error. Lower ACQ6 scores reflect better asthma control.

Fig. 6

Predicted Fraction of Exhaled Nitric Oxide (FeNO) levels over time, adjusted for depressive symptoms (BDI). FeNO decreased significantly for participants assigned to the intervention, but not wait-list controls, when accounting for variance in FeNO contributed by depressive symptoms (group × visit interaction p = .045, main effect of visit p = .006). Analogous interactions were significant when adjusting for anxiety symptoms, and trend-level for psychological distress and global symptoms. Plotted predicted values are adjusted for mean BDI. 95% confidence bars are based on predicted mean estimate ± 1.96 times the standard error. Lower FeNO reflects reduced airway inflammation.