A randomised controlled trial of the effects of a total diet replacement programme in uncontrolled asthma associated with obesity

Abstract

<b>Introduction:</b> Obesity is linked with uncontrolled, severe asthma. The Counterweight-Plus weight management programme (CWP) is an evidence-based, dietician-led, structured diet programme. <b>Aim:</b> To evaluate the effects of CWP versus usual care (UC) on asthma-related outcomes in a randomised, controlled trial in uncontrolled asthma associated with obesity. <b>Methods:</b> We randomised (1:1 CWP:UC) adults with uncontrolled asthma and body mass index (BMI) ≥30kg/m². CWP: 12-week total diet replacement phase (800kcal/day low-energy formula); food reintroduction and weight loss maintenance up to week 52.&nbsp;Primary outcome: change in asthma control questionnaire (ACQ6) score over 16 weeks, adjusting for baseline using ANCOVA (intention-to-treat analysis). Secondary outcome: change in asthma quality of life questionnaire (AQLQ) score. <b>Results:</b> Of 36 participants screened, 35 were randomised and 33 attended 16-week follow-up (17 CWP, 16 UC). Mean (SD) ACQ6 at baseline was 2.6 (1.0) in CWP and 2.7 (1.1) in UC. Weight loss was greater with CWP than UC (mean difference -12.3kg; 95%CI -17.1, -7.5; p&lt;0.001). ACQ6 improved more with CWP than UC (mean difference -0.69; 95%CI -1.37, -0.01; p=0.048). A greater proportion of participants had ≥0.5 improvement in ACQ6 (minimal clinically important difference) with CWP than UC (53% vs 19%; p=0.041). AQLQ improved more with CWP than UC (mean difference 0.76; 95%CI 0.18, 1.34; p=0.013). <b>Conclusion:</b> Weight loss, with a structured low-energy formula diet replacement programme, yields significant improvements in asthma control and quality of life over 16 weeks, compared to usual care, in adults with uncontrolled asthma associated with obesity.