Introduction Of the 5 million patients who receive medication for asthma approximately 5% have severe or difficult to treat disease. A key problem for patients with severe asthma is impaired exercise capacity and often reported as a trigger for symptoms. In COPD it is recognised that reduced Physical Activity (PA) levels can be linked with poorer morbidity and increased exacerbations. In Severe Asthma (SA) there has to date been no formal evaluation of self reported PA levels in comparison to objective measurements and Quality of Life (QoL).
Objectives To evaluate self reported PA in a population of patients with SA compared to 6 Minute Walk Test (6MWT) results.
To compare PA levels with others measures of disease including lung function and QoL measurements (Short Form 36 or SF36)
Methods 35 patients (12 male:17 Female) with SA completed the Dukes Activity Status Index (DASI) which gives an estimated maximum metabolic equivalent (METs) as an estimation of self reported physical function. QoL was measured with the SF36 where Physical component scores (PCS) and Mental Component Scores (MCS) were collected. Objective measures of Forced Expiratory Volume in 1 second percent predicted (FEV1 %) and 6MWT distance (metres) were also collected.
The 6MWT had medium correlations with SF36 MCS (rs = 0.372, p > 0.03) and SF36 PCS (rs = 0.480, p > 0.004) and a strong correlation with the DASI (rs = 0.604, p > 0.0001). Moreover the Physical function component of SF36 (SF36PF) also had a strong correlation with 6MWT (rs = 0.541, p > 0.001). FEV1 showed a medium correlation with 6MWT (rs = 0.413, p > 0.19).
Conclusion Patients appear to estimate PA levels accurately with the DASI, with higher scores of estimated METs correlating with increased 6MWT distance. QoL appears higher in those patients who achieve a greater distance in their 6MWT, especially in relation to their physical function. FEV1 preservation also appears to correlate with improved 6MWT distances. Further investigation of PA in this popoulation is warranted.