Convergent and divergent correlations between clinical assessments and total Respiratory Symptoms Questionnaire score

AsthmaAsthma+COPDCOPDTotal sample
Convergent correlations
 SGRQ total score0.72***0.77***0.77***0.77***
 ACT score−0.84***−0.84***NANA
 EQ VAS−0.43***−0.54***−0.51***−0.52***
 mMRC dyspnoea scale grade0.41***0.47***0.44***0.47***
 Physician-assessed severity#0.31***0.33***0.31***0.34***
Divergent correlations
 Post-BD FEV1 % pred−0.29***−0.37***−0.27***−0.36***
 Post-BD FVC % pred−0.22***−0.34***−0.23***−0.29***
 Post-BD FEV1/FVC−0.20***−0.15**−0.16**−0.23***
 Post-BD FEF25–75% % pred−0.18**−0.070.00−0.14***

Data are presented as n, unless otherwise stated. COPD: chronic obstructive pulmonary disease; SGRQ: St George's Respiratory Questionnaire; ACT: Asthma Control Test; NA: not applicable; EQ VAS: EuroQol Visual Analogue Scale; mMRC: modified Medical Research Council; BD: bronchodilator; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; FEF25–75%: forced expiratory flow at 25–75% of FVC. For each variable, analyses were performed for patients with non-missing data; patient numbers differed for each variable based on data availability. Correlation coefficients >0.7 are regarded as strong, 0.4–0.7 as moderate and <0.4 as weak. #: disease severity was categorised as mild, moderate or severe, as assigned by physician judgement (in order to calculate correlation coefficients, severity categories were assigned a numerical value: mild=1, moderate=2 and severe=3). **: p<0.01; ***: p<0.001.