Control based asthma management results in improved asthma outcomes. The Asthma Control Questionnaire (ACQ-6), is a widely used and well validated metric which strongly predicts future exacerbations.¹ It demarcates between controlled (C), partially controlled (P), and uncontrolled (U), based on cut point scores of <0.75, 0.75<1.5, and ≥1.5 respectively. The global asthma visual analogue scale (VAS) is a 10 cm continuum indicating the overall symptom burden.² It discriminates GINA categories of C, P and U as <1.5, 1.5<7.19, and ≥7.19 respectively. We evaluated how VAS relates to ACQ in terms of predefined GINA cut points. We analysed n=87 patients who attended for asthma screening into clinical trials. 90% of patients were receiving ICS(mean BDP equiv 675 µg/day), of whom 80% received ICS/LABA, 42% with LTRA, mean FeNO 45 ppb, mean FEV1 89%, and mean number +ve skin prick tests were 2. Overall Spearman’s correlation was 0.62, p<0.001.Mean VAS levels for ACQ were: C: 2.2 cm (95% CI 1.35–3.06), P: 2.56 cm (95% CI 2.61–4.50), U: 5.27 cm (95% CI 4.46–6.08), i.e.,<7.19 cm GINA defined cut off (figure 1). There was no significant difference between patients with ACQ≥1.5 vs<1.5 for FeNO (51 ppb vs 41 ppb), or BDP equiv dose (674 µg vs 543 µg). Chi-square test demonstrated a weak relationship between ACQ≥1.5 and GINA defined VAS cut off ≥7.19 cm. A VAS≥7.19 had a sensitivity of 29% and specificity of 92% for detecting an ACQ≥1.5. ROC analysis, using ACQ to compare C vs U/P revealed an optimal cut point for VAS of 1.95 (AUC 0.8, sensitivity 88%, specificity 68%). Comparing U vs P/C revealed VAS cut point of 3.2 cm (AUC 0.7, sensitivity 71%, specificity 57%). We conclude that the GINA defined VAS cut off (≥7.19) is a poor predictor of control in relation to an ACQ≥1.5. Hence, further evaluation is required to define the VAS threshold in relation to control defined by ACQ rather than GINA.

Figure Legend Distribution of ACQ control categories relative to VAS levels.

References

1. Meltzeret al. JACI2011;127:167–172.

2. Ohtaet al. J Asthma2013;50:514–521.