Cutpoints of the ´control of allergic rhinitis and asthma test´ (CARAT) subscales

Abstract

Control of allergic rhinitis and asthma test (CARAT) was designed and validated to measure control of both asthma and allergic rhinitis (AR). The CARAT meets all COSMIN criteria for patient reported outcomes. Cutpoint analysis for (un)control are preliminary. The aim is to identify cutpoints of CARAT to differentiate between controlled and uncontrolled asthma and AR using gold standards. As part of a yearly asthma assessment, patients completed the CARAT together with the Asthma Control Questionnaire (ACQ), Visual Analog Scale (VAS), Global Initiative for Asthma (GINA) assessment and the Allergic Rhinitis And Its Impact On Asthma (ARIA) assessment. Potential cutpoints were related to existing gold standard cutpoints: ACQ and GINA for the CARAT asthma scale, VAS-upper airways and ARIA for the CARAT AR scale. Decisions were based on Area Under the Curve (AUC), sensitivity (SS), specificity (SP), percentage correctly classified patients (PCCP), positive and negative predicted value (PPV and NPV). Data from 382 asthma patients (37% men, mean 55 yrs) suggests potential cutpoints of 14.5 or 15.5 for CARAT asthma scale (based on ACQ (SS82%, SP79%, AUC.88, PCCP81%, PPV.87, NPV.72) and GINA (SS78%, SP61%, AUC.74, PCCP64%, PPV.33, NPV.92)) and 6.5 or 8.5 for CARAT AR scale (based on VAS (SS65%, SP93%, AUC.84, PCCP69%, PPV.98, NPV.33)) and ARIA (SS70%, SP69%, AUC.75, PCCP70%, PPV.79 NPV.58)). We found a suggested cutpoint of 14.5 or 15.5 for the CARAT asthma scale and 6.5 or 8.5 for the CARAT AR scale. This corresponds largely with the preliminary cutpoints of 16 and 8. Further analysis will investigate a single cutpoint per subscale and a cutpoint for the whole CARAT.