Background The revised COPD GOLD guidelines (2011) recommend that validated questionnaires like the CAT (COPD Assessment Test) or the modified MRC (Medical Research Council) breathlessness scale should be used to assess symptoms in COPD against “risk” as assessed by GOLD spirometric staging or exacerbation frequency. We have demonstrated that when either the MRC or CAT scores are used to determine symptoms, there is a significant difference in the proportion of patients being categorised into the risk categories which will affect risk assessment and may influence therapeutic choice.
Aim To determine the CAT threshold for risk assessment at which similar proportions of patients are categorised into the 4 risk categories.
Methods 309 consecutive patients on the AATD registry (PiZZ) were grouped into the four categories (A, B, C, and D) as suggested by GOLD, on the basis of their CAT/mMRC scores and GOLD stage/Exacerbation frequency. Using CAT as the symptom grade, we compared patient distribution in the 4 categories using scores between 10 and 20 to determine the CAT threshold at which the distribution of patients in each group is proportional.
Results The proportion of patients in each of the 4 categories was consistent for each symptom score whether risk was assessed by FEV1 or exacerbation number. However the proportions using CAT 10 and mMRC 0–1, ≥2 were significantly different in each category. When the CAT threshold was changed to 13, the proportions of patients in the four groups were no longer significantly different to those using mMRC.
Conclusion We have demonstrated that in patients with AATD, using CAT score of 13 as the threshold for assessing symptoms results in a similar proportion of patients being categorised into the risk categories. This affects risk assessment and therapeutic choice. Longitudinal follow up and monitoring will enable confirmation of this threshold for patient management.