COPD Assessment Test (CAT) Calculator

About

The COPD Assessment Test (CAT) was developed by Jones et al. in 2009 as a collaborative initiative between GlaxoSmithKline and an international expert panel of pulmonologists. The goal was to create a simple, reliable, and valid instrument for measuring COPD health status that could be easily used in routine clinical practice. Unlike the St. George's Respiratory Questionnaire (SGRQ), which is comprehensive but time-consuming (50 items, 20-30 minutes), the CAT was designed as a short-form alternative that could be completed in under 2 minutes. The CAT contains eight items covering the key domains of COPD impact: cough, phlegm (sputum), chest tightness, breathlessness (dyspnea), activity limitation, confidence, sleep, and energy. Each item is scored on a 0-5 semantic differential 6-point scale, yielding a total score of 0-40. The CAT was validated in an international study across 11 countries involving 1,517 patients, demonstrating strong psychometric properties: high internal consistency (Cronbach's alpha = 0.88), excellent test-retest reliability (intraclass correlation coefficient = 0.80), and good convergent validity with the SGRQ (r = 0.80). The CAT is responsive to treatment — pulmonary rehabilitation, pharmacotherapy optimization, and exacerbation recovery all produce measurable changes in CAT scores. The minimal clinically important difference (MCID) for CAT is 2-3 points. The CAT is endorsed by the GOLD strategy report as an alternative to mMRC for symptom assessment in the ABE classification, with CAT ≥10 defined as "high symptom burden." Beyond clinical practice, the CAT is used as an endpoint in COPD clinical trials and quality improvement initiatives.

Formula

CAT = Cough (0-5) + Phlegm (0-5) + Chest Tightness (0-5) + Breathlessness (0-5) + Activity Limitation (0-5) + Confidence (0-5) + Sleep (0-5) + Energy (0-5). Total: 0–40.

The CAT is calculated by summing the scores for eight individual questions, each rated on a 0-5 scale where 0 represents no impairment and 5 represents maximum impairment for that domain. The eight domains and the specific wording of each item: (1) Cough — "I never cough" (0) to "I cough all the time" (5). (2) Phlegm — "I have no phlegm in my chest at all" (0) to "My chest is full of phlegm" (5). (3) Chest tightness — "My chest does not feel tight at all" (0) to "My chest feels very tight" (5). (4) Breathlessness — "When I walk up a hill or one flight of stairs I am not breathless" (0) to "When I walk up a hill or one flight of stairs I am very breathless" (5). (5) Activity limitation — "I am not limited doing any activities at home" (0) to "I am very limited doing activities at home" (5). (6) Confidence — "I am confident leaving my home despite my lung condition" (0) to "I am not at all confident leaving my home" (5). (7) Sleep — "I sleep soundly" (0) to "I don't sleep soundly because of my lung condition" (5). (8) Energy — "I have lots of energy" (0) to "I have no energy at all" (5). The total score ranges from 0-40. The score correlates with SGRQ total score in a predictable manner (CAT = 0.57 × SGRQ - 7.5). For interpretation: <10 = low impact, 10-20 = medium impact, 21-30 = high impact, >30 = very high impact. The CAT is self-administered and can be completed on paper, electronically (tablet/computer), or via telephone interview. Patients should be instructed to complete all eight items without assistance, rating their average experience over the preceding week.

Score Interpretation

The CAT is a cornerstone instrument in COPD management, formally integrated into the GOLD 2024 strategy as one of two accepted symptom assessment tools (alongside mMRC) for determining the ABE classification. The CAT ≥10 threshold for "high symptom burden" is used to differentiate Group A from Group B, and Group A/B from Group E (although Group E is primarily defined by exacerbation history). The CAT offers several advantages over the mMRC: it provides a more comprehensive assessment across multiple symptom domains rather than dyspnea alone; it has a wider scoring range (0-40 vs 0-4), making it more responsive to change (MCID 2-3 points vs 0.5-1 grade); and it captures non-respiratory domains such as sleep, energy, and confidence that are important to patients but not assessed by mMRC. In clinical practice, CAT is useful for: (1) baseline assessment of COPD health status at diagnosis, (2) monitoring response to therapy including pharmacotherapy, pulmonary rehabilitation, and exacerbation recovery, (3) identifying patients with high symptom burden who may benefit from treatment escalation, (4) providing objective data for treatment discussions with patients, and (5) as a predictor of future exacerbation risk — each 5-point increase in CAT is associated with approximately 20% increased risk of exacerbation. The CAT has also been validated in languages other than English and in electronic administration formats. Beyond COPD, the CAT has been studied in asthma, bronchiectasis, and ILD, though the MCID and threshold values may differ in these populations. The CAT correlates with the 6-minute walk distance (r = -0.4 to -0.6), SGRQ (r = 0.8), FEV1 (r = -0.3 to -0.4), and exacerbation frequency (r = 0.3-0.5). It has been used in over 100 countries and translated into more than 60 languages.

Reference Ranges