What is the CAT?

The one that rules at our house is Wiggam and he’s pretty cute.
With acronyms being so common, if you go looking for CAT it may also be the Centre for Appropriate Technology or Computed Axial Tomography.

The CAT I’m going to talk about is the COPD Assessment Test.

The COPD Assessment Test is a relatively new patient -completed instrument that has been designed to provide a simple and reliable measure of health status in patients with Chronic Obstructive Pulmonary Disease (COPD). It was developed by a multidisciplinary group of international experts including Professor Paul Jones (PhD, FRCP, Professor of Respiratory Medicine, St George's Hospital Medical School, London, England) who is a world leader in the science of health status measurement in lung disease and Professor Christine Jenkins ( Clinical Professor of Medicine at the University of Sydney, thoracic physician at Concord Hospital, and head of the Airways Group at the Woolcock Institute of Medical Research in Sydney).

COPD is a progressive and largely irreversible disease characterized by emphysema and chronic bronchitis which may result in breathlessness, cough and sputum. Patients with COPD often experience an increasing deterioration of their health related quality of life (HRQL).
“Health-related quality of life, utility and productivity outcome instruments have an important role to play in the general well being of subjects with COPD. The ease with which these questionnaires can be understood and completed is pertinent to issues of compliance and therefore of accuracy in assessing the impact of this progressive, chronic disease”. (Health-related quality of life, utility, and productivity outcomes instruments: ease of completion by subjects with COPD – Stahl et al 2003.)
This 2003 study identified how subjects experienced difficulty in completing a number of well used and new questionnaires. It appeared that age, disease severity, gender and socio economic status all impacted on the ability of the COPD subjects to complete the questionnaires. This article also suggests that the indirect assessment of subject’s HRQL, via relatives, care providers or other health professionals, tends to underestimate the level of HRQL impairment.

Over the past decade, more and more research on the development and validation of questionnaires has been undertaken to quantify the impact of disease on daily life and well being from the subject’s point of view. One reason is recognising that individual patients are most concerned about their symptoms (e.g. dyspnoea) and their function (e.g. ability to perform physical tasks), rather than objective measures such as expiratory airflow (B.Gupta& S.Kant: Health Related quality of Life in COPD: The Internet Journal of Pulmonary Medicine, 2009 V11, No.1)
I found many disease specific and generic questionnaires deemed appropriate to respiratory health. Among them are the SF-12, EQ-5D, HS-COPD, EQ-5D, WPAI-COPD, SOLDQ, QLRIQ (see what I mean by acronyms). There is also the Sickness Impact Profile (SIP), Nottingham Health Profile (NHP), Quality Well Being (QWB), and the St George Respiratory Questionnaire (SGRQ) which is more complex but has a strong correlation to the CAT. Some of these have been used in research studies and looking at these assessment tools I can see why the subjects may have struggled to complete them. A number appear quite complex and time consuming. For example the SIP is a 136 item questionnaire that takes 20-30 minutes to complete.

This brings us back to the CAT. According to the user guide (GlaxoSmithKline 2009) it is a validated, short and simple patient-completed questionnaire which has been developed for use in routine clinical practice. Its development involved literature reviews and consultation with physicians and patients. It is not a diagnostic tool (unlike FEV) but rather a tool to measure health status which may give a better understanding to the patient and clinician as to the impact and progression of their COPD. The CAT consists of 8 questions that are easy to understand and that patients should be able to complete independently. Each response attracts a score between 0-5 which is then added to produce a total score. Further research is currently being conducted to define ranges of CAT score severity and to better understand the clinical relevance in a CAT score from one visit to the next. The Cat Development Steering Group has proposed some potential management considerations according to a patient’s score, correlated to impact level and a broad clinical picture (based on appropriate items from the previously mentioned SGRQ). But the scenarios given are for illustrative purposes only as individual patients will vary in the way COPD affects them. For example a score over 30 rates a very high impact level, over 20 is high, 10-20 medium and less than 10 rates a low impact level.
The CAT score needs to be considered in relation to an individuals disease though there is not always a strong relationship between disease stage and health status score (Jones PW. Health status measurement in chronic obstructive pulmonary disease Thorax 2001; 56 880-7).
Its usefulness may be in initial assessment of and monitoring the progression of COPD in patients (perhaps even identifying specific areas of impairment), or possibly to assess the degree of recovery following an acute exacerbation. Its use in assessing whether an individual patient has had a worthwhile response to specific therapy is limited (but it is more reliable for assessing response to therapy in groups of patients). Recommended use of the CAT is every 3-6 months.

Why might we use the CAT?
It is simple and quick to complete (a few minutes).
It provides a framework for discussion with the patient.
It may help identify where COPD has the greatest effect on a patients life.
It may assist in better informed management decisions of the disease.

Used in conjunction with other COPD clinical assessment tools (e.g. spirometry) it can help to ensure a patient is optimally managed. It is recognized that how the CAT is used will vary according to a particular healthcare setting (and country) and we will need to consider if and how we can incorporate it into our practice to ensure it is useful and relevant.

The use of generic questionnaires versus disease specific questionnaires is a discussion in itself.

Irene