INTRODUCTION

HEALTH-RELATED QUALITY OF LIFE

What is Health-Related Quality of Life?

The quality of a person’s life may be considered in terms of its richness, completeness and contentedness. A number of factors contribute to this sense of well-being including good health, a secure social and occupational environment, financial security, spirituality, self-confidence and strong, supportive relationships. These factors are interrelated with each of the others. For instance, a patient will often be able to deal with an illness better if she/he has good family support, a strong faith and the financial ability to acquire nourishing food, shelter and treatment.

Health-related quality of life can be considered as that part of a person’s overall quality of life that is determined primarily by their health status and which can be influenced by clinical interventions. The definition by Schipper and colleagues is both simple and focussed: "the functional effects of an illness and its consequent therapy upon a patient, as perceived by the patient". The final phrase is important because it emphasises that these are the impairments that patients themselves consider important. This is the definition we have used for the development and validation of all our questionnaires.

Why is Health-Related Quality of Life Important?

Most patients seek help from their clinicians because their health-related quality of life is impaired. It may be that they are bothered by their symptoms, worried about their illness or limited in their day-to-day activities. Yes, it is important that clinicians treat the underlying clinical problem (in the case of asthma, the clinical goal is to improve asthma control). However, it is also very important to treat the problems for which the patient is seeking help - their quality of life. In most medical conditions, the correlation between clinical status and health-related quality of life is only modest and this is certainly the case in both asthma and rhinoconjunctivitis. In the past, it was frequently assumed that if clinicians assessed the clinical status of a patient, this would also provided insight into the patient’s quality of life. Let us consider asthma. Certainly, patients with very severe asthma tend to have a worse quality of life than patients with milder disease. However, many studies have shown that quality of life not correlate closely with asthma control. Therefore the impact that asthma has on a patient’s quality of life cannot be inferred from the clinical indices, it must be measured directly.

Health-Related Quality of Life Questionnaires

Since 1990, we have developed and validated a number of disease-specific questionnaires. On this web site, you will find a short description of each questionnaire and some of the published manuscripts describing: a) methods of development b) measurement properties c) evidence of validity and d) how to interpret data.

ASTHMA CONTROL

International guidelines for the treatment of asthma, including the GINA guidelines, have identified that the primary goal of management is to achieve good asthma control. Control has been clearly defined as the minimisation of night time and daytime symptoms, activity limitation, rescue bronchodilator use and airway narrowing.

The Asthma Control Questionnaire has been developed and validated to measure this clinical goal of asthma management. It has strong measurement properties (reliability and responsiveness) and is used extensively throughout the world both in the routine clinical management of patients with asthma and in clinical trials. The Asthma Control Diary was developed and validated at the same time as the questionnaire. They have the same questions but the questionnaire asks how patients have been during the previous week, whereas the diary is completed by patients every morning and evening.