Since the relationships between pulmonary function, exercise capacity, and functional state or quality of life are generally weak, a self report questionnaire has been developed to determine the effect of treatment on quality of life in clinical trials. One hundred patients with chronic airflow limitation were asked how their quality of life was affected by their illness, and how important their symptoms and limitations were. The most frequent and important items were used to construct a questionnaire evaluating four dimensions: dyspnoea, fatigue, emotional function, and the patient's feeling of control over the disease (mastery). Reproducibility, tested by repeated administration to patients in a stable condition, was excellent: the coefficient of variation was less than 12% for all four dimensions. Responsiveness (sensitivity to change) was tested by administering the questionnaire to 13 patients before and after optimisation of their drug treatment and to another 28 before and after participation in a respiratory rehabilitation programme. In both cases large, statistically significant improvements in all four dimensions were noted. Changes in questionnaire score were correlated with changes in spirometric values, exercise capacity, and patients' and physicians' global ratings. Thus it has been shown that the questionnaire is precise, valid, and responsive. It can therefore serve as a useful disease specific measure of quality of life for clinical trials.The relationships between changes in symptomatic and functional state in patients with chronic lung disease and changes in conventional physiological indices are often weak.' 2 This is particularly true for interventions such as respiratory rehabilitation programmes, in which patients are taught to cope with their physiological limitations.36 Direct measurement of the impact on patients' lives is therefore necessary to assess whether interventions are of benefit. Questionnaires that have been developed for this purpose include the oxygen cost diagram7 and the baseline and transition dyspnoea indexes.8 These tools address patients' dyspnoea but do not focus on the many other aspects of their lives that are affected by the illness. The responsiveness (the ability to detect clinically important change, even if that change is small) of these questionnaires has not

ABSTRACr Walking tests, frequently used to document effects of treatment on exercise capacity, have never been standardised. We studied the effects of encouragement on walking test performance in a randomised study that controlled for the nature of the underlying disease, time of day, and order effects. We randomised 43 patients with chronic airflow limitation or chronic heart failure or both to receive or not receive encouragement as they performed serial two and six minute walks every fortnight for 10 weeks. Simple encouragement improved performance (p < 0*02 for the six minute walk), and the magnitude of the effect was similar to that reported for patients in studies purporting to show beneficial effects of therapeutic manoeuvres. Age and test repetition also affected performance. These results demonstrate the need for careful standardisation of the performance of walking tests, and suggest caution in interpreting studies in which standardisation is not a major feature of the study design. Accepted 21 May 1984 ment was given "as necessary." In subsequent experiments using walking tests as measures of exercise capacity encouragement was not held constant. We were concerned that the influence of encouragement might be sufficiently great to rival treatment effects, and therefore we investigated the impact of encouragement on two and six minute walking tests performance in patients with chronic lung and chronic heart disease. Methods PATIENTSWe recruited two groups of subjects who experienced fatigue or dyspnoea while performing activities of daily living. The first, with respiratory conditions, attended a regional referral centre for patients with pulmonary problems and had a best recorded forced expired volume in one second (FEVy) less than 70% of the predicted value. The second group, patients with heart failure, who had been referred by local cardiologists, had impaired left ventricular function demonstrated by angiography, radionuclide scanning, or echocardiography. Exclusion criteria for both groups were as follows:(1) limitation of exercise performance as a result of factors other than fatigue or exertional dyspnoea, 818

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