Measuring symptom response to pharmacological interventions in patients with COPD: a review of instruments used in clinical trials.

OBJECTIVES

To identify and evaluate the instruments used to measure the effect of pharmacological intervention on symptoms of chronic obstructive pulmonary disease (COPD) in clinical trials.

DESIGN

An extensive literature search was conducted for articles published in English in a peer-reviewed journal from 1995 to March 2002 which described a randomised controlled clinical trial measuring symptoms of COPD in response to pharmacological interventions.

PATIENTS

Patients with any severity of COPD.

INTERVENTIONS

Any pharmacological intervention for treatment of COPD.

MEASUREMENTS AND RESULTS

A total of 43 eligible articles were identified. The individual symptoms most frequently measured were dyspnoea/breathlessness, chest tightness or discomfort and exacerbations. There was considerable variability in the methods, terminology and symptom measurement instruments used. The most widely used instruments for measuring dyspnoea were the Borg scale, the Baseline Dyspnoea Index and the Transitional Dyspnoea Index. None of the instruments used had published evidence of rigorous psychometric testing.

CONCLUSIONS

Numerous methods have been employed to assess the symptoms of COPD in clinical trials, making it difficult to compare the results of different trials. No single measurement instrument predominates, and none of the measures identified in the review have undergone rigorous psychometric testing in this patient population. There is a clear need for a fully developed and validated tool for measuring the effects of therapeutic interventions on symptoms in COPD in clinical trials.