Evaluation of Quality of Life instruments for use in COPD care and research: a systematic review

Objective: Quality of Life (QoL) measurements to quantify disease burden have become an important outcome measure in Chronic Obstructive Pulmonary Disease (COPD) research and treatment. A large variety of QoL instruments is available. The objective of this review was to comprehensively evaluate content and psychometric properties of available QoL instruments used in COPD care and research.

Design: A systematic literature search was performed.

Databases: The databases PubMed, Embase, CINAHL, and the Cochrane Library were used.

Review method: Two researchers independently identified eligible studies. Methodological quality of the studies and data on measurement properties were assessed by using the Consensus based Standards for selection of health Measurement Instruments (COSMIN). A best evidence synthesis for each instrument was performed.

Results: 77 studies describing 13 disease-specific and 10 generic QoL instruments were identified. The content of the instruments showed a great variety. 20 instruments measured mobility. Pulmonary symptoms were measured in 11 disease specific instruments. Pain, vitality, and spiritual activities were domains seen only in generic instruments. Social and emotional functioning were domains seen in disease specific instruments as well as in generic instruments. The methodological quality of the studies was mostly rated fair, according to the COSMIN checklist. The psychometric properties of the instruments (validity, reliability and responsiveness) were in general rated positive. The best evidence synthesis showed the strongest positive evidence for the disease specific instruments Chronic Respiratory Questionnaire (CRQ), COPD Assessment Test (CAT), Saint George Respiratory Questionnaire (SGRQ), and Living with COPD questionnaire (LCOPD). The generic instruments received less favorable ratings.

Conclusion: Despite the comprehensive overview we could not uniformly recommend the best instrument to evaluate QoL in COPD patients. However, we could recommend the disease specific instruments CRQ, CAT, SGRQ, or LCOPD. In addition to the best evidence synthesis, the decision to use one instrument over another, will be driven by study purpose and research questions in combination with the domains of the instrument. Given the large availability of instruments we discourage to develop new instruments, instead we encourage to design studies according the COSMIN standards to evaluate the psychometric properties of the existing instruments.