Usefulness of a linear analog scale questionnaire to measure health-related quality of life in elderly patients with chronic obstructive pulmonary disease

Abstract

Objectives: To examine the validity, discriminatory ability, and responsiveness of health-related quality-of-life (HRQoL) questionnaires using a linear analog scale (Quality of Life (QOL) scale) for chronic obstructive pulmonary disease (COPD).

Design: Cross-sectional and longitudinal.

Setting: Outpatient.

Participants: One hundred two elderly subjects with mild to severe COPD.

Measurements: Scores on the QOL scale, the St. George's Respiratory Questionnaire (SGRQ), and the 36-item Short-Form Health Survey questionnaire (SF-36) and various clinical parameters were recorded. The correlations between these QOL questionnaires and various clinical parameters were then examined. The responses of 31 elderly COPD patients to the QOL scale and the SGRQ before and 3 months after the completion of a comprehensive pulmonary rehabilitation program were compared longitudinally.

Results: On cross-sectional study, the QOL scale showed a significant correlation with the total score and three components of the SGRQ. The QOL scale correlated significantly with all components of the SF-36, but the total SGRQ score correlated with only six components of the SF-36, excluding vitality and the mental health index. Both the QOL scale and the total score of the SGRQ correlated significantly with the oxygen cost diagram (OCD), Morale scale, 6-minute walking distance (6MWD), forced expiratory volume in 1 second, and instrumental activities of daily living (IADL) score. When subjects were divided into three groups according to disease severity (mild, moderate, severe) using American Thoracic Society guidelines, the total SGRQ score discriminated between the three groups. The QOL scale could not discriminate between mild and moderate or moderate and severe. On longitudinal study, 3 months after finishing the comprehensive pulmonary rehabilitation program, the QOL scale, the SGRQ, 6MWD, and OCD all showed significant improvement. The difference in the QOL scale after the comprehensive pulmonary rehabilitation program showed a significant correlation with changes in the SGRQ total score and the OCD but not with the 6MWD.

Conclusion: The QOL scale is similar to more-complex questionnaires such as the SGRQ in terms of validity and responsiveness for evaluating disease-specific HRQoL in elderly COPD patients. In clinical settings, the QOL scale, as a simple questionnaire, may be useful for disease-specific HRQoL assessments in elderly COPD patients.