Studies on health-related quality of life in patients with chronic obstructive pulmonary disease

Abstract

Aims. To describe health-related quality of life (HRQL) in chronic obstructive pulmonary disease (COPD), to develop a Swedish version of the St George's Respiratory Questionnaire (SGRQ), to study factors related to HRQL in COPD and to study long-term effects of rehabilitation on exercise tolerance and HRQL.Methods. Two sets of data were collected to meet the research questions.A. Sixty-eight patients with COPD were consecutively recruited and stratified according to FEV1 to represent different levels of the disease. Spirometry and walking test were performed. A control group was recruited from the general population. HRQL was assessed with the Sickness Impact Profile (SIP), the Hospital Anxiety and Depression scale (HAD), the Mood Adjective Check List (MACL) and (patients only) the SGRQ. B. Patients with COPD were consecutively recruited to a randomized controlled study of a multidisciplinary rehabilitation programme (n=26). Controls (n=24) were treated conventionally. Exercise tolerance and HRQL were measured.Results. Major findings were presented in four articles:A1. Compared with controls, patients with COPD scored worse on all the SIP categories except alertness behaviour and communication. The worst dysfunction reported on the SIP were: ambulation, sleep/rest, eating, home management and recreation/pastimes. These differences were noted mainly in patients with an FEV1 < 50% predicted. Physical functioning was most severely affected followed by psychosocial functioning and then emotional well-being. A 2. An established disease-specific questionnaire, the SGRQ, was adapted to Swedish according to a standardized translation and psychometric analysis procedure. Validity was confirmed as the correlation pattern was almost identical to that reported for the original version. Reliability was satisfactory with Cronbach's alpha coefficient > 0.80 for all three SGRQ sections, although overlap of content was seen in two.A 3. The SIP and SGRQ scores showed substantial associations to walking distance and affective measures but modest to pulmonary function. Stepwise multiple regression demonstrated three factors of overriding importance for the full range of generic and specific HRQL measures: dyspnoea-related restriction, exercise tolerance (walking distance), and level of depressed mood (HAD).B. After 12 months the rehabilitation group showed an improved exercise capacity (walking distance and maximal exercise capacity). In contrast, no statistically significant improvement in HRQL was seen. Conclusions. Five major conclusions were drawn: 1) All aspects of HRQL are affected by COPD when pulmonary function (FEV1) is reduced by 50% or more; 2) Physical functioning is most severely affected; 3) Dyspnoea-related restriction, exercise tolerance (walking distance) and level of depressed mood (HAD) are consistent determinants of the full range of HRQL measures; 4) Impacts of COPD can be detected also in Swedish patients by the validated version of the SGRQ; 5) A rehabilitation programme for COPD patients has positive long-term effects on exercise tolerance.