Walking distance is a predictor of exacerbations in patients with chronic obstructive pulmonary disease

BACKGROUND: Patients with chronic obstructive pulmonary disease (COPD) are responsible for a high utilisation of the health care resources, and the cost is expected to increase. Physiological measures of lung function often fail to describe the impact the symptoms have on exacerbations, days of hospitalisation, and on a patient's health. METHODS: Twenty-one patients (14 female) with COPD (65 years, 40-79 years) admitted to the Department of Respiratory Medicine in Uppsala, performed a pulmonary function test (FEV(1)% predicted=37) and health status measurement (St. Georges Respiratory Questionnaire, SGRQ) at discharge. Four to six weeks after discharge, when they were in a stable clinical condition, they performed an exercise test (Incremental Shuttle Walk Test, ISWT) to measure their exercise capacity. RESULTS: Nine of 21 patients (43%) were rehospitalised within 12 month. The mean distance walked in the ISWT was 174m in patients who were hospitalised and 358m in non-hospitalised patients (P<0.001). Oxygen saturation 88% after the ISWT was found in 73% of hospitalised patients in contrast to only 22% in non-hospitalised patients (P<0.05). Activity related health status (SGRQ-activity) was higher (worse) in hospitalised patients than in non-hospitalised patients (75 vs. 50) (P<0.05). The association between walking distance and the risk of rehospitalisation was significant after adjusting for oxygen saturation and health status (hazard risk ratio 0.8 (0.67-0.97) per 10m). This study has shown that walking distance is a good and reliable predictor of rehospitalisations in moderately and severely disabled patients with COPD.