The effect of body mass index on functional parameters and quality of life in COPD patients

Malnutrition increases dyspnea and exercise intolerance in chronic obstructive pulmonary disease (COPD) patients by effecting respiratory muscle strength (RMS) and thereby decreasing quality of life (QoL). This is a prospective study conducted to find out the differences due to pulmonary function tests (PFT), arterial blood gases (ABG), RMS, exercise capacity (EC) and QoL in COPD patients having low and normal body mass index (BMI). The study was carried out between April 2003-June 2004 and included 65 male COPD patients with a mean age of 63.4 +/- 9.6. The patients were grouped into 2: Low BMI group (BMI < 21) and normal BMI group (BMI= 21-28). All patients were investigated with PFT (spirometry, maximal inspiratory and expiratory pressures, diffusion capacity), ABG analyses, Modified Medical Research Council (MMRC) dyspnea scale, determination of EC by 6 minutes walking test (6 MWT) and determination of QoL by Turkish version of St. George Respiratory Questionnaire (SGRQ). Of these cases, 29 (44.6%) had low and 36 (55.4%) had normal BMI; MMRC was higher in the first group without statistical significance (p= 0.074). The first group demonstrated significantly lower diffusion capacity (DLco) and DLco%, PEmax, PEmax%, RMS and RMS% (p< 0.05). ABG analyses, 6 MWT results and SGRQ symptom scores revealed no significant difference. As a conclusion, BMI is closely related to dyspnea score, RMS and QoL in COPD patients, therefore in patients with low BMI pulmonary rehabilitation programs including nutritional support should accompany medical treatment.