The influence of obesity on pulmonary rehabilitation outcomes in patients with COPD

Abstract

Although obesity is increasing in prevalence, relatively little attention has been given to its impact on outcomes in patients with chronic obstructive pulmonary disease (COPD) completing pulmonary rehabilitation. We conducted a retrospective chart review of 114 patients with COPD who completed outpatient pulmonary rehabilitation at our center. Body habitus categories were determined based on body mass index (BMI). Underweight patients (BMI < 21 kg/m 2 ) were excluded from the analysis. Normal weight and overweight patients were classified as nonobese. Obese patients (BMI >30 kg/m 2 ) were compared with non-obese patients in the following areas: forced expiratory volume in 1 s (FEV 1 ) percent predicted, the 6-min walk distance (6MWD), health status, the number of unsupported arm lifts per minute, and functional performance. Health status was determined using the Self-Reported Chronic Respiratory Questionnaire (CRQ-SR), which has dimensions of dyspnea, fatigue, emotion, and mastery. Functional performance was determined using the Pulmonary Functional Status Scale Daily Activities subscore. Compared with non-obese patients, obese patients had a higher FEV 1 percent-predicted (44 ± 15% vs 52 ± 16%; P = 0.01), yet had lower 6MWD (269 ± 11 vs 203 ± 13; P = 0.0002), lower functional status, and greater fatigue at initial evaluation. However, the two groups had similar walk-work, which adjusts for differences in weight. Despite the baseline differences, both groups improved similarly following pulmonary rehabilitation (change in 6MWD was 52 ± 7 m in the non-obese patients versus 47 ± 9 in the obese patients; P = 0.65). Our study suggests that obese COPD patients are referred to pulmonary rehabilitation at an earlier spirometric stage of their disease, but have a poorer exercise performance, a greater degree of functional impairment and greater fatigue levels. This is probably, largely because of the effect of an increased weight burden. However, obesity did not seem to adversely affect the pulmonary rehabilitation outcomes.

The association between co-morbidities and physical performance in people with chronic obstructive pulmonary disease

“…The findings of this systematic review indicate that the presence of co-morbid anxiety (in two crosssectional studies 10,25 ), osteoporosis (one intervention study 24 ) or obesity (in two cross-sectional studies 26,27 , one retrospective 26 ) were associated with reduced physical performance in people with COPD. Associations with reduced physical performance were reported for metabolic disease, 23 higher Charlson index 23 and depression 25,28,29 but not found in other included studies of the same co-morbidities.…”

“…15,24 Obesity did not have an effect on the outcome of PR but was associated with lower baseline 6MWD. 26,27 The presence of co-morbid conditions is increasingly recognised as a major clinical consideration in the management of people with COPD, influencing both therapeutic management and clinical outcomes. 34 Recommendations made in clinical guidelines for 6 Chronic Respiratory Disease Table 2.…”

“…29 The OR of the two studies on the effect of obesity on performance could not be calculated, however both authors concluded that obesity had a negative association with physical performance in COPD patients. 26,27 On the other hand, heart disease had a positive association with physical performance (OR ¼ 2.86, 95% CI ¼ 1.85-3.01). 23 These associations are complicated by two issues.…”

“…First, associations of Charlson index, metabolic disease and heart disease with achievement of minimal clinically important difference in 6MWD reported in a retrospective study by Crisafulli et al, 23 were not replicated in their subsequent prospective study. 24 Second, associations of co-morbidity are reported both with baseline measures of 6MWD (for anxiety, 10,25,29 depression 25,29 and obesity 26,27 ) and with improvements in physical performance after a PR program (for Charlson index, 23 metabolic disease, 23 heart disease, 23 osteoporosis, 24 depression 15,28 and obesity 26,27 ; Table 4). …”

“…26,27 A range of co-morbid conditions were examined in two studies by Crisafulli et al 23,24 including chronic heart failure, coronary disease, diabetes, osteoporosis, dyslipidaemia and hypertension; however, mental health or obesity were not identified or examined in these studies. Details of co-morbidities examined in each study and how they were identified are included in Table 3.…”