Efficacy of standard rehabilitation in COPD outpatients with comorbidities

Abstract

A prospective study was performed to confirm the prevalence pattern of the most frequent co-morbidities and to evaluate whether characteristics of patients, specific comorbidities and increasing number of comorbidities are independently associated with poorer outcomes in a population with complex chronic obstructive pulmonary disease (COPD) submitted for pulmonary rehabilitation (PR).316 outpatients (mean¡SD age 68¡7 yrs) were studied. The outcomes recorded were comorbidities and proportion of patients with a pre-defined minimally significant change in exercise tolerance (6-min walk distance (6MWD) +54 m), breathlessness (Medical Research Council (MRC) score -1 point) and quality of life (St George's Respiratory Questionnaire -4 points).62% of patients reported comorbidities; systemic hypertension (35%), dyslipidaemia (13%), diabetes (12%) and coronary disease (11%) were the most frequent. Of these patients, .45% improved over the minimum clinically important difference in all the outcomes. In a logistic regression model, baseline 6MWD (OR 0.99, 95% CI 0.98-0.99; p50.001), MRC score (OR 12.88, 95% CI 6.89-24.00; p50.001) and arterial carbon dioxide tension (OR 1.08, 95% CI 1.00-1.15; p50.034) correlated with the proportion of patients who improved 6MWD and MRC, respectively. Presence of osteoporosis reduced the success rate in 6MWD (OR 0.28, 95% CI 0.11-0.70; p50.006).A substantial prevalence of comorbidities in COPD outpatients referred for PR was confirmed. Only the individual's disability and the presence of osteoporosis were independently associated with poorer rehabilitation outcomes.

Objectively identified comorbidities in COPD: impact on pulmonary rehabilitation outcomes

“…Osteoporosis, heart disease and metabolic disease have been shown to be positively or negatively associated with changes in 6MWD and SGRQ scores following PR [3,4]. We were not able to corroborate these findings.…”

“…We were not able to corroborate these findings. In our study, comorbidities were assessed using objective measures, while most previous studies used "self-reports" or data from medical records [3,4]. Moreover, previous studies used a different threshold to classify an improvement in 6MWD as clinically relevant (i.e.…”

“…Moreover, previous studies used a different threshold to classify an improvement in 6MWD as clinically relevant (i.e. 54 m) [3,4].…”

COPD comorbidities network

“…At lower p-values, less prevalent and connected nodes are lost with little changes seen within hubs. In fact, 23 comorbidities shown in table 2 hold 56, 69 or 72% of the links depending of the p-values cut-off used for significant association and interestingly many of those comorbidities have been shown to influence important outcomes as described in previous studies [13,14,17,19,20,42,43].…”

“…Using an unbiased approach, we constructed a graphic expression of the complex relationship between prevalence, connections between diseases and clinical variables, the presence of hubs and the clustering of comorbidities. Interestingly, the highly connected comorbidities ( figure 2 and table 2) are known to be associated with important patient-related outcomes [13,14,17,19,20,42,43]. If we assume that the COPD Comorbidity Network is similar in behaviour to common networks seen in daily life, like airports composed of important hubs with many incoming and outgoing connecting flights with less influential airports in minor destinations, then disruption of air traffic will be mostly felt when delays affect large hubs [44].…”