Predictors of Success of Inpatient Pulmonary Rehabilitation Program in COPD Patients

Abstract

Purpose

Pulmonary rehabilitation programs (PR) are an important part of the comprehensive treatment of patients with chronic pulmonary diseases. Patients respond individually to PR. The aim of this study is to identify potential predictors of success of PR to recognise patients who benefit most and to uncover possible reasons for poor response to PR.

Patients and Methods

We included 121 patients with chronic obstructive pulmonary disease (COPD) who completed our 4-week inpatient PR without any exacerbations of disease during PR that could potentially affect PR outcomes. Improvement in distance of ≥30 m on the 6-minute walk test (6MWT) after PR was chosen as a primary marker of physical success. Ninety-one patients achieved improvement of ≥30 m on the 6MWT and were thus considered good responders, and 30 patients were poor responders with improvement in the distance of <30 m on the 6MWT.

Results

We compared baseline clinical characteristics, medication, lung function, physical capacity, body composition, and laboratory blood tests between groups of good and poor responders. The most prominent differences between groups were associated with differences in baseline body composition and erythrocyte-related parameters. Good responders had significantly lower body water content (p = 0.042) and higher body weight (p = 0.036), body fat content (p = 0.049), dry lean mass (p = 0.021), haemoglobin levels (p = 0.040), erythrocyte count (p = 0.017), haematocrit (p = 0.030) and iron level (p = 0.028).

Conclusion

A more muscular body composition and a higher ability to transport oxygen from the blood to the muscles could be beneficial for the outcome of PR.

Plain Language Summary

Pulmonary rehabilitation programs (PR) are important part of management of patients with chronic obstructive pulmonary diseases and other chronic pulmonary diseases. Nevertheless, PR are sparsely available to patients, and patients respond to PR individually. Our study will help identify patients who benefit most from PR and find possible reasons why the physical condition of some patients does not improve with PR. Only patients with chronic obstructive pulmonary disease who completed inpatient pulmonary rehabilitation program without any exacerbations of disease that could potentially affect PR outcomes were included in this study to determine what baseline patient characteristics could predict good and poor responders to PR. The results of our study suggest that a more muscular body composition and a higher ability to transport oxygen from the blood to the muscles could be beneficial to the outcome of PR. We suggest that before sarcopenic or anaemic patients are referred for PR, special care should first be taken to address and remedy their condition to maximise their physical gain in PR.

Keywords:

• pulmonary rehabilitation
• COPD
• predictors
• responders

Abbreviations

1-min STS, 1 minute sit-to-stand test; 6MWT, 6-minute walk test; ALT, alanine aminotransferase; AP, alkaline phosphatase; AST, aspartate aminotransferase; BFMI, body fat mass index; BMI, body mass index; CAT, COPD assessment test; CET, cycle endurance test; COPD, chronic obstructive pulmonary disease; CRP, C-reactive protein; DLCO, diffusing capacity for carbon monoxide; eGF, estimated glomerular filtration; ESWT, endurance shuttle walk test; FEV1, forced expiratory volume in 1 second; FFMI, fat-free mass index; gammaGT, gamma-glutamyl transferase; HbA1c, A1c glycosylated haemoglobin; HDL, high-density lipoprotein cholesterol; ISWT, incremental shuttle walk test; LAMA, long-acting muscarinic antagonist; LDL, low-density lipoprotein cholesterol; LTOT, long-term oxygen treatment; MCH, mean cell haemoglobin; MCHC, mean cell haemoglobin concentration; MCID, minimal clinically important difference; MCV, mean cell volume; MEP, maximal expiratory pressure; MIP, maximal inspiratory pressure; MPV, mean platelet volume; MRC, medical research council dyspnoea scale; NTproBNP, N-terminal pro-Brain natriuretic peptide; PR, pulmonary rehabilitation program; RDW, red cell distribution width; SGRQ, St. George’s Respiratory Questionnaire; TIBC, total iron-binding capacity; UIBC, unsaturated iron-binding capacity; VC, vital capacity.

Data Sharing Statement

Original study data supporting the results can be found at corresponding author on request and are available if needed only to the reviewers for review purposes of this article and no other sharing, comparing or publication of our original data is permitted.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

All authors declare that they have no conflicts of interest in this work.