Enhanced external counterpulsation on exercise tolerance in pneumoconiosis: Insights from comorbidity subgroups efficacy and predictors

Background: To investigate the efficacy of enhanced external counterpulsation (EECP) in improving exercise tolerance in patients with pneumoconiosis, focusing on differences in efficacy with and without lung disease comorbidities, and to identify key predictors of EECP efficacy. Patients and methods: Seventy patients with occupational pneumoconiosis were enrolled in a single-center randomized controlled trial, and were randomly divided into the conventional group (35 patients) and the EECP group (35 patients), and according to the presence or absence of lung disease comorbidities, subjects were divided into the subgroups with and without comorbidities. The conventional group received health management, medication, and individualized exercise prescription, while the EECP group received 1 h of EECP intervention per day for 5 weeks on top of the conventional treatment. Exercise tolerance indexes before and after treatment were assessed by cardiopulmonary exercise test (CPET), including AT-VO2Kg, Max-VO2Kg, AT-O2puls, Max-O2puls, AT-Load, AT-Mets and Max-Mets 7 indicators. Predictors of efficacy were analyzed by univariate and multivariate linear regression using post-treatment AT-VO2Kg as the main dependent variable. Results: Comparison of all CPETs between the EECP and non-EECP groups, and the comorbidity subgroup and the uncomplicated subgroup before treatment showed no statistically significant difference (P > 0.05), and the post-treatment AT-VO2Kg, Max-VO2Kg, AT-O2puls, Max-O2puls, and metabolic equivalents of the EECP group and the uncomplicated subgroup (AT-Mets, Max-Mets) were significantly improved compared with the control group (all P < 0.05), but no significant benefit was seen in the comorbidity subgroup (P > 0.05). Multiple regression analysis showed that comorbidity was a negative predictor of efficacy whereas pre-treatment AT-VO2Kg was a positive predictor. No safety adverse events occurred in either group. Conclusion: EECP safely and effectively improved exercise tolerance in patients with pneumoconiosis, and its efficacy was particularly significant in the comorbidity-free subgroup. The comorbidity subgroup failed to benefit significantly from the EECP intervention, and further analysis showed that comorbidity was an independent negative predictor limiting the treatment effect. In addition, pretreatment AT-VO2Kg served as a positive predictor of efficacy, suggesting that patients with higher baseline cardiorespiratory reserve had a superior benefit from EECP treatment.