The Role Of Hypercapnia On The Effect And Re-excacerbation Of Systemic Corticosteroids For Patients With AECOPD

Objective:To investigate the role of hypercapnia on the short-term effect and re-excacerbation of systemic corticosteroids (SCS) therapy for patients with AECOPD.Methods:We selected 196 cases of AECOPD patients on admission, and divided them into hypercapnia group (PaCO2≥50mmHg) and non-hypercapnia group (PaCO2 <50mmHg) according to the results of arterial blood gas analysis, each group was further divided into long-course (>7days) and short-course (≤7days) sub-groups on the basis of SCS course. Hypercapnia group was of 105 cases, including 56 cases in long-course treatment group,49 ones in short-course group; non-hypercapnia group was of 91 cases, including 39 ones in long-course group and 52 ones in short-course group. We followed up inpatient days, lung function improvement after SCS treatment (△FEV1), and CAT scores after admission on the first day, fifth day and before discharge. We also followed up the time of first acute exacerbation and the number of acute exacerbations in one year after outpatient by clinical or telephone. These results were used to assess and compare the SCS therapy’s short-term and long-term efficacy of hypercapnia and non-hypercapnia groups, and the long course and short course sub-groups of either group by using paired t-test and two independent samples t-test. Then, we calculated the median time of the first acute exacerbation by life table method, and maked survival curves and risk curves, compared the overall distribution of survival curves and risk curves of different subgroups by Generalized Wilcoxon test; and then obtained the hazard ratio of various factors by COX regression model, and analyzed possible reasons of the differences in the results by the average number of exacerbations in one year for each subgroup.Results:Hypercapnia group compared with the non-hypercapnia group, the average inpatient days were longer (mean difference was 3.3d, P<0.05), the amount of improvement in lung function △FEV1 (mean difference was 95.3mL, P<0.05) and CAT clinical symptom score improvement was more pronounced (28.0 down to 15.9 VS 24.3 down to 15.4 points). In hypercapnia group, long-course group with SCS therapy compared with short-course one, the difference in length of hospital stay was not statistically significant (P>0.05); the amount of improvement in lung function was obvious(mean difference was 55.4mL, P<0.05); CAT score on 1-5d in both groups was not statistically significant (P>0.05), but on 5-10d the long-course group was significant decreased (about 4.9 points), the short-course group was not significant changed (P>0.05). In non-hypercapnia group, long-course group with SCS therapy compared with short-course one, the average length of stay was not statistically significant (mean difference was 1.8d, P>0.05); the △FEV1 was statistically significant (mean difference was 22.3mL, P<0.05); CAT score on 1-5d had no difference (9.3VS8.6, P>0.05), on 5-10d there were no significant changes too. Hypercapnia group compared with the non-hypercapnia group, the median survival time was shorter (136VS163d), the overall distribution of the risk curve was higher and the survival curve was lower, AECOPD recurrence risk was higher (P<0.05). Hypercapnia group, the average number of acute exacerbations in one year was more than non-hypercapnia group (mean difference of 0.87 times, P<0.05). In hypercapnia group, long-course group with SCS therapy compared with short-course one, the median survival time was prolonged (148VS123d), the overall distribution of the survival curve was higher, the risk curve was lower, AECOPD recurrence risk was lower (P<0.05), the average number of acute exacerbations in one year had no significant difference (2.20VS2.27times,P>0.05). In non-hypercapnia group, long-course group with SCS therapy compared with short-course one, the median survival time was not statistically significant (P>0.05), the overall distribution of survival curves and risk curves in both groups had more overlap, the risk of AECOPD recurrence had no significant difference (P>0.05), the average number of acute exacerbations in one year had no significant difference (1.40VS1.72times, P>0.05). COX regression model evaluation showed that only hypercapnia (HR= 1.834) and sex (HR=1.466) affect COPD acute exacerbation; in hypercapnia group only SCS course (HR=1.258), COPD course (HR=1.024) and sex (HR= 2.068) were independent risk factors; in non-hypercapnia group only COPD course (HR=1.012) was independent risk factor.Conclusion:1.Systemic corticosteroid therapy in AECOPD with hypercapnia compared with non-hypercapnia, pulmonary function and clinical symptoms improved more obvious; in AECOPD patients with hypercapnia, long course of SCS therapy made clinical symptoms and lung function improvement more obvious.2. Hypercapnia is an independent risk factor for acute exacerbation of COPD, the long course of SCS therapy may postpone first acute exacerbation of COPD, and reduce the risk of exacerbation.