Evaluation of cardiovascular risk after long-term c-PAP therapy in patients with obstructive sleep apnea. A 4-year follow-up

Abstract

Aimof the study: was to investigate in OSA patients the change of Intima-Media Thickness (IMT) during a follow-up period of 51 months, according to the c-PAP adherence, and the role of c-PAP on Flow Mediated Dilation (FMD) and cardiovascular risk.

Methods: This longitudinal study includes two times: “T0” and “T1”. At “T0”, 156 OSA patients (125 M) started c-PAP treatment. At “T1” the study was completed only by 99 patients (78 M), because 57 subjects dropped out the study. At “T1” 30 patients had never used c-PAP, while 69 of them were in optimal c-PAP adherence (>4 hrs/night). At “T0” and “T1” we evaluated anthropometric factors, lenght of c-PAP treatment, c-PAP adherence, and IMT. At “T1”we measured FMD, IMT and Δ-IMT (change in the carotid IMT between T1 and T0, ΔIMT= IMTT1-IMTT0). We defined “negative Δ-IMT” if IMTT1-IMTT0 <0 mm and positive Δ-IMT if IMTT1-IMTT0 ≥0mm.

Results: Patients, who were adherent to c-PAP, had a lower daytime sleepiness, lower PaCO2, and lower IMT (p<0.005). The FMD was higher than FMD of not adherents (p <0.05). The subgroup of negative Δ-IMT used c-PAP for a higher number of hours, compared to those with positive Δ-IMT (p = 0.005). Patients with ΔIMT <0 at “T1” showed lower PaCO2 (p = 0.016). The univariate COX analysis shows, as only significant protective factor for new cardiovascular events, the lenght of c-PAP use (p = 0.045). In the multivariate binomial logistic regression model, considering ΔIMT as the dependent variable, the only significant predictive value was adherence to c-PAP (OR 1.118, p=0.039).

Conclusions: this study demonstrates that adherence to c-PAP improves endothelial function and IMT over time.