Fixed vs Auto-Adjusting CPAP for Prevention of eGFR Decline in OSA

In patients with obstructive sleep apnea (OSA), the use of fixed continuous positive airway pressure (CPAP), but not auto-adjusting CPAP, was associated with the prevention of time-dependent decline in estimated glomerular filtration rate (eGFR), according to an analysis of data from the European Sleep Apnea Database (ESADA) that was presented at the European Respiratory Society International Congress 2017, held September 9 to 13, 2017, in Milan, Italy, and published in Chest.

With debate surrounding the effect of treating OSA on the decline in renal function, the investigators of the current study sought to evaluate the respective effects of fixed CPAP and auto-adjusting CPAP modes on eGFR in a large sample of patients from the ESADA cohort. They calculated eGFR both before and after follow-up via use of the Chronic Kidney Disease-Epidemiology Collaboration equation. Three study groups were involved in the assessment: untreated patients (n=144), patients who received fixed CPAP (n=1178), and patients who received auto-adjusting CPAP (n=485).

On the whole, eGFR decreased over time in the entire population evaluated. The rate of decline in eGFR was significantly greater in the subgroup of patients with eGFR above the median of 91.42 mL/min/1.73 m² at baseline (P <.0001 for effect of baseline eGFR). This decline was diminished or absent (P <.0001 for effect of treatment) in the OSA subgroup treated with fixed CPAP.

Follow-up duration that exceeded the median of 541 days was significantly associated with a decline in eGFR in the untreated and auto-adjusting CPAP groups, but not in the fixed CPAP group (P <.0001 per 2-way ANOVA). A multiple regression analysis demonstrated that decline in eGFR was heightened by the following variables: female sex, advanced age, chronic heart failure, higher baseline eGFR, and longer duration of follow-up. The use of fixed CPAP, however, was linked to a protective effect.

The researchers concluded that when considering the fact that eGFR decreases progressively in patients with OSA, the study findings support the benefits of fixed CPAP on the general health status of patients with the disorder, suggesting that auto-adjusting CPAP should not be the first treatment choice for such patients, particularly those with comorbidities. Additional studies are warranted to explore whether other health aspects that are known to be affected by OSA (eg, metabolic dysfunction and inflammatory activation) might also be affected by the use of fixed CPAP vs auto-adjusting CPAP.

Reference

Marrone O, Cibella F, Pépin JL, et al; ESADA network. Fixed but not autoadjusting positive airway pressure attenuates the time-dependent decline in glomerular filtration rate in patients with obstructive sleep apnea [published online April 23, 2018]. Chest. doi:10.1016/j.chest.2018.04.020