Is auto-titrating noninferior to fixed CPAP for OHS with severe OSA?

A recent study has shown the comparable effectiveness of fixed (fCPAP) and auto-titrating continuous positive airway pressure (APAP), with some outcomes favouring fCPAP, in patients with obesity hypoventilation syndrome (OHS) and severe obstructive sleep apnoea (sOSA).

Twenty-eight of 84 screened participants with OHS + sOSA (mean age 55 years, BMI 54 kg/m2, PaCO₂ 49 mm Hg, AHI 88 events/h) were randomly allocated to either fCPAP (n=13) or APAP (n=15) for 3 months. A sample size of 82 was needed to show noninferiority of APAP vs fCPAP. The change in PaCO₂ was the primary outcome, while changes in quality of life and cardiovascular biomarkers were secondary.

Mean adherence in both groups surpassed 4 h, but 25 percent of the participants did not complete the trial. Both fCPAP and APAP reduced PaCO₂ (‒5.7 vs ‒4.1 mm Hg). However, the test of noninferiority of APAP vs fCPAP remained inconclusive (mean ΔPaCO₂ difference, ‒1.7 mm Hg, 95 percent confidence interval, ‒5.0 to 1.6).

Furthermore, sleep quality and adherence improved more with fCPAP than with APAP, but other outcomes did not differ significantly.

“While the study is not powered to confirm the noninferiority of APAP, some outcomes [that] appeared to favour fCPAP and APAP use in OHS + sOSA should be approached cautiously,” the authors said. “A larger study with protocol modifications is required to confirm these preliminary findings.”

FCPAP is the preferred first-line ventilatory therapy in patients with OHS + sOSA, while APAP is not recommended, according to the authors.