CPAP mask fitting is the most underestimated step in obstructive sleep apnoea therapy. The diagnostic pathway gets the attention. The CPAP device gets the attention. The mask fit — which is the single most consistently identified determinant of long-term adherence — gets less attention than the clinical outcome data would suggest is warranted.

A working read of where mask fitting practice sits in Australian sleep medicine in May 2026.

What drives long-term adherence:

The mask interface is the most common reason patients stop using CPAP. The clinical literature has been consistent on this point for years. The data from device download reviews at most Australian sleep services continues to confirm that mask-related discomfort is the leading cause of therapy discontinuation in the first 90 days. Patients who are still using their original mask at 90 days are typically the patients who are still using CPAP at 12 months.

The fitting session matters. Patients who receive a comprehensive in-person fitting session — multiple mask options offered, fitting confirmed at therapy pressure, sizing checked carefully — have meaningfully higher 30-day and 90-day adherence than patients who receive a single-mask fitting or a remote fitting only.

Three categories of mask interface are dominant:

Nasal masks remain the most commonly fitted interface for new CPAP patients. They are well-tolerated by the majority of patients, give good seal characteristics at typical therapy pressures, and integrate well with the routine of a regular sleep pattern. Most Australian sleep services begin the fitting conversation with a nasal mask option.

Nasal pillows are used selectively. Patients with mild claustrophobia, patients with facial hair, and patients who report discomfort with the bridge-of-nose contact area of a nasal mask often do better with nasal pillows. The seal is more pressure-sensitive than nasal masks and at higher therapy pressures the pillows can be less reliable for some patients.

Full-face masks are used for patients with significant mouth-breathing tendency, patients with high therapy pressures, and patients who have not tolerated nasal mask options. The full-face mask category has improved in design through 2024–25 with several manufacturers releasing lighter, smaller-profile options that have reduced the historical adherence disadvantage that full-face masks carried relative to nasal masks.

The fitting session in 2026:

The well-conducted fitting session at a contemporary Australian sleep service typically takes 30–60 minutes for a new CPAP patient. The session covers explanation of mask options, sizing for two or three candidate interfaces, application of the candidate mask with the therapy device running at the prescribed pressure, and confirmation of seal characteristics at the patient’s normal sleep positions.

The seal check at the patient’s normal sleep positions is the step that is most often abbreviated and most often the source of subsequent adherence problems. Patients who are side sleepers and patients who change positions frequently through the night have different seal challenges than back sleepers, and the fitting session has to test for these.

The therapist-patient conversation about expectations matters. Patients who understand that mask fit may need adjustment in the first 1–2 weeks, that contact-area discomfort may need a different cushion size, and that the early adherence support is part of the therapy package are more likely to persist through early discomfort than patients who expect first-night perfection.

Common fitting errors:

Oversized cushion or undersized cushion. The cushion size that looks right on the mask packaging is often not the cushion size that fits the patient best. A few minutes spent testing alternative sizes on the same mask frame can change the comfort outcome significantly.

Strap tension too high. The compensating strategy when a mask is leaking is usually to pull the straps tighter. This is almost always the wrong solution. A mask that requires high strap tension to seal is usually the wrong size or the wrong cushion. Persistent over-tightening is the cause of much of the early-therapy facial-discomfort reporting.

Inadequate pressure-during-fitting test. A mask that seals at 5 cmH2O but leaks at 12 cmH2O is not a usable mask for a patient prescribed therapy in the higher end of the typical pressure range. The fitting session has to test at therapy pressure.

Adherence support in the first 30 days:

The follow-up touchpoint at 7–14 days from therapy initiation is the single most valuable adherence intervention in the early-therapy period. Patients reached at this point with the opportunity to discuss early experience, address any mask issues, and receive practical advice have meaningfully higher 30-day adherence than patients without that touchpoint.

The device data download review at this stage is useful but secondary. The conversation about how the mask feels and what the patient is experiencing is more predictive of long-term adherence than the AHI on the first 14 nights of therapy.

Mask swap willingness at 30 days. Patients struggling with mask fit at 30 days who are offered the opportunity to try a different mask interface category have meaningfully higher 90-day adherence than patients pressured to persist with the original interface.

For Australian sleep medicine services and CPAP device suppliers in mid-2026, the operational read is that mask fitting investment pays back through long-term adherence. The fitting session that takes 60 minutes saves the patient and the service significantly more time over the following 12 months than a 20-minute fitting session would have. The work of mask fitting is clinical work and treating it as such is the difference between a service with good long-term outcomes and a service with high attrition through the first 90 days.

The next 12 months will likely bring more design iteration at the mask interface category and continued improvements in the comfort and seal characteristics of the leading mask options. The fundamentals of good fitting practice will continue to be the clinical work that determines long-term outcomes.