CPAP compliance: Medicare’s 4-hour, 70% rule

The rule, as Medicare writes it

Two documents set it. The national coverage determination says when CPAP is covered at all. The local coverage determination used by the DME contractors says what "benefit" means in numbers.

NCD 240.4, Continuous Positive Airway Pressure (CPAP) Therapy for Obstructive Sleep Apnea. CPAP is covered for adults with OSA. Coverage is initially limited to a 12-week period, to identify the patients who benefit from it; after that, CPAP is covered only for patients who benefited during those 12 weeks. The provider must educate the patient in the use of the device before therapy starts. The diagnosis has to rest on a clinical evaluation plus a positive attended polysomnogram in a sleep laboratory, or an unattended home sleep test with a Type II or Type III device, or a Type IV device measuring at least three channels.

LCD L33718, Positive Airway Pressure (PAP) Devices for the Treatment of Obstructive Sleep Apnea (revision effective for services on or after 1 January 2024). This is where the numbers are.

• Adherence. Use of PAP for four hours or more per night on 70% of nights during a consecutive 30-day period, at any time during the first three months of initial use.
• The re-evaluation. No sooner than the 31st day and no later than the 91st day after starting therapy, the treating practitioner must conduct a clinical re-evaluation and document that the patient is benefiting. That means an in-person re-evaluation documenting that the OSA symptoms have improved, and objective evidence of adherence, reviewed by the treating practitioner.
• Failing the trial. A patient who fails the initial 12-week trial can re-qualify, but only with both an in-person re-evaluation by the treating practitioner to determine why PAP did not work, and a repeat sleep test in a facility (a Type 1 study).
• Coverage criteria. An AHI or RDI of 15 or more events per hour with a minimum of 30 events; or 5 to 14 events per hour with a minimum of 10 events, plus documentation of excessive daytime sleepiness, impaired cognition, mood disorders or insomnia, or of hypertension, ischemic heart disease or a history of stroke.

Four things practices get wrong about the rule:

1. The window is any consecutive 30 days in the first 90, not the first 30. A patient who struggles for three weeks and then settles can still qualify on days 40 to 69.
2. 70% of 30 nights is 21 nights. Nine misses in a window are survivable; the tenth ends it. A patient who has not used the device by night 10 has no headroom left in any window that started on night 1.
3. Four hours is per night, not an average. Seven hours on Monday and one on Tuesday is one compliant night, not two.
4. The re-evaluation has a floor and a ceiling. Day 31 at the earliest, day 91 at the latest, in person, with the adherence data reviewed. A visit on day 95 is outside the window.

Commercial plans publish their own criteria. Check the plan. The rest of this page follows Medicare.

Where the compliance data lives

Modern PAP devices report each night’s use through a built-in modem to the manufacturer’s cloud platform. ResMed’s AirView, for one, describes itself as a secure, cloud-based system for managing patients with sleep-disordered breathing, with one-click compliance reports and online data reports covering up to 365 days of therapy data and up to 90 days of detailed data.

The compliance report is the artifact everyone needs: nightly usage, the share of nights at four hours or more across the chosen 30-day window, and usually the residual AHI and mask leak alongside.

Three parties depend on it. The DME supplier needs it to keep the device covered past the trial. The treating practitioner needs it in hand at the re-evaluation, because the LCD requires objective adherence evidence reviewed by that practitioner. And the practice’s follow-up team needs it every day in the first month, because that team is the only one of the three that can still change the number.

The gap in most practices is the third one. The platform reports nightly. Nobody’s job is to open it on day 4 and notice that a patient has stopped.

Why compliance fails

The reasons are operational more often than clinical.

• The first two weeks decide it. The arithmetic above means a patient who stops in week one has already lost the first window and is racing the calendar for a second. Programs that reach every new patient in the first week are watching the only interval where a phone call still changes the outcome.
• Discomfort presents as data, not as a phone call. Mask leak, pressure intolerance, dryness and claustrophobia show up as short sessions, high leak numbers and skipped nights. The patient does not ring the office to report it. The mask goes in the closet.
• The wrong metric gets watched. Total hours and weekly averages hide a patient who sleeps eight hours with the mask on three nights and skips four. The rule counts nights at four hours or more.
• Nobody owns days 31 to 91. The re-evaluation is scheduled when the front desk gets to it, which is often after day 91, or before the patient has a qualifying window to document.
• The data lives in a portal the follow-up team does not open. The manufacturer’s platform is built for the DME supplier and the clinician. The coordinator who should be calling patients daily is not logged into it.
• The patient was never reached. Wrong number, no consent to text, calls placed during working hours, three attempts and then silence.

None of these require a sleep physician to fix. They require a program.

How RTM pays for the follow-up

Nightly PAP use, transmitted by the device itself, is therapy-adherence data for the respiratory system from an FDA-defined medical device. That is the textbook case for remote therapeutic monitoring (RTM), and the RTM code set has a respiratory device family for it. The figures are the CY2026 national non-facility amounts; your locality will differ.

Two different counts. RTM device days count the days the device transmitted data in a 30-day period. Compliance counts the nights the patient used the device for four hours or more. They are not the same number and they do not run on the same clock. A patient with thirty days of transmitted data and twelve compliant nights is billable under 98976 and failing the trial. A program has to keep both counts, per patient, and act on the second one.

The rules that apply.

• RTM does not require an established patient relationship, so it can begin on the setup day.
• Consent is documented before the service begins.
• One practitioner bills for a patient in a 30-day period, and RPM cannot be billed for the same patient.
• Physicians and the non-physician practitioners eligible to bill evaluation and management services bill RTM. Auxiliary personnel can furnish the monitoring under general supervision.
• 98980 needs at least one interactive communication with the patient or caregiver in the month and twenty minutes of a person’s time. The software’s messages do not count as either. Time is logged by the person who spent it, as it is spent.
• The monitoring has to be medically reasonable and necessary. The code descriptors set no end date; adherence monitoring can continue month by month for as long as that holds.
• RTM can run alongside chronic care management or principal care management for the same patient, with no minute counted twice.

The 2026 code guide has the full RTM table, the 2-to-15-day logic and the codes that cannot be billed together. The RTM software page covers what the tooling has to do.

What a compliance program looks like

Run as a calendar, not as a policy.

Day 0. Setup and education, documented (98975). RTM consent recorded with a timestamp. The device registered to the patient on the manufacturer’s platform, and the practice’s path to the data confirmed: a feed, an export, or a report someone pulls. Contact preferences and the best time of day recorded.

Days 1 to 14. Read the usage data daily. Sort every patient into a bucket: on track, slipping, no data, device problem. Reach the slipping and silent patients within a day, by text or by phone, in the practice’s own wording. Mask and pressure complaints go to the clinician or the DME supplier the same day. Log every contact.

Days 15 to 30. Run the window arithmetic for each patient: is there a consecutive 30-day span, starting on any day so far, that can still reach 21 compliant nights? If not, the plan changes now: re-fit, pressure adjustment, re-education, a different interface. Waiting for day 30 to find out wastes the only weeks that matter.

Day 30. The first RTM device period closes: 98976 if the device transmitted on sixteen or more days, 98984 if on two to fifteen. The calendar month closes separately: twenty minutes of a person’s time and one interactive communication documented (98980), or the ten-minute code if that is what the month held.

Days 31 to 91. Book the in-person re-evaluation as soon as the patient has a qualifying window, not as late as the ceiling allows. Bring the compliance report to the visit. Document the symptom improvement and the practitioner’s review of the adherence data. Send the DME supplier what it needs for continued coverage.

Beyond day 91. Continue the monthly RTM cycle while it is medically necessary. Patients who failed the trial go on a separate track: the in-person re-evaluation of why, and the facility-based repeat study, before a new trial starts.

Who does what. The coordinator or medical assistant does the daily read, the buckets and the outreach, under the practitioner’s general supervision. The practitioner does the treatment management, the re-evaluation and the clinical calls. The biller works from a gate that shows, per patient and per period, which elements are met and which are not.

How Caesar Health runs it

Caesar runs PAP adherence as an RTM program inside a clinic operating system, the same layer that answers the practice’s phone and books its schedule. It is not a sleep-specific product, and it is not a device. The RTM software page has the full account; the short version:

• The monthly cycle, the buckets, the review queue and the billing gate are live.
• Outreach to slipping and silent patients runs by SMS and phone in your approved wording, consent-checked before every message, and written back to the EMR you already use.
• The agent drafts the monthly note and the patient message. A person reviews, approves and logs the minutes as they are spent. A person sets Ready for Billing.
• PAP usage data reaches the program today through the compliance reports your PAP platform already produces. Direct connections to manufacturer platforms are on the roadmap. When they ship, the import swaps and nothing downstream changes.
• Caesar does not choose the code, submit the claim, or make a clinical decision. Your biller and your clinicians do.

Caesar Health is HIPAA compliant, signs a Business Associate Agreement at contract, and has SOC 2 Type II in progress.

Start a pilot with one month of new PAP starts. We run the first 90 days in your EMR, with your staff on the review queue, and you read the compliance numbers and the billing gate at the end of it.