Scheduling and Documenting Recertifications of Medical Necessity for Oxygen

Recertification scheduling and documentation requirements depend on the date when home oxygen therapy began. Contractors request the following information on all recertifications:

• Date and results of the most recent arterial blood gas or oximetry tests prior to the recertification date;

• Name of the provider conducting the most recent arterial blood gas or oximetry tests performed prior to the recertification date and the conditions under which this test were conducted; and

• Estimated length of need for oxygen (Section B on the Form CMS-484)
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Contractors establish the schedule for recertifying the need for oxygen for patients beginning home oxygen therapy in accordance with the requirements below:

1. Recertifications

Group I: Recertification requirements are to be determined by the contractor.

Group II: If oxygen test results on the initial certification were in Group II, according to §1834(a)(5) of the Act, recertification of all oxygen patients must be performed within 90 days after initial certification for all patients who begin coverage after January 1, 1991, with an arterial blood gas result at or above a partial pressure of 55 mm Hg or an arterial oxygen saturation percentage at or above 89. Repeat blood gas study must be performed between the 61st - 90th day of home oxygen therapy. Retesting is required only if a claim for oxygen therapy will be filed for the fourth or later months.

If recertification is due, contractors do not pay the next month's claim if the test was not performed during the required time frame. If a qualifying test is not obtained between the 61st and 90th day of home oxygen therapy, but the patient continues to use oxygen and a test is obtained at a later date, contractors instruct suppliers to use the date of the repeat test as the date of service on a subsequent claim, and if that test meets Group II criteria, they resume payments from that point of time.


2. New Orders - In the following situations, a new order must be obtained and kept on file by the supplier, but neither a new CMN nor a repeat blood gas study are required:

• If the prescribed maximum flow rate changes but remains within one of the following categories: (a) less than 1 LPM, (b) 1-4 LPM, (c) greater than 4 LPM

• If the physician has initially specified a delivery system, and a change is made from one type of stationary system to another (i.e., concentrator, liquid, gaseous).