M1021: CMS OASIS Q&As

The determination of the primary and secondary diagnoses must be completed by the assessing clinician in conjunction with the physician/allowed practitioner. If the assessing clinician identifies the diagnosis that is the focus of the care and reports it in M1021 – Primary Diagnosis, and ICD-10-CM coding guidelines required that the selected diagnosis is subject to mandatory multiple coding, the addition of the etiology code and related sequencing is not a technical correction because a diagnosis is being added. If any diagnosis is being added, in this case for etiology/manifestation coding requirements, the assessing clinician must be contacted and agree. If, based on the review of the comprehensive assessment and plan of care, the auditor questions the accuracy of the primary diagnosis selected by the assessing clinician, this is not considered a “technical error” and the coding specialist may not automatically make the correction without consulting with the assessing clinician. If after discussion of the etiology/manifestation coding requirement between the assessing clinician and the coding specialist, the assessing clinician agrees with the coding specialist or auditor that the sequence of the diagnosis codes should be modified to more accurately reflect the diagnosis that is most related to the current POC per ICD-10-CM coding guidelines, agency policy will determine how (e.g., by whom) this change is made.

Coding may be done in accordance with agency policies and procedures, as long as the assessing clinician determines the primary and secondary diagnoses and records the symptom control ratings. The clinician should provide the medical diagnoses requested in M1021/1023 - Diagnoses and Symptom Control. A coding specialist in the agency may enter the actual alphanumeric ICD-10-CM codes once the assessment is completed. The HHA has the overall responsibility for providing services and assigning ICD-10-CM codes. It is expected that each agency will develop their own policies and procedures and implement them throughout the agency that allows for correction or clarification of records to meet professional standards. It is prudent to allow for a policy and procedure that would include completion or correction of a clinical record in the absence of the original clinician due to vacation, sick time, or termination from the agency.

Any additional diagnosis listed on the claim should follow the OASIS definitions for primary and secondary diagnosis found in the OASIS Guidance Manual. Include only current diagnoses actively addressed in the plan of care or that have the potential to affect the patient’s responsiveness to treatment and rehabilitative prognosis even if not the focus of any home health treatment itself. Exclude resolved diagnoses or those that do not have the potential to impact the skilled services provided by the HHA, even if they are known/documented diagnoses. Adhere to the ICD-10-CM Official Guidelines for Coding and Reporting when assigning ICD-10-CM diagnosis codes. Note that the CY2019 Home Health Final Rule has stated that, “Because ICD–10 coding guidelines require reporting of all secondary diagnoses that affect the plan of care, we would expect that more secondary diagnoses would be reported on the home health claim given the increased number of secondary diagnosis fields on the home health claim compared to the OASIS item set.”

For case-mix adjustment purposes, the principal diagnosis reported on the home health claim will determine the clinical group for each 30-day period of care. In Change Request 11272, CMS has updated billing instructions to clarify that there will be no need for the HHA to complete an ‘‘Other follow-up’’ assessment (RFA 05) just to make the diagnoses match. Therefore, for claim ‘‘From’’ dates on or after January 1, 2020, the ICD–10–CM code and principal diagnosis used for payment grouping will be from the claim rather than the OASIS. As a result, the claim and OASIS diagnosis codes will no longer be expected to match in all cases. Additional claims processing guidance, including the role of the OASIS item set will be included in the Medicare Claims Processing Manual, Chapter 10.

Guidance in Chapter 3 of the current OASIS Guidance Manual for M1021/M1023 Diagnoses and Symptom Control states the primary diagnosis is the chief reason the patient is receiving home care and the diagnosis most related to the current home health Plan of Care. Other diagnoses are defined as “comorbid conditions that exist at the time of the assessment that are actively addressed in the patient’s Plan of care OR that have the potential to affect the patient’s responsiveness to treatment and rehabilitation prognosis, even if the condition is not the focus of any home health treatment itself”. M1021 - Primary Diagnosis and M1023 - Other Diagnoses are reported at Start of Care and Resumption of Care. After completing a comprehensive assessment of the patient and receiving input from the physician/allowed practitioner, the clinician will report the patient’s current primary and other diagnoses at the SOC (and ROC if applicable). Diagnoses may change following an inpatient facility stay for the Resumption of Care. The chief reason an agency is caring for a patient may change. The focus of the care may change. At each required time point the clinician will assess and report what is true at the time of the assessment.