The purpose of patient relationship categories and modifiers is to facilitate the attribution of patients and care episodes to clinicians who serve patients in different roles as part of the assessment of the cost of care. Patient relationship categories and modifiers define and distinguish the relationship and responsibility of a physician or applicable practitioner with a patient at the time of furnishing an item or service.

The patient relationship categories on the operational list are:

X1 Continuous/broad services

This category could include clinicians who provide the principal care for a patient, where there is no planned endpoint of the relationship. Care in this category is comprehensive, dealing with the entire scope of patient problems, either directly or in a care coordination role.

Examples include, but are not limited to: Primary care, specialists providing comprehensive care to patients in addition to specialty care, etc.
   
X2 Continuous/focused services

This category could include a specialist whose expertise is needed for the ongoing management of a chronic disease or a condition that needs to be managed and followed for a long time.

Examples include, but are not limited to: A rheumatologist taking care of a patient’s rheumatoid arthritis longitudinally but not providing general primary care services.
   
X3 Episodic/broad services

This category could include clinicians that have broad responsibility for the comprehensive needs of the patients, but only during a defined period and circumstance, such as a hospitalization.

Examples include, but are not limited to: A hospitalist providing comprehensive and general care to a patient while admitted to the hospital.
       
X4 Episodic/focused services

This category could include a specialist focused on particular types of time-limited treatment. The patient has a problem, acute or chronic, that will be treated with surgery, radiation, or some other type of generally time-limited intervention.

Examples include, but are not limited to: An orthopedic surgeon performing a knee replacement and seeing the patient through the postoperative period.
   
X5 Only as ordered by another clinician

This category could include a clinician who furnishes care to the patient only as ordered by another clinician. This relationship may not be adequately captured by the alternative categories suggested above and may need to be a separate option for clinicians who are only providing care ordered by other clinicians.

Examples include, but are not limited to: A radiologist interpreting an imaging study ordered by another clinician.

Note: The same provider and patient may have more than one relationship. For example, a patient is seen by a pulmonologist in the hospital for exacerbation of his COPD. This would be reported with modifier X4. If the pulmonologist continues to treat the patient for COPD, the relationship would then be reported with modifier X2. The NPI of the ordering physician or applicable practitioner (if different from the billing physician or applicable practitioner) should also be reported.

For more information: https://www.cms.gov/Medicare/Quality-Initiatives-Patient-Assessment-Instruments/Value-Based-Programs/MACRA-MIPS-and-APMs/Patient-Relationship-Categories-and-Codes-Posting-FINAL.pdf