Diagnosis Codes: M05.79, M17.12, Z79.1, Z79.899
Rationale to code this encounter as 99213:
- History—The history of present illness was extended. The review of systems was comprehensive, and two of the three past, family and social history were documented. This makes the history level comprehensive.
- Eight systems were examined. This makes the exam level comprehensive.
- Medical decision making—The diagnoses are two established problems stable. Labs were ordered, and the labs were done to monitor toxicity of medication. This makes the MDM low complexity.
The Current Procedural Terminology (CPT) indicates that only two of the three components are needed for an established patient (history, exam and medical decision making). The presenting problems were self-limited or minor: “A problem that runs a definite and prescribed course, is transient in nature and is not likely to permanently alter health status OR has a good prognosis with management/compliance” (CPT 2016). Although the history and the exam are at a comprehensive level, the medical decision making was low complexity. This determines that the visit meets the medical necessity of a Level 3 visit.
- M05.79 is rheumatoid arthritis with rheumatoid factor of multiple sites without organ or system involvement;
- M17.12 is unilateral primary osteoarthritis, left knee;
- Z79.1 is long-term (current) use of non-steroidal anti-inflammatories (NSAID); and
- Z79.899 is other long-term (current) drug therapy.