Why Old Medical Code Sets Are Still Essential: A Comprehensive Guide

Old Medical Code Set

Remaining current is indispensable in the healthcare industry, yet relying solely on present codes may not always be the optimal solution.

When tasked with conducting an audit, handling an appeal, or conducting research on the appropriate code usage for a previous encounter, having a thorough understanding of the code descriptors and guidelines that were applicable in the past can significantly impact the outcome of your work. Here’s a brief overview of how you can effectively leverage historical medical code sets.

Audit Using the Correct Codes and Rules

Medical coding auditors, whether employed by healthcare practices, facilities, consultants, insurers, or external authorities, play a crucial role in enabling healthcare organizations to focus their training efforts where they are most needed. Accurate coding brings numerous benefits, including timely claim reimbursement, improved patient experiences, and reduced concerns about financial and legal repercussions associated with coding errors.

However, conducting audits often presents a challenge as they frequently take place in a different quarter or year than the actual date of service (DOS). Consequently, the codes, descriptors, and guidelines in effect during the DOS may differ from the current ones. To ensure the accuracy of an audit, it is essential to utilize the historical code sets that were applicable during the DOS. According to a senior auditor with AAPC Services, having access to historical code sets is a transformative advantage.

For example, let’s consider a scenario where an auditor examines the coding for initial hospital inpatient evaluation and management (E/M) services that occurred in the latter half of 2022 during May 2023. The descriptors and guidelines for those inpatient E/M codes underwent significant changes between the 2022 and 2023 code sets. The following table featuring the cpt code 99223 serves as an example of how the descriptors were modified.


­­­­­­­ Code Descriptor
2022 cpt code 99223 The evaluation and management of a patient in an initial hospital care setting involve three essential elements: a thorough history assessment, a comprehensive physical examination, and medical decision-making of a high level of complexity. Additionally, counseling and coordination of care with other healthcare professionals or relevant agencies are provided based on the nature of the problem(s) and the needs of the patient and their family. Typically, this level of care is required for patients with severe conditions warranting hospital admission. In general, around 70 minutes are dedicated to direct patient interaction and care on the hospital floor or unit.
2023 cpt code 99223 For the evaluation and management of a patient in an initial hospital inpatient or observation setting, a medically appropriate history and/or examination, along with a high level of medical decision-making, are necessary. When determining the appropriate code based on total time spent on the date of the encounter, a minimum of 75 minutes must be met or exceeded.

Significant changes were made to the E/M guidelines to address the shift from the previous emphasis on the three key components of history, examination, and medical decision making (MDM) to the 2023 focus on either MDM or total time. However, applying the 2023 rules to a 2022 date of service (DOS) could lead auditors to mistakenly assert that a service from 2022 was coded incorrectly.

It is important to note that auditors must also be knowledgeable about the current codes and rules. They often provide training to improve documentation and coding practices for areas that require attention, ensuring that providers and coders are informed and capable of applying the latest rules in their work. As a result, auditors require access to both historical and current code sets to fulfill their responsibilities effectively.

Appeal Based on DOS Rules

The principles that apply to auditing based on the date of service (DOS) can be extended to working on appeals. Whether you are a healthcare provider or a payer, verifying the accuracy of a claim based on the DOS is crucial. In addition to reviewing the provider’s documentation, consulting the guidelines provided in the relevant code set can assist in determining the correct coding. It may be necessary to delve into code sets from previous years to identify the applicable rules.

As an additional tip, apart from historical code sets, having access to past versions of the National Correct Coding Initiative (NCCI) edits can be beneficial, as suggested by Brink. Similarly, referring to relevant fee schedule data, such as Medicare Physician Fee Schedule (MPFS) fees and indicators that were in effect on the DOS, can also aid in ensuring the accuracy of a claim.

Research to Support Legal Cases and More

Professionals engaged in researching and coding encounters that occurred in previous years greatly benefit from the availability of historical code sets.

A prime example is legal professionals who are involved in cases where accurately determining the appropriate coding on a specific date of service (DOS) is crucial, such as in fraud cases.

Medical researchers and health statisticians also find historical code sets invaluable. They may require knowledge of the codes that were applicable to a particular diagnosis or procedure over a span of years for their studies. Having access to this code information enables researchers to swiftly search and identify relevant records pertinent to their research.

Where to Find Historical Code Sets

According to Brink, having access to historical code sets significantly simplifies the task of delivering high-quality work, regardless of one’s profession, the type of retrospective review, or the length of time spent in the field. Many coders, auditors, and healthcare-related organizations maintain shelves stocked with old code books, such as those for CPT®. Certain code sets, such as ICD-10-CM, ICD-10-PCS, and HCPCS Level II, can also be found online.

If obtaining physical copies of past code books is inconvenient, storing them poses a challenge, or the format of older online files is not preferred, there are coding software options available that offer access to historical coding data. For example, Codify currently offers subscribers a beta version feature that includes specific past code sets, guidelines, Medicare fee data, and Medicare and Medicaid NCCI edits. The software may even indicate when changes were made to a code, allowing for a quick overview of the update history of the code being researched.

Brink mentions that as code sets change, it is not uncommon for her desk or lap to be filled with books as she works in the traditional manner. However, with the assistance of software, the time spent reviewing changes, making notes regarding old codes or guideline modifications, juggling between two different methods, and hoarding physical books is eliminated.



Request a Free Quote