Clinicians and coders are different: Examples of disparities in primary care coding

Area of Science:

• Health Informatics
• Medical Coding
• Database Bias

Background:

• Administrative databases are increasingly used for healthcare research.
• Traditionally, coding professionals assigned International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes.
• Physicians are increasingly assigning ICD-9-CM codes for primary care visits.

Purpose of the Study:

• To compare ICD-9-CM codes assigned by physicians and professional coders.
• To identify causes for discrepancies in medical coding.
• To discuss the implications of coding bias on research.

Main Methods:

• Four patient cases were selected for analysis.
• Codes were assigned independently by a physician and a professional coder.
• A comparative analysis of assigned ICD-9-CM codes was performed.

Main Results:

• There was zero percent agreement between the physician and professional coder on the absolute ICD-9-CM codes assigned.
• Significant differences were observed in the coding of patient encounters.
• Potential sources of bias in administrative data coding were identified.

Conclusions:

• Discrepancies in ICD-9-CM coding between physicians and professional coders are substantial.
• Coding bias in administrative databases can impact research validity.
• Further investigation into coding practices and standardization is warranted.