[Diagnosis Coding in German Medical Practices: A Retrospective Study Using Routine Data]

Area of Science:

• Medical Informatics
• Health Services Research
• Clinical Documentation

Background:

• Physicians diagnose diseases using the International Statistical Classification of Diseases and Related Health Problems, 10th revised version, German modification (ICD-10-GM).
• Accurate and detailed coding is crucial for health services research and quality assessment.
• Variations in coding practices among different medical specialties are expected.

Purpose of the Study:

• To analyze the spectrum and depth of ICD-10-GM code utilization across various physician groups.
• To assess the coding quality by examining the use of terminal (final character) codes.
• To measure the inequality in ICD-10-GM code usage within different specialties.

Main Methods:

• Retrospective analysis of 22,287,583 datasets from 900 medical practices across Brandenburg and North Rhine.
• Data collected during the accounting period of October 2014 to September 2015.
• Normalized Gini coefficient used to measure inequality in code usage.

Main Results:

• 97.6% of all datasets were coded to the final character (terminal) using ICD-10-GM.
• Primary care physicians used the broadest variety of ICD-10-GM codes (71.1% of all possible terminal codes).
• Ophthalmologists exhibited the highest inequality in ICD-10-GM code usage (Gini coefficient: 0.93), while primary care physicians showed the lowest (Gini coefficient: 0.56).

Conclusions:

• Specialists predominantly use a limited set of ICD-10-GM codes.
• Primary care physicians demonstrate a wide variety of ICD-10-GM code usage and high rates of terminal coding, suggesting superior documentation quality.
• Findings highlight significant differences in coding practices between primary care and specialist physicians.