What was the biggest structural change in ICD-10 compared to ICD-9?

The significant structural change in ICD-10 compared to ICD-9 is the introduction of laterality, which refers to the specification of right versus left side in coding certain conditions. This change allows for a more accurate representation of patients' conditions, especially for injuries or diseases that may occur on one side of the body, such as in the case of limb or eye issues. Previously, in ICD-9, these distinctions were not as finely detailed, potentially leading to confusion and less precise data for healthcare providers and researchers.

Implementing laterality aids in improving clinical documentation and facilitates better patient care by allowing healthcare professionals to pinpoint and treat conditions more effectively based on their location. This emphasis on laterality exemplifies a focus on enhancing specificity and accuracy in coding, which is one of the overall aims in transitioning to ICD-10 from ICD-9.