The impact of conversion to International Classification of Diseases, 10th revision (ICD-10) on an academic ophthalmology practice.

Purpose: To determine the financial and clinical impact of conversion from International Classification of Disease, 9th revision (ICD-9) to ICD-10 coding.

Design: Retrospective, database study.

Materials and methods: Monthly billing and coding data from 44,564 billable patient encounters at an academic ophthalmology practice were analyzed by subspecialty in the 1-year periods before (October 1, 2014, to September 30, 2015) and after (October 1, 2015, to September 30, 2016) conversion from ICD-9 to ICD-10.

Main outcomes and measures: Primary outcome measures were payments per visit, relative value units per visit, number of visits, and percentage of high-level visits; secondary measures were denials due to coding errors, charges denied due to coding errors, and percentage of unspecified codes used as a primary diagnosis code.

Results: Conversion to ICD-10 did not significantly impact payments per visit ($306.56±$56.50 vs $321.43±$38.12, P =0.42), relative value units per visit (7.15±0.56 vs 7.13±0.84, P =0.95), mean volume of visits (1,887.08±375.02 vs 1,863.83±189.81, P =0.71), or percentage of high-level visits (29.7%±4.9%, 548 of 1,881 vs 30.0%±1.7%, 558 of 1,864, P =0.81). For every 100 visits, the number of coding-related denials increased from 0.98±0.60 to 1.84±0.31 ( P <0.001), and denied charges increased from $307.42±$443.39 to $660.86±$239.47 ( P =0.002). The monthly percentage of unspecified codes used increased from 25.8%±1.1% (485 of 1,881) to 35.0%±2.3% (653 of 1,864, P <0.001).

Conclusion: The conversion to ICD-10 did not impact overall revenue or clinical volume in this practice setting, but coding-related denials, denied charges, and the use of unspecified codes increased significantly. We expect these denials to increase in the next year in the absence of Medicare's 1-year grace period.