Appropriateness of outpatient antibiotic prescribing among privately insured US patients: ICD-10-CM based cross sectional study

Abstract

Abstract Objective To assess the appropriateness of outpatient antibiotic prescribing for privately insured children and non-elderly adults in the US using a comprehensive classification scheme of diagnosis codes in ICD-10-CM (international classification of diseases-clinical modification, 10th revision), which replaced ICD-9-CM in the US on 1 October 2015. Design Cross sectional study. Setting MarketScan Commercial Claims and Encounters database, 2016. Participants 19.2 million enrollees aged 0-64 years. Main outcome measures A classification scheme was developed that determined whether each of the 91\u2009738 ICD-10-CM diagnosis codes “always,” “sometimes,” or “never” justified antibiotics. For each antibiotic prescription fill, this scheme was used to classify all diagnosis codes in claims during a look back period that began three days before antibiotic prescription fills and ended on the day fills occurred. The main outcome was the proportion of fills in each of four mutually exclusive categories: “appropriate” (associated with at least one “always” code during the look back period, “potentially appropriate” (associated with at least one “sometimes” but no “always” codes), “inappropriate” (associated only with “never” codes), and “not associated with a recent diagnosis code” (no codes during the look back period). Results The cohort (n=19\u2009203\u2009264) comprised 14\u2009571\u2009944 (75.9%) adult and 9\u2009935\u2009791 (51.7%) female enrollees. Among 15\u2009455\u2009834 outpatient antibiotic prescription fills by the cohort, the most common antibiotics were azithromycin (2\u2009931\u2009242, 19.0%), amoxicillin (2\u2009818\u2009939, 18.2%), and amoxicillin-clavulanate (1\u2009784\u2009921, 11.6%). Among these 15\u2009455\u2009834 fills, 1\u2009973\u2009873 (12.8%) were appropriate, 5\u2009487\u2009003 (35.5%) were potentially appropriate, 3\u2009592\u2009183 (23.2%) were inappropriate, and 4\u2009402\u2009775 (28.5%) were not associated with a recent diagnosis code. Among the 3\u2009592\u2009183 inappropriate fills, 2\u2009541\u2009125 (70.7%) were written in office based settings, 222\u2009804 (6.2%) in urgent care centers, and 168\u2009396 (4.7%) in emergency departments. In 2016, 2\u2009697\u2009918 (14.1%) of the 19\u2009203\u2009264 enrollees filled at least one inappropriate antibiotic prescription, including 490\u2009475 out of 4\u2009631\u2009320 children (10.6%) and 2\u2009207\u2009173 out of 14\u2009571\u2009944 adults (15.2%). Conclusions Among all outpatient antibiotic prescription fills by 19\u2009203\u2009264 privately insured US children and non-elderly adults in 2016, 23.2% were inappropriate, 35.5% were potentially appropriate, and 28.5% were not associated with a recent diagnosis code. Approximately 1 in 7 enrollees filled at least one inappropriate antibiotic prescription in 2016. The classification scheme could facilitate future efforts to comprehensively measure outpatient antibiotic appropriateness in the US, and it could be adapted for use in other countries that use ICD-10 codes.