Infection Control & Hospital Epidemiology (2019), 40,372–374 doi:10.1017/ice.2018.341


Concise Communication


Changes in outpatient antibiotic utilization, 2000–2016: More people are receiving fewer antibiotics Noelle M. Cocoros DSc, MPH1


, Aileen Ochoa MPH1 and Michael Klompas MD, MPH1,2


1Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, Massachusetts and 2Division of Infectious Diseases, Department of Medicine, Brigham and Women’s Hospital, Boston, Massachusetts


Abstract


Weexamined annual outpatient antibiotic dispensings within a health insurance plan covering ~970,000 members per year during 2000–2016. The proportion of members with antibiotic dispensings decreased from 33.3% in 2000 to 25.9% in 2016. This trend was consistent in all stratifications of age, race/ethnicity, sex, and comorbidities.


(Received 1 August 2018; accepted 6 December 2018)


High rates of inappropriate antibiotic prescribing in the outpatient setting have raised concern, and many initiatives are in place to try to decrease inappropriate prescribing. The effectiveness of such efforts has been described at the individual clinician and practice levels, but few data on the impact of stewardship efforts at the population level are available, particularly in the United States. Recent reports are conflicting and most examine relatively short periods.1–4 The Centers for Disease Control and Prevention, for example, reported that outpatient antibiotic use declined by 5% from 2011 to 2014.1 Another group found no change in annual national outpatient antibiotic prescription dispensings in 2013–2015.2 In both cases, it is unclear whether different trends would have been observed if the study had encompassed a longer duration of surveillance. A third study reported a decline in out- patient antibiotic use from 1999 to 2014, but the study was limited to children 19 years and younger.4 Our objective was to examine trends in outpatient antibiotic utilization among members of a multistate insurance plan from 2000 through 2016, including whether and how utilization varies in different demographic and chronic disease subgroups.


Methods


We utilized claims data from a commercial health insurance plan in New England that covers ~1 million people annually. We iden- tified all members with ≥1 day of enrollment per year from 2000 through 2016. All ages were included, with age calculated on the last day of each year. We assessed evidence of comorbidities using the Charlson comorbidity index.5 Members were flagged as having comorbidities if they had≥1 International Classification of Disease, Ninth Revision (ICD-9) or ICD-10 diagnosis code of interest in the


Author for correspondence: Noelle M. Cocoros, Email: Noelle_cocoros@


harvardpilgrim.org Cite this article: CocorosNM,et al. (2019). Changes in outpatient antibiotic utilization,


2000–2016: More people are receiving fewer antibiotics. Infection Control & Hospital Epidemiology, 40: 372–374, https://doi.org/10.1017/ice.2018.341


© 2019 by The Society for Healthcare Epidemiology of America. All rights reserved.


365 days prior to the antibiotic dispensing date, or prior to January 1 of the year of interest for those not receiving antibiotics. Outpatient antibiotic prescription dispensings were identified in


claims via National Drug Codes (primarily penicillins, cephalospor- ins, β lactams,macrolides, lincosamides, quinolones, trimethoprim- sulfamethoxazole, urinary antibacterials, and tetracyclines). If a person was dispensed 2 antibiotics on the same day, both were counted if theywere for different generic names; 2 codes on the same day were counted as 1 antibiotic dispensing if they had the same generic name. We calculated the proportion of members with antibiotic pre-


scription dispensings per year, stratified by age, sex, race, Hispanic ethnicity, and selected comorbidities. We conducted a sensitivity analysis among the subset of patients that were continuously enrolled throughout the entire study period, censoring only the date of death. We applied a linear regression model to examine the time trend in those receiving an antibiotic. We used SAS version 9.4 software (SAS Institute, Cary, NC) for our analysis. The Harvard Pilgrim Health Care Institutional Review Board


approved this study.


Results On average, 968,904 members were included in the analysis per year. We observed an overall decrease in the proportion of members receiving antibiotics per year, from 33.3% in 2000 to 25.9% in 2016 (P < .0001) (Fig. 1). The effect was consistent when stratified by age, sex, race, Hispanic ethnicity, and comorbidities (Table 1). We did not observe substantial changes in the popula- tion demographics over time (ie, by age, sex, race/ethnicity, or comorbidity; data not shown). In addition, members with ≥2 anti- biotic prescriptions dispensed also decreased per year, from 15.4% in 2000 to 10.9% in 2016. Wecompared utilization in different subgroups in 2016, the last


full year for which data were available. Utilization (defined here as ≥1 antibiotic dispensed in 2016) was highest among children aged 0–4 years (31.8%) and among adults aged 60–64 years (31.6%). Females had a higher antibiotic utilization rate than males


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