Dissecting the mechanisms of a 5-year decline in antibiotic prescribing
Authors: Kissler Stephen M. , Klevens R. Monina , Barnett Michael L. , Grad Yonatan H. 
Published: January 2020

AbstractImportanceThe mechanisms driving the recent decline in outpatient antibiotic prescribing are unknown.ObjectiveTo estimate the extent to which reductions in the number of antibiotic prescriptions filled per outpatient visit (stewardship) and reductions in the monthly rate of outpatient visits (observed disease) for infectious disease conditions each contributed to the decline in annual outpatient antibiotic prescribing rate in Massachusetts between 2011 and 2015.DesignOutpatient medical and pharmacy claims from the Massachusetts All-Payer Claims Database were used to estimate rates of antibiotic prescribing and outpatient visits for 20 medical conditions and their contributions to the overall decline in antibiotic prescribing. Trends were compared to those in the National Ambulatory Medical Care Survey (NAMCS).SettingOutpatient visits in Massachusetts between January 2011 and September 2015.Participants5,075,908 individuals with commercial health insurance or Medicaid in Massachusetts under the age of 65 and 495,515 patients included in NAMCS.Main outcomes and measuresThe number of antibiotic prescriptions avoided through reductions in observed disease and reductions in per-visit prescribing rate per medical condition.ResultsBetween 2011 and 2015, the January antibiotic prescribing rate per 1,000 individuals in Massachusetts declined by 18.9% and the July antibiotic prescribing rate declined by 13.6%. The mean prescribing rate for children under 5 declined by 42.8% (95% CI 21.7%, 59.4%), principally reflecting reduced wintertime prescribing. The monthly rate of outpatient visits per 1,000 individuals in Massachusetts declined (p < 0.05) for respiratory infections and urinary tract infections. Nationally, visits for medical conditions that merit an antibiotic prescription also declined between 2010 and 2015. Of the estimated 358 antibiotic prescriptions per 1,000 individuals avoided over the study period in Massachusetts, 59% (95% CI 54%, 63%) were attributable to reductions in observed disease and 41% (95% CI 37%, 46%) to reductions in prescribing per outpatient visit.Conclusions and relevanceThe decline in antibiotic prescribing in Massachusetts was driven by a decline in observed disease and improved antibiotic stewardship, with a contemporaneous reduction in visits for conditions prompting antibiotics observed nationally. A focus on infectious disease prevention should be considered alongside antibiotic stewardship as a means to reduce antibiotic prescribing.Key pointsQuestionHow did the separate mechanisms of improved stewardship and reductions in observed disease contribute to a 5-year decline in outpatient antibiotic prescribing in Massachusetts from 2011-2015?FindingsIn an observational analysis of insurance claims, reduced monthly rates of outpatient visits for infectious conditions and reduced probability of prescribing an antibiotic per outpatient visit both contributed to the decline in antibiotic prescribing. An estimated 358 antibiotic prescriptions per 1,000 individuals were avoided over the study period through the two mechanisms, 211 of which were attributable to reductions in outpatient visits and 147 to reduced antibiotic prescribing per visit.MeaningPreventing the need for outpatient visits should be considered alongside antibiotic stewardship as a means of reducing antibiotic prescribing.