In this study of 229 commercial health plans in the US, we found substantial variation in the rate of antibiotic utilization, with high-utilizing plans dispensing nearly 70% more antibiotics per capita than low-utilizing plans. There was similarly large variation in the proportion of broad-spectrum antibiotics used by health plans, ranging from 34% of all antibiotics in plans at the lower end of the spectrum to 59% in plans at the higher end. Geographic region was strongly associated with health plans’ rate of antibiotic utilization: after controlling for other factors, plans in the Southern U.S. used 0.16 more antibiotics PMPY than plans in the Western U.S., a difference larger than 1 standard deviation of utilization rates nationally.
This variation in antibiotic utilization has substantial implications for health and health care costs in the United States. Overprescribing of antibiotics results in unnecessary drug side effects and promotes population-level resistance to antibiotics, which - consistent with our data - is greater in Southern than in Western states.18–20
While resistance to any antibiotic is promoted by high-volume use, excessive prescribing of broad-spectrum agents is of particular concern, since this promotes resistance to agents that are commonly used to treat serious or complicated infections where the consequences of treatment failure can be severe.2, 21
Finally, unnecessary antibiotic use has important cost implications.3
Of an estimated $1.9 billion spent on antibiotics per year by health plans in our study cohort, direct drug costs could be reduced by 16% if health plans reduced their antibiotic utilization to the current 25th
percentile of costs, and by 26% if plans reduced their utilization to the current 10th
percentile of costs.
As with European antibiotic studies and other investigations into variation in the delivery of health care, it is difficult to determine the “correct” amount of antibiotic utilization. Nonetheless, understanding variation can provide valuable information to health plans and policymakers seeking to improve care quality and reduce unnecessary spending.12, 14
Wennberg and colleagues were among the first to highlight the importance of reporting variation, pointing to large geographic differences within the U.S. in the use of health care interventions such as surgical procedures.22
For interventions where an optimal rate of utilization is known, these data can stimulate benchmarking, allowing health plans and institutions to set achievable goals for their practice and to monitor progress toward these goals.23
Where an optimal rate of utilization is not known, reports of variation can help health plans and institutions understand their performance relative to their peers. This can prompt plans with relatively high rates of utilization to examine why their delivery of services varies substantially from the norm, to determine whether this represents a remediable problem in quality, and if so to investigate how to improve their care quality.24
Our results suggest that overall rates of antibiotic utilization are well-suited to a variation-centered approach. A number of commercial health plans are achieving far lower rates of antibiotic utilization than others. Of course, not all health plans are comparable; for example, plans whose enrollees have greater illness severity and barriers to accessing care may have legitimate reasons for prescribing more antibiotics than others.25
Thus, a high observed rate of antibiotic utilization should not be an end unto itself, but should prompt in-depth analysis to identify non-clinical factors that promote increased antibiotic use. Such analyses can be further guided by evaluation of prescribing rates within age-and sex strata to evaluate whether certain patient subgroups have disproportionately high antibiotic utilization rates relative to a health plan’s peers. Where appropriate, local initiatives can be crafted to address the factors that promote increased antibiotic use, preferably borrowing from previous research to employ active forms of clinician education and other methods proven to reduce unnecessary antibiotic prescribing 26–28
This is the approach taken by the National Committee for Quality Assurance in creating this measure for the HEDIS program, in which overall antibiotic utilization has been included in the “use of services” domain which tracks utilization and can be useful for comparison and identification of achievable goals without any specific performance targets.
Although we cannot definitively establish a “correct” rate of antibiotic utilization in commercial health plans, a variety of data suggest opportunities for improvement in the U.S. Numerous studies have documented substantial overuse of antibiotics in the U.S, and cross-national comparisons have found that Americans receive approximately 20% more antibiotics per capita than Europeans, with only 3 of 27 European countries having higher rates of antibiotic dispensing than the U.S. 1–3, 10
Patients in the Netherlands, the lowest-prescribing European country, receive 60% fewer antibiotics than patients in the United States.10, 29
Reducing antibiotic utilization is a complex endeavor and requires attention not only to clinical efficacy but to patient satisfaction and downstream health services utilization. Nonetheless, controlled trials to reduce inappropriate antibiotic use in the outpatient setting found no increase in subsequent health services utilization (e.g., office visits or telephone calls) and little to no adverse impacts on patient satisfaction.28
Our study has several limitations. The data collected were from the first year in which this measure was implemented by HEDIS. Although plans were given detailed instructions for complying with this measure, it is possible that certain plans had not perfected their data-collection and reporting processes. In addition, data is not publicly reported for the first year of any HEDIS measure. As is common, some plans chose not to report their results during this first year, and it is difficult to know whether these plans did not participate because they expected their performance to be poor or because of other factors. (For example, over half of non-reporting plans had fewer than 10,000 members, compared with 7% of reporting plans, suggesting the possibility that smaller plans might have had fewer resources available to put towards a first-year, non-publicly reported measure). Nonetheless, we did receive data from 83% of plans, and all HEDIS data are audited, suggesting that our results are representative of the target population.
Other characteristics of our methods merit consideration in interpreting this study’s findings. First, the manner in which data was reported by health plans may result in slight imprecision in our calculation of overall antibiotic utilization rates. However, this imprecision is likely to be small in relation to the large variation in rates among plans. Second, our estimates of drug cost data were based on extrapolations from another national data source (NAMCS) combined with utilization data from the study plans and do not precisely reflect the actual drug costs incurred by plans (which may be influenced by negotiated deals with drug suppliers, and so forth). Thus, our drug cost analyses should be interpreted as reasonable estimates rather than a precise accounting of real drug costs, and do not account for downstream cost expenditures or savings associated with reduced antibiotic use. Third, we did not have access to clinical data such as comorbid conditions, and thus we could not control for inter-plan differences in members’ health beyond that which is correlated with patient age and sex. Finally, we collected data only on HMOs and POS plans participating in the HEDIS program. While the strong majority of eligible commercial health plans participate in the HEDIS program, we cannot know the generalizability of our results to plans not participating in HEDIS or to persons with public insurance (such as Medicaid), other forms of commercial insurance, or no insurance at all,
It is difficult to improve health care quality unless it can be measured. The substantial unexplained variation in antibiotic utilization across U.S. health plans suggests opportunities to improve the quality and costs of antibiotic prescribing. We believe the NCQA antibiotic utilization measure should stimulate additional efforts to understand and improve antibiotic utilization at the health plan level--particularly for health plans in the higher range of antibiotic use. If successful, these efforts are likely to improve quality of care and to generate meaningful cost savings from reduced antibiotic costs—a “win-win” for patients, payors, and the public health.
Outpatient antibiotic utilization varies substantially among commercial health plans in ways not explained by patient case mix. As a result:
- Antibiotic utilization is likely to be a valuable marker of prescribing quality for health plans.
- Health plans with high rates of antibiotic utilization may benefit from targeted quality improvement programs to reduce unnecessary antibiotic use.
- Cost savings from reducing unnecessary antibiotic use are substantial.