A decade of outpatient antimicrobial use in older adults in Ontario: a descriptive study

Oral Antibiotics and Risk of Serious Cutaneous Adverse Drug Reactions

Importance

Serious cutaneous adverse drug reactions (cADRs) are potentially life-threatening drug hypersensitivity reactions involving the skin and internal organs. Antibiotics are a recognized cause of these reactions, but no studies have compared relative risks across antibiotic classes.

Objectives

To explore the risk of serious cADRs associated with commonly prescribed oral antibiotics, and to characterize outcomes of patients hospitalized for them.

Design, Setting, and Participants

Nested case-control study using population-based linked administrative datasets among adults aged 66 years or older who received at least 1 oral antibiotic between 2002 and 2022 in Ontario, Canada. Cases were those who had an emergency department (ED) visit or hospitalization for serious cADRs within 60 days of the prescription, and each case was matched with up to 4 controls who did not.

Exposure

Various classes of oral antibiotics.

Main Outcomes and Measures

Conditional logistic regression estimate of the association between different classes of oral antibiotics and serious cADRs, using macrolides as the reference group.

Results

During the 20-year study period, we identified 21 758 older adults (median age, 75 years; 64.1% female) who had an ED visit or hospitalization for serious cADRs following antibiotic therapy and 87 025 matched controls who did not. In the primary analysis, sulfonamide antibiotics (adjusted odds ratio [aOR], 2.9; 95% CI, 2.7-3.1) and cephalosporins (aOR, 2.6; 95% CI, 2.5-2.8) were most strongly associated with serious cADRs relative to macrolides. Additional associations were evident with nitrofurantoin (aOR, 2.2; 95% CI, 2.1-2.4), penicillins (aOR, 1.4; 95% CI, 1.3-1.5), and fluoroquinolones (aOR, 1.3; 95% CI, 1.2-1.4). The crude rate of ED visits or hospitalization for cADRs was highest for cephalosporins (4.92 per 1000 prescriptions; 95% CI, 4.86-4.99) and sulfonamide antibiotics (3.22 per 1000 prescriptions; 95% CI, 3.15-3.28). Among the 2852 case patients hospitalized for cADRs, the median length of stay was 6 days (IQR, 3-13 days), 9.6% required transfer to a critical care unit, and 5.3% died in the hospital.

Conclusion and Relevance

Commonly prescribed oral antibiotics are associated with an increased risk of serious cADRs compared with macrolides, with sulfonamides and cephalosporins carrying the highest risk. Prescribers should preferentially use lower-risk antibiotics when clinically appropriate.

Identifying Patterns of Primary Care Antibiotic Prescribing for a Spinal Cord Injury (SCI) Cohort Using an Electronic Medical Records (EMR) Database

Background

Individuals with a spinal cord injury (SCI) are considered higher users of antibiotics. However, to date there have been no detailed studies investigating outpatient antibiotic use in this population.

Objectives

(1) To describe primary care antibiotic prescribing patterns in adults with SCI rostered to a primary care physician (PCP), and (2) to identify patient or PCP factors associated with number of antibiotics prescribed and antibiotic prescription duration.

Methods

A retrospective cohort study using linked health administrative and electronic medical records (EMR) databases from January 1, 2013 to December 31, 2015 among 432 adults with SCI in Ontario, Canada. Negative binomial regression analyses were conducted to identify patient or physician factors associated with number of antibiotics prescribed and prescription duration.

Results

During the study period, 61.1% of the SCI cohort received an antibiotic prescription from their PCP. There were 59.8% of prescriptions for urinary tract infections (UTI) and 24.6% of prescriptions for fluoroquinolones. Regression analysis found catheter use was associated with increased number of antibiotics prescribed (relative risk [RR] = 3.1; 95% CI, 2.3-4.1; p < .001) and late career PCPs, compared to early-career PCPs, prescribed a significantly longer duration (RR = 1.8; 95% CI, 1.1-3.1; p = .02).

Conclusion

UTIs were the number one prescription indication, and fluoroquinolones were the most prescribed antibiotic. Catheter use was associated with number of antibiotics, and PCP's years of practice was associated with duration. The study provided important information about primary care antibiotic prescribing in the SCI population and found that not all individuals received frequent antibiotics prescriptions.

Population-based outpatient antimicrobial use in Newfoundland and Labrador: a retrospective descriptive study

BACKGROUND

Data that have been reported on antimicrobial use in Newfoundland and Labrador (NL) do not appear to be representative of use at the population level. We sought to use pharmacy network data on prescriptions to describe outpatient antimicrobial use in NL.

METHODS

We analyzed all outpatient antimicrobial prescriptions dispensed between June 1, 2017, and June 8, 2021, from the provincial pharmacy network database and translated deidentified data into SPSS. We excluded prescriptions for parenteral and topical antimicrobials, antivirals and antifungals. We described antimicrobial use using the prescription rate and defined daily dose (DDD) rate.

RESULTS

Overall, we analyzed 1 586 534 prescriptions dispensed to 394 708 people by 3431 prescribers. The rate of antimicrobial use was 741 prescriptions per 1000 population per year (7161 DDD/1000 population/yr). The median duration of prescriptions was 7 (interquartile range 7-10) days. The prescription rate decreased from 867 to 546 per 1000 population per year (-37%) over the study period, and the mean DDD rate decreased from 8387 to 5356 DDD per 1000 population per year (-36.1%). Antimicrobials with the highest DDD rate were amoxicillin (1568 DDD/1000/yr), doxycycline (864 DDD/1000/yr) and ciprofloxacin (633 DDD/1000/yr). Prescribers wrote a mean of 102 (standard deviation 248) prescriptions per year; 3 prescribers wrote more than 2500 prescriptions per year. Overall, 9203 (2.3%) of the 394 708 people in the study population received 4 or more prescriptions per year.

INTERPRETATION

The rate of antimicrobial use in NL is lower than previously described in national surveillance data. Potential targets for stewardship intervention include prolonged duration of prescriptions, high-rate prescribers and high-rate patients, but further research is needed to assess the appropriateness of prescriptions according to diagnosis.

Appropriateness of Outpatient Antibiotic Use in Seniors across Two Canadian Provinces

Antimicrobials are among the most prescribed medications in Canada, with over 90% of antibiotics prescribed in outpatient settings. Seniors prescribed antimicrobials are particularly vulnerable to adverse drug events and antimicrobial resistance. The extent of inappropriate antibiotic prescribing in outpatient Canadian medical practice, and the potential long-term trends in this practice, are unknown. This study is the first in Canada to examine prescribing quality across two large-scale provincial healthcare systems to compare both quantity and quality of outpatient antibiotic use in seniors. Population-based analyses using administrative health databases were conducted in British Columbia (BC) and Ontario (ON), and all outpatient, oral antimicrobials dispensed to seniors (≥65 years) from 1 January 2000 to 31 December 2018 were identified. Antimicrobials were linked to an indication using a 3-tiered hierarchy. Tier 1 indications, which always require antibiotics, were given priority, followed by Tier 2 indications that sometimes require antibiotics, then Tier 3, which never require antibiotics. Prescription rates were calculated per 1000 population, and trends were examined overall, by drug class, and by patient demographics. Prescribing remained steady in both provinces, with 11,166,401 prescriptions dispensed overall in BC, and 27,656,014 overall in ON. BC prescribed at slightly elevated rates (range: 790 to 930 per 1000 residents), in comparison to ON (range: 745 to 785 per 1000 residents), throughout the study period. For both provinces, a Tier 3 diagnosis was the most common reason for antibiotic use, accounting for 50% of all indication-associated antibiotic prescribing. Although Tier 3 indications remained the most prescribed-for diagnoses throughout the study period, a declining trend over time is encouraging, with much room for improvement remaining. Elevated prescribing to seniors continues across Canadian outpatient settings, and prescribing quality is of high concern, with 50% of all antimicrobials prescribed inappropriately for common infections that do not require antimicrobials.

Efficacy and safety of quinolones vs. other antimicrobials for the treatment of uncomplicated urinary tract infections in adults: a systematic review and meta-analysis

INTRODUCTION AND HYPOTHESIS

In the present study, we aimed to compare the efficacy and safety of quinolones with trimethoprim-sulfamethoxazole (TMP/SMX), nitrofurantoin, fosfomycin, and β-lactams for the treatment of uncomplicated urinary tract infections (UTIs) in adults.

METHODS

All controlled clinical trials assessing quinolones for uncomplicated UTIs in adults were searched from PubMed, Embase, and Cochrane Library databases. Meta-analyses were used to evaluate the efficacy and safety in randomized controlled trials (RCTs).

RESULTS

A total of 47 RCTs consisting of 8992 patients were included in the present analysis. The clinical and bacteriological remission rates of quinolones were significantly higher (P < 0.01) compared with β-lactams and nitrofurantoin, while quinolones showed similar clinical and bacteriological remission rates compared with TMP/SMX and fosfomycin. Moreover, the bacterial resistance and relapse rates of quinolones were significantly lower (P < 0.01) compared with TMP/SMX, β-lactams, and nitrofurantoin. Regarding the adverse drug reactions (ADRs), quinolones did not bring higher risks, while the incidence of ADRs in the quinolone group was also even significantly lower (P < 0.01) compared with the TMP/SMX and nitrofurantoin groups, including the most reported ADRs associated with the gastrointestinal tract.

CONCLUSIONS

Compared with other anti-UTI drugs, quinolones exerted an excellent effect on clinical remission and bacteriological eradication, and the application of quinolones did not bring a higher risk of ADRs.

Outpatient antibiotic use in British Columbia, Canada: reviewing major trends since 2000

BACKGROUND

With 90% of all antibiotics in Canada being used in the community setting, tracking outpatient prescribing is integral to mitigate the issue of antimicrobial resistance. In 2005, a provincial programme was launched in British Columbia (BC) to disseminate information regarding the judicious use of antibiotics. These efforts include educational campaigns, updated practitioner guidelines and academic detailing. The impact of provincial stewardship on community prescribing requires ongoing evaluation.

OBJECTIVES

This study examines outpatient prescribing to quantify rates of antibiotic use, evaluate major trends over time and identify new targets for stewardship.

METHODS

A retrospective cohort design using population-level data.

RESULTS

This study included over 3.5 million unique individuals with a total of 51 367 938 oral antibiotic prescriptions dispensed over a 19 year period (2000-18). Overall antibiotic utilization decreased by 23% over the course of the study period. This trend in the reduction of antibiotic prescription was observed across all major antibiotic classes, apart from the class of other antibacterials, which was mostly related to use of nitrofurantoin. The largest magnitudes of decreased prescribing were observed in the paediatric population. Prescribing across two distinct eras of provincial stewardship reaffirmed preliminary findings of programme efficacy, when compared with pre-stewardship levels of antibiotic use.

CONCLUSIONS

Outpatient prescribing in BC is decreasing overall, and this study confirms an association between provincial stewardship interventions and improvements in antibiotic use. Pronounced declines in paediatric populations are promising, and further research is underway to examine prescribing quality.

Regional variation in the potentially inappropriate first-line use of fluoroquinolones in Canada as a key to antibiotic stewardship? A drug utilization review study

Background

Serious adverse effects of fluoroquinolone antibiotics have been described for more than decade. Recently, several drug regulatory agencies have advised restricting their use in milder infections for which other treatments are available, given the potential for disabling and possibly persistent side effects. We aimed to describe variations in fluoroquinolone use for initial treatment of urinary tract infection (UTI), acute bacterial sinusitis (ABS), and acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in the outpatient setting across Canada.

Methods

Using administrative health data from six provinces, we identified ambulatory visits with a diagnosis of uncomplicated UTI, uncomplicated AECOPD or ABS. Antibiotic exposure was determined by the first antibiotic dispensed within 5 days of the visit.

Results

We identified 4,303,144 uncomplicated UTI events among 2,170,027 women; the proportion of events treated with fluoroquinolones, mostly ciprofloxacin, varied across provinces, ranging from 18.6% (Saskatchewan) to 51.6% (Alberta). Among 3,467,678 ABS events (2,087,934 patients), between 2.2% (Nova Scotia) and 11.2% (Ontario) were dispensed a fluoroquinolone. For 1,319,128 AECOPD events among 598,347 patients, fluoroquinolones, mostly levofloxacin and moxifloxacin, ranged from 5.8% (Nova Scotia) to 35.6% (Ontario). The proportion of uncomplicated UTI and ABS events treated with fluoroquinolones declined over time, whereas it remained relatively stable for AECOPD.

Conclusions

Fluoroquinolones were commonly used as first-line therapies for uncomplicated UTI and AECOPD. However, their use varied widely across provinces. Drug insurance formulary criteria and enforcement may be a key to facilitating better antibiotic stewardship and limiting potentially inappropriate first-line use of fluoroquinolones.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06467-z.

Comparing prescribing and dispensing databases to study antibiotic use: a validation study of the Electronic Medical Record Administrative data Linked Database (EMRALD)

BACKGROUND

Monitoring and studying community antibiotic use is a critical component in combating rising antimicrobial resistance.

OBJECTIVES

To validate an electronic medical record dataset containing antibiotic prescriptions and to quantify some important differences between prescribing and dispensing databases.

METHODS

We evaluated antibiotics prescribed and dispensed to patients ≥65 years of age during 2011-15. We compared the EMRALD prescribing database with the validated Ontario Drug Benefit (ODB) dispensing database. Using ODB as the gold standard and limiting to EMRALD physicians, we calculated sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) with 95% CIs. We also compared the relative change in antibiotic use prescribed by all physicians to this population over time between the databases using Poisson regression models.

RESULTS

In this population, 74% of all antibiotics dispensed were from non-EMRALD physicians. Trends in use were discordant over time. When we limited ODB to EMRALD prescribers only to assess the validity of EMRALD data, we observed good sensitivity and excellent specificity for correctly identifying antibiotics at 85% (95% CI 84%-85%) and 98% (95% CI 98%-98%), respectively. The PPV was 78% (95% CI 78%-78%) and the NPV was 99% (95% CI 99%-99%). All performance measures were higher among the highest prescribing physicians.

CONCLUSIONS

We demonstrated EMRALD is well suited for studying antibiotic prescribing by EMRALD physicians. However, due to the frequency with which patients receive antibiotic prescriptions from their non-primary care physicians, we caution against the use of non-population-based prescribing databases to infer antibiotic use rates or trends over time.

Predictors and variability of antibiotic prescribing amongst family physicians

BACKGROUND

Rising rates of antimicrobial resistance are driven by overuse of antibiotics. Characterizing physician antibiotic prescribing variability can inform interventions to optimize antibiotic use.

OBJECTIVES

To describe predictors of overall antibiotic prescribing as well as the inter-physician variability in antibiotic prescribing amongst family physicians.

METHODS

We conducted a 5 year cohort study of antibiotic prescribing rates by family physicians in Ontario, Canada using a repository of electronic medical records. Using multilevel logistic regression models fitted with random intercepts for physicians, we evaluated the association of patient-, physician- and clinic-level characteristics with antibiotic prescribing rates.

RESULTS

We included 3956921 physician-patient encounters, 322129 unique patients and 313 physicians from 41 family medicine clinics. Physicians prescribed a median of 54 (interdecile range 28-95) antibiotics per 1000 encounters. Female children aged 3-5 years were most likely to receive antibiotics compared with men ≥65 years (OR 4.01, 95% CI 3.89-4.13). The only significant physician-level predictor was median daily patient visits of ≥20 compared with <10 (OR 1.28, 95% CI 1.06-1.55). The median ORs without and with patient characteristics were 1.68 and 1.69, respectively. Thus, the odds of receiving an antibiotic varied by 1.7-fold for the same patient simply by virtue of encountering two different physicians.

CONCLUSIONS

We observed substantial inter-physician variability in antibiotic prescribing that could not be explained by sociodemographic and clinical patient differences, suggesting that risk adjustment of antibiotic prescribing practices may not be required for audit and feedback of family physicians working in similar practice settings.

Prevalence and Determinants of Antibiotic Consumption in the Elderly during 2006-2017

Elderly people are a particularly important population with regard to antibiotic overuse, using around 50% more antibiotics per capita than younger adults. The aim of this study was to analyze the prevalence, associated factors and evolution over time of antibiotic consumption among the Spanish population aged ≥ 65 years from 2006 to 2017. A descriptive cross-sectional study was conducted using data from the Spanish National Health Survey in 2006, 2011/2012 and 2017, and from the European Health Survey in Spain in 2009 and 2014. The sample consisted of 26,891 non-institutionalized individuals ≥ 65 years. Antibiotic consumption was the dependent variable, and sociodemographic variables, lifestyle habits and health status were analyzed using a logistic regression model. The prevalence of antibiotic consumption was 4.94%, with a marked increase from 2006 (4.64%) to 2017 (5.81%) (p < 0.0001). Higher antibiotic consumption was associated with poor or very poor self-perceived health status, no polypharmacy and not having been in hospital during the previous twelve months, while a lower consumption was linked to being limited but not severely due to a health problem and not being at all limited.

Comparative Effectiveness Of Fluoroquinolone Antibiotic Use In Uncomplicated Acute Exacerbations Of COPD: A Multi-Cohort Study

Purpose

Fluoroquinolone antibiotics are associated with rare, but severe adverse events. They are frequently used for the treatment of acute exacerbations of COPD (AECOPD). While their effectiveness in severe exacerbations requiring hospitalisation has been well documented, the potential benefit in the ambulatory setting is less clear, especially in uncomplicated patients with COPD.

Patients and characteristics

We carried out a retrospective cohort study using health care databases from six Canadian provinces in subjects visiting their physician for uncomplicated COPD. Subjects dispensed either a quinolone or other antibiotics were compared using inverse probability of treatment weights with high dimensional propensity scores on 30-day outcomes, including repeat visits, hospitalisation for AECOPD and subsequent antibiotic prescription. Results from each province were combined by random effects meta-analysis.

Results

We identified 286,866 AECOPD events among 203,642 unique individuals. The frequency of fluoroquinolone use, mostly levofloxacin and moxifloxacin, varied by province and ranged from 8% to 32% of AECOPD antibiotic prescriptions. The risk of a repeat ambulatory care visit was increased among patients who were dispensed a fluoroquinolone compared with other antibiotics (OR 1.32, 95% CI 1.27-1.36). The risk of a hospitalisation for AECOPD was also higher with fluoroquinolones (OR 1.52, 95% CI 1.33-1.74). There was no difference in subsequent antibiotic prescriptions (OR 1.00, 95% CI 0.94-1.07).

Conclusion

There is no apparent benefit in short-term outcomes with fluoroquinolones as compared to other antibiotics for the ambulatory treatment of AECOPD in uncomplicated patients. These findings support current recommendations that fluoroquinolones be reserved for AECOPD in patients with recurrent exacerbations, significant co-morbidity or requiring hospitalisation.

Fluoroquinolone use for uncomplicated urinary tract infections in women: a retrospective cohort study

OBJECTIVES

The United States Food & Drug Administration released an advisory in 2016 that fluoroquinolones be relegated to second-line agents for uncomplicated urinary tract infections (UTIs) given reports of rare but serious side effects; similar warnings have followed from Health Canada and the European Medicines Agency. The objective was to determine whether alternative non-fluoroquinolone agents are as effective as fluoroquinolones in the treatment of UTIs.

METHODS

We conducted a retrospective population-based cohort study using administrative health data from six Canadian provinces. We identified women (n = 1 585 997) receiving antibiotic treatment for episodes of uncomplicated UTIs (n = 2 857 243) between January 1 2005 and December 31 2015. Clinical outcomes within 30 days from the initial antibiotic dispensation were compared among patients treated with a fluoroquinolone versus non-fluoroquinolone agents. High-dimensional propensity score adjustments were used to ensure comparable treatment groups and to minimize residual confounding.

RESULTS

Fluoroquinolone use for UTI declined over the study period in five of six Canadian provinces and accounted for 22.3-48.5% of treatments overall. The pooled effect across the provinces indicated that fluoroquinolones were associated with fewer return outpatient visits (OR 0.89, 95%CI 0.87-0.92), emergency department visits (OR 0.74, 95%CI 0.61-0.89), hospitalizations (OR 0.83, 95%CI 0.77-0.88), and repeat antibiotic dispensations (OR 0.77, 95%CI 0.75-0.80) within 30 days.

CONCLUSIONS

Fluoroquinolones are associated with improved clinical outcomes among women with uncomplicated UTIs. This benefit must be weighed against the risk of fluoroquinolone resistance and rare but serious fluoroquinolone side effects when selecting first-line treatment for these patients.

Validating a popular outpatient antibiotic database to reliably identify high prescribing physicians for patients 65 years of age and older

Objective

Many jurisdictions lack comprehensive population-based antibiotic use data and rely on third party companies, most commonly IQVIA. Our objective was to validate the accuracy of the IQVIA Xponent antibiotic database in identifying high prescribing physicians compared to the reference standard of a highly accurate population-wide database of outpatient antimicrobial dispensing for patients ≥65 years.

Methods

We conducted this study between 1 March 2016 and 28 February 2017 in Ontario, Canada. We evaluated the agreement and correlation between the databases using kappa statistics and Bland-Altman plots. We also assessed performance characteristics for Xponent to accurately identify high prescribing physicians with sensitivity, specificity, positive predictive value (PPV), and negative predictive value.

Results

We included 9,272 physicians. The Xponent database has a specificity of 92.4% (95%CI 92.0%-92.8%) and PPV of 77.2% (95%CI 76.0%-78.4%) for correctly identifying the top 25^th percentile of physicians by antibiotic volume. In the sensitivity analysis, 94% of the top 25^th percentile physicians in Xponent were within the top 40^th percentile in the reference database. The mean number of antibiotic prescriptions per physician were similar with a relative difference of -0.4% and 2.7% for female and male patients, respectively. The error was greater in rural areas with a relative difference of -8.4% and -5.6% per physician for female and male patients, respectively. The weighted kappa for quartile agreement was 0.68 (95%CI 0.67–0.69).

Conclusion

We validated the IQVIA Xponent antibiotic database to identify high prescribing physicians for patients ≥65 years, and identified some important limitations. Collecting accurate population-based antibiotic use data will remain vital to global antimicrobial stewardship efforts.

Antibiotic dispensation rates among participants in community-driven health research projects in Arctic Canada

Background

Community-driven projects that aim to address public concerns about health risks from H. pylori infection in Indigenous Arctic communities (estimated H. pylori prevalence = 64%) show frequent failure of treatment to eliminate the bacterium. Among project participants, treatment effectiveness is reduced by antibiotic resistance of infecting H. pylori strains, which in turn, is associated with frequent exposure to antibiotics used to treat other infections. This analysis compares antibiotic dispensation rates in Canadian Arctic communities to rates in urban and rural populations in Alberta, a southern Canadian province.

Methods

Project staff collected antibiotic exposure histories for 297 participants enrolled during 2007–2012 in Aklavik, Tuktoyaktuk, and Fort McPherson in the Northwest Territories, and Old Crow, Yukon. Medical chart reviews collected data on systemic antibiotic dispensations for the 5-year period before enrolment for each participant. Antibiotic dispensation data for urban Edmonton, Alberta (average population ~ 860,000) and rural northern Alberta (average population ~ 450,000) during 2010–2013 were obtained from the Alberta Government Interactive Health Data Application.

Results

Antibiotic dispensation rates, estimated as dispensations/person-years (95% confidence interval) were: in Arctic communities, 0.89 (0.84, 0.94); in Edmonton, 0.55 (0.55, 0.56); in rural northern Alberta, 0.63 (0.62, 0.63). Antibiotic dispensation rates were higher in women and older age groups in all regions. In all regions, the highest dispensation rates occurred for β-lactam and macrolide antibiotic classes.

Conclusions

These results show more frequent antibiotic dispensation in Arctic communities relative to an urban and rural southern Canadian population.

Regional variability in outpatient antibiotic use in Ontario, Canada: a retrospective cross-sectional study

BACKGROUND

Regional variability in antibiotic use is associated with both antibiotic overuse and antimicrobial resistance. Our objectives were to benchmark outpatient antibiotic use and to evaluate geographic variability among health regions in the province of Ontario, Canada.

METHODS

This was a cross-sectional study of antibiotics dispensed from outpatient retail pharmacies in Ontario between March 2016 and February 2017. We analyzed variability in the number of antibiotic prescriptions dispensed per 1000 population among Ontario's 14 health regions with crude and adjusted Poisson regression models. Adjusted models controlled for rurality, 4 physician characteristics and 6 population characteristics.

RESULTS

There were 8 352 578 antibiotics dispensed during the 1-year study period or 621 per 1000 population. The most commonly prescribed antibiotic classes were narrow-spectrum penicillins, macrolides, first-generation cephalosporins and second-generation fluoroquinolones, with adult women receiving the highest rate of prescriptions: 985 antibiotic prescriptions per 1000 population. There was geographic variability in total and class-specific antibiotic use. In the health region with the highest use 778 antibiotics were dispensed per 1000 population whereas in the health region with the lowest use 534 antibiotics were dispensed per 1000 population. The adjusted marginal standardized antibiotic prescription rates for the health regions with the highest and lowest use were 787 (95% confidence interval [CI] 658-934) and 546 (95% CI 494-606) antibiotic prescriptions per 1000 population, respectively.

INTERPRETATION

We described baseline antibiotic usage in Ontario over a 12-month period, noting variability among some health regions. Our findings highlight the need for interventions to optimize antibiotic use and slow the emergence of antimicrobial resistance.

Outpatient Antibiotic Prescribing for Older Adults in the United States: 2011 to 2014

OBJECTIVES

To characterize antibiotics prescribed to older adults to guide efforts to improve antibiotic use.

DESIGN

Descriptive analysis.

SETTING

Ambulatory.

PARTICIPANTS

Adults aged 65 and older in the United States.

MEASUREMENTS

Information on outpatient antibiotic prescriptions dispensed for older adults from 2011 to 2014 was extracted from the IQVIA Xponent database. A chi-square trend analysis was conducted to assess annual changes in antibiotic prescribing rates. A descriptive analysis of prescribing rates by antibiotic, age group, sex, state, Census region, and provider specialty was conducted.

RESULTS

From 2011 to 2014, outpatient antibiotic prescribing rates remained stable in older U.S. adults (P = .89). In 2014, older adults were dispensed 51.6 million prescriptions (1,115 prescriptions/1,000 persons). Persons aged 75 and older had a higher prescribing rate (1,157 prescriptions/1,000 persons) than those aged 65 to 74 (1,084 prescriptions/1,000 persons). Prescribing rates were highest in the South 1228 prescriptions/1,000 persons) and lowest in the West (854 prescriptions/1,000 persons). The most commonly prescribed class was quinolones, followed by penicillins and macrolides. Azithromycin was the most commonly prescribed drug, followed by amoxicillin and ciprofloxacin. Internists and family physicians prescribed 43% of antibiotic courses.

CONCLUSION

On average, in 2014, U.S. adults aged 65 and older received enough outpatient antibiotic courses for every older adult to receive at least 1. Quinolones and azithromycin are potential targets for assessing the appropriateness of antibiotic prescribing in this population. Interventions to improve use targeting internists and family physicians in the South Census region might have the potential to have the greatest effect.