Presented at the Society for Academic Emergency Medicine annual meeting, Boston, MA, June 2011.
Original Research Contribution
National Study of Antibiotic Use in Emergency Department Visits for Pneumonia, 1993 Through 2008
Version of Record online: 17 MAY 2012
© 2012 by the Society for Academic Emergency Medicine
Academic Emergency Medicine
Volume 19, Issue 5, pages 562–568, May 2012
How to Cite
Neuman, M. I., Ting, S. A., Meydani, A., Mansbach, J. M. and Camargo, C. A. (2012), National Study of Antibiotic Use in Emergency Department Visits for Pneumonia, 1993 Through 2008. Academic Emergency Medicine, 19: 562–568. doi: 10.1111/j.1553-2712.2012.01342.x
Dr. Camargo was funded, in part, by NIH grant R01 [grant AI-93723] (Bethesda, MD).
The authors have no potential conflicts of interest to disclose.
Supervising Editor: Christopher R. Carpenter, MD, MSc.
- Issue online: 17 MAY 2012
- Version of Record online: 17 MAY 2012
- Received September 8, 2011; revisions received October 27 and November 16, 2011; accepted November 16, 2011.
ACADEMIC EMERGENCY MEDICINE 2012; 19: 562–568 © 2012 by the Society for Academic Emergency Medicine
Objectives: The Infectious Disease Society of America (IDSA) and American Thoracic Society (ATS) developed guidelines for the management of community-acquired pneumonia (CAP); however, there are sparse data on actual rates of antibiotic use in the emergency department (ED) setting.
Methods: Data were obtained from the National Hospital Ambulatory Medical Care Survey (NHAMCS) for ED visits during 1993 through 2008 for adults with a diagnosis of pneumonia.
Results: During the study period there were an estimated 23,252,000 pneumonia visits, representing 1.8% of all ED visits. The visit rate for pneumonia during this 16-year period may have increased (p trend = 0.055). Overall, 66% of adult patients with a primary diagnosis of pneumonia had documentation of an antibiotic administered while in the ED. There was an increase in antibiotic administration for adults with pneumonia from 1993 through 2008 (49% to 80%; p trend < 0.001). Specifically, there was an increase in use of macrolides from 1993 to 2006 (20% to 30%, p trend < 0.001) and a marked increase in use of quinolones from 0% to 39% from 1993 through 2008 (p trend < 0.001). Penicillin and cephalosporin use remained stable. Use of an antibiotic consistent with 2007 IDSA/ATS guidelines increased from 22% (95% confidence interval [CI] = 16% to 27%) of cases in 1993–1994 to 68% (95% CI = 63% to 73%) of cases in 2007–2008 (p trend < 0.001).
Conclusions: ED visit rates for pneumonia increased slightly from 1993 through 2008. Although antibiotic administration in the ED has increased for adults with CAP, guideline-concordant antibiotics may not be consistently administered.
Antimicrobial timing and selection have been developed as a benchmark measure of quality of care for adults presenting to an emergency department (ED) with community-acquired pneumonia (CAP). The American Thoracic Society (ATS) and Infectious Disease Society of America (IDSA) developed guidelines for the management of CAP independently in 19931 and 2001,2 but in 2007 they developed a guideline together.3 Despite some changes in specific antimicrobial therapy recommended, and the time frame in which to administer antibiotics, most of the recommendations have not substantially changed. The 2007 combined IDSA/ATS guideline recommends that antibiotics be administered during the course of the ED visit for adults with CAP.3
Using a nationally representative database of ED visits, we sought to: 1) characterize U.S. ED visits for adults with pneumonia, 2) examine whether there has been an increase in the administration of antibiotics during the course of the ED stay for adults with pneumonia, and 3) examine trends in individual antibiotic regimens over time.
This was a review of estimated national visits to EDs for adults with pneumonia using data from the 1993 through 2008 National Hospital Ambulatory Medical Care Survey (NHAMCS).
Setting and Population
Large national databases such as NHAMCS have been used to conduct epidemiologic pneumonia studies4 and as a tool to benchmark ED care.5–7 The NHAMCS is a four-stage probability sample of visits to noninstitutional general and short-stay hospitals, excluding federal, military, and Veterans Affairs hospitals, in the United States. The NHAMCS is conducted annually by the Division of Health Care Statistics of the National Center for Health Statistics (NCHS), Centers for Disease Control and Prevention, and covers geographic primary sampling units, hospitals within primary sampling units, EDs within hospitals, and patients within EDs. Hospital staff collected data during a randomly assigned 4-week data period for each of the sampled hospitals, during each year of the study period. When the data collection forms were completed, they were sent to the NCHS where they were coded using the International Classification of Disease, Ninth Revision, Clinical Modification (ICD-9-CM), with a maximum of three diagnoses assigned to each case.
In this study, a pneumonia ED visit was defined as any ED visit with an ICD-9-CM code of 480–486, in any of the three diagnosis fields. We analyzed ED visit rates by diagnosis (pneumonia in any three of the diagnosis fields or as a primary diagnosis), age, sex, race, region (Northeast, Midwest, South, and West), and month of visit. Ethnicity was not analyzed as it was not well reported (e.g., in 2008 the nonresponse rate was 24%). Categorization by region was performed using standardized geographical divisions defined by the U.S. Bureau of the Census. Visits were further analyzed by whether or not a hospital admission resulted and by the urgency (“urgent/emergent” or “nonurgent”) of the visit at triage. To keep analyses between earlier and later years consistent, we coded visits that occurred after a change in coding in 1997 (1997 through 2008), as “urgent/emergent” if recorded as “less than 15 minutes” or “15–60 minutes,” and as “nonurgent” if recorded as “>1 to 2 hours.” Visits with a primary diagnosis of pneumonia were analyzed by whether a chest x-ray was ordered (1993 through 2004) and by medication given during the ED visit for the years 1993 through 2008. For patients with a diagnosis of pneumonia, we evaluated trend in antibiotic administration over the course of the study period and examined specific antibiotic usage.
We performed all analyses using STATA 11.2 (StataCorp, College Station, TX). National estimates were obtained through use of assigned patient visit weights. Confidence intervals (CIs) were calculated using the relative standard error of the estimate. Most rates were calculated using midyear age, sex, race, and region-specific population estimates for 1993 through 2008 from the U.S. Census Bureau with these rates reported per 1,000 per year for U.S. population. ED-based (as opposed to population-based) rates using NHAMCS yearly age- or race-specific all-cause ED visit estimates as the denominator were calculated for select analyses. Trends in ED visit totals over time were computed using weighted linear regression, while trends in U.S. population and ED visit rates were assessed using weighted logistic regression, with two-tailed p < 0.05 considered statistically significant. A standard model building approach was used for both types of analyses where the variable of interest (e.g., race, sex) was controlled, and then rates or totals for pneumonia ED visits were compared by year. Trends in the proportion of patients receiving antibiotics over time, as well concordant antibiotic usage, were tested using weighted logistic regression analyses.
Between 1993 and 2008 there were an estimated 23,252,000 ED visits for pneumonia in the United States. These pneumonia ED visits represent 1.8% of all ED visits over this time period (Table 1). Of the ED pneumonia visits, 71% had pneumonia listed as the primary diagnosis.
|n||No. of Visits in 1,000s||95% CI||Rate per 1,000 U.S. Population||95% CI||Rate per 1,000 ED Visits||95% CI|
|Age group (yr)|
|80 and older||1,590||5,730||5,135–6,325||37.7||33.8–41.6||59.2||55.1–63.3|
|Age 65 and older||3,281||11,784||10,700–12,800||20.8||18.9–22.6||46.8||44.5–49.1|
|Age by sex|
|Females, 65 and older||1,738||6,324||5,695–6,953||19.1||17.2–21.0||42.4||39.6–45.2|
|Males, 65 and older||1,543||5,460||4,912–6,009||23.3||21.0–25.6||53.2||49.8–56.6|
Overall annual rates from 1993 through 2008 for ED visits with a diagnosis of pneumonia may have increased from 4.5 (95% CI = 3.7 to 5.3) per 1,000 U.S. population in 1993–1994 to 5.3 (95% CI = 4.2 to 6.3) in 2007–2008 (p trend = 0.055; Figure 1). ED visit rates for pneumonia varied by month, with the highest rates observed in December, January, and February (see Data Supplement S1, available as supporting information in the online version of this paper).
The mean age for visits with a diagnosis of pneumonia was 62 years (no difference by sex) with the highest visit rate in those people age 80 years and older (Figure 2). Visit rates (per 1,000 U.S. population) were higher in blacks (6.7; 95% CI = 5.9 to 7.5) than whites (5.2; 95% CI = 4.7 to 5.6) and did not differ based upon region of the United States (Table 1). Whites had a slight increasing trend in the pneumonia visit rate per 1,000 U.S. population over time (p trend = 0.059) while rates for blacks increased significantly (p trend = 0.02, data not shown). Overall, the visit rate for blacks was 1.3 times higher than the rate for whites; however, proportionately, whites had a greater percentage of ED visits for pneumonia (1.9%) when compared to blacks (1.3%; p < 0.001). These findings emphasize that although blacks have a higher rate of pneumonia cases than whites within the U.S. population, their proportion of ED visits related to pneumonia is smaller, suggesting that there may be differences in who is receiving treatment for pneumonia in the ED. Visit rates for females and males remained stable (p trend = 0.12 and 0.08, respectively). Most pneumonia visits (85%; 95% CI = 84% to 87%) had documentation of a chest x-ray, 74% (95% CI = 72% to 77%) were coded as urgent/emergent, and 57% (95% CI = 55% to 59%) resulted in a hospital admission (data not shown).
There was a significant increase in antibiotic administration, as well as concordant antibiotic usage from 1993 through 2008 across all regions (Northeast, Midwest, South, West) and seasons (winter, spring, summer, fall; all p < 0.001). Only 66% (95% CI = 64% to 68%) of ED patients with pneumonia as a primary diagnosis had documentation of receiving an antimicrobial while in the ED. However, the percentage of pneumonia visits in which an antibiotic was administered increased from 49% in 1993–1994 (95% CI = 43% to 55%) to 80% in 2007–2008 (95% CI = 76% to 84%; p trend < 0.001; Table 2). Overall antibiotic usage was higher for patients discharged from the ED compared to admitted patients, but use increased for both groups of patients during the study period (Figure 3). Similarly, use of antibiotics consistent with IDSA/ATS guidelines was higher for patients discharged from the ED compared to admitted patients, but use increased for both groups of patients during the study period (Figure 3).
|Disposition||% Receiving Any Antibiotics (95% CI)||% Receiving Concordant Antibiotics (95% CI)|
|1993–1994||49 (43–55)||22 (16–27)|
|1995–1996||54 (48–60)||26 (21–32)|
|1997–1998||52 (46–58)||24 (18–30)|
|1999–2000||60 (54–66)||37 (31–43)|
|2001–2002||69 (64–73)||53 (47–58)|
|2003–2004||78 (74–82)||62 (57–67)|
|2005–2006||78 (73–83)||65 (60–70)|
|2007–2008||80 (76–84)||68 (63–73)|
|p < 0.001||p < 0.001|
|1993–1994||30 (23–37)||4 nc|
|1995–1996||44 (35–54)||15 nc|
|1997–1998||45 (37–52)||14 (10–19)|
|1999–2000||49 (41–57)||27 (19–34)|
|2001–2002||62 (55–69)||41 (34–49)|
|2003–2004||73 (67–79)||57 (51–63)|
|2005–2006||78 (70–86)||62 (52–71)|
|2007–2008||76 (71–81)||61 (54–68)|
|p < 0.001||p < 0.001|
|1993–1994||76 (67–85)||52 (41–64)|
|1995–1996||68 (57–78)||41 (29–53)|
|1997–1998||73 (63–84)||45 (30–60)|
|1999–2000||75 (64–86)||49 (34–64)|
|2001–2002||79 (72–85)||66 (56–75)|
|2003–2004||86 (82–91)||71 (62–81)|
|2005–2006||83 (76–89)||75 (67–82)|
|2007–2008||87 (82–93)||79 (73–86)|
|p = 0.0002||p < 0.001|
Among patients with a primary diagnosis of pneumonia, 27, 25, and 6% were given cephalosporins, macrolides, and penicillins, respectively (Figure 4). The most commonly prescribed antibiotic for these ED visits was ceftriaxone which was prescribed for 20% of pneumonia ED visits. Erythromycin was the second most common antibiotic prescribed (19%), followed by cefuroxime (0.7%) and clarithromycin (0.2%). The use of macrolides increased from 1993 through 2006 (20% to 30%, p trend < 0.001), but dropped from 2006 through 2008 (30% to 21%, p trend = 0.002). Quinolones increased from 0% to 39% (p trend < 0.001), while the use of penicillins was stable (p trend = 0.24) over the same time period.
Pneumonia accounts for a large proportion of ED visits in the United States and is associated with a high rate of morbidity and mortality.8–10 We observed that rates of pneumonia were disproportionately higher among blacks and the elderly. The high rate of hospitalization and inconsistent patterns of antibiotic administration reported in this study of U.S. EDs suggest that pneumonia remains a challenge for clinicians in U.S. EDs. In light of staffing shortages and concerns about overcrowding,11–13 the high volume of pneumonia ED visits reported in this study is troubling and should refocus attention to the significant role EDs play in the nationwide management of this condition.
Emergency department visit rates for pneumonia were 1.3 times higher for blacks compared to whites. This discrepancy is similar to the black/white discrepancy in ED visit rates for all causes.14 Other studies have reported higher15–17 and lower rates18 of prevalence or morbidity for pneumonia by blacks compared to whites. Indeed, in the general population, blacks have been shown to have poorer access to care, poorer health outcomes, and higher reliance on EDs for care.14
Despite publication of guidelines by IDSA and ATS in 1993, 1999, and 2007,1–3 which were intended to improve the appropriateness of antimicrobial prescribing practices, management of pneumonia has been shown to vary considerably among institutions.4,19,20 While some degree of variability is expected and probably appropriate, it is generally accepted that appropriate selection and timely administration of antimicrobials is prudent for treatment of pneumonia.21,22 Although the percentage of patients with a primary diagnosis of pneumonia receiving an antibiotic in the ED has increased over time, over one-third of patients still did not receive antibiotics in the ED. Although many of these patients likely received medication before coming to the ED, or as an inpatient, this figure is nonetheless low. Earlier antimicrobial administration for pneumonia is associated with lower 30-day mortality,23 and it has been found that administration of the first dose of antimicrobials in the ED, as opposed to within the inpatient hospital setting, is associated with a significant reduction in time to receipt of medication for pneumonia.22 Given the high percentage of ED patients who did not receive antimicrobials in this study (34%), it appears that a greater effort should be made to provide EDs with the resources and expertise needed for timely treatment of the large population of ED pneumonia patients.
Beyond timeliness, appropriate choice of antimicrobial is another management challenge of pneumonia. In response to confusion regarding differences in earlier IDSA and ATS guidelines, the two organizations developed consensus guidelines in 2007 to improve the care of adults with CAP.3 Utilization of pneumonia guidelines is supported by evidence that their use has led to improvement in clinically relevant outcomes.24–26 The 2007 IDSA/ATS consensus guidelines recommend a macrolide antibiotic for the previously healthy outpatient with no recent antibiotic exposure.3 For those outpatients with pneumonia with comorbidities or recent antibiotic use, the use of a respiratory fluoroquinolone, or the combination of a beta-lactam antibiotic and macrolide antibiotic, is recommended. In regions with a high (>25%) rate of macrolide-resistant Streptococcus pneumoniae, a fluoroquinolone is recommended for adults with CAP. Although we observed that the rate of antibiotic administration concordant with IDSA/ATS recommendations has increased over the study period, 20% of adults in 2007 and 2008 did not receive an antibiotic consistent with these guidelines. Although it is possible that antibiotic administration may have occurred prior to arrival, or after admission for hospitalized patients, it is concerning that 24% of hospitalized patients did not receive an appropriate antibiotic regimen within the ED setting in 2007 and 2008 and that antibiotic administration was lower for hospitalized than for discharged patients. Our findings are consistent with previous reports demonstrating that despite national guidelines, the timing of antibiotic administration and appropriate antibiotic selection are below national goals.4,27–31 However, our data should be interpreted in the context of other data sources, such as the use of national core measures by the Centers for Medicare and Medicaid Services.
Over the study period, there has been a dramatic increase in the prevalence of resistant organisms responsible for pneumonia, such as resistant S. pneumoniae and methicillin-resistant Staphylococcus aureus,32,33 which likely explains the increasing use of antimicrobials targeting these organisms. Despite continued debate, it is generally agreed that, given widespread penicillin resistance, use of penicillin for pneumonia treatment is not prudent.34,35 We found that 6% of all patients with pneumonia as a primary diagnosis, and 8% of those who received any antimicrobial for a primary diagnosis of pneumonia (data not shown), still received penicillin during this time period. This becomes more alarming given results of a study that showed that improper antimicrobial selection in the ED usually is not corrected when a patient is subsequently transferred to the inpatient setting.36
Because the NHAMCS lacks individual identifiers, the NHAMCS only documents the number of individual visits to the ED, not the number of individual patients making visits. Nonetheless, total ED visits still reflect an important measure of ED utilization and morbidity. Second, the NHAMCS data only contain information about interventions that occurred in the ED. As a result, anything that may have occurred before the ED visit, or after disposition for hospitalized patients, most likely will not be recorded (e.g., antibiotic use before ED visit). In this study, however, we were concerned only with documenting the treatment of pneumonia that occurs in the ED. Future studies should account for these timing factors and should explore the relationship between ED length of stay and antibiotic administration. Third, our study investigates patients with a diagnosis of pneumonia, but the validity of ICD-9 codes for the diagnosis of pneumonia is not well established and does not allow for distinction of community-acquired versus health care–associated pneumonia. However, one study found that ICD-9 coding performed better than DRG codes for the diagnosis of pneumonia. In this study, overall accuracies of ICD-9 codes were in the range of 80% to 86% when evaluated against clinician chart review as a criterion standard for pneumonia diagnosis.37 We may have overestimated the rate of guideline-concordant antibiotic usage in patients with chronic comorbid conditions, those at risk of pneumonia due to Pseudomonas aeruginosa or methicillin-resistant S. aureus, and patients with recent antimicrobial use, since the NHAMCS database lacks this detailed clinical information.
The generalizability of the study also may be limited to settings in which NHAMCS obtains sampling data and may not apply to other populations, such as federal, military, and Veterans Affairs hospitals. Our observation that antibiotic administration was higher among discharged patients may be partially explained by the fact that the NHAMCS data collection tool only allowed for up to six medications to be listed and that admitted patients generally receive more medications in the ED setting. Additionally, it is likely that adults with health care–associated pneumonia are overrepresented among those admitted to the hospital, and that group is also more likely to have received antibiotics prior to arrival to the ED. Last, a limitation of the retrospective study design is that data may be missed due to relying on documentation in, and retrieval from, medical records. Nevertheless, this combined database provides important information on outcomes that are known to be collected with accuracy (e.g., medication treatment and ED disposition).38,39
High national ED visit rates and inconsistent treatment patterns present a widespread challenge for emergency physicians caring for adults with community-acquired pneumonia. Antibiotic administration in the ED setting increased during 1993 through 2008 for adults with pneumonia. Nonetheless, approximately one-third of adults with pneumonia did not receive an antibiotic in the ED, and fewer received a regimen consistent with national guidelines. Along with adherence to the national core measures for quality of care of adults with pneumonia, future efforts should be made to improve the timeliness and appropriateness of antibiotic administration in the ED setting.
- 2American Thoracic Society. Guidelines for the management of adults with community-acquired pneumonia. Am J Respir Care Med. 2001; 163:1730–54.
- 10Emergency department management of pneumonia. Can Respir J. 1999; 6(Suppl A):10A–4A., .
- 14National Hospital Ambulatory Medical Care Survey: 1999 emergency department summary. Adv Data. 2001; 320:1–36., .
- 30National Hospital Ambulatory Medical Care Survey: 2005 emergency department summary. Adv Data. 2007; 1–32., , .
Data Supplement S1. Distribution of pneumonia visits by month.
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|ACEM_1342_sm_DataSupplementS1.TIF||40K||Supporting info item|
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