Original Contribution

The effect of an observation unit on the rate of ED admission and discharge for pyelonephritis^?

Jon W. Schrock MD ^a,?, Svetlana Reznikova MD ^b, Suki Weller MD ^c

^aDepartment of Emergency Medicine, MetroHealth Medical Center, Case Western Reserve University School of Medicine,

Cleveland, OH 44109-1998, USA

^bDepartment of Emergency Medicine, Case Western Reserve University School of Medicine, Cleveland, OH 44109-1998, USA

^cSeton Hospital, Austin, TX, USA

Received 19 January 2009; revised 2 March 2009; accepted 3 March 2009

Abstract

Objectives: We sought to determine if the opening of an adult emergency department (ED) observation unit (OU) would impact the rate of hospital admission and ED discharges for pyelonephritis.

Methods: A retrospective cohort study was performed with all adult patients from October 2003 through December 2006 in the ED meeting inclusion criteria for pyelonephritis. Clinical, demographic, and laboratory data were recorded. Primary outcomes were rates of admission, ED discharge, and return ED visits before and after the opening of our OU. We compared admission, discharge, and readmission rates using the ?² test.

Results: Nine hundred thirty charts were reviewed with 633 included for analysis. urine cultures were performed on 420 subjects with 71% being positive. The percentage of patients admitted to a hospital Inpatient unit from the ED decreased from 36% to 26% (relative risk [RR], 0.73; P = .01) after opening the OU. The percentage of patients discharged home from the ED decreased from 65% to 51% (RR, 0.76; P b .001). Among OU patients, 29% were admitted to the hospital for further inpatient care. Emergency department recidivism was unchanged by opening the OU (RR, 0.86; P = .68).

Conclusions: The creation of an OU appears to influence admission decisions of ED physicians. We found that the creation of an OU significantly reduced hospital admissions for pyelonephritis but also significantly reduced ED discharges to home for pyelonephritis at our institution.

Introduction

Emergency department (ED) Observation Units (OUs) have been present since the 1970s and are becoming a more

^? Research presented at the American College of Emergency Physicians Scientific Assembly in Seattle, Wash, October, 18 2007.

* Corresponding author. Tel.: +1 216 778 5747; fax: +1 216 778 5349.

E-mail address: [email protected] (J.W. Schrock).

prominent fixture in emergency medicine (EM). They provide an alternative disposition for patients with moderate illness that would benefit from a brief hospital stay. More than one third of academic EDs have an OU and almost one half plan to open one [1].

The initial reported advantages of OU included decreas- ing hospital costs, allowing time to evaluate patients without a clear diagnosis, and avoiding inappropriate discharges. Although initially, most of the early OU patients were treated for alcohol intoxication or overdose, patients

0735-6757/$ - see front matter. doi:10.1016/j.ajem.2009.03.003

with chest pain are now the most common source of admission [2-4].

Pyelonephritis is a common infection that predominately occurs in women at an annual rate of 1.3 cases per 1000 [5]. At one time, medical dogma suggested that these patients needed hospital admission for an extended period to receive Intravenous antibiotics [6]. It was also common practice to hold patients for 24 hours after transitioning from intrave- nous to oral antibiotics before their discharge [7].

Current medical practice has changed significantly, and now most patients presenting to the ED with pyelone- phritis are treated and safely discharged home. However, between one quarter and one half are too ill to send home based on clinical judgment and require some type of in- hospital care [8,9].

Observational care has been shown to be effective in treating pyelonephritis and preventing hospital admissions in selected populations of patients [10,11].

Others have been critical of the true financial benefit of these units, suggesting transferring resources from an inpatient unit to an OU did not result in an overall cost savings [12,13]. It has been suggested that the opening of an OU may change physician behavior resulting in decreased ED discharges that may mitigate any potential savings [14]. This anomaly of reduced ED discharges has been seen in similar studies on Pediatric asthma patients [15]. If the creation of an OU truly results in real changes in physician admission and discharge practices, this knowl- edge would be important to assist in physician education and creating realistic budget forecasts for institutions planning to open an OU.

Therefore, the goals of this study were to determine if the opening of an adult OU would change the rate of admission and ED discharge for pyelonephritis. Secondary goals were to determine if the creation of an OU changed rates of recidivism for pyelonephritis and to offer insight into the ED management of pyelonephritis.

Methods

We conducted a retrospective cohort study of all patients presenting with an ED diagnosis of pyelonephritis from October 2003 until December 2006. The intervention being studied was the opening of our OU in April 2005. The post- OU assessment period was longer by 3 months as our OU was opened in stages and was not operating at full capacity until August 2005. Our protocol was approved by our institutional internal review board who allowed an exemption for informed consent. This study was conducted at our urban ED, which treats approximately 90 000 patients annually. Our OU is a 14-bed unit staffed by board-certified or prepared emergency physicians and only accepts admissions from our ED. For a period of 1 year, 2 internal medicine board-certified physicians also occasionally workED shifts in our OU. The

OU operates at all times with a bed utilization rate of 91% and is open to admissions whenever bed space permits.

Selection of participants

Patients were identified using the International Classifi- cation of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) for pyelonephritis. Code 509 was used for identification of patients. Identified patients were then screened for enrollment. Inclusion criteria included flank pain, a urinalysis with 5 white blood cells per high-power field or greater than trace Leukocyte esterase on Urine dipstick evaluation, and age 18 years or older. We also excluded pregnant patients and patients who lacked a urinalysis result. Visits by patients who were seen in the ED in the prior 7 days were treated as return visits.

Data collection and analysis

All data was recorded by trained abstractors (SW, SR, JWS) using a standardized abstraction form. Data were collected using our ED-based electronic medical record system, (EPIC Systems Corporation; Madison, Wis). All missing data were reviewed using a second computerized system (OnBase, Hyland Software Inc, Cleveland, Ohio) containing the optically scanned paper records from the patient’s visit. When scanned charts were unavailable, the paper chart was retrieved and reviewed.

Data evaluated included demographic information age, sex, presenting symptoms, and clinical history including the presence of diabetes and renal disease. A priori, we defined renal disease as elevated creatinine greater than 1.5 mg/dL at presentation, a history of renal calculi, altered renal anatomy such as suprapubic catheter placement, or nephrostomy tube placement. Congenital abnormalities such as duplicated collecting systems were also considered to fit the definition of renal disease because patients with altered anatomy and renal stones are considered to have complicated pyelone- phritis by most urologists [16,17].

Other identified risk factors such as recent sexual intercourse, recent urinary tract infection , and family history of UTI were infrequently recorded in the medical record and therefore not used [18].

Additional data elements include vital signs and labora- tory values including serum white blood cell count, results of urine, or blood cultures. We also noted use of antiemetics in the ED, antibiotics used in the ED and OU were recorded, and result and usage of imaging studies including computed tomography (CT) and ultrasound.

Finally, we recorded total length of hospital admission and length of OU care, along with patient disposition from the initial ED visit (discharge to home, hospital admission, or OU admission). Disposition after OU care was also recorded and patients were followed for 7 days after discharge to home to see if a repeat ED visit or repeat admission occurred. All

Fig. 1 Admission decisions before and after the creation of the EDOU. Total numbers shown with percentages (%) based on total subjects included in each pre/post EDOU arm.

data were entered into a structured Panorama 4.0 data base, (Provue Development, Huntington Beach, Calif), and we used STATA 9.2, (StataCorp, College Station, Tex) for all statistical analysis.

Data are reported as medians with interquartile ranges (IQR) and percentages as appropriate. Rates of admission, discharge, and ED recidivism were analyzed using the ?2 test (with P values b.05 considered significant) and Relative risks (RRs) were calculated. The power of this study to detect a 10% difference in the proportion of admission was 0.9 with ? = .05 using a 2-tailed test.

Results

A total of 930 encounters were screened with 633 meeting all inclusion criteria. A flow diagram representing the dispositions of patients can be seen in Fig. 1. The 297 excluded patients included 156 with no flank pain (53%), 20 who were pregnant (6.7%), and 103 less than 18 years old (35%). The remaining 18 (6.1%) patients were initially recorded as index visits but later found to have a prior ED visit within 7 days. Demographic and clinical information collected on the patients enrolled has been separated by time of enrollment and can be seen in Table 1.

Urine cultures were performed on 420 subjects with 297 (71%) being positive. Organisms identified by urine

culture can be seen in Table 2. Of all patients diagnosed with pyelonephritis, 36 (5.7%) did not receive antibiotics in the ED including 12 and 24 in the pre and post OU groups respectively. In most of these patients, 31 (4.9%) were discharged home, whereas 3 (0.47%) were admitted to the OU and 2 (0.32%) were admitted to the hospital. Of those patients discharged home, 4 (0.63%) returned and were admitted within 7 days. Quinolones were the most common type of antibiotic given in the ED administered to 451 (71%) of all patients. Sixty-three (10%) of all patients received a second antibiotic in the ED. The type of antibiotics given and their rate of administration can be seen in Table 3. Blood cultures were obtained in 28% of patients and were positive in 11 patients. The blood culture organisms were the same as the urine culture organisms in all but three patients. In 2 of these patients, the blood culture grew Staphylococcus epidermidis, while the urine culture showed no growth. These results were treated as contaminants and the patients did not undergo treatment of bacteremia. In a third patient, the blood culture grew group B Streptococcus and the urine culture grew Klebsiella species. This patient was evaluated for bacteremia and treated for the group B streptococcus infection. In the ED population, there were 3 (0.5%) patients given an additional diagnosis of sepsis, and an additional 3 (0.5%) patients were diagnosed with para- nephric abscess. No deaths occurred within the 7 days of ED presentation.

Organism	n (%)
E coli	225	(53.6)
No growth	123	(29.3)
Klebsiella species	18	(4.3)
Proteus species	10	(2.4)
Enterobacter species	9	(2.1)
Group B Streptococcus	7	(1.7)
Staphylococcus aureus	7	(1.7)
Staphylococcus saprophyticus	7	(1.7)
Citrobacter species	4	(1.0)
Enterococcus species	3	(0.7)
Streptococcus species	3	(0.7)
Yeast	2	(0.5)
Escherichia fergusonii	1	( 0.2)
Pseudomonas species	1	(0.2)

A total of 211 (33%) of patients underwent a CT evaluation. Only 21 (3.3%) of patients underwent an Ultrasonographic evaluation.

Table 1 Subject baseline characteristics

Characteristic	Pre-OU (n = 249) Post-OU (n = 384)
Race
White	144	(58%) 221	(58%)
African	70	(28%) 113	(29%)
American
Hispanic	30	(12%) 40	(10%)
Asian	1	(0.4%) 2	(0.5%)
Other	4	(1.6%) 8	(2%)
Sex
Female	221	(89%) 334	(87%)
Age (y)	32	(IQR, 24-41) 32.5	(IQR, 23.5-46)
Systolic blood	129	(SD 106-152) 127	(SD, 106-148)
pressure
(mm Hg)
Diastolic blood	74	(SD, 60-88) 73	(SD, 60-88)
pressure
(mm Hg)
Heart rate (bpm)	99	(SD, 79-119) 94	(SD, 74-114)
Temperature	98.9	(IQR, 98-100.9) 98.3	(IQR, 97.3-99.8)
(?F)
Serum white	11.7	(SD, 7.2-16.2) 10.9	(SD, 6.4-15.4)
blood cell
count (K/uL)
Diabetes	34	(13.6%) 41	(10.7%)
Renal disease	65	(26.1%) 90	(23.4%)
Abdominal pain	149	(60%) 228	(58%)
Vomiting	115	(46%) 133	(35%)
Dysuria	141	(57%) 198	(52%)
Frequency/	125	(50%) 142	(37%)
urgency

After the OU was opened, the proportion of patients admitted to a hospital inpatient unit for pyelonephritis from the ED decreased from 35% to 26% (RR, 0.73; 95% confidence interval, 0.57-0.93; P b .05). The proportion of patients who were discharged from the ED after treatment decreased from 64% to 51% (RR, 0.78; 95% confidence interval, 0.68-0.89; P b.001). The rate of overall ED hospital and OU admissions for all diseases (admissions from the ED to either the hospital or the OU) for the years the study was conducted, 2003 through 2006, are 16.2% (16%-16.5%), 17% (16.7%-17.3%), 16.3 (16%-16.5%), and 18.9% (18.6%-

19.1%), respectively. Among the patients admitted to the EDOU for observation, 26 (28%) were admitted to the hospital for further inpatient care. Rates of return ED visits within 7 days after ED discharge before and after the opening of the EDOU were unchanged totaling 7% and 6%, respectively (RR, 0.86; 0.48-1.56; P = .62).

The median length of stay in the OU was 22 hours (IQR, 17.5-25.0 hours). The time in the OU for patients discharged home and admitted was 19.6 hours (IQR, 16.4-24 hours) and

25.3 hours (IQR, 22-28.5 hours), respectively. For patients

admitted to the hospital, the median length of stay was 3 days (IQR, 3-4 days).

Discussion

Table 2 Urine culture results

We used pyelonephritis as our test condition because it is commonly seen in ED practice. Pyelonephritis is also often diagnosed clinically with limited information, often only with a history, physical examination, and urinalysis. Neither the method of diagnosis nor the management of this disease has changed significantly in the last decade. The treatment of pyelonephritis has remained unchanged as well, including antibiotic therapy and treatment of pain, vomiting, and dehydration if needed. We felt using pyelonephritis as our test illness would offer a stable platform to compare admission practices after opening an OU. The incidence of preexisting diseases including diabetes and renal disease was similar in both groups (see Table 1).

Escherichia coli was the most common organism isolated in urine culture comprising more than half of all isolates. Quinolones were the most common antibiotic used for treatment with aminoglycosides and cephalosporins being used at a much lower percentage. This suggests a distinct change in antibiotic preference seen in prior ED studies evaluating this disease, which showed ampicillin as the most

Table 3 Antibiotics administered in the ED

Antibiotic a	n (%)
Quinolone	459 (70%)
Aminoglycoside	72 (11%)
Cephalosporin	66 (10%)
Ampicillin	31 (4.7%)
Sulfonamide	24 (3.6%)
a Clindamycin, nitrofurantonin, doxycycline, and vancomycin each used in less than 1% of ED patients.

common antibiotic prescribed [19]. The rate of ED patients who did not receive antibiotics in the ED was higher than expected. We surmise that these patients look well and that the treating physician felt they could wait until they filled their prescriptions to begin treatment. As a group, the rate of recidivism was slightly higher compared to the overall population (11% and 7%, respectively). However, the numbers of patient who did not receive ED antibiotics and were discharged are too small for meaningful statistical analysis. We found a rather surprisingly high percentage of patients, 28%, who received blood cultures. This does not appear warranted as they have not been found to affect outcome and are not recommended for patients with uncomplicated pyelonephritis [20-23].

The rate of CT imaging was higher than anticipated with one third of all patients undergoing a CT imaging procedure. Although CT may be useful if the diagnosis remains in question, it is not recommended for routine use in the evaluation of pyelonephritis [24]. It is not clear if this is an institutional phenomenon or a more common practice in emergency medicine.

This study demonstrated that the creation of an OU at our institution resulted in a significant decrease in hospital admissions for pyelonephritis. This decrease in hospital admissions was offset by a decrease in ED discharges of 23%. The decrease in ED discharges after opening an OU was seen by Brillman and Tandberg [14] who evaluated the effect of an OU on asthma admissions.

What cannot be accounted for are physician behaviors, specifically, admission and discharge practices of physi- cians who are given a new option for patient disposition. This would be the third OU study to show a decrease in ED discharges after the opening of an OU [14,15]. So why does physician behavior change with the creation of an OU? Physicians are comfortable with what they know. It seems plausible that new EM graduates who trained in a residency with an OU would be more comfortable admitting patients to an OU compared to an EM physician with 20 years of experience who is familiar with making a binary decision of hospital admission or discharge. It is also plausible that the decrease in ED discharges is because ED physicians are more comfortable with OU admissions. In our institution, all OU physician coverage is from our ED group and OU admissions do not require an outside accepting physician. It is possible the ease of admission to an OU lowers a physician’s threshold to admit a patient. It is also possible that creation of an OU decreases the risk tolerance of a physician. This would increase OU admissions for patients who might otherwise have been sent home but were seen and felt they would do better if “watched overnight.” As physicians were not queried at the time of admission for this study, we cannot offer a concrete conclusion on this opinion. A more nefarious explanation would be to increase billing collec- tions from OU admissions. This would be an unlikely scenario in our institution as more than one third of our

OU patients have no medical insurance. Despite the decreased rate of ED discharges, the rate of recidivism did not significantly change.

We are not aware if the decisions to admit or discharge were made solely by physicians or in combination with input from patients. It has been suggested that ED patients have a higher risk tolerance with a decision to Discharge home when compared with ED physicians [25]. If admission decisions were made by physicians in a paternalistic manner, without patient input, we might expect a higher admission rate.

Few studies have evaluated factors associated with rates of admission and discharge in ED populations. A large multicentered study by Chamberlain et al [26] found EDs with pediatric residents admitted patients at a much higher rate and had a greater rate of recidivism when compared with equivalent EDs without residents. It seems unlikely that residents are contributing that significantly to admission rates in this study. In our institution, all patients are seen by an attending ED physician who is responsible for all decisions of disposition. We do not know what influence, if any, ED residents have on the decision to admit to an OU or the hospital. This factor was not evaluated in this study.

Most prior research concerning ED hospital admissions has focused on Patient variables such as socioeconomic or insurance status [27-29]. Still other studies have focused on poor medical outcomes after ED discharge [30-32].

The decision to admit a patient is a complicated method of processing data obtained from multiple sources such as patient history, physical examination, laboratory examina- tions, radiologic examinations, and patient preferences. The complexity of this decision-making process, to admit or discharge a patient, inherently makes it difficult to study. As health care expenses continue to increase, it is likely that health care agencies and hospitals will more closely evaluate ED admission practices. Unwarranted admissions are seen as an indicator of poor-quality exposing patients to disease and wasting Health care resources [33].

The use of protocols have been used to assist with the ED management and disposition of patients with pyelonephritis [34,35]. No such protocols were in place during the study period. These protocols may be helpful for reducing admissions but ideally would be used to quickly assist in decisions of disposition. Ideally, a clinical protocol should be easy to apply, accurate, and provide assistance in Disposition decisions in a rapid fashion.

Limitations

Our intention was to produce a sample that is representa- tive of most patients diagnosed with pyelonephritis with a high degree of certainty. This led to the creation of inclusion criteria that seemed to allow the greatest potential for enrollment. These liberal inclusion criteria may have allowed patients with another clinical condition, such as a patient

with nephrolithiasis who was misdiagnosed with pyelone- phritis, to be enrolled. The inclusion criteria created explicitly did not include urine culture results as these are not always performed in the ED setting and never available at the time of ED diagnosis or disposition. Given our high rate of positive urine cultures that were performed, we feel our inclusion criteria offered a good representation of an ED population presenting with pyelonephritis.

We may have enrolled a lower number of Geriatric patients with pyelonephritis as they often have more atypical symptoms such as vomiting, fatigue, respiratory difficulty, and/or Mental status changes [35,36]. Patients with spinal cord injuries who have neurogenic bladders were only included if they could sense flank pain. This would lead to the exclusion of patients with high complete spinal cord lesions. The retrospective nature of the study may not allow analysis of risk factors such as recent UTIs or recent intercourse, which were not included in the medical record. The decision to not include these risk factors was made a priori by the study team as we felt the frequency that these items were recorded in the medical record would not have allowed useful statistical analysis. Because this study was conducted at a single site, the results may not be generalized to EDs with significantly different patient populations.

An economic/cost analysis was not an objective of this study and was not performed. We cannot draw conclusions on how changes in admission practices after the creation of an OU affect medical finances.

We did not have the opportunity to question the admitting faculty as to their reasoning for admission to an OU or a hospital unit. As with many other academic groups, we have expanded our overall number of faculty with most hires being recent EM residency graduates. It is unclear how younger faculty might be more (or less) inclined to use an OU, but this raises an interesting question for future research.

Conclusion

We found that the creation of an OU resulted in a significant reduction in hospital admissions for pyelone- phritis, which was expected. An unexpected significant reduction in ED discharges to home for pyelonephritis also occurred. The creation of an OU did not change the rate of recidivism for patients diagnosed with pyelonephritis. Further study is needed to determine why physician Disposition decisions change with the creation of an OU and if they affect patient outcomes and Medical costs.

References

1. Mace SE, Shah J. Observation medicine in emergency medicine residency programs. Acad Emerg Med 2002;9:169-71.
2. Landers FA, Waeckerle J, McNbney WK. Observation ward utiliza- tion. Jacep 1975;4:123-5.
3. Diamond NJ, Schofferman JA, Elliot JW. Evaluation of an emergency department observation ward. JACEP 1976;5:29-31.
4. Martinez E, Reilly BM, Evans AT, et al. The observation unit: a new interface between inpatient and outpatient care. Am J Med 2001;110:274-7.
5. Czaja CA, Scholes D, Hooton TM, et al. Population-based epidemiologic analysis of acute pyelonephritis. Clin Infect Dis 2007;45:273-80.
6. Ronald AR. Current concepts in the management of urinary tract infections in adults. Med Clin North Am 1984;68:335-49.
7. Caceres VM, Stange KC, Kikano GE, et al. The clinical utility of a day of hospital observation after switching from intravenous to oral antibiotic therapy in the treatment of pyelonephritis. J Fam Pract 1994;39:337-9.
8. Nicolle LE, Friesen D, Harding GK, et al. Hospitalization for acute pyelonephritis in Manitoba, Canada, during the period from 1989 to 1992; impact of diabetes, pregnancy, and aboriginal origin. Clin Infect Dis 1996;22:1051-6.
9. Pinson AG, Philbrick JT, Lindbeck GH, et al. ED management of acute pyelonephritis in women: a cohort study. Am J Emerg Med 1994;12:271-8.
10. Ward G, Jorden RC, Severance HW. Treatment of pyelonephritis in an observation unit. Ann Emerg Med 1991;20:258-61.
11. Israel RS, Lowenstein SR, Marx JA, et al. Management of acute pyelonephritis in an emergency department observation unit. Ann Emerg Med 1991;20:253-7.
12. Sinclair D, Green R. Emergency department observation unit: can it be funded through reduced inpatient admission? Ann Emerg Med 1998;32:670-5.
13. Cooke MW, Higgins J, Kidd P. Use of emergency observation and assessment wards: a systematic literature review. Emerg Med J 2003;20:138-42.
14. Brillman JC, Tandberg D. Observation unit impact on ED admission for asthma. Am J Emerg Med 1994;12:11-4.
15. Gouin S, Macarthur C, Parkin PC, et al. Effect of a Pediatric observation unit on the rate of hospitalization for asthma. Ann Emerg Med 1997;29:218-22.
16. Nickels JC. The management of acute pyelonephritis in adults. Ca J Urol 2001;8:29-38.
17. Bergeron MG. Treatment of pyelonephritis in adults. Med Clin North Am 1995;79:619-49.
18. Scholes D, Hooton TM, Roberts PL, et al. Risk factors associated with acute pyelonephritis in healthy women. Ann Intern Med 2005;142:20-7.
19. Thanassi M. Utility of urine and blood cultures in pyelonephritis. Acad

Emerg Med 1997;4:797-800.

1. McMurray BR, Wrenn KD, Wright SW. Usefulness of blood cultures in pyelonephritis. Am J Emerg Med 1997;15:137-40.
2. Chen Y, Nitzan O, Saliba W, et al. Are blood cultures necessary in the management of women with complicated pyelonephritis? J Infect 2006;53:235-40.
3. MacMillan MC, Grimes DA. The limited usefulness of urine and blood cultures in treating pyelonephritis in pregnancy. Obstet Gynecol 1991;78:745-8.
4. Velasco M, Martinez JA, Moreno-Martinez A, et al. Blood cultures for women with uncomplicated acute pyelonephritis: are they necessary? Clin Infect Dis 2003;37:1127-30.
5. Sandler CM, Choyke PL, Bluth E, Bush Jr WH, et al. Expert panel on urologic imaging. Acute pyelonephritis. Reston (Va): American College of Radiology (ACR); 2005. p. 1-5.
6. Davis MA, Keerbs A, Hoffman JR, et al. Admission decisions in emergency department chest pain patients at low risk for myocardial infarction: patient versus physician preferences. Ann Emerg Med 1996;28:606-11.
7. Chamberlain JM, Patel KM, Pollack MM. Association of emergency department care factors with admission and discharge decisions for pediatric patients. J Pediatr 2006;149:644-9.
8. Sox CM, Burstin HR, Edwards RA, et al. Hospital admissions through the emergency department: does insurance status matter? Am J Med 1998;105:506-12.
9. Stern RS, Weissman JS, Epstein AM. The emergency department as a pathway to admission for poor and high-cost patients. JAMA 1991;266:2238-43.
10. Jackson P. The impact of health insurance status on emergency room services. J Health Soc Policy 2001;14:61-74.
11. Sklar DP, Crandall CS, Loeliger E, et al. Unanticipated death after discharge home from the emergency department. Ann Emerg Med 2007;49:735-45.
12. Fan JS, Kao WF, Yen DH, et al. Risk factors and prognostic predictors of unexpected intensive care unit admission within 3 days after ED discharge. Am J Emerg Med 2007;25:1009-14.
13. Kefer MP, Hargarten SW, Jentzen J. Death after discharge from the emergency department. Ann Emerg Med 1994;24:1102-7.
14. Steel K, Gertman PM, Crescenzi C, et al. Iatrogenic illness on a General medical service at a university hospital. N Engl J Med 1981;304:638-42.
15. Elkharrat D, Chastang C, Boudiaf M, et al. Relevance in the emergency department of a decisional algorithm for outpatient care of women with acute pyelonephritis. Eur J Emerg Med 1999;6: 15-20.
16. Ramakrishnan K, Scheid DC. Diagnosis and management of acute pyelonephritis in adults. Am Fam Physician 2005;71: 933-42.
17. Liang SY, Mackowiak PA. Infections in the elderly. Clin Geriatr Med 2007;23:441-56, viii.