a b s t r a c t

Introduction: Outpatient Stress testing (OST) after evaluation in the emergency department (ED) is an acceptable evaluation method for patients presenting to the ED with low-risk chest pain (CP). However, not all patients return for OST. Barriers to follow-up evaluation exist and are poorly understood. In this study, we examined the influence of demographic and social characteristics on OST compliance.

Methods: Data were collected on low-risk CP patients with scheduled OSTs. OST compliance was assessed and then ana- lyzed for correlation with potential barriers including Insurance type; age; sex; race; employment status; the distance the patient lived from the hospital; whether or not the patient had a primary care physician; whether or not the patient had a history of hypertension or diabetes; and whether or not the patient had a history of tobacco, alcohol, or illicit drug use. Results: A total of 275 patients were enrolled over a 5-month period. These patients had an OST follow-up rate of 61.82% within 72 hours of discharge from the ED. Patients with Medicaid were statistically less likely (odds ratio [OR], 0.439) to complete OST. Patients with Commercial insurance (OR, 1.8225), who were employed (OR, 2.299), or who were retired (OR, 3.44) were more likely to complete OST. All of the other variables analyzed were not statistically significant factors in OST compliance.

Conclusion: More than one-third of low-risk CP patients do not follow-up with scheduled OST. Of the variables

analyzed, both employment status and insurance type were statistically significant and should be included in risk stratification strategies for OST.

(C) 2016

Introduction

Chest pain concerns comprise more than 8 million emergency department (ED) visits in the United States annually, the second most common ED concern of adults [1]. In a multisite prospective trial evaluating missed Acute cardiac ischemia in the ED, of the 10, 689 patients examined, 224 patients (2.1%) with confirmed acute myocardial infarction (AMI) and 246 patients (2.3%) with confirmed unstable angina were inappropriately discharged from the ED [2].

The risk-adjusted mortality of these inappropriately discharged groups was nearly twice as high (1.9 and 1.7, respectively) than those admitted to the hospital [2]. The challenge in correctly identifying patients who are high-risk for AMI and unstable angina resides in the variability of symptoms in patients presenting with disease, the ability of the ED to rapidly assess a large volume of patients that are clinically low-risk for AMI and unstable angina, and avoiding inappropriate discharge of those with acute coronary syndrome (ACS).

Outpatient stress testing (OST) evaluation is one of the accepted methods of further evaluating low-risk patients with chest pain following

* Corresponding author. Tel.: +1 706 721 4467.

E-mail address: [email protected] (M. Lyon).

evaluation of serial electrocardiogram (ECG) and cardiac enzyme levels. Current American Heart Association guidelines for evaluation of low-risk chest pain patients recommend a functional study within 72 hours of dis- charge from the ED to complete the cardiac workup [3]. Time-spaced tropo- nin measurements, ECGs, and arranged outpatient functional studies for determined low-risk patients can be used to rule out ACS. This approach has been shown to have equivalent Morbidity and mortality rates as com- pared with patients who received their functional study inpatient [4].

Very little is known about patient compliance with 72-hour outpatient cardiac function testing. One study showed a compliance rate of 72.5% with OST. However, this study was performed in Canada with a different popula- tion, both demographically and with respect to insurance status [5]. The ob- jective of our study was to assess patient compliance with OST within 72 hours of discharge. In addition, our objective was to evaluate demographic and social characteristics that may correlate with compliance rates.

Methods

This was a prospective observational study evaluating patient com- pliance with 72-hour OST from May 1, 2013, to September 30, 2013, at an academic medical center with a 9-bed ED-based chest pain unit (CPU) in a metropolitan area with a population of about 400, 000. All

http://dx.doi.org/10.1016/j.ajem.2015.12.083

0735-6757/(C) 2016

M. Story et al. / American Journal of Emergency Medicine 34 (2016) 790-793 791

“low-risk” patients discharged from the CPU and scheduled for outpa- tient stress testing were eligible for the study. Low-risk patients are de- fined as those who meet the criteria in Table 1. These criteria were used as the inclusion criteria for the study. Exclusion criteria included patients with ongoing chest pain, patients with a history of coronary ar- tery bypass grafting, or patients with a stent.

All patients were entered into an electronic quality assurance log at the time of discharge from the ED that included the follow-up stress test appointment time. All patients were given an appointment time and date (within 72 hours of discharge) before leaving the CPU. At discharge from the CPU, patients were given a written standardized discharge in- struction sheet that described the stress test procedure, reason for the test, explanation that their evaluation was not complete until the stress test was completed, and detailed directions to the stress test location. There was no charge or deductible payment required before or at the time the stress test was performed. For patients with insurance, prior authorization was obtained by the clinic staff in advance of the stress test appointment (generally between 24 and 72 hours after discharge from the CPU). patients without insurance were scheduled for the next available appointment, generally within 24 hours. If a patient did not show up for his or her scheduled stress test, the patient was contacted by the stress echocardiogram nurse, and a second appoint- ment was scheduled for the patient.

All OSTs were either exercise or chemical stress echocardiograms. At the discretion of the testing cardiologist, the stress test may be con- verted at test time to a nuclear stress test, transthoracic echocardio- gram, or coronary computed tomography. If the patient was admitted in the interim between discharge from the CPU and the stress test, this was noted.

Patient records using the electronic medical record were reviewed for ultimate diagnosis, demographic data, presence of a Primary care physician , and coronary risk factors. The electronic quality assur- ance log was used to determine the date of the scheduled test, when and how the patient was contacted if the patient did not show to the ap- pointment, and when the patient was rescheduled. Differences in com- pliance rates among the variables were assessed using a ?² analysis with an ? value of 0.05. All analyses were performed using R Version

3.1.0. This project was approved by the Institutional Review Board at the study institution.

Results

During the study period, there were 480 patients evaluated in the CPU. A total of 275 patients (57.3%) were classified as low-risk chest pain patients, and their OST appointment was scheduled before ED discharge; all were included in the final analyses. Patient participation in their scheduled OST is shown in the Figure.

For the 90 patients (32.7%) for which no test was performed, the stress echocardiogram nurse attempted to contact them to reschedule the test with the following results: voice-mail messages were left for 62 participants who did not return the phone call, 14 patients could not be contacted because of nonworking phone numbers, 4 patients stated that they felt that the test was not important or did not want the test, 2 patients were told by their PCP that the stress test was not needed, and 1 patient could not obtain transportation for the test. Seven patients were rescheduled for a second appointment and failed

Table 1

Patients eligible for OST study

Inclusion criteria Exclusion criteria

to keep the appointment. No further contact was attempted with these patients. Nine patients were rescheduled for a second appoint- ment and came in for their appointment. These patients all obtained testing within 1 week of discharge from the CPU. All had a normal stress test result.

Of the 275 patients, 170 (61.82%) completed the OST within 72 hours. Two patients were admitted before their OST for reasons of chest pain and atrial ventricular ectopy. Three patients’ OSTs were can- celed for reasons of hypertension, drop in hematocrit, or cardiologist concern of patient risk factors less than 24 hours postdischarge (Figure). The relationship between patient compliance with OST and other variables was examined. The relationship between OST compliance and commercial insurance type; age; sex; race; distance of household from the hospital; whether the patient has a PCP; whether the patient has a history of hypertension or diabetes; and whether the patient uses tobacco, alcohol, or illicit drugs were found not to be statistically

significant (Table 2).

In contrast, the relationship between OST and having Medicaid, having commercial insurance, and employment status were found to be statistically significant (Table 3). In Table 3, the show-rate percent- ages are represented individually. The P value and odds ratio consider the values in the categories against each other, such as commercial insurance vs. no commercial insurance. When comparing insurance variables, all factors were compared with show rate individually.

When comparing employment variables, unemployment was the common denominator used to calculate the P value and odds ratio for the employment and retired categories. For the study period, the percentages for payer type for our study population were 20.6% commercial insurance, 25.9% Medicaid, 20.0% Medicare, 32.2% self-pay, and 1.3% other.

Discussion

Many physicians are reluctant to rely on OST because of perceived poor compliance risk. In our study, 61.82% of patients were compliant with attending their scheduled OST within 72 hours of ED discharge. This is troubling given the possibility of misdiagnosed or untreated cor- onary artery disease in the 38.18% of patients who failed to keep their appointment and those that miss the 72-hour window postdischarge.

The higher compliance in those with commercial insurance, those without Medicaid, or those who are employed suggests that it may be important to have unemployed, noncommercially insured, and Medic- aid low-risk patients receive their stress test before discharge. This ap- proach might require more work on the part of ED and outpatient cardiology staff but may save lives.

Limitations

There were several limitations to this study. First, the sample size was small. Second, this was a prospective, observational study, which also included data elements from the electronic medical record and a quality assurance database. Although participants were willing to fill out surveys upon discharge, many participants who did not return for their follow-up stress echocardiogram did not complete the follow-up survey. This was for several reasons. All patients who did not show up for their scheduled appointment were contacted, and the majority (62 of 90) had a working phone number that accepted a voice-mail mes- sage. Some participants could not be reached via the phone numbers they gave us, that is, the number was not in use. Others did not answer their phones, and sometimes messages could not be left. When mes- sages were left, few calls were returned. In addition, the protocol was

Chief concern of chest pain or symptom considered an angina equivalent

Ongoing chest pain

perhaps too restricted in terms of follow-up calls (2 calls per day, for up to 72 hours after discharge) and may need to be expanded to allow

Normal or nondiagnostic ECG History of CABG

TIMI score of 1 or 2 Have a stent

CABG, Coronary artery bypass grafting; TIMI, Thrombolysis in Myocardial Infarction.

for more complete follow-up. Therefore, the full range of reasons for not obtaining the recommended testing could not be assessed. In addi- tion, participants were only followed to the point of stress testing (or

792 M. Story et al. / American Journal of Emergency Medicine 34 (2016) 790-793

6 (3.5%)

TTE

2 Tests Performed After Admit

3 (1.9%)

Refused

Admit for CP: 1 Normal Inpatient Stress Echo After Admit

10 (6.4%)

Inconclusive, Borderline, Equivocal*

8 (5.1%)

Abnormal

7 (4.5%) Probably Normal

Admit for Atrial & Ventricular Ectopy: 1 Abnormal Inpatient Stress Echo After Admit

9 Normal

1 Positive Inpatient TTE: Admit for Global Hypokinesis

129 (82.2%)

Normal

1 Test Performed Before Admit

157 (92.3%)

Performed

2 (1.2%)

CTA

5 (3.0%)

Nuclear

9 (3.3%) Test

Performed Post 72hrs

90 (32.7%) No

Test Performed

3 (1.1%) Admitted w/in 72hrs

3 (1.1%)

Cancelled

170 (61.8%)

Show

99 (36.0%)

No Show

275 Total

Figure. Flowquery of low risk patient participation TTE = transthoracic echocardiogram CTA = computed tomography angiography *Borderline, equivocal, and inconclusive results.

M. Story et al. / American Journal of Emergency Medicine 34 (2016) 790-793 793

Table 2

OST compliance and variables of interest

Table 3

Statistically significant variables

Variable	Show rate, n/(%)	Average	P value		Variable	Show rate (%)	P value	Odds ratio	95% CI
Any insurance	107/65.24		.4524		Commercial insurance	72.22	.0306	1.82	1.05-3.15
no insurance	65/60.75				No commercial insurance	58.79
With Medicare	33/60.00		.5936		Medicaid	47.27	.0064	0.44	0.24-0.80
No Medicare	138/63.89				No Medicaid	67.13
Male	63/64.95		.5884		Employed	72.81	.0037	2.30	1.36-3.89
Female	106/61.63				Unemployed	53.79		3.44	0.71-16.74
White	62/60.78		.1217		Retired	80.00

CI, confidence interval.

African American	103/65.19
With PCP	86/95.56		.5730
No PCP	33/100
Hypertension	99/61.11		.4741
No hypertension	70/65.42
Diabetes No diabetes	30/57.69 139/64.06		.3938

Tobacco use 51/59.30 .6789

No tobacco use 113/64.57

Alcohol use 35/57.38 .3167

No alcohol use 134/64.42

Drug use 10/71.43 .5051

No drug use 159/62.60

Show group age 169 52.40 (y) .1350

No show group age 100 50.20 (y)

Show group distance to hospital 166 13.51 (mile) .5316

No show group distance to hospital 98 12.14 (mile)

72 hours). Patients were not followed up long term to learn if testing was obtained at another facility at a later date or if there were additional complications that did not allow for this. Because follow-up communication was not possible with 76 of the 90 patients, it is unknown if there were any significant cardiac events or deaths in this population.

Conclusion

This study found that, at the study site, more than one-third of low- risk CP patients did not follow up with their scheduled OST. Patients with commercial insurance, those who are not on Medicaid, and those who are employed or retired are more likely to successfully complete their OST. Patients who do not fit into 1 of the 4 categories listed

above may be less likely to complete their OST. Despite being in a met- ropolitan area, few patients listed transportation as a reason for not keeping their appointments. Using OSTs to rule out ACS in low-risk chest pain patients within 72 hours of ED discharge may be more appro- priate for some patients than others. This study suggests that employ- ment and insurance status should be included in risk stratification strategies in selecting appropriate patients for OST.

Statement of conflict of interest.

The authors state that they have no competing conflicts of interest.

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