Original Contribution

Unexplained chest pain in the ED: could it be panic?^?

Guillaume Foldes-Busque MPs ^a,b,?, Andre Marchand PhD ^a,c, Jean-Marc Chauny MD ^d, Julien Poitras MD ^b,e, Jean Diodati MD ^c, Isabelle Denis MSc ^a,

Marie-Josee Lessard BSc ^a, Marie-Eve Pelland MPs ^a, Richard Fleet MD, PhD ^a,b,e

^aDepartment of Psychology, Universite du Quebec a Montreal, Quebec, Canada

^bAxe de recherche en medecine d’urgence affiliated university hospital centre Hotel-Dieu de Levis,

Laval University, Quebec, Canada

^cFernand-Seguin Research Centre, Quebec, Canada ^dSacre-Coeur Hospital Research Centre, Quebec, Canada ^eFaculty of Medicine, Laval University, Quebec, Canada

Received 9 February 2010; accepted 23 February 2010

Abstract

Purpose: This study aimed at (1) establishing the prevalence of paniclike anxiety in emergency department (ED) patients with unexplained chest pain (UCP); (2) describing and comparing the sociodemographic, medical, and psychiatric characteristics of UCP patients with and without paniclike anxiety; and (3) measuring the rate of identification of panic in this population.

Basic Procedure: A structured interview, the Anxiety Disorders Interview Schedule for the Diagnostic and Statistical Manual of Mental disorders, Fourth Edition, was administered to identify paniclike anxiety and evaluate patients’ psychiatric status. Anxious and depressive symptoms were evaluated with self-report questionnaires. Medical information was extracted from patients’ medical records.

Main Findings: The prevalence of paniclike anxiety was 44% (95% CI, 40%-48%) in the sample (n = 771). psychiatric disorders were more common in panic patients (63.4% vs 20.1%), as were suicidal thoughts (21.3% vs 11.3%). Emergency physician diagnosed only 7.4% of panic cases.

Principal Conclusions: Paniclike anxiety is common in ED patients with UCP, and this condition is rarely diagnosed in this population.

(C) 2011

Introduction

Context

^? Sources of support: This research was funded by grants to the first authors from the Groupe Interuniversitaire de Recherche sur les Urgences (GIRU), the Fonds de Recherche en Sante du Quebec (FRSQ) (no. 11842), as well as ongoing support from the research center of the CHAU Hotel- Dieu de Levis hospital and the Montreal Sacre-Coeur Hospital.

* Corresponding author. CHAU Research Centere, Hotel-Dieu de

Levis, 143 rue Wolfe, Levis, Quebec, Canada, G6V 3Z1.

E-mail address: [email protected] (G. Foldes-Busque).

Between 52% and 77% of patients presenting to the emergency department (ED) with complaints of chest pain remain without a clear diagnosis at discharge [1-3]. Despite a favorable long-term cardiovascular prognosis [4-10], unex- plained chest pain (UCP) is a major Public health concern. Several studies indicate that, in as many as 80% of UCP patient, symptoms persist up to 12 years after the initial

0735-6757/$ - see front matter (C) 2011 doi:10.1016/j.ajem.2010.02.021

medical evaluation [2,6,8,11,12]. Unexplained chest pain is also associated with high rates of limitation of daily activities (eg, housework, walking, and exercising) and increased work absenteeism or disability [9,13-15]. The UCP patients make repeated ED visits and are frequent users of health care services such as primary care, cardiology, gastroenter- ology, and neurology subspecialties [13,16-18].

The Symptom profile of patients with UCP is similar to the one of panic attack (PA) patients [19-25]. Chest pain and other symptoms associated with heart disease (eg, palpitations, tachycardia) are common during PA, and individuals with recurrent attacks often catastrophize their symptoms and believe that they are having a myocardial infarction [23]. Panic attack may appear as a symptom of a number of mental disorders, the most common of which is panic disorder (PD) [26]. The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revised

[27] criteria for PA and PD are presented in Table 1. For simplicity, PA and PD will be referred to in this article as panic or paniclike anxiety.

Table 1 Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria for panic attack (PA) and panic disorder (PD)

PA: discrete period of intense fear or discomfort that develops abruptly

1. Reaches a peak within 10 min
2. Accompanied by >=4 of the following symptoms
   1. Palpitations or tachycardia
   2. Sweating
   3. Muscle trembling or shaking
   4. Feeling of choking
   5. Sensations of shortness of breath or smothering
   6. Chest pain or discomfort
   7. Nausea or abdominal distress
   8. Feeling dizzy, unsteady, lightheaded, or faint
   9. Derealization (feelings of unreality) or depersonalization (being detached from oneself)
   10. Fear or losing control or going crazy
   11. Fear of dying
   12. Paresthesia
   13. Chills or hot flushes PD
3. Both (1) and (2)
   1. Recurrent unexpected PA
   2. At least one of the attacks has been followed by 1 mo (or more) of the following
      1. Persistent concern about having additional attacks
      2. Worry about the implications of the attack or its consequences (eg, losing control, having a myocardial infarction, “going crazy”)
      3. Marked change in behavior due to fear of further PAs
4. Presence or absence of agoraphobia
5. The attacks are not due to the direct Physiologic effects of a substance or a general medical condition
6. The attacks are not better accounted for by another mental disorder

The similarity between UCP patients and patients with paniclike anxiety is remarkable yet underrecognized. Studies demonstrate that patients with paniclike anxiety are frequent users of medical services, particularly emergency medical services [16,17,28-34]. Among this population, up to 91% seek medical attention for chest pain in the ED [16]. This statistic is consistent with the finding that 17% to 43% of patients who presented to the ED for chest pain have paniclike anxiety [35-39]. Of those patients, only 6% are discharged with the diagnosis of panic correctly identified [35,39].

Mounting evidence linking panic to UCP in ED patients underscores the importance of this problem. However, many studies in this area have significant methodological limitations. For example, most consist of small samples [35,36,38-40] and do not systematically use established gold standard measures for diagnosing panic (structured interviews) [36-41]. Moreover, few studies have specifically examined the prevalence of panic (not limited to PD) in ED patients.

The ED physicians may be the medical specialists most frequently consulted by panic patients in their initial stages of the disorder. The low screening rate for panic has significant implications for patients. Untreated, panic usually reoccur, and associated symptoms and disorders often persist over time [22,42-44], resulting in repeated ED visits for a problem for which effective treatments exist [45-51]. There is a critical need to focus on advance understanding of UCP in the ED to improve care for these patients and limit the personal and social costs associated with panic.

Objectives

The objectives of the present study were to (1) establish the prevalence of panic in ED patients presenting with UCP,

(2) describe and compare the psychologic distress and sociodemographic and medical characteristics of patients with and without panic, and (3) measure the screening rate for panic by ED physicians.

Method

Design

This is a cross-sectional study of panic in ED patients with UCP. The ethics committee at the Montreal Sacre-Coeur Hospita and the affiliated university hospital centre Hotel- Dieu de Levis approved the research protocol.

Setting

Montreal Sacre-Coeur Hospital serves an urban popula- tion, and the affiliated university hospital centre Hotel-Dieu de Levis serves a rural and urban population. The 2 hospitals are roughly 150 miles apart. Each ED receives approximately 50 000 visits per year.

Participants

Consecutive participants were recruited from Monday to Friday between 8 AM and 4 PM. To be considered eligible, patients had to be at least 18 years old, be fluent in written and oral English or French, and have negative serial electrocardiogram and cardiac enzyme tests (troponin t b 0.06). Exclusion criteria included any objective medical cause for chest pain (eg, cause identifiable by radiography; positive stress test; or objective symptoms of ischemia, arrhythmia, and/or myocardic necrosis), any medical condi- tion that could invalidate the interview (eg, psychotic state, intoxication, intellectual deficiency, and cognitive disorder), any unstable medical condition, and any documented trauma.

Protocol

Research assistants accessed the ED database to identify consecutive patients who presented with chest pain and consulted patients’ medical records to assess eligibility. The evaluation interview was administered to eligible patients who consented to participate. The interview included questions about sociodemographic and medical variables and psychiatric status (including the presence of panic). Participants also completed questionnaires about symptoms of anxiety and depression. The research assistants were trained in the administration of the semistructured diagnostic interview and supervised by doctoral students in psychology and a licensed psychologist. The evaluation interviews were audio recorded and 25% of interviews were randomly selected for review to measure Interrater agreement on Psychiatric diagnoses.

Three medical archivists and 1 registered nurse abstracted the participants’ medical files to obtain further details about the ED evaluation, including referrals for outpatient tests, medical history, medical treatment received in the ED, identification of panic, and tests results (including outpatient tests). An identified case of panic was defined as a PA or PD discharge diagnosis by the ED physician. The abstractors were provided with a standardized abstraction form and detailed codebook. They were blind to the study’s specific objectives and to the participants’ psychiatric status. Medical files were reviewed a minimum of 30 days after the participant was discharged. Ambiguous cases were discussed with the principal investigator; discrepancies were presented to the research team physicians and resolved by consensus. Two abstractors evaluated interrater agreement with data from 104 randomly selected participants (10%).

Measures

• • 1. Sociodemographic and medical interview

This brief interview gathered sociodemographic data, family medical history, and information about type of chest pain (typical, atypical, or nonanginal). Chest pain was

deemed typical when it was substernal, appeared after exertion, and was quickly relieved by rest or nitroglycerin. Atypical chest pain was defined as pain that met 1 or 2 of the criteria for typical chest pain. Nonanginal chest pain was defined as pain that met none of the criteria for typical chest pain.

• • 1. Diagnostic interview

The Anxiety Disorders Interview Schedule for Diag- nostic and Statistical Manual of Mental Disorders, Fourth Edition (ADIS-IV) is a diagnostic interview recommended for the evaluation of PD for research purposes [41]. It was available in French [52] and English [53]. The ADIS-IV has good psychometric properties, most notably good interrater validity for panic (k = 0.79) [54] and interrater reliability (k = 0.80) for panic in patients who present in the ED [35]. The following symptoms and disorders were evaluated: PA in the past month, PD with or without agoraphobia, social phobia, specific phobia, obsessive- compulsive disorder, posttraumatic stress disorder, gener- alized anxiety disorder, major depression, dysthymia, bipolar disorder, hypochondria, somatoform disorder, substance abuse, and substance dependence.

• • 1. Self-report questionnaires

The self-report questionnaires were available in English and French-Canadian versions. The Agoraphobic Cogni- tions Questionnaire (ACQ) measures the frequency of catastrophic thoughts about the consequences of panic [55,56]. The State-Trait Anxiety Inventory (STAI) [57,58] measures trait anxiety (standard reaction to anxiety- provoking situations) and state anxiety (anxiety at the moment the test is administered). The Anxiety Sensibility Index (ASI) measures the tendency to attribute negative consequences to anxiety symptoms [59,60]. Finally, the Beck Depression Inventory (BDI-II) measures the pres- ence and severity of depressive symptoms [61,62]. All of the self-report questionnaires have good to excellent psychometric properties. Based on prior study [35], presence of suicidal ideation was evaluated with question 9 from the BDI-II.

Statistical analyses

All analyses were conducted with SPSS 13 for Windows (SPSS Inc, Chicago, Ill). Analyses of variance were conducted to compare participants with and without panic on continuous variables. When the assumptions of analysis of variance were not met, analysis of variance was replaced with the nonparametric Mann-Whitney test. Comparisons of participants on categorical variables were conducted with ?2 test or Fisher exact test. Significance level was set at P b .05. The 95% confidence intervals (CIs) for prevalence percen- tages were calculated using Wilson’s method.

Results

Participants

Between 2005 and 2008, 4750 ED patients with chest pain were screened for eligibility. Of those 4750 patients, 1694 were potentially eligible for participation and 3056 did not meet eligibility criteria. Consent was obtained from 1059 (62.5%) patients. Following medical chart review, 244 patients (21%) were excluded because they did not meet the inclusion criteria and 44 patients (4%) were excluded because their files were inaccessible. The final sample included 771 participants. See Fig. 1 for details on the sample Selection process.

Statistical analyses revealed that patients who refused to participate were more often female, older, more likely to have a family income less than $60 000 and more often retired than participants (P b .05).

Prevalence of panic

The ADIS-IV was used to diagnose the presence of panic. Paniclike anxiety was diagnosed in 339 patients (44%; 95% CI, 40%-48%), and participants were divided into the panic

group (PG) (n = 339) and the no panic group (NPG) (n = 432). Interrater agreement for ADIS-IV panic diagnoses was very high (k = 0.82) for the 196 randomly selected interviews (25%).

Sociodemographic characteristics for the PG and NPG

Sociodemographic characteristics for the 2 groups are presented in Table 2. The PG participants were significantly younger than NPG participants, and there were more women and fewer retired participants in the PG than in the NPG. No other significant differences in Sociodemographic variables between the 2 groups were observed.

Psychiatric morbidity

In total, 63.4% (95% CI, 58%-69%) (n = 214) of

participants in the PG and 20.1% (95% CI, 16%-24%) (n = 87) of participants in the NPG had at least one psychiatric disorder. Panic disorder was the most common diagnosis in the PG. The next most common diagnoses in both groups were generalized anxiety disorder, specific phobia, and major depression. Not all patients completed the interview,

Fig. 1 Patient’s flowchart.

NPG (n = 432)		PG (n = 339) P
Age, mean (SD)	56.69 (14.95)	50.28 (14.74) b.001
Female	43.1% (186)	52.2% (177) .011
Married or cohabitating	65.3% (282)	62.2% (211) .384
Employment status		b.001
Employed	53% (229)	61.9% (209)
Unemployed	12% (52)	16.7% (57)
Retired	35% (151)	21.5% (73)
Postsecondary	44.8% (189)	43.7% (148) .762
education
Family income	66.3% (267)	64.2% (210) .566
>= $60 000 a
a Twenty-nine patients in the NPG and 12 in the PG did not respond to this question. SD indicates standard error.

resulting in missing data for some disorders. See Table 3 for further details.

Table 2 Sociodemographic characteristics of PG and NPG

Psychologic distress

Participants in the PG reported more symptoms of anxiety (ACQ; STAI; ASI) and depression (BDI-II) than NPG participants. Suicidal ideation was more common in the PG (21.3%; 95% CI, 16%-27%) than in the NPG (11.3%; 95% CI, 8%-15%). Table 4 presents detailed results for measures of psychologic distress. Questionnaire results were included in the analyses only for participants who responded to 95% or more of the items, resulting in the exclusion of 29% of ACQ data, 26% of STAI data, 25% of ASI data, and 23% of BDI-II data. Significant differences were found between participants with greater than 5% missing data and participants who responded to at least 95% of the questionnaire items. Participants with greater than 5% missing data had lower incomes (45.1% vs 29%; P b .001), were more frequently unemployed (49.6% vs 39.7%; P b .009), and had fewer diagnoses of musculo- skeletal pain at discharge (21.3% vs 14.8%; P b .021). There were no other significant differences in socio-

Table 3 Psychiatric morbidity

demographic characteristics and diagnoses at discharge between these groups.

Type of chest pain

The representation of the 3 types of chest pain (typical, atypical, and nonanginal) was comparable in the 2 groups (P = .262). In the PG, 19.3% of the participants reported nonanginal pain, 72.9% reported atypical pain, and 7.9% reported typical pain. In the NPG, 15.4% of participants reported nonanginal pain, 74.5% reported atypical pain, and 10.1% reported typical pain.

Risk factors associated with cardiovascular disease

Although there were significantly more smokers in the PG than in the NPG (28% vs 21%; P = .016), NPG participants had hypertension (36% vs 28%; P = .014) and hypercholes- terolemia (30% vs 21.5%; P = .007) more frequently than PG participants. There were no significant differences between groups for obesity (PG = 25% vs NPG = 23.3%), diabetes (PG = 11.1% vs NPG = 10.1%), history of heart disease (PG = 4.2% vs NPG = 4.4%), and family history of heart disease (PG = 66.3% vs NPG = 63.3%). Finally, there was no significant difference between groups in pooled risk factors for heart disease (PG: M = 1.79 +- 1.25 vs NPG: M = 1.94 +- 1.29; P = .108). Interrater agreement between abstractors was good to excellent for heart disease risk factors, with a k of 0.72 to 0.91.

Length of stay in the ED and medical diagnoses

Globally, 34.4% (n = 116) of the PG participants and 20.8% (n = 90) of the NPG were transported to the ED by ambulance (P b .001). The rate of hospitalization for the 2 groups was comparable (PG: 6.6% vs NPG: 9.6%; P = .106); however, participants in the NPG were hospitalized in cardiology significantly more frequently than participants in the PG (8% vs 4.4%; P = .017). The Mann-Whitney test

psychiatric conditions	NPG % (n)	PG %	(n)	P
At least one psychiatric disorder	20.1% (87/432)	63.4%	(215/339)	b.001
PD	-	47.2%	(160/339)	b.001
Agoraphobia	1.4% (6/432)	13.3%	(45/339)	b.001
Social phobia	2.3% (10/430)	6.9%	(23/336)	.002
Generalized anxiety disorder	6.3% (27/431)	21.5%	(72/335)	b.001
Obsessive-compulsive disorder	0.7% (3/430)	2.7%	(9/333)	.025
Specific phobia	11.6% (50/431)	16.5%	(56/334)	.027
Posttraumatic stress disorder	1.6% (7/428)	2.4%	(8/333)	.450
Major depression	3% (13/427)	13.2%	(44/334)	b.001
Hypochondria	0.2% (1/428)	1.2%	(4/333)	.173
Substance abuse or dependence	1.6% (7/427)	4.5%	(15/332)	.019

Questionnaires	NPG mean +- SD	PG mean +- SD	P	n
ACQ	1.33 +- 0.39	1.66 +- 0.50	b.001	NPG = 320
				PG = 226
STAI
State anxiety	37.67 +- 10.03	41.73 +- 11.00	b.001	NPG = 331
				PG = 224
Trait anxiety	36.49 +- 9.44	42.53 +- 10.64	b.001	NPG = 331
				PG = 241
ASI	15.37 +- 10.23	22.83 +- 12.49	b.001	NPG = 333
				PG = 242
BDI-II	9.21 +- 7.24	13.85 +- 10.24	b.001	NPG = 343
				PG = 248
Suicidal thoughts (BDI-II question 9)			b.001	NPG = 345
				PG = 244
No suicidal thoughts, % (nb)	88.7% (306)	78.7% (192)
Suicidal thoughts, % (nb)	11.3% (39)	21.3% (52)

revealed that length of stay in the ED was shorter for PG participants than for NPG participants, with a median of 10.93 hours (range, 0.24-144 hours) and 11.85 hours (range, 0.72- 139 hours), respectively (P = .043). The frequency of requests for consultation with a specialist was comparable between the 2 groups (PG = 24.8% vs NPG = 27.3%).

Table 4 Measures of psychological distress

To facilitate analysis, medical diagnoses at discharge were divided into categories. The diagnoses satisfied the study exclusion and inclusion criteria as they were not confirmed by a diagnostic test. The frequency of each type of diagnosis was comparable between the 2 groups, with the exception of psychiatric diagnoses, which were more frequent in the PG (see Table 5). Interrater agreement between abstractors varied from good to perfect (k = 0.65- 1.00), depending on the diagnostic category.

Referrals at discharge

Referrals for outpatient tests were more frequent for the NPG (31%, n = 134) than for the PG (20.9%, n = 71; P b

.002). Test results for 14 participants (6 from the NPG and 8 from the PG) were unavailable and not included in

subsequent analyses. The proportion of explained chest pain after outpatient tests was greater in the NPG. Almost every case of chest pain with an identified cause was of Cardiac origin (see Table 6). Interrater agreement for cardiac diagnoses (k = 0.97) and interrater agreement for gastric diagnoses (k = 0.91) were excellent.

Physician recognition of paniclike anxiety

The rate of recognition of panic by ED physicians was 7.4% (n = 25). Only 3 of those participants were referred to a psychiatrist or psychologist. Furthermore, diagnoses of anxiety by the ED physician were more frequent in the PG than in the NPG (14.5% vs 7.6%; P = .002). Abstractor agreement for physician diagnosis of anxiety, PA, and PD were very good to excellent (k = 0.79-1.00).

Discussion

To our knowledge, this is the largest prospective multicenter study to date to specifically address the issue

Table 5 Frequency of diagnosis (by category) at discharge

Table 6 Results of medical evaluations ordered at discharge

Diagnosis NPG PG P (n = 432) (n = 339)

CPUE/NCCP/atypical 44.7% (193) 38.6% (131) .105 chest pain Digestive/abdominal causes 11.6% (50) 16.2% (55) .058 Pulmonary causes 1.9% (8) 2.4% (8) .623 Cardiac causes 3.7% (16) 2.7% (9) .419 Musculoskeletal causes 17.6% (76) 16.5% (56) .695 Psychiatric causes 8.3% (36) 20.9% (71) b.001 Other 4.6% (20) 8% (27) .052

CPUE indicates chest pain of unclear etiology; NCCP, noncardiac chest pain.

NPG (n = 426)		PG (n = 331)	P
Any confirmed medical cause Confirmed coronary artery disease Percutaneous transluminal coronary angioplasty Positive coronarography Positive stress test Positive sestamibi test Confirmed gastric/abdominal causes	8.2% (35)	2.1% (7)	b.001
	7% (30)	2.1% (7)	.002
	1.9% (8)	0.6% (2)	.199
	4.0% (17)	1.5% (5)	.041
	1.6% (7)	0 (0)	.020
	2.1% (9)	0.6% (2)	.124
	1.2% (5)	0 (0)	.072

of panic in ED patients with UCP. It is also the only study conducted in a general ED to use a gold standard method (structured psychiatric interview) to diagnose panic and to focus on objectively low-risk ED chest pain patients while including patients who presented by ambulance.

The results reveal that nearly half of patients who left the ED without a clear diagnosis for their chest pain experienced paniclike anxiety in the month before consultation. This is a higher rate of panic than previously reported. To our knowledge, Fleet et al [35] previously published the only large scale study to focus on panic in ED chest pain patients while systematically using a structured interview. They reported a prevalence of PD of roughly 25% but did not assess PA per se. Moreover, the latter single site study took place in a specialized cardiology ED where almost all patients consult for cardiovascular symptoms. As such, theses difference in study method and setting may also explain difference in panic prevalence.

The results of this study underscore the considerable psychosocial impact of panic. Panic patients present more severe symptoms of Depression and anxiety and are more likely to be diagnosed with one or more ADIS-IV comorbid psychiatric disorders than patients without panic. Patients with paniclike anxiety are twice as likely to have suicidal thoughts as patients without panic. Furthermore, the frequent ambulance use illustrates the extent to which panic is terrifying for patients. Although panic does not necessarily constitute a psychiatric disorder, authors in this field have indicated that it is strongly associated with high level of distress and psychiatric morbidity [22,63-65]. Overall, this study confirms the suspected association between UCP and panic and highlights the psychologic distress associated with this anxiety problem.

The absence of differences between the PG and NPG regarding the type of chest pain is incongruent with prior research that found that panic is more frequent in patients with atypical chest pain [66]. However, much of the published literature describes patients with chest pain of various etiologies. In contrast, the present study focused on low-risk patients (negative serial cardiac enzymes and normal electrocardiogram).

To our knowledge, this is the first study to present detailed data on medical evaluations of ED patients with UCP. The results demonstrate that a cardiac cause for chest pain is identified during medical follow-up is uncommon. However, the finding that a cardiac cause for chest pain is identified in 2.1% of patients with panic implies that, even in cases where panic may constitute a cause of UCP, organic causes may coexist with panic.

The final objective of the present study was to measure the diagnostic rate of panic by ED physicians. The results indicate that, only 7.4% of patients with panic were correctly diagnosed. This low diagnostic rate is similar to the 6% rate found in prior studies [35,39]. Positive clinical evaluation of panic does not seem to result in an increase

in the number of referrals for mental health care; referral to a psychologist or psychiatrist is the exception rather than the rule. The low rate of identification of panic may be attributable to several factors. First, emergency physicians may be unfamiliar with panic diagnoses. Secondly, the similarity between panic symptoms and the symptoms of other medical conditions may complicate its identification. Finally, the tendency of both physicians and patients to focus on physical symptoms and organic causes of pain may interfere with the identification of psychogenic causes [67]. The low diagnostic rate suggests that panic is rarely considered as a differential diagnosis or even as a rule-out diagnosis for UCP. The low diagnostic rate observed in the present study is particularly surprising because the participating physicians were informed of the study’s objectives.

This study has several limitations that must be considered in the interpretation of its results. First, the recruitment of participants during daytime hours from Monday to Friday may limit generalization of the findings to the larger population of ED patients with UCP. Because anxious patients often report an increase in symptoms in the evening and UCP patients who presented to the ED after 4 PM were not systematically enrolled, our results may underestimate the prevalence of panic. However, given that the median hospital stay for patients with UCP is more than 10 hours, many patients who arrived in the evening may have been included in the sample. Secondly, the generalizability of the study’s results may be limited by the elevated rate of refusal to participate and the differences between participants and nonparticipants. The most frequent reason for refusal was physical illness (eg, nausea, fatigue). Although it is possible that many patients who refused to participate would have been excluded after examination of their medical files, this hypothesis cannot be confirmed. Finally, for some variables, differences were found between participants who responded to at least 95% of the self-report questionnaire items and those who did not. Although these differences were few, they may limit the generalizability of the results for those measures.

Conclusion

Results of this study suggest that patients with panic and chest pain frequently present to the ED. The poor rate of identification for panic suggests that research efforts should be aimed at the development and validation of brief and concise screening measures to identify panic in the ED and target continuing medical education efforts toward this group of physician. Early identification of paniclike anxiety promotes appropriate care and facilitates access to treat- ment. Improved care and access could decrease Medical costs, ED visits, and the social, physical, occupational burdens associated with this condition.

Acknowledgments

The authors express their sincere gratitude to Joannie Poirrier-Bisson BSc and Genevieve Belleville PhD for their respective contributions to recruitment and for coordinating this research project.

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