American Journal of Emergency Medicine (2012) 30, 331-337

Original Contribution

Factors associated with self-reported pain scores among ED patients^?

Catherine A. Marco MD?, Jacqueline Nagel, Ellen Klink MPH, David Baehren MD

University of Toledo College of Medicine, Toledo, OH 43614, USA

Received 29 October 2010; revised 1 December 2010; accepted 8 December 2010

Abstract

Introduction: Pain is a common presenting complaint among emergency department (ED) patients. The verbal numeric pain scale is commonly used in the ED to assess self-reported pain. This study was undertaken to describe and compare pain scores in a variety of painful conditions and identify factors associated with self-reported pain scores.

Methods: The study was a prospective, observational, descriptive survey study conducted at an urban university hospital ED. Eligible participants included consenting adults 18 years and older, with an acute painful condition, who spoke English, and were not in severe distress. Through a structured interview, collected data included pain score; diagnosis; medical history; previous painful experiences; and demographic information including age, insurance status, and highest level of education completed. Results: Among 268 eligible participants, 263 (98%) consented and completed the study protocol. Seventy-one percent of participants were 50 years old or younger; 55%, women; and 68%, white. Fifty- four percent had private insurance, and 81%, high school education or higher. The most common chief complaints were soft tissue injury (33%), abdominal pain (18%), and chest pain (13%). The median self- reported pain score was 7/10 (mean, 6.7; interquartile range, 6-9; range, 0-10). The most common previous painful experiences were childbirth (21%), major trauma (18%), and surgery (14%). Participants cited reasons for self-reported pain scores, including current feeling of pain (62%), comparison to previous pain (31%), and comparison to hypothetical pain (12%). The number of Previous ED visits was positively correlated with current pain score (spearman correlation R = 0.28; P b .001). The chief complaints associated with the highest pain scores included Dental pain (mean pain score, 8.5) and back pain (mean pain score, 7.6). Chief complaints associated with the lowest pain scores included chest pain (mean pain score, 5.2) and other medical conditions (mean pain score, 5.3). Factors associated with higher pain scores included younger age (P b .001, Kruskal-Wallis), Medicaid insurance (P = .02), and lower educational status (P = .01). There was not a statistically significant association between current pain score and sex, race, previous painful experiences, or number of hospital admissions.

Conclusion: Emergency department patients with acute painful conditions report a wide range of self- reported pain scores. Participants rated pain based on current feeling of pain or comparison to previous or hypothetical pain. Chief complaints with highest pain scores included dental pain and back pain. Factors associated with higher pain scores included younger age, Medicaid insurance, lower educational status, and higher number of previous ED visits.

(C) 2012

^? Presented, in part, at the Midwest Society for Academic Emergency Medicine Meeting, November 2010, Dayton, OH.

* Corresponding author. Department of Emergency Medicine, University of Toledo College of Medicine, Toledo, OH 43614, USA. Tel.: +1 419 383 6343; fax: +1 419 383 3357.

0735-6757/$ – see front matter (C) 2012 doi:10.1016/j.ajem.2010.12.015

Introduction

Treatment of pain and related conditions has been identified as the most common reason for emergency department (ED) visits [1]. Pain management results in improved patient satisfaction, reduced anxiety, and improved comfort [2,3]. However, despite widespread consensus that pain relief should be one of the priorities of the medical profession, numerous studies have documented inadequate pain management in ED patients [4-10].

The verbal Numeric rating scale is commonly used to assess pain by self-report in EDs. Previous studies have demonstrated that both verbal numeric rating scales and visual analog scales are valid methods of measurement of self-reported pain [11-13].

Emergency department patients report variable levels of pain, even with similar types of diagnoses or injuries [14,15]. Variable levels of perceived pain have been reported in the literature according to sex, age, depression, and anxiety [16-18].

This study was undertaken to describe and compare pain scores in a variety of painful conditions and identify factors associated with self-reported pain scores.

Methods

The study was a prospective, observational, descriptive survey study conducted at an urban university hospital ED. The study was approved by the XXXX Institutional Review Board. Included were all consenting adult ED patients 18 years and older with acute painful conditions. Pain scores were measured by self-report. The primary outcome was current pain score in the ED.

Inclusion/exclusion criteria“>Inclusion/exclusion criteria

All consenting adult ED patients 18 years and older with acute painful conditions were eligible for the study.

Exclusion criteria included prisoners, non-English- speaking patients, mentally incapacitated patients, and patients in severe distress. Patients who chose not to participate and those who did not fully complete the survey were excluded from the study.

Procedures

After informed consent was obtained by the research assistant, ED patients with painful conditions were enrolled as participants. Pain scores were measured by self-report. Research assistants interviewed patients after triage. Infor- mation collected included pain scores; diagnosis; current medications; previous painful experiences; and demographic information including age, insurance status, education, and education status (see attached structured interview).

Outcomes measures

Information collected included triage pain scores; diag- nosis; current medications; previous painful experiences; and demographic information including age, insurance status, education, and education status.

Statistical methods

survey responses were described overall and stratified by several patient factors. Categorical data were described with frequency and percentage. Because the distribution of pain scores on an interval scale did not appear normally distributed, the median and interquartile range (25th- 75th percentile) were reported.

Factors (eg, chief complaint, age, sex, and previous painful conditions) associated with current pain score were explored using nonparametric tests: Mann-Whitney U tests for 2-group comparisons and Kruskal-Wallis tests for more than 2 groups. P b .05 was indicative of an overall association between current pain score and the factor. If a factor had more than 2 groups (or response choices) and had a significant overall test of association with current pain score (P b .05), then the groups were compared to each other 2 at a time to determine which were different. A Bonferroni approach was used to adjust the critical P value for multiple testing: P b .05/ number of comparisons.

Results

Of the 268 patient interviewed, 263 participated and were included in the analyses. Descriptive statistics of the participants are detailed in Table 1. Seventy-one percent of participants were 50 years old or younger; 55%, women; and 68%, white. Fifty-four percent had private insurance, and 81%, high school education or better. Sixty-two percent decided their current pain score based on “what I am feeling right now.” The most common chief complaints were soft tissue injury (33%), abdominal pain (18%), and chest pain (13%). Twenty-five percent were taking narcotic medica- tions. The median current pain score was 7 on a 0-to-10 scale. The most common painful experiences overall included childbirth (21%), major trauma (18%), and surgery (14%).

Factors associated with current pain score are presented in Table 2. Overall, at least some of the age groups differed with respect to median current pain score (P = .001). Comparing the age groups 2 at a time, the median current pain score of patients 65 years and older was significantly lower (median, 5) than that of age groups 18 to 30 (median, 8), 31 to 40 (median, 7), and 41 to 50 years (median, 8) (P b .005 was used as statistical significance to adjust for multiple comparisons). Overall, at least some of the insurance groups differed with respect to current pain score (P = .02). Comparing the groups 2 at a time would require a P b .008 for statistical

Table 1 (continued)

Patient characteristic n Frequency (%) Surgery 14 (5)

Patient characteristic	n	Frequency (%)
Age (y) 18-30 31-40 41-50 51-65 65 and older Sex Male Female Race African American White Asian Hispanic Other Insurance Medicare Medicaid Private Self-pay Other Education Grade school High school College Postgraduate education How to decide on current pain score? (N1 reason possible) What I am feeling right now Comparison to previous pain Comparison to hypothetical pain Knowledge of pain scale Other, no reason, do not know Chief complaint (N1 possible) Abdominal pain Back pain Chest pain Headache Soft tissue injury Other medical Other pain Current medications (N1 possible) None Narcotic OTC (aspirin, NSAID, acetaminophen) Other What would be a pain score of “0”? Normal day When I was younger Never Miscellaneous responses What would be a pain score of “10”? (N1 possible) Major trauma Current Childbirth Broken bone	253
		75	(30)
		69	(27)
		36	(14)
		42	(17)
		31	(12)
	258
		116	(45)
		142	(55)
	259
		72	(28)
		176	(68)
		0
		7	(3)
		4	(2)
	248
		37	(15)
		21	(8)
		133	(54)
		56	(23)
		1	(b1)
	262
		49	(19)
		156	(60)
		45	(17)
		12	(5)
	263
		164	(62)
		81	(31)
		31	(12)
		8	(3)
		12	(5)
	263
		46	(18)
		29	(11)
		33	(13)
		11	(4)
		86	(33)
		30	(11)
		28	(11)
	104
		10	(10)
		55	(53)
		42	(40)
		18	(17)
	260
		127	(49)
		95	(36)
		27	(10)
		11	(4)
	259
		44	(17)
		40	(15)
		25	(10)
		19	(7)

Myocardial infarction 10 (4)

Toothache 7 (3)

Kidney stone 4 (2)

Migraine 6 (2)

Death 1 (b1)

Not categorized 39 (15)

Cannot think of any 44 (17)

Miscellaneous 1 (b1)

Most painful experience (N1 possible) 257

Childbirth 54 (21)

Major trauma 45 (18)

Surgery 36 (14)

Broken bone 25 (10)

Current 15 (6)

Toothache 12 (5)

Kidney stone 9 (4)

Myocardial infarction 4 (2)

Migraine 5 (2)

Death 1 (b1)

Not categorized 24 (9)

Cannot think of any 11 (4)

Miscellaneous 1 (b1)

Most painful experience of family member (N1 possible)

252

Major trauma 47 (19)

Table 1 Descriptive statistics of 263 participants

Surgery 27 (11)

Myocardial infarction 24 (10)

Death 23 (9)

Broken bone 13 (5)

Childbirth 11 (4)

Kidney stone 7 (3)

Migraine 2 (1)

Toothache 1 (b1)

Not categorized 68 (27)

Cannot think of any 39 (15)

Miscellaneous 23 (9)

Overall frequencies

Fracture 255 143 (56)

Childbirth with medication 195 83 (43)

Childbirth without medication 190 46 (24)

Kidney stone 253 41 (16)

Myocardial infarction 253 26 (10)

Patient characteristic	n	Median (IQR)
Triage pain	237	8 (5-10)
Current pain	262	7 (5-9)
No. of ED visits	263	1 (1-3)
No. of hospital admissions	261	1 (1-1)

Interquartile range, 25th to 75th percentile. NSAID indicates nonsteroi- dal anti-inflammatory drug; IQR, interquartile range.

significance. “Near significance” was reached with Medicaid vs private (P = .013) and with private vs self-pay (P = .014). Private pay respondents had lower median pain score (7) than Medicaid (median, 9) and self-pay (median, 8).

Table 2 Median current pain scores by subgroups

Patient characteristic n Median current pain score (IQR) Kruskal-Wallis or Mann-Whitney U 2-tailed

P value testing overall pain score differences

Age (y) P = .001; overall, at least some of the age groups differ

18-30 74 8 (6-10)

31-40 69 7 (6-9)

41-50 36 8 (5-9)

51-65 42 7.5 (4-9)

65 and older 31 5 (1-6)

with respect to current pain score; comparing the age groups 2 at a time, the median current pain score of patients 65 y and older was significantly lower than age groups 18-30, 31-40, and 41-50 y. (using P b .005 to adjust for multiple comparisons)

Sex .09

Male 115 7 (4-9)

Female 142 8 (5-10)

Race .3

African American 72 8 (6-10)

White 175 7 (5-9)

Hispanic and others 11 7 (5-10)

Insurance P = .02; overall, at least some of the insurance groups

Medicare 37 6 (3-10)

Medicaid 21 9 (7-10)

Private 132 7 (5-8)

Self-pay 56 8 (6-10)

Education

Grade school 49 8 (7-10)

High school 155 7 (5-9)

College 45 6 (5-8)

Postgraduate education 12 5 (4-7)

differ with respect to current pain score; comparing the groups 2 at a time would require a P b .008 for statistical significance. Near significance was reached with Medicaid vs private (P = .013) and with private vs self-pay (P = .014)

P = .01; overall, at least some of the education groups differ with respect to current pain score; comparing the groups 2 at a time, median pain score for patients with grade school education was near significantly higher than high school (P = .012) and significantly higher than college (P = .006) and postgraduate (P = .006)

Fracture bone 142 7.5 (5-10) .6

Not 112 7 (5-9)

Childbirth with medication 83 8 (5-10) .7

Not 111 7 (5-10)

Childbirth without medication 46 8 (6-9) .9

Not 143 8 (5-10)

Kidney stone 41 8 (6-10) .1

Not 211 7 (5-9)

Myocardial infarction 26 7.5 (2-9) .3

Not 226 7 (5-9)

Most painful experience

(N1 possible)

n Median (IQR) current pain score of patients who identified this as their most painful experience

Current 14 9 (5-10)

Childbirth 54 8 (6-10)

Kidney stone 9 8 (6-9)

Toothache 12 8 (5-10)

Surgery 36 7 (3-8)

Myocardial infarction 4 7 (3-9)

Major trauma 45 7 (5-8)

Broken bone 25 6 (2-7)

Migraine 5 5 (5-8)

Not categorized, cannot think of any, and miscellaneous

36 8.5 (6.5-10)

Patient characteristic n Spearman correlation with current pain score

No. of ED visits 262 R = 0.28 (P b .001) No. of hospital admissions 260 R = 0.1 (P = .1)

Overall, at least some of the education groups differed with respect to current pain score (P = .01). Comparing the groups 2 at a time, the median pain score for patients with grade school education (median, 8) was “near” significantly higher than high school (median, 7; P = .012) and significantly higher than college (median, 6; P = .006) and postgraduate (median, 5; P = .006).

Participants on narcotics before the ED visit had higher pain scores (mean, 7.4) compared to those not on narcotics (mean, 6.5).

The number of ED visits was positively correlated with current pain score (R = 0.28; P b .001).

Pain scores differed by chief complaint. The chief complaints associated with the highest pain scores included dental pain (mean pain score, 8.5) and back pain (mean pain score, 7.6). Chief complaints associated with the lowest pain scores included chest pain (mean pain score, 5.2) and other medical conditions (mean pain score, 5.3) (Table 3).

There was not a statistically significant association between current pain score and sex, race, bone fracture, childbirth with or without medication, kidney stone, myocardial infarction, or number of hospital admissions (P all N.05).

Discussion

Pain is typically assessed by self-report, as a subjective phenomenon [19,20]. Previous studies have demonstrated that clinicians’ perception of patients’ pain does not correlate well with self-reported pain [21-26]. Self-reports of pain are often variable for similar clinical conditions, and self-reports of pain may be influenced by a variety of factors including clinical, psychologic, and social issues, including physical pain, psychosocial factors, age, sex, ethnicity, cultural background, anxiety, and functional impairment [27-32]. Commonly used scales in emergency medicine include the verbal numeric pain scale, the visual analog scale, adjective descriptors, the faces scale, color scale, visual “thermometers,” functional assessments, and the 5-point global scale (“0-4”) [33-38]. The verbal numeric

Chief complaint	n	Mean pain score
Abdominal pain	46	7.1
Chest pain	31	5.2
Back pain	28	7.6
Dental pain	8	8.5
Headache	9	7.2
Soft tissue injury	86	6.8
Other medical condition	30	5.3
Other painful condition	25	7.4

pain scale (verbal estimated pain on a 0-10 scale) is commonly used to assess both acute and chronic pain. The verbal numeric pain scale and the visual analog scale have demonstrated concordance [11,39].

The subjective nature of pain makes pain inherently difficult to quantify and to apply in clinical practice. A prospective study of postoperative patients showed a wide variation between repeat measurements [40]. Scores on the verbal scale tend to be higher than other scales, limiting the usefulness of the high end of the scale [11]. Clinical application of the scores becomes difficult when scores tend to fall between 6 and 10 (or higher). The subjective nature of pain scales is reinforced by a study that showed 25% of subjects significantly lowered their pain score after either written or video education regarding the pain scale [41]. Subjectivity on the part of physicians can impair the delivery of adequate analgesia.

Pain scores have been incorporated into ED triage and into the clinical practice of physicians and nurses. The assessment of pain is a necessary component of pain management and is associated with improved analgesic administration patterns. A prospective study demonstrated that trauma patients with a pain score greater than 4 were more likely to receive analgesia if the pain scale is used [42]. A study using children showed no improvement in delivery of or promptness of the delivery of analgesia [43].

This study attempted to elucidate factors associated with self-reports of pain among ED patients. Participants in this study rated pain based on current feeling of pain or comparison to previous or hypothetical pain. This study demonstrated that younger, less educated, and less affluent patients tend to rate their pain higher than other groups.

Patients with higher numbers of recent ED visits also rated their pain higher than their cohorts. Particularly in light of recent findings suggesting that patients with high numbers of ED visits have lower acuity [44,45], this finding may suggest subjective inflation of pain scores.

These findings emphasize the subjective and variable nature of self-reports of pain among ED patients.

Future research should address educational efforts to assist patients in providing accurate self-assessments of pain. In addition, education of health care providers regarding the subjective and variable nature of self-reports of pain and their application to pain management may be useful in improving clinicians’ assessment and management of painful ED conditions.

Table 3 Chief complaints and pain scores of ED patients with painful conditions

Limitations

This study was conducted at a single institution and may not reflect patient experiences in other settings. This study relied on patient self-reports of painful experiences and may be limited by independent recall and accurate reporting of experiences. The near significant finding of correlation of Medicaid insurance and pain scores should be interpreted with caution.

Conclusions

Emergency department patients with acute painful condi- tions report a wide range of self-reported pain scores. Participants rated pain based on current feeling of pain or comparison to previous or hypothetical pain. The chief complaints associated with the highest pain scores included dental pain and back pain. Chief complaints associated with the lowest pain scores included chest pain and other medical conditions. Factors associated with higher pain scores included younger age, Medicaid insurance, lower educational status, and higher number of previous ED visits.

Acknowledgment

The authors thank Nancy Buderer, MS, for her statistical expertise and data analysis.

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