Background
Adults age 65 years and older make an estimated 250,000 US emergency department (ED) visits each year for evaluation after motor vehicle collision (MVC), making this the second most common cause of injury resulting in ED visits for this age group [
1],[
2]. The number of older adults experiencing an MVC is anticipated to double between 2010 and 2030 [
3]. Prolonged hospital stays and high mortality rates have been described for older adults experiencing injuries requiring admission after MVC [
4]-[
6], and high rates of acute pain and distress have been described for individuals of all ages with severe injuries [
7],[
8]. However, 80% of older adults who present to the ED after MVC are discharged to home after evaluation [
9], and outcomes for these patients have received little study.
Among younger adult MVC patients who are discharged to home after ED evaluation, acute pain and distress symptoms are common [
10]. These symptoms cause substantial suffering, and are also important predictors of persistent pain and psychological sequelae after MVC, which constitute an important post-injury public health problem [
11]. While the epidemiology of acute pain and psychological symptoms has been described in younger adults, initial pain and psychological symptoms in older adults presenting to the ED after MVC have not been well characterized. Understanding age-related differences in acute pain and psychological symptoms following MVC has the potential to help providers anticipate the types and severity of problems older patients experience after MVC. In addition, examining associations between patient age, acute pain, and psychological symptoms may provide insights into the mechanisms underlying the initial response to injury across the lifespan and the influence of this response on the development of persistent post-MVC, which is a major public health problem in developed countries [
11]. Early analgesic treatment and education regarding movement and pain-relief can improve outcomes after MVC [
12],[
13], but further work is needed to identify high risk patients and to understand mechanisms leading to persistent pain and psychological sequelae.
The objective of this study is to compare pain, distress symptoms, and recovery expectations between older and younger adults who present to the ED after MVC and are discharged to home, and to examine associations between patient and collision characteristics and pain and distress symptoms for these two age groups.
Results
The EA CRASH study screened 10,634 adults between February 2009 and October 2011; OA CRASH screened 561 adults between June 2011 and March 2013. From these two studies, 948 adults from EA CRASH and 91 adults from OA CRASH met eligibility criteria, consented to participation, and met subsequent criteria for these analyses (Figure
1). After reclassifying 5 patients age 65 years from EA CRASH as older adults, analyses were then conducted on 943 individuals age 18 to 64 years and 96 individuals age 65 years or older.
Relative to younger adults, older adults had less formal education, worse self-rated health, and were more likely to report pain during the month prior to the MVC (Table
1). The majority of older and younger patients were drivers, wore seat belts, and reported moderate or severe vehicle damage. Older adults were more likely to report airbag deployment, likely because they were more often involved in head-on or side-impact collisions. Older adults were also more likely to be transported by ambulance, and to report a greater sense of life threat during the collision. Computed tomography was used more often than plain radiography to image the cervical spine in older adults (Table
2). Overall, plain radiographs and computed tomography scans were both performed more frequently for older adults than younger adults. Clinically apparent fractures were exclusion criteria for both studies; the diagnosis of fractures after enrollment was more common among older than younger adults, but occurred in less than ten percent of adults in both groups. Older adults were more likely than younger adults to be admitted (13% vs. 1%) or observed (8% vs. 1%) than younger adults.
Table 1
Characteristics of patients presenting to the emergency department after motor vehicle collision, by age group (years)
Age, mean (SD), years | 35 (13) | 72 (6) |
Female, % | 60 | 52 |
Education, % |
8-11 years | 4 | 12 |
High school | 19 | 21 |
Post high school* | 39 | 29 |
College graduate | 25 | 20 |
Post graduate | 12 | 18 |
General health, % |
Excellent | 31 | 18 |
Very good | 41 | 34 |
Good | 22 | 29 |
Fair | 7 | 16 |
Poor | 1 | 3 |
Average pain past month, % |
None (0) | 65 | 44 |
Mild (1–3) | 15 | 24 |
Moderate (4–6) | 12 | 17 |
Severe (6+) | 9 | 16 |
≥4 drinks per week, % | 39 | 17 |
Pain catastrophizing, % | 44 | 33 |
Depressive symptoms, % | 20 | 25 |
Driver, % | 86 | 84 |
Seat-belt, % | 90 | 93 |
Collision type†, % | | |
Head-on | 57 | 48 |
Side-impact | 34 | 44 |
Rear-ended | 36 | 27 |
Air bags deployed, % | 29 | 53 |
Damage severity, % |
Minor | 14 | 13 |
Moderate | 31 | 48 |
Severe | 55 | 39 |
Life threatǂ (0–10), mean (SD) | 4.2 (3.1) | 4.9 (3.6) |
Arrived by ambulance, % | 58 | 88 |
Table 2
Radiographic imaging use, fractures, and disposition, by age group
Plain radiography | | |
Cervical spine, % | 27 | 6 |
Chest, % | 32 | 43 |
Pelvis, % | 9 | 14 |
Total radiographs, mean(SD) | 1.2 (1.1) | 1.6 (1.1) |
Computed tomography (CT) scans | |
Head, % | 24 | 45 |
Cervical spine, % | 23 | 36 |
Chest, % | 5 | 19 |
Abdomen/pelvis, % | 8 | 17 |
Total CT scans, mean(SD) | 0.7 (1.0) | 1.4 (1.4) |
Fractures, % | | |
Spine | 0 | 2* |
Rib | <1 | 3 |
Sternum | <1 | 2 |
Other | <1 | 1 |
Disposition, % | | |
Discharged | 98 | 79 |
Observation | 1 | 8 |
Admitted | 1 | 13 |
Mean pain scores in older and younger adults were identical (Table
3). Moderate or severe pain in one or more body region was reported by 77% (95% confidence interval [CI], 67% to 84%) of older adults and 80% (95% CI, 77% to 82%) of younger adults. Both older and younger patients reported a median of 3 (IQR 2–5) body regions with pain (pain score ≥1). The distribution of body regions with pain differed between older and younger adults. Moderate or severe chest pain was reported by 42% (95% CI, 20% to 38%) of older adults compared to 20% (95% CI, 17% to 22%) of younger adults (Figure
1). In contrast, neck and back pain were reported by 25% (95% CI, 17% to 34%) and 31% (95% CI, 23% to 41%) of older adults, respectively, compared to 54% (95% CI, 50% to 57%) and 56% (95% CI, 53% to 60%) of younger adults, respectively.
Table 3
Pain, distress, and anticipated recovery after motor vehicle collision, by age group
Pain severity, mean (95% CI) | | 5.5 | (5.3–5.7) | | 5.5 | (5.0–6.0) |
Distress, mean (95% CI)* | | 19 | (19–20) | | 16 | (14–17) |
Anticipated time for physical recovery ≥30 days, % (95% CI)†
| | 11 | (9–13) | | 41 | (28–55) |
Anticipated time for emotional recovery ≥ 30 days, % (95% CI) | | 17 | (15–20) | | 45 | (35–55) |
Mean distress scores were slightly lower in older adults than in younger adults (15.5, 95% CI 14 to 17 vs. 19.2, 95% CI 19 to 20). However, the prevalence of substantial distress (distress score ≥ 13 [
24]) was nevertheless high in both groups, with half of older adults and 68% of younger adults experiencing substantial distress. A higher percentage of older adults than younger adults reported an anticipated time to physical recovery of 30 days or more (41%, 95% CI 28%-55% vs. 11%, 95% CI 9%-13%). Similarly, a higher percentage of older adults reported an anticipated time for emotional recovery of 30 days or more (45%, 95% CI 35%-55% vs. 17%, 95% CI 15%-20%).
Among younger adults, females and those with less formal education had higher rates of pain and distress (Tables
4,
5). Trends in these relationships were also observed among older adults. For both younger and older adults, patients with higher reported pre-MVC depressive symptoms and higher pain catastrophizing in the ED had higher mean pain and distress scores than those that did not. Younger adults who were not rear-ended had higher distress scores than those who were rear-ended; this association was not observed in older adults. This interaction between age category and rear-end collision on the outcome of distress was statistically significant (p < 0.01); no other interactions between age category and the characteristics examined in Tables
4 and
5 were statistically significant or were suggested by visual inspection of the results.
Table 4
Mean emergency department pain scores (0–10 scale) for younger and older adults by patient and collision characteristics
Sex | | | | |
Female | 565 | 5.7 (5.5,5.9) | 52 | 5.6 (4.9,6.3) |
Male | 369 | 5.3 (5.0,5.5) | 44 | 5.4 (4.6,6.3) |
Education | | | | |
8-11 years | 42 | 7.1 (6.3,7.9) | 11 | 6.2 (4.6,7.8) |
High school | 180 | 5.8 (5.5,6.1) | 20 | 5.4 (4.3,6.4) |
Post high school | 365 | 5.9 (5.7,6.1) | 28 | 6.2 (5.1,7.2) |
College grad | 234 | 5.0 (4.7,5.3) | 29 | 5.5 (4.5,6.4) |
Post grad | 111 | 4.4 (4.0,4.8) | 17 | 4.3 (3.2,5.4) |
Pain catastrophizing | | | | |
Yes | 409 | 6.1 (5.9,6.3) | 31 | 6.4 (5.5,7.2) |
No | 513 | 5.1 (4.9,5.3) | 63 | 5.1 (4.4,5.7) |
Depressive symptoms | | | | |
Yes | 191 | 6.0 (5.6,6.3) | 22 | 6.5 (5.6,7.5) |
No | 741 | 5.4 (5.2,5.6) | 68 | 5.0 (4.4,5.6) |
Driver | | | | |
Yes | 801 | 5.5 (5.3-5.6) | 79 | 5.4 (4.8,5.9) |
No | 133 | 5.9 (5.5-6.3) | 15 | 6.1 (4.5,7.8) |
Rear-ended | | | | |
Yes | 334 | 5.5 (5.2,5.8) | 26 | 5.6 (4.6,6.5) |
No | 600 | 5.6 (5.4,5.7) | 68 | 5.5 (4.8,6.1) |
Damage severity | | | | |
Severe | 500 | 5.5 (5.3,5.7) | 35 | 5.3 (4.5,6.1) |
Moderate | 276 | 5.6 (5.3,5.9) | 43 | 5.7 (5.0,6.5) |
No or minor | 127 | 5.2 (4.7,5.6) | 11 | 4.2 (2.6,5.8) |
Table 5
Mean emergency department distress scores (0–52 scale) for younger and older adults by patient and collision characteristics
Sex | | | | |
Female | 560 | 21.1 (20.3,21.9) | 52 | 16.9 (14.5,19.3) |
Male | 369 | 16.3 (15.3,17.2) | 44 | 13.9 (11.2,16.7) |
Education | | | | |
8-11 years | 42 | 24.4 (21.3,27.5) | 11 | 17.4 (11.9,22.9) |
High school | 178 | 20.2 (18.8,21.7) | 20 | 14.0 (9.65,18.4) |
Post high school | 360 | 19.9 (18.9,20.9) | 28 | 15.8 (12.4,19.2) |
College grad | 235 | 17.6 (16.3,18.9) | 29 | 17.5 (13.6,21.5) |
Post grad | 112 | 16.9 (15.3,18.5) | 17 | 13.0 (9.6,16.5) |
Pain catastrophizing | | | | |
Yes | 408 | 22.0 (21.2,23.0) | 32 | 19.9 (17.0,22.7) |
No | 510 | 16.8 (16.0,17.7) | 64 | 13.4 (11.2,15.5) |
Depressive symptoms | | | | |
Yes | 190 | 22.7 (21.2,24.2) | 23 | 18.9 (15.8,21.9) |
No | 737 | 18.3 (17.6,19.0) | 69 | 14.1 (11.9,16.2) |
Driver | | | | |
Yes | 801 | 19.4 (18.7,20.1) | 79 | 15.3 (13.3,17.3) |
No | 133 | 17.7 (16.0,19.4) | 15 | 16.8 (12.3,21.3) |
Rear-ended | | | | |
Yes | 337 | 17.0 (16.0,18.0) | 26 | 17.5 (13.5,21.5) |
No | 592 | 20.4 (19.6,21.2) | 70 | 14.8 (12.8,16.8) |
Damage severity | | | | |
Severe | 497 | 21.2 (20.3,22.1) | 35 | 16.5 (13.2,19.8) |
Moderate | 277 | 18.0 (16.8,19.1) | 43 | 15.2 (12.6,17.8) |
No or minor | 125 | 14.1 (12.5,15.7) | 11 | 13.9 (9.0,18.8) |
Sensitivity analyses were conducted in which the sample of older adults was further restricted in order to make them more similar to the younger cohort. Among the subset of older adults who were not taking daily opioids prior to the collision, did not have a fracture, and were discharged home (n = 68), the mean pain score (5.1, 95% CI 4.5 to 5.7) and mean distress score (12.9, 95% CI 10.6 to 15.2) were similar to scores for the overall sample of older adults. Comparisons between these scores and scores for younger patients did not change the overall findings that older patients had similar pain scores, lower distress scores, and were more likely to have an anticipated time for physical recovery or emotional recovery of 30 days or more when compared to younger adults.
Limitations
We compare results from two studies with minor differences in inclusion and exclusion criteria and assessment measures. In the study of younger adults, 5% of patients were excluded because they were unwilling to provide a blood sample; this was not an exclusion criterion for the older sample. The OA CRASH study used different instruments for assessing depressive symptoms than EA CRASH. Although the accuracies of each of these three instruments for identifying depressive symptoms when compared to a criterion standard diagnosis of depression is good or excellent (area under ROC >0.8 for each of the three measures vs. criteria standard [
23]), it is possible that the use of different measures caused different estimates for the frequency of depression or associations between depression and pain and distress for older vs. younger adults.
Only 67% and 46% of eligible patients participated in the EA CRASH and OA CRASH studies, respectively. Among eligible patients, reasons for non-participation were similar for younger and older adults. For both studies, some patients declined to participate because they were either in too much pain, were too overwhelmed or stressed, or were too weak, ill, or tired. The total number of patients who decline participation for any of these reasons was 15% of eligible patients in the EA CRASH study and 19% of eligible patients in the OA CRASH. Non-enrollment of these and other patients likely creates some selection bias, but whether selection bias due to eligible patients declining to participate results in over- or under-estimates of pain and distress symptoms is unknown. Also, only non-Hispanic Caucasian patients were enrolled in EA CRASH, and the analysis of participants in OA CRASH was restricted to non-Hispanic Caucasians. The experiences of pain and distress and the effect of age on these experiences may be different in other racial and ethnic groups [
25].
Discussion
Adults age 65 and older are a growing injury population [
26]-[
28], but the types of problems faced by older adults after common injury mechanisms have not been well characterized. In this prospective study of adults presenting to the ED with minor injuries due to MVC, we observed that acute pain was as much a problem for older adults as for younger adults, with more than 75% of patients in both age groups experiencing moderate or severe pain. In addition, while average distress scores were lower in older adults than younger adults, more than half of both older and younger adults presenting to the ED after MVC experienced substantial distress symptoms.
Persistent pain after MVC is a major public health problem and acute pain is the strongest single risk factor for persistent pain [
29]. Our findings of similar acute pain scores among older and younger adults suggests that persistent pain is likely to be at least as common among older adults as among younger adults. Our finding of a mean pain score of 5.5 in the older adults is also consistent with nationally-representative data, in which 61% of older adults who were discharged after an MVC-related ED visit had moderate or severe pain [
1]. In addition, the majority of both younger and older patients had moderate or severe pain for each damage severity category, a finding that is consistent with prior research indicating that acute pain severity is largely independent of the severity of the collision [
29], [
30]. Further studies which evaluate chronic pain outcomes and predictors of chronic pain among older adults are needed, as are studies which evaluate etiologic mechanisms of chronic pain in both groups.
Posttraumatic stress disorder (PTSD) is another common and morbid health problem resulting from MVC [
31], and the initial psychological response to MVC is an important indicator of PTSD risk following MVC [
32]-[
34]. PTSD is also known to be prevalent in approximately 1% of older adults [
35], and advanced age may exacerbate symptoms of PTSD [
36]. In addition, the acute stress response that results from the experience of life-threat may be an important mechanism contributing to persistent post-MVC pain [
37]. Although the problem of PTSD after MVC has not been described among older adults experiencing MVC, other injuries, such as falls, are known to cause PTSD in older adults [
38],[
39]. Our results suggest that substantial distress is experienced by more than half of both older and younger adults presenting to the ED after MVC and suggest that PTSD is a problem in older adults. Interventions to treat the acute psychological response to MVC (e.g. cognitive-behavioral interventions) might be efficacious in reducing both persistent pain-related disability [
40] and psychological sequelae [
41],[
42] in both age groups.
Older adults were more likely than younger adults to have an anticipated time to physical recovery or emotional recovery of 30 days or more. Patient’s expectations for health outcomes are correlated with and likely influence actual health outcomes [
43], and evidence from observational studies of other types of musculoskeletal pain indicates that older adults typically do require more time to recover than younger patients [
44],[
45]. Thus, it seems likely that the differences in anticipated recovery times between older and younger patients in our study result largely from accurate patient assessments of the actual time that they will need to recover.
In our sample, pain catastrophizing was strongly associated with both pain severity and distress symptoms among both younger and older adults. Pain catastrophizing has previously been associated with pain severity among adults with spinal cord injury [
46] and associated with pain severity and function among older adults with osteoarthritis [
47]. Further, decreases in pain catastrophizing during the course of a multi-component intervention to treat chronic pain were associated with decreases in pain severity and disability [
48]. Depression was also associated with pain severity and peritraumatic distress among older and younger adults in our study. Whether interventions to reduce pain catastrophizing or depression can improve pain and functional outcomes for patients presenting to the ED after MVC is unknown.
Among younger adults, those with less formal education had more pain and distress; this relationship was previously described for a subset of this cohort [
49]. Increased pain and distress among less educated patients may be because these patients have less understanding of the nature of injury, less self-efficacy or more limited coping skills, or an increased burden of financial stress from MVC. The data for older adults suggest a similar inverse relationship between educational attainment and pain and distress. Further studies to better understand factors accounting for increased acute pain and distress among ED patients with lower socioeconomic status are needed.
A greater proportion of older adults than younger adults experienced moderate or severe chest pain and fewer experienced moderate or severe back or neck pain. Persistent neck, shoulder, and back pain after MVC (i.e. whiplash syndrome) is a well described phenomenon [
50]. It is unclear whether acute chest pain after MVC leads to a persistent pain condition in older adults. Five of the 40 older adults in the study with moderate or severe chest pain were found to have rib or sternal fractures. The cause of chest pain in the remaining 35 patients is not known, but some likely had radiographically-occult rib fractures.
More older adults came to the ED via ambulance than younger adults. Contrary to our expectations, recent work by our group does not support the presence of a lower threshold for ambulance transport for older adults experiencing MVC [
51]. Ambulance transport can be a stressful experience for patients [
52], but also provides an opportunity for prehospital treatment. Prehospital care may have affected pain and distress symptoms in the study sample, but existing evidence suggests that older adults are less likely to receive analgesics than younger adults during prehospital care [
53]. Further studies are needed which examine the influence of prehospital care on longitudinal pain outcomes among older adults experiencing MVC.
Prior studies have characterized outcomes after minor blunt trauma in older adults, but have included a large proportion of patients who presented to the ED after a fall [
54],[
55]. MVCs are distinct from falls because the older adults who experience MVC are, on average, higher functioning and more likely to be living independently than patients who fall [
56]. Further, our results indicate that acute pain is a substantial problem among older adults who present to the ED after MVC; acute pain is less common after a fall and when present usually results from a long bone fracture. We observe that acute pain is common among older adults receiving emergency care after MVC. Further understanding of long-term outcomes after MVC among older adults and the factors which improve and impede the recovery process after MVC are needed to guide the initial care of this growing and vulnerable trauma population. Understanding the long-term impact of MVC on older adults also has the potential to inform the ongoing debate regarding driver safety among older adults [
57],[
58].
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Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
GP and TPM conceived the study and supervised participant enrollment, data management, and data analysis. SM provided critical revisions for the manuscript and provided strategies to improve data presentation. TT assisted with data analysis and development of the figures. JJ, DL, DP, RD, NR, and PH each assisted in formulating the study and questionnaire, data collection, and also provided critical feedback on the manuscript. TPM takes responsibility for the paper as a whole. All authors read and approved the final manuscript.