Article, Orthopedics

Snow shovel–related injuries and medical emergencies treated in US EDs, 1990 to 2006

Abstract

Background: Injuries and Medical emergencies associated with snow shovel use are common in the United States.

Methods: This is a retrospective analysis of data from the National Electronic Injury surveillance System. This study analyzes the epidemiologic features of snow shovel-related injuries and medical emergencies treated in US emergency departments (EDs) from 1990 to 2006.

Results: An estimated 195 100 individuals (95% confidence interval, 140 400-249 800) were treated in US EDs for snow shovel-related incidents during the 17-year study period, averaging 11 500 individuals annually (SD, 5300). The average annual rate of snow shovel-related injuries and medical emergencies was 4.15 per 100 000 population. Approximately two thirds (67.5%) of these incidents occurred among males. Children younger than 18 years comprised 15.3% of the cases, whereas older adults (55 years and older) accounted for 21.8%. The most common diagnosis was Soft tissue injury (54.7%). Injuries to the lower back accounted for 34.3% of the cases. The most common mechanism of injury/nature of medical emergency was acute musculoskeletal exertion (53.9%) followed by slips and falls (20.0%) and being struck by a snow shovel (15.0%). Cardiac-related ED visits accounted for 6.7% of the cases, including all of the 1647 deaths in the study. Patients required hospitalization in 5.8% of the cases. Most snow shovel-related incidents (95.6%) occurred in and around the home.

Conclusions: This is the first study to comprehensively examine snow shovel-related injuries and medical emergencies in the United States using a nationally Representative sample. There are an estimated 11 500 snow shovel-related injuries and medical emergencies treated annually in US EDs.

Introduction

In the United States, snow shovels are used seasonally in a variety of public and private settings.

Most snow shovel use occurs in and around the home by individuals who represent a cross-section of the American workforce (16 years and older) [1,2]. Snow shoveling is a strenuous form of physical exertion that leads to injury, hospitalization, and even death of many people each year [3-5]. The general public is at risk for snow shovel-related injuries and medical emergencies, yet receives little, if any, instruction on snow shovel use and safety.

Previous studies on snow shovel safety have focused on a limited geographic area, such as a single state or county, or on a relatively limited patient population [3,4,6-12]. These studies have shown that snow shovel use can result in serious and even fatal injury in both adults and children. Slips and falls and overexertion while snow shoveling are important causes of snow shovel injury [6-9]. Many injuries are due to the nonergonomic design of the standard snow shovel [6,8,13], which has varied little since its invention in the 1840s [6,13]. Manual snow shoveling can be a particularly hazardous activity because of the strain it places on the cardiovascular system [1,2,14-18]. Previous studies have shown that periods of heavy snowfall are often associated with increased incidence of myocardial infarction, angina, and sudden cardiac death [1,2,4,7,10,12,14-25].

Given the prevalence and severity of adverse outcomes associated with snow shovel use, the objective of this research was to determine the epidemiologic features of snow shovel-related injuries and medical emergencies treated in US emergency departments (EDs) between January 1, 1990 and December 31, 2006. This is the first study to comprehensively examine snow shovel-related injuries and medical emergencies in the United States using a nationally representative sample.

Methods

Data were obtained from the National Electronic Injury Surveillance System , which is operated by the US Consumer Product Safety Commission. The NEISS collects data on consumer product-related and sports activity-related injuries from a network of 100 hospital EDs, representing a stratified probability sample of the 6100 hospitals in the United States and its territories with a 24-hour ED with at least 6 beds [26]. Urban, suburban, rural, and children’s hospitals are represented in the sample [27]. Data reported to the NEISS are weighted to allow national Injury estimates.

Established in 1972, the NEISS sampling frame was revised in 1978, 1990, and 1997. At all sampled hospitals, ED medical records are viewed by professional NEISS coders, and data regarding patients’ age, sex, injury diagnosis, body part injured, product(s) involved, disposition from the ED, and a brief narrative describing the incident are recorded. Analysis for this study was conducted from June 2007 to August 2007 with revisions in April 2009.

Snow shovel-related injuries and medical emergencies were identified by the NEISS product code for manual snow or ice removal tools (product code 1415). Injuries involving ice removal tools other than snow shovels, such as ice picks and ice scrapers, were identified using information in the NEISS narratives and were removed from the data set. The national estimates in this study were based on the weighted data from 4733 patients treated in US EDs from January 1, 1990, to December 31, 2006. Patients of all ages were included.

All NEISS narratives were reviewed to classify the mechanism of injury/nature of medical emergency into one of the following categories: (1) cardiac-related, (2) slip/fall,

(3) struck by snow shovel, (4) acute musculoskeletal exertion, and (5) other. Cases were assigned to the cardiac- related category if the NEISS narrative indicated that the ED visit was associated with chest pain, myocardial infarction, cardiac arrhythmia, or palpitations. Acute musculoskeletal exertion injuries included painful conditions of the muscu- loskeletal system after snow shoveling. In instances of potential overlap among these categories, the mechanism of injury that occurred first temporally was given priority; for example, an injury caused by slipping and falling subsequent to a myocardial infarction would be assigned to the cardiac- related category. National Electronic Injury Surveillance System narrative information was inconclusive as to the mechanism of injury for an estimated 7400 cases (3.8%).

In this study, the “laceration” diagnosis category includes the NEISS categories of laceration, amputation, and avul- sion; the “soft tissue injury” category includes the NEISS categories of sprain, strain, contusion, abrasion, and hematoma; and the “other” injury diagnosis category includes the NEISS categories of concussion, internal organ injury, crushing, dislocation, nerve damage, foreign body, puncture, hemorrhage, and other. Diagnosis informa- tion was not documented for 13 unweighted cases. The body region categories used in this study include the head (NEISS categories of head, face, mouth, eyeball, and ear), trunk (NEISS categories of neck, shoulder, upper trunk, lower trunk, and pubic region), arm/hand (NEISS categories of finger, hand, wrist, lower arm, elbow, and upper arm), leg/ foot (NEISS categories of upper leg, lower leg, knee, ankle, foot, and toe), and “other” (NEISS category of injury to z25% of the body). Information on body region injured was not documented in an estimated 1000 cases (0.5%). The disposition from the ED category of “hospitalized” includes the NEISS categories of admitted, transferred, and held shorter than 24 hours for observation, and the “treated/ released” category for disposition from the ED includes “left against medical advice.” Disposition was not documented for 3 unweighted cases.

Data were analyzed using SPSS version 17.0 (2006; SPSS Inc, Chicago, Ill). All 95% confidence intervals (CIs) were calculated using SAS (version 9.1; SAS Institute, Inc, Cary, NC) and SAS-callable SUDAAN software (version 10; Research Triangle Institute, Research Triangle Park, NC). The sample weight assigned to each case was obtained from the Consumer Product Safety Commission and was based on the inverse probability of selection. Snow shovel-related injury rates were calculated using US census data obtained from Census 2000 and the US Census Bureau’s intercensal (1990-2000) and postcensal (2000-2007) national population estimates. Computation of Relative risks (RRs) with 95% CI was performed. Linear regression was used to evaluate the secular trend in injury rates. Significance for statistical testing was determined using ? = .05. All data reported in

this article are national estimates unless otherwise specified. Estimates were not calculated when the actual number of cases was less than 20 because these estimates would be unstable. National injury estimates are rounded to the nearest 100 in the text (except for the estimate of fatal injuries), and percentages are reported to the nearest 10th decimal place in the text and figures. This study was approved by our institutional review board.

Results

From 1990 to 2006, an estimated 195 100 individuals (95% CI, 140 400-249 800) were treated in US EDs for snow shovel-related incidents, averaging 11 500 injuries and medical emergencies annually (SD, 5300). The average annual rate of snow shovel-related injuries and medical emergencies was 4.15 per 100 000 population. The annual rate demonstrated an increasing trend over the 17-year study period, but this increase was not statistically significant (Fig. 1). Males comprised 67.5% of the cases (131 600 cases). Ages ranged from 1 to 95 years, with a mean age of

39.2 years (SD, 20.0 years) and median age of 39 years. Children (b18 years old) comprised 15.3% of the cases (29 900 cases), and 18- to 54-year olds accounted for the greatest proportion of the cases (122 700 cases [62.9%]). Individuals 55 years and older comprised 21.8% of the patients (42 500 cases). Of the 125 900 cases for which location of the incident was documented, most (120 400 cases [95.6%]) occurred in and around the home (Table 1).

Diagnosis

The most common snow shovel-related diagnosis was soft tissue injury, which accounted for 54.7% (n = 106 500) of the cases. Lacerations were the second most common diagnosis, comprising 16.0% (n = 31 000) of the cases. Fractures accounted for 6.6% (n = 12 900) of the cases (Table 1).

Body region

The body region most commonly involved was the trunk, which accounted for 56.5% (n = 109 700) of the cases (Table 1). More specifically, injuries to the lower back accounted for 34.3% (n = 66 900) of the cases. Compared with other body regions, injuries to the trunk region were twice as likely to be diagnosed as a soft tissue injury (RR, 2.04; 95% CI, 1.86- 2.24). The second most commonly involved region of the body was the arms and hands (30 900 cases; 15.9%) followed by the head region (28 600 cases; 14.7%). The arms and hands were more likely than other body regions to sustain fractures (RR, 3.78; 95% CI, 2.95-4.85). The head was more than 12 times more likely to sustain a laceration than another type of injury (RR, 12.54; 95% CI, 10.02-15.68).

Disposition

Most patients (182 100; 93.4%) were treated and released from the ED. Patients who were hospitalized comprised 5.8% (n = 11 200) of the cases (Table 1). Individuals presenting with cardiac-related symptoms were almost 15

Fig. 1 Estimated rate of snow shovel-related injuries and medical emergencies per 100 000 population by year 1990 to 2006.

Patients injured from slips and falls were also at an increased risk for hospitalization (RR, 1.80; 95% CI, 1.34-2.44) compared with other patients, as were individuals with fractures (RR, 4.71; 95% CI, 3.51-6.32). Over the 17-year study period, there were an estimated 1647 deaths, averaging 97 deaths annually. All of these fatalities were cardiac related.

Table 1 Characteristics of snow shovel-related injuries and medical emergencies treated in US EDs, 1990 to 2006

Mechanism of injury/nature of medical emergency

The most common mechanism of injury/nature of medical emergency was acute musculoskeletal exertion (101 100 cases; 53.9%) followed by slips and falls (37 600 cases; 20.0%) and being struck by a snow shovel (28 200 cases; 15.0%). Cardiac-related ED visits accounted for 6.7% (n = 12 500) of the cases (Fig. 2). Mechanism of injury was often closely associated with the body region injured and the type of injury. Being struck by a snow shovel was strongly associated with an injury to the head (RR, 17.50;

95% CI, 15.07-20.32) when compared with other injury mechanisms. Patients struck by a snow shovel were at increased risk for lacerations (RR, 17.53; 95% CI, 14.35- 21.42) compared with patients injured by other mechanisms. Acute musculoskeletal exertion was more likely to affect the trunk region of the body (RR, 3.57; 95% CI, 3.18-4.00) than other injury mechanisms. Slips and falls were more likely to injure the legs and the feet (RR, 3.31; 95% CI, 2.47-4.43) and were almost 19 times more likely to result in a fracture (RR, 18.67; 95% CI, 13.17-26.46) than other mechanisms of injury.

Injuries to children (<18 years old)

The characteristics of snow shovel-related injuries and medical emergencies varied among the age groups. Among study patients, children (b18 years old) were almost 15 times more likely than adults to be injured because of being struck by a snow shovel (RR, 14.85; 95% CI, 12.09-18.23). Children were also at greater risk than adults for lacerations (RR, 11.43; 95% CI, 9.63-13.57). Head injuries accounted

Fig. 2 Mechanism of injury or nature of emergency of snow shovel-related visits to US EDs, 1990 to 2006.

for 67.0% (20 006/29 873) of the Pediatric cases, and children were almost 13 times as likely as adults to sustain an injury to the head (RR, 12.83; 95% CI, 10.51-15.66).

Injuries to adults (18-54 years old)

Adult patients 18 to 54 years were more likely to sustain acute musculoskeletal exertion injuries while using a snow shovel (RR, 2.34; 95% CI, 2.09-2.62) than the other age groups. soft tissue injuries predominated among this age group, accounting for 66.5% (81 400/122 374) of the cases (Fig. 3). Patients in the 18- to 54-year age group were also more likely than other patients to sustain injuries to the trunk (RR, 1.87; 95% CI, 1.68-2.09).

and older, accounting for 43.1% (17 626/40 920) of the cases in this age group. Soft tissue injuries were sustained by 43.8% (18 529/42 340) of the older adults in this study.

Discussion

Snow shoveling can be a hazardous activity to some individuals because of the demands it places on the cardiovascular system [1,2,14-18]. Chest pain, cardiac arrest, and other heart-related symptoms accounted for 6.4% of the ED visits studied (Fig. 2). Cardiac-related cases were the most serious of those studied, accounting for more than half of the hospitalizations and 100% of the deaths.

Snow shoveling requires the coordinated movement of the major muscle groups and requires a high level of

Fig. 3 Snow shovel-related diagnosis by age group, 1990 to 2006.

simultaneous exertion from the legs, arms, and back [1,6,13]. A 1996 study of sedentary men found that the relative heart rate exceeded the upper limits recommended for aerobic exercise after only 2 minutes of snow shoveling [5]. During snow shoveling, systolic Blood pressure and heart rate greatly increase [5,21,28].

Snow shoveling is generally not a year-round activity, and snowfall levels are unpredictable; therefore, it is difficult to prepare physically for snow shoveling. The cardiovascular demands of snow shoveling are also increased by the freezing temperatures that are typically present. Freezing temperatures alone can increase cardiac workload by causing Peripheral vasoconstriction and increasing blood viscosity. Previous studies have shown that Cold temperatures alone (even without vigorous physical exertion) are associated with myocardial infarction in at-risk patients [7,18,29].

More than half of the snow shovel-related ED visits in this study resulted from acute musculoskeletal exertion. Soft tissue injuries occurred in virtually every region of the body; however, the lower back was the region most frequently affected. Many of these injuries are likely to be related to the design of the snow shovel itself. The standard snow shovel is nonergonomic in design and inefficient, which has prompted a number of experts to call for ergonomically designed shovels to help prevent overexertion [6,8,13]. Most snow shovels today differ little from their counterparts of 100 years ago [6]. The shaft of the conventional snow shovel is a straight pole without handgrips, often short in length relative to the height of the user [8]. This design requires users to bend and twist repeatedly, creating harmful compression and shearing forces on the spine [13,30]. Snow shovel blades are often composed of heavy metal, such as steel. The considerable weight of the shovel, and the force needed to move it, may tend to make injuries more severe [31]. For example, an individual using a heavy shovel would be more likely to suffer from an injured wrist should the shovel strike a large rock hidden under the snow.

Recently, a variety of ergonomically designed shovels has been introduced [32,33,34]. These models often feature a curved, adjustable shaft, which is longer in length than that of the standard shovel, thus decreasing the need for bending. Ergonomic shovel blades are usually made of plastic or nonreinforced aluminum, which helps minimize the need for heavy lifting. Studies have shown that snow shovels with curved shafts can decrease the need for trunk flexion considerably and thereby decrease the risk of acute musculoskeletal exertion injury [6,8,13]. Other more creative snow shovel designs such as the Sno Wovel (Structured Solutions II LLC, New Canaan, CT) eliminate the need for bending altogether, allowing the user to simply walk behind the shovel and push as one would a lawn mower [32].

Children younger than 18 years are also at risk for snow shovel-related injuries. The most common type of injury among children was a laceration (Fig. 3), and more than 60% of snow shovel-related injuries to children involved being struck by a shovel. Some of these injuries may have resulted from horseplay or other inappropriate uses of a

snow shovel. To help prevent such injuries, snow shovel use by children should be appropriately supervised. Child caretakers should remember that snow shovels are not designed for small children. When a child attempts to shovel snow, the end of the shovel shaft is often positioned near the child’s head, making head injury more likely. Two thirds of snow shovel-related injuries to children in this study were in the head region.

Slip and fall incidents, which accounted for one fifth of the study cases, are another important source of snow shovel-related injury. Icy sidewalks and streets are extre- mely slippery, perhaps more so than any other surface [35]. Snow shovelers can help protect themselves by wearing high-traction footwear and by paying careful attention to where they step [7,35]. Roof shoveling is extremely hazardous and is unnecessary in most parts of the country [9]. There are alternatives to show shoveling, which include use of salts, deicing sprays, heated sidewalk mats, and snow blowers. Some communities and volunteer groups offer snow shoveling services for older adults and other at-risk individuals [11]. Such programs seem to be successful in improving safety by clearing snow and ice from walkways while decreasing the occurrence of snow shovel-related injury [1,11,36].

The American Academy of Orthopedic surgeons has published guidelines on the prevention of snow shoveling injuries [37]. It recommends that individuals consult a physician before shoveling snow. Sedentary individuals or those with preexisting medical conditions should consider hiring someone to shovel for them. Shovelers should wear appropriate clothing and slip-resistant boot or shoes, warm up with light exercise before shoveling, and then pace themselves while shoveling. They should try to push the snow instead of lifting it and avoid large shoveling jobs by clearing snow early and often [37].

Limitations

This study has several limitations. It underestimates the number of injuries and medical emergencies associated with snow shovel use in the United States because only cases treated in EDs were included in the data set. Findings of this study may not be representative of snow shovel-related injuries and medical emergencies treated in other types of health care facilities or those that did not receive medical treatment at all. Data reported to the NEISS are limited by the detail provided in ED medical records. Missing data and inconsistent documentation in medical records and NEISS narratives also occur. The narrative portion of the NEISS database lacked relevant details, such as the type of snow shovel used, the length of time that the patient was shoveling, and the Safety precautions taken, if any. This level of detail would have been useful for the development of Prevention strategies. Despite these limitations, the strength of this study is its large nationally representative sample obtained over a 17-year period.

Conclusions

This is the first study to comprehensively examine snow shovel-related injuries and medical emergencies in the United States using a nationally representative sample. There are an estimated 11 500 snow shovel-related injuries and medical emergencies treated annually in US EDs. Most of these incidents occur to males in and around the home. The most common mechanisms of injury/nature of medical emergency are acute musculoskeletal exertion, slips and falls, and being struck by a snow shovel. Cardiac-related ED visits accounted for an important minority (6.7%) of the cases in this study, including all of the reported deaths.

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