A case-crossover study of transient risk factors for occupational acute hand injury

Background: Workers with acute hand injuries account for over 1 000 000 emergency department visits annually in the United States.

Aims: To determine potential transient risk factors for occupational acute hand injury.

Methods: Subjects were recruited from 23 occupational health clinics in five northeastern states in the USA. In a telephone interview, subjects were asked to report the occurrence of seven potential risk factors within a 90-minute time period before an acute hand injury. Each case also provided control information on exposures during the month before the injury. The self-matched feature of the study design controlled for stable between-person confounders.

Results: A total of 1166 subjects were interviewed (891 men, 275 women), with a mean age (SD) of 37.2 years (11.4). The median time interval between injury and interview was 1.3 days. Sixty three per cent of subjects had a laceration. The relative risk of a hand injury was increased when working with equipment, tools, or work pieces not performing as expected (11.0, 95% CI 9.4 to 12.8), or when using a different work method to do a task (10.5, 95% CI 8.7 to 12.7). Other transient factors in decreasing order of relative risk were doing an unusual task, being distracted, and being rushed. Wearing gloves reduced the relative risk by 60% (0.4, 95% CI 0.3 to 0.5). Occupational category, job experience, and safety training were found to alter several of these effects.

Conclusion: The results suggest the importance of these transient, potentially modifiable factors in the aetiology of acute hand injury at work. Attempts to modify these exposures by various strategies may reduce the incidence of acute hand injury at work.

     

Transient risk factors for acute traumatic hand injuries: a case-crossover study in Hong Kong

Objectives

To identify the remediable transient risk factors of occupational hand injuries in Hong Kong in order to guide the development of prevention strategies.

Methods

The case‐crossover study design was adopted. Study subjects were workers with acute hand injuries presenting to the government Occupational Medicine Unit for compensation claims within 90 days from the date of injury. Detailed information on exposures to specific transient factors during the 60 minutes prior to the occurrence of the injury, during the same time interval on the day prior to the injury, as well as the usual exposure during the past work‐month was obtained through telephone interviews. Both matched‐pair interval approach and usual frequency approach were adopted to assess the associations between transient exposures in the workplace and the short‐term risk of sustaining a hand injury.

Results

A total of 196 injured workers were interviewed. The results of the matched‐pair interval analysis matched well with the results obtained using the usual frequency analysis. Seven significant transient risk factors were identified: using malfunctioning equipment/materials, using a different work method, performing an unusual work task, working overtime, feeling ill, being distracted and rushing, with odds ratios ranging from 10.5 to 26.0 in the matched‐pair interval analysis and relative risks ranging between 8.0 and 28.3 with the usual frequency analysis. Wearing gloves was found to have an insignificant protective effect on the occurrence of hand injury in both analyses.

Conclusions

Using the case‐crossover study design for acute occupational hand injuries, seven transient risk factors that were mostly modifiable were identified. It is suggested that workers and their employers should increase their awareness of these risk factors, and efforts should be made to avoid exposures to these factors by means of engineering and administrative controls supplemented by safety education and training.     

急性职业性手外伤的病例交叉研究

目的 用病例交叉研究方法探讨急性职业性手外伤的瞬时危险因素。方法 对166例急性职业性手外伤患者进行问卷调查，分别用配对间隔和日常频率2种方法计算各危险因素的危险度。结果 配对间隔研究无法计算OR值，但设备（工具）异常、非日常工作任务、操作方式改变和注意力不集中主要出现在伤害阶段。日常频率分析发现，设备（工具）异常和匆忙的RR值和95％可信区间下限均大于1；而加班和戴手套的RR值虽然大于1，但95％可信区间下限均小于1；非日常工作任务、操作方式改变、身体不适或生病、注意力不集中无法计算RR值。结论 设备（工具）异常和匆忙作业是导致手外伤发生的危险因素。手外伤的预防措施应着重于控制各种瞬时危险因素。     

A case-crossover study of occupational traumatic hand injury: methods and initial findings

BACKGROUND: Acute hand injury is the leading cause of occupational injury treated in United States' hospital emergency departments (e.g., laceration, crush or fracture). To identify risk factors for traumatic hand injuries, we conducted a case-crossover study of transient exposures (e.g., being rushed) for acute occupational traumatic hand injury. METHODS: The case-crossover method, which uses subjects as their own controls, was used to identify risk factors for occupational hand injury. Two hundred and thirty-two subjects were recruited from 17 occupational health clinics in New England and interviewed by telephone a median of 1.2 days after their injury. The a priori hazard period was defined as 10 min before the injury. Two control periods were used: one was 60-70 min prior to the injury (matched-pair interval analysis); the other was the total work-time exposed, on average, in the previous month (usual frequency analysis). RESULTS: In the usual frequency analysis, the relative risk for using malfunctioning or different-from-usual equipment or tools in the hazard period was 25.5 (95% confidence interval = 18.4-35.2). Relative risks were also significantly elevated for performing a task using an unusual work method, doing an unusual task, being distracted, or being rushed. Wearing gloves appeared to be protective (relative risk = 0.8, 95% CI = 0.5-1.2). Matched-pair interval analysis, where appropriate, provided similar findings but had much wider confidence intervals. CONCLUSIONS: This study demonstrates that the case-crossover design is a feasible and efficient method for studying transient risk factors for sudden-onset traumatic occupational hand injury. The usual frequency analysis proved more useful than the match-pair approach to control period selection.     

Extended work hours and risk of acute occupational injury: A case-crossover study of workers in manufacturing

OBJECTIVE: This study was designed to determine whether injury risk among manufacturing workers was related to hours worked during the previous week. METHODS: A case-crossover design was utilized to contrast hours worked prior to an injury shift with those worked prior to a non-injury shift for hourly workers. Paired t-tests were used to determine significance of the difference. Conditional logistic regression was used to assess dose-response. RESULTS: Hours worked prior to injury significantly exceeded hours during the control week. Workers who worked more than 64 hr in the week before the shift had an 88% excess risk compared to those who worked 40 hr or fewer, P < 0.05. CONCLUSION: The study provides evidence that injury risk is related to time worked during the previous week. Control of overtime in manufacturing may reduce risk of worker injury.     

A case-crossover study of transient risk factors for occupational hand trauma by gender

An estimated 8.2 million occupational injuries occur annually to women in the United States. This case-crossover study of 1166 subjects compares transient risk factors for occupational traumatic hand injury to women and men. Study subjects were recruited over a 3-year period (1997 to 2000) from 23 occupational health clinics in five New England states. The case-crossover design was used to estimate the short-term risk of an acute hand injury while controlling between-person potential confounders. Subjects reported on the occurrence of seven transient exposures within a 90-min period and provided control exposure information during the month before an acute hand injury. A total of 275 women and 891 men were interviewed a median of 1.3 days after injury. Lacerations were the most common injury type in both women (58%) and men (64%). Relative risks for women were higher for being distracted, doing unusual tasks, and working with malfunctioning equipment or materials, and were lower than men for being rushed. Gloves provided significant protection for males and females. Results suggest the importance of considering both the prevalence of various exposures and gender in modifying risk factors to reduce the incidence of acute hand injury in the workplace. Thus, greater emphasis should be placed on the planning of safer working environments for all workers.     

Short-term exposure to desert dust and the risk of acute myocardial infarction in Japan: a time-stratified case-crossover study

Particulate matter from natural sources such as desert dust causes harmful effects for health. Asian dust (AD) increases the risk of acute myocardial infarction (AMI). However, little is known about the risk of myocardial infarction with nonobstructive coronary arteries (MINOCA), compared to myocardial infarction with coronary artery disease (MI-CAD). Using a time-stratified case-crossover design and conditional logistic regression models, the association between short-term exposure to AD whereby decreased visibility (< 10 km) observed at each monitoring station nearest to the hospitals was used for exposure measurements and admission for AMI in the spring was investigated using a nationwide administrative database between April 2012 and March 2016. According to presence of revascularization and coronary atherosclerosis, AMI patients (n = 30,435) were divided into 2 subtypes: MI-CAD (n = 27,202) or MINOCA (n = 3233). The single lag day-2 was used in AD exposure based on the lag effect analysis. The average level of meteorological variables and co-pollutants on the 3 days prior to the case/control days were used as covariates. The occurrence of AD events 2 days before the admission was associated with admission for MINOCA after adjustment for meteorological variables [odds ratio 1.65; 95% confidence interval (CI) 1.18–2.29], while the association was not observed in MI-CAD. The absolute risk difference of MINOCA admission was 1.79 (95% CI 1.21–2.38) per 100,000 person-year. These associations between AD exposure and the admission for MINOCA remained unchanged in two-pollutant models. This study provides evidence that short-term exposure to AD is associated with a higher risk of MINOCA, but not MI-CAD.     

金属制造业职业伤害危险因素的病例交叉研究

目的 探讨金属制造业职业伤害的瞬时危险因素.方法 采用配对病例交叉研究的方法,研究对象为广东省中山市4个职业伤害定点医院收治的来自金属制造业的由机械压力导致的职业意外伤害患者208人,采集伤害发生前30 min内危险因素的暴露情况,伤害发生前一天同一时段12种急性危险因素的暴露情况.结果 采用条件logistic回归分析,结果显示,更换工作岗位(OR =20.76,95％ CI=2.04～210.53),突然加班(OR =10.11,95％ CI=2.57～39.75)是职业伤害的危险因素(P＜0.01),而其他危险因素没有统计学意义.结论 更换工作岗位和突然加班是职业伤害的危险因素.     

Fatigue increases the risk of injury from sharp devices in medical trainees: results from a case-crossover study.

BACKGROUND: Extreme fatigue in medical trainees likely compromises patient safety, but regulations that limit trainee work hours have been controversial. It is not known whether extreme fatigue compromises trainee safety in the healthcare workplace, but evidence of such a relationship would inform the current debate on trainee work practices. Our objective was to evaluate the relationship between fatigue and workplace injury risk among medical trainees and nontrainee healthcare workers. DESIGN: Case-crossover study. SETTING: Five academic medical centers in the United States and Canada. PARTICIPANTS: Healthcare workers reporting to employee healthcare clinics for evaluation of needlestick injuries and other injuries related to sharp instruments and devices (sharps injuries). Consenting workers completed a structured interview about work patterns, time at risk of injury, and frequency of fatigue. RESULTS: Of 350 interviewed subjects, 109 (31%) were medical trainees. Trainees worked more hours per week (P<.001) and slept less the night before an injury (P<.001) than did other healthcare workers. Fatigue increased injury risk in the study population as a whole (incidence rate ratio [IRR], 1.40 [95% confidence interval {CI}, 1.03-1.90]), but this effect was limited to medical trainees (IRR, 2.94 [95% CI, 1.71-5.07]) and was absent for other healthcare workers (IRR, 0.97 [95% CI, 0.66-1.42]) (P=.001).Conclusions. Long work hours and sleep deprivation among medical trainees result in fatigue, which is associated with a 3-fold increase in the risk of sharps injury. Efforts to reduce trainee work hours may result in reduced risk of sharps-related injuries among this group.     

Alcohol and cannabis use as risk factors for injury – a case-crossover analysis in a Swiss hospital emergency department

Background  

There is sufficient and consistent evidence that alcohol use is a causal risk factor for injury. For cannabis use, however, there is conflicting evidence; a detrimental dose-response effect of cannabis use on psychomotor and other relevant skills has been found in experimental laboratory studies, while a protective effect of cannabis use has also been found in epidemiological studies.     

Risk of injury after alcohol consumption: a case-crossover study in the emergency department

This paper reports a case-crossover analysis in a sample of 961 patients who consulted the emergency department (ED) due to an injury in Santa Clara, California, and in Pachuca, Mexico. In the analysis in which usual alcohol consumption during the last 12 months served as the control value, the estimated relative risk of injury in the hour after alcohol consumption, as compared with no alcohol consumption during that time, was 4.33 (CI, 3.55-5.27). After controlling for alcohol use in the 1-h period before injury, the relative risks for consecutive 1-h periods (2-6 h) before the injury were not significantly greater than one, indicating that the induction time was less than 1 h. The relative risk varied greatly depending on race-ethnicity and acculturation among the Hispanics in Santa Clara, with Mexicans in Pachuca showing the highest risk and the high acculturation group in Santa Clara showing the lowest risk. Violence-related injuries were associated with higher relative risk. Relative risk also varied depending on the presence of alcohol dependence and usual frequency of drunkenness: patients with alcohol dependence and patients with high frequency of usual drunkenness had lower risks than patients without alcohol dependence and with lower self-reported episodes of drunkenness in the last year. When blood alcohol content at ED admission was used instead of self-reported alcohol consumption, similar results were obtained. These findings have important public health consequences. Each episode of alcohol consumption results in an increase in the short-term risk for an injury, especially for a violence-related injury. Patients with the lowest usual involvement with alcohol are subject to a higher elevation in their risk for an injury immediately after alcohol consumption compared to patients who drink more heavily.     

The case-crossover design: a method for studying transient effects on the risk of acute events

A case-control design involving only cases may be used when brief exposure causes a transient change in risk of a rare acute-onset disease. The design resembles a retrospective nonrandomized crossover study but differs in having only a sample of the base population-time. The average incidence rate ratio for a hypothesized effect period following the exposure is estimable using the Mantel-Haenszel estimator. The duration of the effect period is assumed to be that which maximizes the rate ratio estimate. Self-matching of cases eliminates the threat of control-selection bias and increases efficiency. Pilot data from a study of myocardial infarction onset illustrate the control of within-individual confounding due to temporal association of exposures.     

Characteristics of working hours and the risk of occupational injuries among hospital employees: a case-crossover study

Objectives:We investigated the association of working hours with occupational injuries in hospital shift work.Methods:Registry data of occupational injuries of hospital employees from 11 towns and 6 hospital districts were linked to daily payroll data to obtain working hours for 37 days preceding the first incidence of the injury (N=18 700). A case-crossover design and associated matched-pair interval analysis were used to compare working hour characteristics for three separate hazard windows among the same subjects. Conditional logistic regression was used to calculate odds ratios (OR) with 95% confidence intervals (CI).Results:We found an elevated risk of an occupational injury for workdays with evening shifts (OR 1.09, 95% CI 1.03–1.14) and workdays following night shifts (OR 1.33, 95% CI 1.17–1.52). After excluding commuting injuries, the risk increased during the evening shifts (OR 1.15, 95% CI 1.09–1.23) and the work days following night shifts (OR 1.44, 95% CI 1.24–1.69), but was no more significant during the morning shifts. Injury risk increased following a week of ≥5 morning shifts or ≥3 evening shifts, but did not increase according to the number of preceding night shifts or quick returns. The length of the work shift (OR 1.22, CI 1.06–1.42) – not the length of the weekly working hours – was associated with an increased risk.Conclusions:The results indicate an increased occupational injury risk during the evening shifts and during work days following night shifts, with the risk increasing according to the number of evening but not night shifts.     

Rapid weather changes are associated with increased ischemic stroke risk: a case-crossover study

Observational studies focusing on absolute meteorological values suggest an association between meteorological parameters and stroke risk but these results are inconsistent and conflicting. Since changes in weather can provoke atrial fibrillation, we examined the association between rapid weather changes and stroke risk in 1694 patients with determinable onset of stroke symptoms in a case-crossover study in central Germany. Days one to three before stroke onset were classified as hazard periods and day seven as the respective control period. Risk of ischemic stroke in relation to 24 h differences in mean ambient temperature, relative humidity and atmospheric pressure was determined. The association between temperature and stroke risk appears to be close to linear with an increase in stroke risk of 11 % (odds ratio 1.11, 95 % confidence interval 1.01–1.22) for each 2.9 °C temperature decrease over 24 h. In individuals with a higher cardiovascular risk, stroke risk increased by 30 % (1.30, 1.06–1.61). Risk for cardioembolic strokes increased by 26 % (1.26, 1.06–1.50). Rapid positive or negative changes in relative humidity (>5 %) and atmospheric pressure (>10 hPa) increased stroke risk by a maximum of 30 % (1.30, 1.02–1.66) and 63 % (1.63, 1.10–2.42). In individuals with a higher cardiovascular risk, rapid changes in atmospheric pressure were associated with a four-times higher stroke risk (4.56, 1.26–16.43). Our results suggest that rapid decreases in ambient temperature and rapid changes in relative humidity and atmospheric pressure increase stroke risk under temperate climate conditions. Individuals with a high cardiovascular risk profile seem to be at greater risk.     

Use of a prescribed ephedrine/caffeine combination and the risk of serious cardiovascular events: a registry-based case-crossover study

Ephedrine and herbal ephedra preparations have been shown to induce a small-to-moderate weight loss. Owing to reports on serious cardiovascular events, they were banned from the US market in 2004. There have been no large controlled studies on the possible association between prescribed ephedrine/caffeine and cardiovascular events in general. The authors linked data from four different sources within Statistics Denmark, using data on 257,364 users of prescribed ephedrine/caffeine for the period 1995-2002. The data were analyzed using a case-crossover technique with a composite endpoint: death outside of a hospital, myocardial infarction, or stroke. To account for effects of chronic exposure and effects in na?ve users, the authors performed a secondary case-control study nested within the cohort of ephedrine/caffeine ever users. Among 2,316 case subjects, 282 (12.2%) were current users of ephedrine/caffeine. The case-crossover analysis yielded an odds ratio of 0.84 (95% confidence interval: 0.71, 1.00); after adjustment for trends in ephedrine/caffeine use, it was 0.95 (95% confidence interval: 0.79, 1.16). Subgroup analyses revealed no strata with significantly elevated risk. In the case-control substudy, there was no increased risk among na?ve users or users with large cumulative doses. Prescribed ephedrine/caffeine was not associated with a substantially increased risk of adverse cardiovascular outcomes in this study.     

特发性室速短期暴露危险因素的病例交叉研究

5%CI∶1.44～3.50).结论 强体力活动、生气、悲伤、激动、感染是IVT的危险因素.病例交叉研究能有效地识别,并揭示其作用强度.