Psychological Outcome of Injured Workers at 3 Months after Occupational Injury Requiring Hospitalization in Taiwan

Abstract

Introduction: After a traumatic event, a significant proportion of victims develop psychiatric disorders. Trauma has been an important ailment among workers. This study aimed to determine the prevalence of post-traumatic stress disorder (PTSD) and other psychiatric disorders at three months after occupational injuries. Methods: Our study candidates were injured workers in Taiwan who were hospitalized for 3 days or longer and received hospitalization benefits from the Labor Insurance program. A two-staged survey study was conducted. A self-reported questionnaire including the Brief Symptom Rating Scale (BSRS-50) and Post-traumatic Symptom Checklist (PTSC) was sent to workers at 3 months after injury. Those who met the criteria were recruited for the second stage phone interview with a psychiatrist using the Mini-international Neuropsychiatrie Interview (MINI). Results: A total of 2001 workers completed the questionnaire (response rate 45.5%). Among them, 357 (17.8%) fulfilled the criteria for the MINI interview and were invited. A total of 148 (41.5%) completed the phone interview. The estimated rates of PTSD, partial PTSD (PPTSD), major depression, comorbid PTSD/PPTSD and major depression, and either PTSD/PPTSD or major depression were 2.7, 4.1, 3.0, 2.3, and 7.5%, respectively. The estimated rates of either PTSD/PPTSD or major depression among workers who suffered from intracranial injury, fracture, burn, crushing injury, and open wound of upper limbs were 10.4, 6.9, 5.9, 5.8 and 0%, respectively. Conclusions: At three months after occupational injuries, a significant proportion of workers suffered from psychiatric disorders. The rates of psychiatric disorders occurring after intracranial injuries were significantly higher than those occurring after non-intracranial injuries.

Introduction

Accidents are among the leading causes of death in most developed countries in recent years and were ranked as the 6th leading cause of death in Taiwan in 2008¹⁾. According to the Institute of Occupational Safety and Health in Taiwan in 2004, occupational accidents were the 2nd most important cause of death among workers²⁾. Occupational injury is defined as death, any personal injury or disease resulting from an occupational accident³⁾. According to the Bureau of Labor Insurance, there are three types of medical benefits for occupational injury, including inpatient benefits, outpatient benefits, and medical examination benefits. In 2008, of the workers who received medical benefits for occupational injury, more than 14,000 workers received inpatient benefits due to occupational injuries⁴⁾.

Traumatic events or natural disasters are known to induce psychiatric disorders, including post-traumatic stress disorder (PTSD), major depression, anxiety, etc.^5–7). PTSD is the most commonly studied and probably the most frequent psychological disorder that develops after traumatic events and natural disasters^{7, 8)}. After the World Trade Center event in New York, the survivors suffered an increased risk of PTSD and depression⁹⁾. In Taiwan, the lifetime prevalence rate of depression in the general population was reported to be 1.14%²⁵⁾, and the prevalence of PTSD reported in survivors of earthquakes varied widely, ranging from 4.4–21.7%^10–13). After accidents resulting in hospitalization, PTSD and depression were observed among the victims¹⁴⁾. Only few studies examined the rates of psychiatric disorders after occupational injuries. Asmundson et al. in 1998 reported that the rate of PTSD among injured workers was 34.7%, and workers with PTSD had a higher rate of depression than those without PTSD¹⁵⁾. MacDonald et al. found that 55% of workers after occupational injury were diagnosed with PTSD only, and major depression was the most frequent coexisting disorder¹⁶⁾. To the best of our knowledge, no study on mental conditions had been conducted in Asia; thus, the occurrence rates of PTSD and major depression after occupational injuries in Asian workers have been unknown.

The objective of this study was to determine the prevalence rates of post-traumatic stress disorder and other psychiatric disorders after occupational injuries. Since injury types might vary the rates of PTSD and other psychiatric disorders after occupational injury because of their injury characteristics¹⁷⁾ and intracranial injury has been considered a predisposing psychiatric condition, we also compared the rates of developing psychiatric disorders after intracranial injury and non-intracranial injuries.

Methods

Participants

Between February 1 and August 31, 2009, a total of 4,403 workers who were hospitalized for 3 days or longer and received the Inpatient Hospitalization Benefit portion of Occupational Accident Medical Benefits from Labor Insurance program were utilized as subjects. The subjects were recruited consecutively. This study was approved by the Institutional Review Board of the National Taiwan University Medical Center.

Procedure

This study was a two-stage investigation. The details of the first stage of investigation were previously reported¹⁸⁾. Briefly, the first stage involved a self-reported questionnaire including demographics, the Brief Symptom Rating Scale (BSRS-50) and the Post-traumatic Symptom Checklist (PTSC) for screening of mental conditions. The demographic part was designed by psychiatrists, a psychologist, and public health professionals to inquire about risk factors, including family history of psychiatric disorder, life events before and after the occupational injury and financial burden as well as individual characteristics such as gender, age and marital and educational status. The self-reported questionnaire with a cover letter explaining the purpose of our study was sent to the homes of all subjects at 3 months after injury. Completion and return of the questionnaire was considered the subject's consent to participate. However, if a subject did not respond to the questionnaire, we tried to make contact by phone, invited the subject to participate and obtained oral informed consent after full explanation of the study procedures. At least 3 tries were made to encourage the study subjects before giving up. When the questionnaire was incompletely answered, a phone interview was performed to complete all questions. The candidates for the second-stage phone interview by MINI received such interview within 2 wk of the first-stage questionnaire screening. In this study, psychiatrists used the Taiwanese version of the MINI to assess the prevalence of different psychiatric disorders (including PTSD, suicidality within 1 month and current major depression within 2 wk). For the second-stage phone interview by psychiatrists using the Mini-international Neuropsychiatric Interview (MINI), we recruited those participants fulfilling the following criteria: (1) those with a general severity index (GSI) score for the BSRS of 2 standard deviations above the norm (i.e., 70) or higher, (2) those who had any item of PTSC reported at the “severe” level or higher or (3) those who had any 2 items of PTSC reported at “moderate” levels or higher.

Instruments

The BSRS-50 consists of a 50-item self-report rating scale that is used to measure 10 psychophysiological symptom groups and has been tested in Taiwan. The test-retest reliability coefficients ranged from 0.73 to 0.91. The rate of accurate classification for psychiatric and nonpsychiatric cases was 75.8%, with a sensitivity of 66.7% and a specificity of 86.7%¹⁹⁾. For the BSRS, an adjusted T score was determined in accordance with a previous study to examine the severity of psychological symptoms in injured workers²⁰⁾. A T score of 50 was considered identical to the mean of the reference group, and the standard deviation (SD) was set at 10. A general severity index (GSI) score of greater than or equal to two SDs higher than the mean score of the reference group (i.e., GSI ≥ 70) was considered psychologically severe.

The PTSC is a 3-item checklist for quick screens of PTSD symptoms in the past one week, corresponding to the DSM-IV symptom clusters of PTSD, namely, reexperiencing, numbness and hyperarousal²⁰⁾. These items are “Has encountering a reminder of the injury event caused physical discomfort (including sweating, tremor, racing heart, tachypnea, nausea, or diarrhea),” “have you been unable to have sad or happy feeling after this event,” and “have you become easily startled after this event?” The response to each item is rated on a five-point Likert scale, namely 0 (no), 1 (mild), 2 (moderate), 3 (severe) and 4 (very severe). Respondents were asked to refer to the traumatic event caused at work.

The MINI, a short structured diagnostic interview instrument, has been used to evaluate the presence of DSM-IV and ICD-10 psychiatric disorders with a test-retest reliability of 0.75, sensitivity of 0.70 or higher and specificity of 0.85 or higher²²⁾. Using data from the PTSD module of the MINI, the criteria for PTSD were defined as follows: 1. one positive response to the symptom of intrusion item; 2. at least three out of six symptoms of avoidance/numbing items; 3. at least two out of five symptoms of hyperarousal items; and 4. the presence of distress and impairment. Subjects who did not meet these criteria for PTSD but who endorsed the presence of a combination of two of the three clusters (intrusion, avoidance/numbing, hyperarousal) and endorsed distress or impairment, were considered to have PPTSD. A previous study had defined partial PTSD (PPTSD) as the presence of a combination of two of the three criteria-B, C and D²³⁾. Those diagnosed as having PPTSD were reported to suffer from higher comorbid DSM-IV psychiatric disorders and functional impairments^{24, 25)}. Therefore, the rate of PPTSD was also estimated in this study.

Statistical Analyses

All statistical analyses were conducted with JMP 5.0 (SAS Institute Inc.). The descriptive statistics were used to examine the prevalence rate of PTSD and other psychiatric disorders, the background demographic characteristics, and exposure characteristics among workers after occupational injury. The occurrence rates of mental diseases at 3 months after the occupational injuries were estimated by multiplying the percentage of high scores in BSRS or the PTSC by the percentage diagnosed as having psychiatric disorders by the MINI interview among those who participated in the MINI interviews. The occurrence rates of mental diseases at 3 months in a specific type (e.g., fracture) of occupational injuries were estimated by multiplying the percentage of high scores in the BSRS or PTSC in a specific type of occupational injuries by the percentage diagnosed as having psychiatric disorders by the MINI interview in that type of occupational injuries. The standard errors of estimated rates were estimated by the square root of p (1–p) / n, where p is an estimate proportion and n is total number of subjects. In order to test the difference of estimated rates of psychiatric disorders between workers sustaining intracranial injury and non-intracranial injuries, the test statistic is the 95% confidence interval of the difference proportion P1 and proportion P2, which is the 95% CI of P1–P2=p1-p2 + – 1.96∗sqrt (p1 (1–p1) / n1 + p2 (1–p2) / n2). Differences were considered significant if the confidence interval did not contain 0. Chi-square tests and one-way analysis of variance were used to analyze group differences. Differences were considered significant if the p value was smaller than 0.05. Cronbach's α was used to measure the internal consistency of the BSRS and PTSC scores for injured workers.

Results

At the time of the survey 3 months after occupational injury, 2,402 (54.6%) of the injured workers did not complete the questionnaire survey. While we tried to contact them by phone, 1,299 (29.5%) did not answer the phone, 707 (16.1%) refused to answer the questionnaire, and 396 (9.0%) could not be reached because we had the wrong phone number. Therefore, a total of 2001 injured workers completed the first stage of investigation, with a response rate of 45.5% (Fig. 1). The mechanisms of injuries are compared between responders and non-responders in Table 1. The most important cause of injuries was transportation accidents (38.0%), followed by caught in or compresses by equipment or objects (20.1%), falls (11.9%), etc. The most frequent type of occupational injury was fracture (55.3%), followed by intracranial injury (10.9%), crushing injury (9.5%) (crushing injury: occurs when a body part is subjected to a high degree of force or pressure, usually after being squeezed between two heavy objects.), etc. (Table 1). The causes and types of injuries were not statistically different between those who responded to the survey and those who did not. Among those who completed the questionnaire, the majority were males (73.1%), and the average age was 42 yr (SD=12.2). Most were married (62.6%) and had an education level of high school or above (42.6%). Moreover, the majority had no family history of psychiatric morbidity (99.2%) and no previous occupational injury experience before this event (84.1%). The average percentage of family income contributed by the injured worker before injury was 57.9%. Regarding injury-related variables, most of the subjects did not lose consciousness as a result of their injury (84.9%) and had a serious injury severity or above. The average length of hospital stay immediately after injury was about 9 days, and the average total length of stay in 3 months was about 11 days. Furthermore, about 70% of the injured workers believed the injury affected their physical appearance, 96.2% had no life event within one month before this injury, and 90.2% had no life event after this injury (Table 2).

Fig. 1.

Enrollment of subjects in the study.

Table 1. Injury mechanisms and injury types in participants and non-participants

Variables	Participants (n=2,001)	Non-participants (n=2,402)	p value
Injury mechanisms (%)			0.7
Transportation accident	37.8	38.4
Caught in or compressed by equipment or objects	20.1	16.7
Falls	11.9	13.4
Slips or loss of balance	10.0	9.4
Cutting	10.0	10.2
Others∗	10.3	11.7
Injury types (%)			0.6
Fracture	55.3	54.2
Intracranial injury	10.9	11.1
Open wound of upper limbs	3.3	3.4
Crushing injury	9.5	10.2
Burns	3.4	4.5
Others∗∗	17.6	16.6

∗  Including matter flying down, caught in or crushed in collapsing materials, struck against objects, exposure to harmful substances or environments, contact with hot or low temperature, breaking and improper action.

∗∗  Including dislocation, sprain and strain of joints and ligaments, cellulitis, traumatic amputation, injury of muscle and tendon, injury of nerves or superficial injury.

Table 2. Characteristics of injured workers who completed the questionnaire (Total=2,001)

Characteristics	N	%
Gender
Female	539	26.9
Male	1,462	73.1
Age (yr)	(Mean ± SD)	42.0 ± 12.2
17–29	386	19.3
30–44	765	38.2
45–59	743	37.1
≥60	107	5.3
Education
Elementary school or below	238	11.9
Junior high school	409	20.4
High school	853	42.6
College or above	501	25.1
Marital status
Single	585	29.2
Married	1,253	62.6
Divorced/separated	121	6.1
Widowed	42	2.1
Family history of psychiatric morbidity
Yes	16	0.8
No	1,985	99.2
% of family income contributed by the injured worker before injury (Mean ± SD)	57.9	35.3
Previous occupational injury experience before this event
Yes	318	15.9
No	1,683	84.1
Related to this injury
Loss of consciousness as a result of this injury
Yes	302	15.1
No	1,699	84.9
Self-rated severity
Minor	236	11.8
Moderate	697	34.8
Serious	417	20.8
Severe	477	23.8
Critical	174	8.6
Length of hospital stay after injury, days
Immediately after injury (mean ± SD)	8.9	8.9
Total for 3 mo (mean ± SD)	10.9	12.2
Whether this injury affected physical appearance
Yes, minor	907	45.3
Yes, major	493	24.7
No	601	30.0
Life event within one month before this injury
Yes	76	3.8
No	1,925	96.2
Life event after this injury
Yes	197	9.8
No	1,804	90.2

The internal consistency of the PTSC as measured by Cronbach's α was 0.78 for our study subjects. The correlation between the GSI of the BSRS and summary score of the PTSC was 0.80. The PTSC was highly correlated with the following psychophysiological symptom groups of the BSRS, namely, anxiety (0.79), obsessive-compulsive (0.74), phobic anxiety (0.73) and depression (0.72).

Approximately 12% of the participants scored 70 or higher on the BSRS-50, and the most important psychophysiological symptoms were psychoticism, paranoid ideation tendency, and phobic-anxiety. Approximately 13.4% fulfilled the criteria of the PTSC, and the most frequently reported symptoms were “physical discomfort (including sweating, tremor, racing heart, tachypnea, nausea, or diarrhea) caused by encountering a reminder of the injury event and becoming easily startled.” A total of 357 (17.8%) scored high on either the BSRS-50 or PTSC and were candidates for a phone interview. Among these candidates, 148 respondents (41.5%) completed the MINI interview. Among the 209 injured workers who did not complete the second-stage interview, 143 (68.4%) did not answer the phone, 44 refused to participate in the interview (21.1%) and 22 (10.5%) could not be reached because we had the wrong phone numbers. The responders and non-responders to the MINI had similar scores in the BSRS-50 and PTSC.

Among the 148 workers who completed the MINI interview at three months after their occupational injury, the prevalence rates of PTSD, PPTSD, major depression, and comorbid PTSD/PPTSD and major depression were 14.9, 23.0, 17.2 and 13.1%, respectively (Table 3). Since 17.8% of injured workers scored high in the first-stage screening, the estimated rates of PTSD, PPTSD, major depression, and comorbid PTSD/PPTSD and major depression of the 2001 injured workers were 2.7, 4.1, 3.0 and 2.3%, respectively (Table 3).

Table 3. Prevalence rates of psychiatrie disorders among Mini-international Neuropsychiatrie Interview (MINI) interviewees and estimated prevalence rates of psychiatric disorders 3 mo after occupational injuries

Psychiatric disorders	MINI interviewees (n=148)		% with high score in screening by BSRS and PTSC	Estimated rates (n=2,001)
	n	% (95% CI)		% (95% CI)
Post-traumatic stress disorder	22	14.9 (9.2, 20.6)		2.7 (2.0, 3.4)
Partial Post-traumatic stress disorder	34	23.0 (16.2, 29.8)		4.1 (3.2, 5.0)
Major depression	25	16.9 (11.1, 23.3)		3.0 (2.3, 3.9)
Both PTSD and Major depression	10	6.8 (4.6, 9.0)	17.8	1.2 (–0.5, 2.9)
Either PTSD or major depression	37	25.0 (18.1, 31.9)		4.4 (1.1, 7.7)
Both PTSD/PPTSD and Major depression	19	12.8 (7.7, 18.5)		2.3 (1.6, 3.0)
Either PTSD/PPTSD or major depression	63	42.6 (34.7, 50.7)		7.5 (6.4, 8.8)

In addition, the estimated rates of either PTSD/ PPTSD or major depression among workers suffered from intracranial injury, fracture, burn, crushing injury, and open wound of upper limbs were 10.4, 6.9, 5.9, 5.8 and 0%, respectively (Table 4). Comparison of the rates of either PTSD/PPTSD or major depression occurring after intracranial injuries to those after non-intracranial injuries showed that the former were significantly higher than those occurring after non-intracranial injuries.

Table 4. Estimated prevalence rates of psychiatric conditions 3 mo after different occupational injuries

Mental condition	Fracture (n=1,107)	Intracranial injury (n=218)	Open wound of upper limbs (n=67)	Crushing injury (n=190)	Burns (n=68)
% with high score in screening by BSRS and PTSC	17.7	26.6	13.4	20.0	11.8
	Prevalence, % (95% CI)	Prevalence, % (95% CI)	Prevalence, % (95% CI)	Prevalence, % (95% CI)	Prevalence, % (95% CI)
PTSD	2.6 (1.7, 3.5)	5.7 (2.6, 8.8)	0.0	2.9 (0.5, 5.3)	0.0a
PPTSD	3.5 (2.4, 4.6)	3.8 (1.3, 6.3)	0.0	2.9 (0.5, 5.3)	5.9 (0.3, 11.5)
Major depression	2.6 (1.7, 3.5)	5.7 (2.6, 8.8)	0.0	2.9 (0.5, 5.3)	3.0 (–1.1, 7.1)
(PTSD/PPTSD and major depression)	1.8 (1.0, 2.6)	4.8 (2.0, 7.6)	0.0	2.9 (0.5, 5.3)	3.0 (–1.1, 7.1)
Either PTSD/PPTSD or major depression	6.9 (5.4, 8.4)	10.4 (6.3, 14.5)a	0.0	5.8 (2.5, 9.1)	5.9 (0.3, 11.5)

a  Significantly different from those after non-intracranial injuries (p=0.033).

Discussion

Despite the knowledge that PTSD and major depression are common psychiatric sequels following traumatic events^{23, 24)}, this is the first study on the occurrence rates of PTSD and major depression after occupational injuries in Asian workers. This study found that the prevalence rates of PTSD, PPTSD, major depression, and comorbid PTSD/PPTSD and major depression at 3 months after injury were 2.7, 4.1, 3.0 and 2.3%, respectively. As a total, 7.5% suffered from any of these psychiatric disorders.

The occurrence rates of PTSD/PPTSD and depression 3 months after occupational trauma found in this study were lower than previously reported in Western countries. O'Donnell et al. found that the prevalences of PTSD and depression 3 months after physical injury requiring admission to a trauma service in Australia were 8.6 and 10.4%, respectively¹⁴⁾. On the other hand, Asmundson et al. reported that the rates of PTSD and PPTSD among 139 Canadian injured workers were 34.7 and 18.2%¹⁵⁾. Comparison with the current study showed that the prevalences of PTSD and other psychiatric disorders were higher than the rates found in this study. Injury severity may contribute significantly to prevalence differences. In our study subjects, the average length of hospital stay was 8.9 days (SD=8.9); yet, participants in the study of O'Donnell et al. had a longer average length of stay, 10.13 days (SD=9.64), in the Trauma Centre. Variability of injury type may also have particular relevance to the prevalence difference. Individuals with traumatic brain injury had higher risk of developing psychiatric disorders. In the study of O'Donnell et al., 56% of the participants met criteria for a mild traumatic brain injury and had loss of consciousness of 30 min or less. Compared with the previous study, 11.1% of the subjects in our study suffered intracranial injury, and 15.1% of the subjects had loss of consciousness as a result of the injury. The lower rates found in this study might be attributed to the general lower prevalence of psychiatric diagnosis in Taiwan²⁶⁾. Lifetime prevalence rates of psychiatric disorders in Taiwan were generally lower than those in the United States²⁷⁾. For example, the lifetime prevalence rate of any psychiatric disorders was 21.6% in Taiwan and 35.6% in the US. However, according to the United States National Comorbidity Survey, the lifetime prevalence rate of any psychiatric disorders in the US increased to 57.4% in 2007, which indicated that the lifetime prevalence rates of psychiatric disorders may not be comparable. Such a phenomenon is not only present in Taiwan but is also present in other Asian countries. The estimated lifetime prevalences of PTSD and PPTSD were 1.7 and 2.7%, respectively, in Korea²⁸⁾, and that of PTSD was 0.6% in Hong Kong²⁹⁾; on the other hand, the lifetime prevalence rates were 7–9% and 19–20% for PTSD and PPTSD, respectively, in Western countries^30–32). It was believed that Asian people were more concerned about psychiatric disorders and their associated stigma, and thus more reluctant to seek medical attention while psychiatric symptoms developed.

To the best of our knowledge, no investigation on PTSD after non-occupational injuries was available in Taiwan for comparison. On the other hand, major depression lifetime prevalence was estimated to be 1.14% by Compton et al. (1991) using integrated data sets from the National Institute of Mental Health Epidemiologic Catchment Area survey and the Taiwan Psychiatric Epidemiological Project according to DSM-III criteria. Our observed prevalence rate of major depression at one point (3.0%) was much higher than the lifetime prevalence in the general population. Taking the BSRS-50 as another example for comparison, our observed GSI of 52.8 ± 16.2 in the participants was significantly higher than that in the general population²¹⁾. In addition, 12.1% of our participants scored higher than 70 for the GSI of the BSRS-50, as compared with 2.5% in the general population. Thus, despite lacking direct comparisons in mental conditions, a higher risk of developing psychiatric problems was quite likely after occupational injuries.

In this study, both PTSD and PPTSD were considered psychiatric sequels observed following occupational injuries. People with either PTSD or PPTSD reported significantly more interference with work or school performance than traumatized persons without PTSD²⁴⁾. Nevertheless, among the three clusters of symptoms (intrusion, avoidance/numbing, hyperarousal) defined for PTSD, the diagnosis of PPTSD required only two, and therefore, the latter was conceivably less severe symptomatically. Vietnam veterans in the US sustaining PPTSD were reported to be less dysfunctional than those sustaining PTSD, as indicated by shorter work loss (3.3 days) compared with those with PTSD (11.4 days)³³⁾. However, a study in Korea showed that PPTSD might induce similar levels of disturbance as PTSD in terms of mean dysfunctional days in work²⁸⁾. In the current study, we found no statistical differences in the GSI of BSRS and summary score of PTSC between workers with PTSD and those with PPTSD. In addition, workers with either PTSD or PPTSD had similar percentages of returning to work at 3 months after injury, both of which were poorer than those workers without these conditions.

Comorbid conditions of PTSD/PPTSD and major depression were seen in our injured workers. This was compatible with other studies. This study found that the prevalence rate of comorbid PTSD/PPTSD and major depression was 2.3%. Among Israeli veterans sustaining PTSD, 50% had concurrent major depression, and 95% developed at least one episode of major depression in their lifetime³⁴⁾. The comorbid condition occurred early after traumatic events as well, as 44.5% of PTSD patients also had major depression at 1 month after injury and 43.2% had major depression at 4 months after injury³⁵⁾. Although major depression represented the most important comorbid mental condition of PTSD, other mental disorders could be comorbid conditions as well^{16, 36)}. After physical injuries requiring hospitalization, the prevalences of comorbid PTSD and depression at 3 months and 12 months were 5% and 6%, respectively³⁷⁾.

This study found that the estimated rates of either PTSD/PPTSD or major depression in workers with intracranial injury were higher than workers with non-intracranial injuries (fracture, open wound of upper limbs, crushing injury, and burns). Due to the limited number of participants and the number of workers developing psychiatric disorders, we did not have the statistical power to examine the occurrence rates after all types of injuries. Rather, we only examined whether workers sustaining intracranial injuries had higher rates of developing either PTSD/ PPTSD or major depression after the injuries. A higher rate of psychiatric disorders was found (p=0.033) after intracranial injuries than non-intracranial injuries. We therefore considered intracranial injury a risk factor for developing mental conditions after occupational injury. To avoid type I errors caused by multiple testing, we only tested the hypothesis concerning whether intracranial injuries resulted in a higher risk of psychiatric disorders. We found that workers sustaining intracranial injuries did have a higher risk of having psychiatric disorders 3 months after injury as compared with those sustaining non-intracranial injuries. Individuals who sustained a traumatic brain injury often experienced a combination of physical, cognitive, emotional and behavior symptoms in the days or weeks after injury^{38, 39)}. In more severe cases, intellectual impairment and executive dysfunction were observed^{40, 41)}. Therefore, intracranial injuries in our study workers affected the coping skills required to handle the psychological distress⁴²⁾. In addition, the numerous problems associated with intracranial injury might have consolidated the psychological arousals, such as depression, agitation, amnesia, impaired attention, and anxiety⁴³⁾ and thus contributed to the development of PTSD. Since this is the first study comparing the occunence rates of PTSD and major depression after various types of occupational injuries, further research is needed to determine the mechanisms behind the high occunence rates of psychiatric disorders after intracranial injury. Thus, workers with intracranial injury should be screened early and treated for emotional and cognitive symptoms as the indicators for neurobehavioral impairments in order to prevent the development of PTSD as well as other psychiatric disorders within the acute period after injury.

According to the previous studies, female gender, low education level, divorced/widowed marital status and being elderly were significant predictors for psychiatric disorders, including PTSD and major depression. It is possible that the differences in mental health outcomes by injury type may be attributed to possible (non work-related) risk factors. However, in our study, the distributions of these possible factors (gender, education level, marital status, and age) were not different among those who sustained an intracranial injury (with high mental consequences) open wound of upper limbs (with low mental consequences), and other types of injuries (intermediate consequences). Thus, we believed gender, education level, marital status, and age did not contribute to the differences in mental health outcomes by injury type.

Several limitations in this study should be noted. First, the response rate to the questionnaire was low. It is possible that those who were still hospitalized or those with more severe psychological distress also had more difficulty responding to the questionnaire survey. However, the gender proportion, mechanisms of injuries, and types of injuries were similar between those completed the questionnaire and those who did not. However, the scores of the BSRS and PTSC were not different between respondents and non-respondents. Second, workers who were not covered by the Labor Insurance Hospitalization Benefits portion of the Occupational Accident Medical Benefits were not included as candidates for participation. Those who suffered from severe occupational injuries might not be able to respond to the interview in this study. Third, because these data were obtained by phone interview and not by face-to-face evaluation by a psychiatrist, the observed morbidity was only based on epidemiological criteria. Based on the findings of this study, a significant proportion of workers suffered from psychiatric disorders at three months after occupational injuries. Fourth, not all workers meeting the criteria for the MINI interview participated in the interview. As a result, a final mental diagnosis based on the MINI criteria was lacking for MINI candidates who did not participate in the interview. Therefore, we were unable to perform logistic regression for all 2001 participants using MINI diagnosis as the outcome variable.

In conclusion, PTSD, PPTSD, major depression and comorbidity were not uncommonly observed at three months after occupational injuries. The prevalence rates varied significantly among different types of injuries, with the highest rate after intracranial injuries. Development of an early intervention program to detect and manage psychiatric disorders following occupational injuries is warranted.

Acknowledgments

This study was supported by grant IOSH98-M315 from the Institute of Occupational Safety & Health, Council of Labor Affairs, Taiwan, R. O. C.

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