- Email: [email protected]
Carbon monoxide poisoning in Northeast of Iran
Accepted Manuscript Carbon Monoxide poisoning in Northeast of Iran M. Khadem-Rezaiyan, R. Afshari, Associate Professor of Clinical Toxicology PII:
S1752-928X(16)30004-X
DOI:
10.1016/j.jflm.2016.04.002
Reference:
YJFLM 1333
To appear in:
Journal of Forensic and Legal Medicine
Received Date: 19 October 2015 Revised Date:
23 February 2016
Accepted Date: 1 April 2016
Please cite this article as: Khadem-Rezaiyan M, Afshari R, Carbon Monoxide poisoning in Northeast of Iran, Journal of Forensic and Legal Medicine (2016), doi: 10.1016/j.jflm.2016.04.002. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Carbon Monoxide poisoning in Northeast of Iran Khadem-Rezaiyan M1, Afshari R2,3
SC
RI PT
1. Resident of Community Medicine and Public Health, Student Research Committee, Department of Community Medicine and Public Health, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 2. Addiction Research Centre, Imam Reza (p) Hospital, Mashhad University of Medical Sciences, Mashhad, Iran. 3. BC Centre for Disease Control, Vancouver, Canada.
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Correspondence to: R. Afshari,
M AN U
Word count: 1629 Running head: CO poisoning in Iran Conflict of Interest: None Keywords: Epidemiologic, CO Poisoning, Khorasan Razavi province, Iran
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EP
Associate Professor of Clinical Toxicology Addiction Research Centre, Imam Reza Hospital, Ibn-e-Sina street, Mashhad, 91735-348, Iran Tel: + 98 511 7683925 [email protected]
BC Centre for Disease Control, Vancouver, Canada.
ACCEPTED MANUSCRIPT
Carbon Monoxide poisoning in Northeast of Iran Abstract Background: CO poisoning is still a public health concern especially in developing countries. We aimed to focus on CO poisoning secular trends based on registry data for the
RI PT
recent 7 years in Northeast of Iran.
Methods: Registry database of Imam Reza Hospital in Mashhad, Iran was analyzed. All
admitted cases with CO exposure during 2004 to 2011 were included. Data from two national censuses were used for calculating rates. Data analyses was performed by SPSS 11.5. P<0.05
SC
was considered statistically significant.
Results: There were 443 CO related admissions (0.9% of all poisonings which equals to a
M AN U
prevalence rate of 1.9 per 100,000) during the 7-year period. Mean age was 32.3±18.2 years and 60% of subjects were male. CO prevalence rate was not changed during this period. Case fatality rate was higher in men (5.4% vs. 4.4%). Self-employment and manual or office workers were at greatest risk. Age specific prevalence and mortality rates were highest in >60 age group. (2.9 and 3.1 per 100,000, respectively)
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Conclusion: As it seems that current health prevention studies are not effectively working, these secular trends can enlighten health policy makers to implement proper population based interventions like education or regulations for CO detectors. We believe that almost all cases
EP
of accidental CO poisoning can be prevented.
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Keywords: Epidemiology, Carbon Monoxide, Poisoning, Khorasan Razavi province
1
ACCEPTED MANUSCRIPT INTRODUCTION Poisoning is one the preventable health problems worldwide(1). One example is carbon monoxide (CO), which is one of many ubiquitous contaminants of our environment. It is responsible for a large percentage of the accidental poisonings and deaths reported throughout the world each year(2,3). It is a colorless, odorless, tasteless, and non-irritating
RI PT
gas that is a product of incomplete combustion mainly originates from motor vehicles, heaters, appliances that use carbon based fuels, household fires and even recreational
boats(4,5). However, the most common sources of CO are faulty, poorly maintained or inadequately ventilated gas appliances such as stoves and heaters (6).
SC
Exposure to CO can be extremely harmful to human health with the early effects of poisoning often going unnoticed. CO intoxication causes tissue hypoxia (7) and can result in a variety of
M AN U
acute symptoms in low doses, including headache, dizziness, weakness, nausea, confusion, disorientation, and visual disturbances (8). In extreme cases, exposure leads to unconsciousness, coma, convulsions and even death. As these symptoms are commonly nonspecific and variable, it can be difficult to detect or diagnose them therefore, intoxicated cases may be misreported and underestimated (9).
In the United States, 50,000 annually emergency department visits are due to CO poisoning
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and 38% of poisoning deaths for 10-19 year olds in the U.S. were attributable to carbon monoxide (8,10). It is important to know that even after treatment, CO intoxicated patients may have neuropsychological sequelae (11).
Iran as one of the main natural gas producers, has a widespread domestic use of natural gas.
EP
Though with such widespread use of gas appliances and their potential dangers, the epidemiology of CO poisoning are still largely unknown in Iran which could be due to lack of
AC C
epidemiological studies. In an attempt to investigate this major issue of public health, the present study was conducted in order to describe the epidemiology of unintentional CO related poisoning in Khorasan Razavi province in Northeast Iran.
METHODS This cross sectional study focused on Khorasan Razavi province of north east Iran. Khorasan Razavi occupies about 118,884 square kilometers of the country. It has an estimated population of six million, which is approximately 8% of Iran's total population. Data were analyzed across a 7-year period, from March 20, 2004 to March 21, 2011. We included all 2
ACCEPTED MANUSCRIPT cases of clinically diagnosed carbon monoxide poisoning which were admitted in the single toxicology department of province. These cases were classified based on the International Classification of Diseases, Tenth Revision (ICD-10) code T58. However, people who died on the site or prior to admission were not included in this study. Data were analyzed by annual trends, age, gender, marriage and occupational status, day and month in which the CO related
RI PT
incident occurred, as well as the outcome of patient (alive/dead). Calculation of rates per 100,000 inhabitants of Khorasan Razavi province were performed using census data for the year 2006(12).
Statistical Package for Social Sciences version 11.5 was used for data analysis. Descriptive
SC
analysis is presented with frequency (percentage) and mean (standard deviation). Chi square test and independent sample t test were used for analytical analysis. P<0.05 was considered
M AN U
statistically significant.
RESULTS Annual trends
Totally there were 49189 admissions during 2004 to 2011 out of which 443(0.9%) were due
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to CO poisoning which equals to a prevalence rate of 1.9 per 100,000. Figure 1 shows that despite total poisoning rate had nearly doubled during 2004 to 2011 (from 95 to 172 per 100,000) but CO prevalence rate has not changed significantly (from 2.2 to 2.1 per 100,000).
EP
Highest rate of admissions happened in 2010 (17%). Nearly ninety percent (319) of CO intoxicated patients were completely cured.
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Gender
Sixty percent of individuals (268) were male. Case fatality rate was 5.4% in men and 4.4% in women in admitted cases. This is equal to a mortality rate of 0.81 and 0.41 per 100,000 in male and female populations, respectively. Although prevalence rate was higher in males, but it has risen in females and passed males for the first time in 2011 during the study period. (Figure 2) Age Mean (SD, min-max) age of admitted patients was 32.3(18.2, 1-88) years. Although there was not any significant difference in mean age between two genders but it seems that CO 3
ACCEPTED MANUSCRIPT poisoning is being more happened in older men. (p=0.009 in males and p=0.39 in females) (Figure 3) Most patients were in 20-30 age group (154, 34.8%). However, the highest age specific prevalence rate (ASPR) was in >60 years followed by 20-30 age group. Females had dominance over males in admissions in ages below 20 years. This different distribution was
RI PT
statistically significant. (p=0.007) (Table 1) Most deaths were in >60 age group. While other age groups had an age specific mortality rate (ASMR) of below 1 per 100,000 but ASMR in >60 age group was 3.14 per 100,000. A comparison and relationship of ASPR and ASMR can be found in figure 4.
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Occupational and marriage status
Sixty percent (181) of individuals were married. The occupations with the highest incidence
M AN U
of CO poisoning in men were self-employed (102,59%) and manual or office workers (both 19,11%). In females, housekeepers (100,78%) and students (18,14%) had the highest ranks. Time
Most admissions happened on Tuesdays (73,16.5%). Not surprisingly, at starting of cold months of the year, December (98,22%) was the highest single month for admissions and
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followed with 54% of CO poisonings (238) in 3 months of winter. (p=0.002) (Figure 5) There
DISCUSSION
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was no relation between gender and year, season, month or day of admission.
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Over the 7 years’ period of this study, CO exposure was attributed to 443 poisonings and 18 deaths. The proportional CO poisoning rate was nearly one-tenth of a similar research in north-west of Iran which could be due to warmer climate in east of Iran which leads to less usage of heaters(13). Other studies from Uganda and USA have higher rates: mortality rates have a wide range from 31% to 1-2% (13,14,15). CO intoxication was relatively even in this period in Iran but in has increased in some countries(16). Individuals with 20-30 years old are at greater risk of poisoning than other groups. However, considering population pyramids and calculating age specific prevalence rates reveal that >60 years old individuals are at the greatest risk which is consistent with other studies(14,17,18). This could be due to limited mobility or poorer economic situations to afford for professional 4
ACCEPTED MANUSCRIPT maintenance. Besides, poorer cardiovascular capacity and pulmonary reserve can worsen the situation for them. (14) However CDC article reported that the nonfatal rate for CO exposure in children aged <4 years was the highest rate for any age group of children or adults(19). In this study men were more likely to be admitted due to CO poisoning which is inconsistent with another study from Uganda(14). However this study supports higher case fatality rate in
RI PT
men which have been reported before(14,20). Engaging of men in high –risk behaviors or high risk manual activities have been suggested for this difference. In current study, selfemployment and manual work had the highest risk for CO poisoning in men. Most female patients were housewives. It has been reported that most common exposure sites in house are
SC
kitchen and bathroom(21).
CO poisoning occurred mostly during the winter months which supports others
M AN U
studies(14,18). This could be expected as domestic gas appliances are perhaps mostly used in cold weather conditions. Besides closed windows and poor ventilation can be other contributing factors.
The seasonal pattern and specific age group being at highest risk shows the importance of prevention programs. Public educations, with appropriate medium can have enormous effect
TE D
to reduce exposure. For example, short messages about proper installation and maintenance of gas appliances prior to beginning of cold months could be of great value. Other measures including checking gas appliances, checking flues for blockage, having adequate ventilation and using CO detectors should be reminded annually to the public(14,22, 23).
EP
This study was performed on a hospital registry, so it may be an underestimation of total number of CO intoxicated patients. Besides some cases of minor CO poisoning may not be
AC C
diagnosed as the symptoms are non-specific(24). We did not have any data for the location that poisoning was happened, so these analyses are lacking. However long study period and generalizability could be two of strength points of this study.
CONCLUSION Understanding the epidemiology of CO poisoning is a highly valuable tool for resource allocation and raising awareness. These data can help health decision makers to implement appropriate community oriented interventions. We believe that almost all cases of accidental
5
ACCEPTED MANUSCRIPT CO poisoning can be prevented with appropriate public education, prevention programs and regulations on CO-emitting devices.
Conflict of interest
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None to be declared.
REFERENCES
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1- Afshari R, Khadem-Rezaiyan M, Balali-Mood M. Spider bite (latrodectism) in
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Mashhad, Iran. Hum Exp Toxicol. 2009 Nov;28(11):697-702. doi: 10.1177/0960327109350668. Epub 2009 Oct 7. 2- Raub JA, Mathieu-Nolf M, Hampson NB, Thom SR. Carbon monoxide poisoning--a public health perspective. Toxicology. 2000 Apr 7;145(1):1-14. 3- Raub JA, Mathieu-Nolf M, Hampson NB, Thom SR. Carbon monoxide poisoning--a public health perspective. Toxicology. 2000 Apr 7;145(1):1-14. 4- Kao LW, Nanagas KA. Carbon monoxide poisoning. Emerg Med Clin N Am 2004;22:985e1018. 5- LaSala G, McKeever R, Okaneku J, Jacobs D, Vearrier D. The epidemiology and characteristics of carbon monoxide poisoning among recreational boaters. Clin Toxicol (Phila). 2015 Feb;53(2):127-30. doi: 10.3109/15563650.2014.996571. Epub 2015 Jan 8. 6- Stefanidou M, Athanaselis S, Koutselinis A. Carbon monoxide: old poisonrecent problems. Leg Med 2003;5(4):253e4. 7- Cho CH, Chiu NC, Ho CS, Peng CC. Carbon monoxide poisoning in children. Pediatr Neonatol. 2008 Aug;49(4):121-5. doi: 10.1016/S1875-9572(08)60026-1. 8- Hampson NB, Weaver LK. Carbon monoxide poisoning: a new incidence for an old disease. Undersea Hyperb Med. 2007 May-Jun;34(3):163-8. 9- Nazari J, Dianat I, Stedmon A. Unintentional carbon monoxide poisoning in Northwest Iran: a 5-year study. J Forensic Leg Med. 2010 Oct;17(7):388-91. doi: 10.1016/j.jflm.2010.08.003. 10- Mendoza JA, Hampson NB. Epidemiology of severe carbon monoxide poisoning in children. Undersea Hyperb Med. 2006 Nov-Dec;33(6):439-46. 11- Weaver LK. Carbon Monoxide Poisoning N Engl J Med 2009;360:1217-25. 12- Iran Statistics Center. Available online at: www.amar.org.ir Accessed on May 2015. 13- Nazari J, Dianat I, Stedmon A. Unintentional carbon monoxide poisoning in Northwest Iran: a 5-year study. J Forensic Leg Med. 2010 Oct;17(7):388-91. doi: 10.1016/j.jflm.2010.08.003. 14- Malangu N. Acute poisoning at two hospitals in Kampalae Uganda. J Forensic Leg Med 2008;15:489e92. 15- Varon J, Marik PE, Fromm RE Jr, Gueler A. Carbon monoxide poisoning: a review for clinicians. J Emerg Med. 1999 Jan-Feb;17(1):87-93. 6
ACCEPTED MANUSCRIPT 16- Shie HG, Li CY. Population-based case-control study of risk factors for unintentional
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mortality from carbon monoxide poisoning in Taiwan. Inhal Toxicol 2007;19:905−12. 17- Cook M, Simon PA, Hoffman RE. Unintentional carbon monoxide poisoning in Colorado, 1986 through 1991. Am J Public Health 1995;85:988e90. 18- Wilson RC, Saunders PJ, Smith G. An epidemiological study of acute carbon monoxide poisoning in the West Midlands. Occup Environ Med 1998;55:723e8. 19- Unintentional non-fire-related carbon monoxide exposures--United States, 2001-2003. MMWR Morb Mortal Wkly Rep. Jan 21 2005;54(2):36-39. 20- Cobb N, Etzel RA. Unintentional carbon monoxide-related deaths in the United States, 1979e1988. J Am Med Assoc 1991;266(5):659e63. 21- Harper A, Croft-Baker J. Carbon monoxide poisoning: undetected by both patients and their doctors. Age Ageing. 2004 Mar;33(2):105-9. 22- Yoon SS, Macdonald SC, Parrish RG. Deaths from unintentional carbon monoxide poisoning and potential for prevention with carbon monoxide detectors. JAMA. 1998 Mar 4;279(9):685-7. 23- Afshari R, Majdzadeh R, Balali-Mood M. Pattern of acute poisonings in Mashhad, Iran 1993-2000. J Toxicol Clin Toxicol. 2004;42(7):965-75. 24- Thom S, Keim L. Carbon monoxide poisoning: A review. Epidemiology, pathophysiology, clinical findings, and treatment options including hyperbaric therapy. Clin Toxicol 1989;27:141–56.
7
ACCEPTED MANUSCRIPT
Acknowledgement
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SC
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We would like to thank Miss Mihandoust for her kind cooperation in gathering of these data.
ACCEPTED MANUSCRIPT
Table 1- Number of admissions and deaths in two genders alongside with age specific prevalence and mortality rates Admission Mortality ASPR (×105) ASMR (×105) Male Female Male Female
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0 0.41 0.28 0.58 0.83 0.40 3.14 5.64
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0(0) 1(50) 1(50) 0(0) 1(33) 0(0) 3(43) 6(33)
SC
0(0) 1(50) 1(50) 3(100) 2(67) 1(100) 4(57) 12(67)
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10(44)* 13(56) <10 years 0.56 34(48) 37(52) 10-20 years 1.80 94(61) 60(39) 20-30 years 2.69 55(74) 19(26) 30-40 years 1.80 33(73) 12(27) 40-50 years 1.56 12(52) 11(48) 50-60 years 1.15 30(57) 23(43) >60 years 2.97 268(60) 175(40) Total 12.53 *Data is represented as Frequency (percentage) ASPR=Age Specific Prevalence Rate ASMR= Age Specific Mortality Rate
ACCEPTED MANUSCRIPT
3.0
200.0 180.0
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160.0
120.0
1.5
100.0 80.0
1.0
per 100000
140.0
2.0
60.0 40.0
0.5
SC
per 100,000
2.5
20.0
0.0
0.0
2005
2006
2007
2008
2009
2010
2011
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2004
Co Poisoning Rate
Total Poisoning Rate
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Figure 1- Total and CO poisoning rates in Khorasan Razavi province during 2004-2011
3 2.5
EP
2 1.5 1
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Prevalence rate (per 100,000)
3.5
0.5
0
2004
2005
2006
2007
2008
2009
2010
2011
Year Male
Female
Figure 2- Prevalence rate of CO poisoning in two genders from 2004 to 2011
ACCEPTED MANUSCRIPT 50 45
35 30 25 20 2005
2006
2007
2008
2009
Years Female
2011
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Male
2010
SC
2004
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Age
40
3.5
2.5 2 1.5
EP
Per 100,000
3
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Figure 3- Mean (SD) of age in two genders from 2004 to 2011
1
AC C
0.5
0
<10
10-20
20-30
Age Specific Prevalence Rate
30-40
40-50
50-60
>60
Age Specific Mortality Rate
Figure 4- Age specific prevalence and mortality rates in different age groups (2004-2011)
ACCEPTED MANUSCRIPT
25.0
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15.0 10.0 5.0 0.0
Female
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Male
SC
Percentage
20.0
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EP
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Figure 5-Percentage of admissions in due to CO poisoning in different months of 2004-2011
ACCEPTED MANUSCRIPT Research Highlights
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CO poisoning rate has been constant in recent years Mean age of CO intoxicated men is rising The highest risk is in >60 years’ age group Proper educational community based interventions could be helpful
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• • • •
S1752-928X(16)30004-X
DOI:
10.1016/j.jflm.2016.04.002
Reference:
YJFLM 1333
To appear in:
Journal of Forensic and Legal Medicine
Received Date: 19 October 2015 Revised Date:
23 February 2016
Accepted Date: 1 April 2016
Please cite this article as: Khadem-Rezaiyan M, Afshari R, Carbon Monoxide poisoning in Northeast of Iran, Journal of Forensic and Legal Medicine (2016), doi: 10.1016/j.jflm.2016.04.002. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
Carbon Monoxide poisoning in Northeast of Iran Khadem-Rezaiyan M1, Afshari R2,3
SC
RI PT
1. Resident of Community Medicine and Public Health, Student Research Committee, Department of Community Medicine and Public Health, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran 2. Addiction Research Centre, Imam Reza (p) Hospital, Mashhad University of Medical Sciences, Mashhad, Iran. 3. BC Centre for Disease Control, Vancouver, Canada.
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Correspondence to: R. Afshari,
M AN U
Word count: 1629 Running head: CO poisoning in Iran Conflict of Interest: None Keywords: Epidemiologic, CO Poisoning, Khorasan Razavi province, Iran
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EP
Associate Professor of Clinical Toxicology Addiction Research Centre, Imam Reza Hospital, Ibn-e-Sina street, Mashhad, 91735-348, Iran Tel: + 98 511 7683925 [email protected]
BC Centre for Disease Control, Vancouver, Canada.
ACCEPTED MANUSCRIPT
Carbon Monoxide poisoning in Northeast of Iran Abstract Background: CO poisoning is still a public health concern especially in developing countries. We aimed to focus on CO poisoning secular trends based on registry data for the
RI PT
recent 7 years in Northeast of Iran.
Methods: Registry database of Imam Reza Hospital in Mashhad, Iran was analyzed. All
admitted cases with CO exposure during 2004 to 2011 were included. Data from two national censuses were used for calculating rates. Data analyses was performed by SPSS 11.5. P<0.05
SC
was considered statistically significant.
Results: There were 443 CO related admissions (0.9% of all poisonings which equals to a
M AN U
prevalence rate of 1.9 per 100,000) during the 7-year period. Mean age was 32.3±18.2 years and 60% of subjects were male. CO prevalence rate was not changed during this period. Case fatality rate was higher in men (5.4% vs. 4.4%). Self-employment and manual or office workers were at greatest risk. Age specific prevalence and mortality rates were highest in >60 age group. (2.9 and 3.1 per 100,000, respectively)
TE D
Conclusion: As it seems that current health prevention studies are not effectively working, these secular trends can enlighten health policy makers to implement proper population based interventions like education or regulations for CO detectors. We believe that almost all cases
EP
of accidental CO poisoning can be prevented.
AC C
Keywords: Epidemiology, Carbon Monoxide, Poisoning, Khorasan Razavi province
1
ACCEPTED MANUSCRIPT INTRODUCTION Poisoning is one the preventable health problems worldwide(1). One example is carbon monoxide (CO), which is one of many ubiquitous contaminants of our environment. It is responsible for a large percentage of the accidental poisonings and deaths reported throughout the world each year(2,3). It is a colorless, odorless, tasteless, and non-irritating
RI PT
gas that is a product of incomplete combustion mainly originates from motor vehicles, heaters, appliances that use carbon based fuels, household fires and even recreational
boats(4,5). However, the most common sources of CO are faulty, poorly maintained or inadequately ventilated gas appliances such as stoves and heaters (6).
SC
Exposure to CO can be extremely harmful to human health with the early effects of poisoning often going unnoticed. CO intoxication causes tissue hypoxia (7) and can result in a variety of
M AN U
acute symptoms in low doses, including headache, dizziness, weakness, nausea, confusion, disorientation, and visual disturbances (8). In extreme cases, exposure leads to unconsciousness, coma, convulsions and even death. As these symptoms are commonly nonspecific and variable, it can be difficult to detect or diagnose them therefore, intoxicated cases may be misreported and underestimated (9).
In the United States, 50,000 annually emergency department visits are due to CO poisoning
TE D
and 38% of poisoning deaths for 10-19 year olds in the U.S. were attributable to carbon monoxide (8,10). It is important to know that even after treatment, CO intoxicated patients may have neuropsychological sequelae (11).
Iran as one of the main natural gas producers, has a widespread domestic use of natural gas.
EP
Though with such widespread use of gas appliances and their potential dangers, the epidemiology of CO poisoning are still largely unknown in Iran which could be due to lack of
AC C
epidemiological studies. In an attempt to investigate this major issue of public health, the present study was conducted in order to describe the epidemiology of unintentional CO related poisoning in Khorasan Razavi province in Northeast Iran.
METHODS This cross sectional study focused on Khorasan Razavi province of north east Iran. Khorasan Razavi occupies about 118,884 square kilometers of the country. It has an estimated population of six million, which is approximately 8% of Iran's total population. Data were analyzed across a 7-year period, from March 20, 2004 to March 21, 2011. We included all 2
ACCEPTED MANUSCRIPT cases of clinically diagnosed carbon monoxide poisoning which were admitted in the single toxicology department of province. These cases were classified based on the International Classification of Diseases, Tenth Revision (ICD-10) code T58. However, people who died on the site or prior to admission were not included in this study. Data were analyzed by annual trends, age, gender, marriage and occupational status, day and month in which the CO related
RI PT
incident occurred, as well as the outcome of patient (alive/dead). Calculation of rates per 100,000 inhabitants of Khorasan Razavi province were performed using census data for the year 2006(12).
Statistical Package for Social Sciences version 11.5 was used for data analysis. Descriptive
SC
analysis is presented with frequency (percentage) and mean (standard deviation). Chi square test and independent sample t test were used for analytical analysis. P<0.05 was considered
M AN U
statistically significant.
RESULTS Annual trends
Totally there were 49189 admissions during 2004 to 2011 out of which 443(0.9%) were due
TE D
to CO poisoning which equals to a prevalence rate of 1.9 per 100,000. Figure 1 shows that despite total poisoning rate had nearly doubled during 2004 to 2011 (from 95 to 172 per 100,000) but CO prevalence rate has not changed significantly (from 2.2 to 2.1 per 100,000).
EP
Highest rate of admissions happened in 2010 (17%). Nearly ninety percent (319) of CO intoxicated patients were completely cured.
AC C
Gender
Sixty percent of individuals (268) were male. Case fatality rate was 5.4% in men and 4.4% in women in admitted cases. This is equal to a mortality rate of 0.81 and 0.41 per 100,000 in male and female populations, respectively. Although prevalence rate was higher in males, but it has risen in females and passed males for the first time in 2011 during the study period. (Figure 2) Age Mean (SD, min-max) age of admitted patients was 32.3(18.2, 1-88) years. Although there was not any significant difference in mean age between two genders but it seems that CO 3
ACCEPTED MANUSCRIPT poisoning is being more happened in older men. (p=0.009 in males and p=0.39 in females) (Figure 3) Most patients were in 20-30 age group (154, 34.8%). However, the highest age specific prevalence rate (ASPR) was in >60 years followed by 20-30 age group. Females had dominance over males in admissions in ages below 20 years. This different distribution was
RI PT
statistically significant. (p=0.007) (Table 1) Most deaths were in >60 age group. While other age groups had an age specific mortality rate (ASMR) of below 1 per 100,000 but ASMR in >60 age group was 3.14 per 100,000. A comparison and relationship of ASPR and ASMR can be found in figure 4.
SC
Occupational and marriage status
Sixty percent (181) of individuals were married. The occupations with the highest incidence
M AN U
of CO poisoning in men were self-employed (102,59%) and manual or office workers (both 19,11%). In females, housekeepers (100,78%) and students (18,14%) had the highest ranks. Time
Most admissions happened on Tuesdays (73,16.5%). Not surprisingly, at starting of cold months of the year, December (98,22%) was the highest single month for admissions and
TE D
followed with 54% of CO poisonings (238) in 3 months of winter. (p=0.002) (Figure 5) There
DISCUSSION
EP
was no relation between gender and year, season, month or day of admission.
AC C
Over the 7 years’ period of this study, CO exposure was attributed to 443 poisonings and 18 deaths. The proportional CO poisoning rate was nearly one-tenth of a similar research in north-west of Iran which could be due to warmer climate in east of Iran which leads to less usage of heaters(13). Other studies from Uganda and USA have higher rates: mortality rates have a wide range from 31% to 1-2% (13,14,15). CO intoxication was relatively even in this period in Iran but in has increased in some countries(16). Individuals with 20-30 years old are at greater risk of poisoning than other groups. However, considering population pyramids and calculating age specific prevalence rates reveal that >60 years old individuals are at the greatest risk which is consistent with other studies(14,17,18). This could be due to limited mobility or poorer economic situations to afford for professional 4
ACCEPTED MANUSCRIPT maintenance. Besides, poorer cardiovascular capacity and pulmonary reserve can worsen the situation for them. (14) However CDC article reported that the nonfatal rate for CO exposure in children aged <4 years was the highest rate for any age group of children or adults(19). In this study men were more likely to be admitted due to CO poisoning which is inconsistent with another study from Uganda(14). However this study supports higher case fatality rate in
RI PT
men which have been reported before(14,20). Engaging of men in high –risk behaviors or high risk manual activities have been suggested for this difference. In current study, selfemployment and manual work had the highest risk for CO poisoning in men. Most female patients were housewives. It has been reported that most common exposure sites in house are
SC
kitchen and bathroom(21).
CO poisoning occurred mostly during the winter months which supports others
M AN U
studies(14,18). This could be expected as domestic gas appliances are perhaps mostly used in cold weather conditions. Besides closed windows and poor ventilation can be other contributing factors.
The seasonal pattern and specific age group being at highest risk shows the importance of prevention programs. Public educations, with appropriate medium can have enormous effect
TE D
to reduce exposure. For example, short messages about proper installation and maintenance of gas appliances prior to beginning of cold months could be of great value. Other measures including checking gas appliances, checking flues for blockage, having adequate ventilation and using CO detectors should be reminded annually to the public(14,22, 23).
EP
This study was performed on a hospital registry, so it may be an underestimation of total number of CO intoxicated patients. Besides some cases of minor CO poisoning may not be
AC C
diagnosed as the symptoms are non-specific(24). We did not have any data for the location that poisoning was happened, so these analyses are lacking. However long study period and generalizability could be two of strength points of this study.
CONCLUSION Understanding the epidemiology of CO poisoning is a highly valuable tool for resource allocation and raising awareness. These data can help health decision makers to implement appropriate community oriented interventions. We believe that almost all cases of accidental
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ACCEPTED MANUSCRIPT CO poisoning can be prevented with appropriate public education, prevention programs and regulations on CO-emitting devices.
Conflict of interest
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None to be declared.
REFERENCES
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1- Afshari R, Khadem-Rezaiyan M, Balali-Mood M. Spider bite (latrodectism) in
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Mashhad, Iran. Hum Exp Toxicol. 2009 Nov;28(11):697-702. doi: 10.1177/0960327109350668. Epub 2009 Oct 7. 2- Raub JA, Mathieu-Nolf M, Hampson NB, Thom SR. Carbon monoxide poisoning--a public health perspective. Toxicology. 2000 Apr 7;145(1):1-14. 3- Raub JA, Mathieu-Nolf M, Hampson NB, Thom SR. Carbon monoxide poisoning--a public health perspective. Toxicology. 2000 Apr 7;145(1):1-14. 4- Kao LW, Nanagas KA. Carbon monoxide poisoning. Emerg Med Clin N Am 2004;22:985e1018. 5- LaSala G, McKeever R, Okaneku J, Jacobs D, Vearrier D. The epidemiology and characteristics of carbon monoxide poisoning among recreational boaters. Clin Toxicol (Phila). 2015 Feb;53(2):127-30. doi: 10.3109/15563650.2014.996571. Epub 2015 Jan 8. 6- Stefanidou M, Athanaselis S, Koutselinis A. Carbon monoxide: old poisonrecent problems. Leg Med 2003;5(4):253e4. 7- Cho CH, Chiu NC, Ho CS, Peng CC. Carbon monoxide poisoning in children. Pediatr Neonatol. 2008 Aug;49(4):121-5. doi: 10.1016/S1875-9572(08)60026-1. 8- Hampson NB, Weaver LK. Carbon monoxide poisoning: a new incidence for an old disease. Undersea Hyperb Med. 2007 May-Jun;34(3):163-8. 9- Nazari J, Dianat I, Stedmon A. Unintentional carbon monoxide poisoning in Northwest Iran: a 5-year study. J Forensic Leg Med. 2010 Oct;17(7):388-91. doi: 10.1016/j.jflm.2010.08.003. 10- Mendoza JA, Hampson NB. Epidemiology of severe carbon monoxide poisoning in children. Undersea Hyperb Med. 2006 Nov-Dec;33(6):439-46. 11- Weaver LK. Carbon Monoxide Poisoning N Engl J Med 2009;360:1217-25. 12- Iran Statistics Center. Available online at: www.amar.org.ir Accessed on May 2015. 13- Nazari J, Dianat I, Stedmon A. Unintentional carbon monoxide poisoning in Northwest Iran: a 5-year study. J Forensic Leg Med. 2010 Oct;17(7):388-91. doi: 10.1016/j.jflm.2010.08.003. 14- Malangu N. Acute poisoning at two hospitals in Kampalae Uganda. J Forensic Leg Med 2008;15:489e92. 15- Varon J, Marik PE, Fromm RE Jr, Gueler A. Carbon monoxide poisoning: a review for clinicians. J Emerg Med. 1999 Jan-Feb;17(1):87-93. 6
ACCEPTED MANUSCRIPT 16- Shie HG, Li CY. Population-based case-control study of risk factors for unintentional
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mortality from carbon monoxide poisoning in Taiwan. Inhal Toxicol 2007;19:905−12. 17- Cook M, Simon PA, Hoffman RE. Unintentional carbon monoxide poisoning in Colorado, 1986 through 1991. Am J Public Health 1995;85:988e90. 18- Wilson RC, Saunders PJ, Smith G. An epidemiological study of acute carbon monoxide poisoning in the West Midlands. Occup Environ Med 1998;55:723e8. 19- Unintentional non-fire-related carbon monoxide exposures--United States, 2001-2003. MMWR Morb Mortal Wkly Rep. Jan 21 2005;54(2):36-39. 20- Cobb N, Etzel RA. Unintentional carbon monoxide-related deaths in the United States, 1979e1988. J Am Med Assoc 1991;266(5):659e63. 21- Harper A, Croft-Baker J. Carbon monoxide poisoning: undetected by both patients and their doctors. Age Ageing. 2004 Mar;33(2):105-9. 22- Yoon SS, Macdonald SC, Parrish RG. Deaths from unintentional carbon monoxide poisoning and potential for prevention with carbon monoxide detectors. JAMA. 1998 Mar 4;279(9):685-7. 23- Afshari R, Majdzadeh R, Balali-Mood M. Pattern of acute poisonings in Mashhad, Iran 1993-2000. J Toxicol Clin Toxicol. 2004;42(7):965-75. 24- Thom S, Keim L. Carbon monoxide poisoning: A review. Epidemiology, pathophysiology, clinical findings, and treatment options including hyperbaric therapy. Clin Toxicol 1989;27:141–56.
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Acknowledgement
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We would like to thank Miss Mihandoust for her kind cooperation in gathering of these data.
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Table 1- Number of admissions and deaths in two genders alongside with age specific prevalence and mortality rates Admission Mortality ASPR (×105) ASMR (×105) Male Female Male Female
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0 0.41 0.28 0.58 0.83 0.40 3.14 5.64
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0(0) 1(50) 1(50) 0(0) 1(33) 0(0) 3(43) 6(33)
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0(0) 1(50) 1(50) 3(100) 2(67) 1(100) 4(57) 12(67)
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10(44)* 13(56) <10 years 0.56 34(48) 37(52) 10-20 years 1.80 94(61) 60(39) 20-30 years 2.69 55(74) 19(26) 30-40 years 1.80 33(73) 12(27) 40-50 years 1.56 12(52) 11(48) 50-60 years 1.15 30(57) 23(43) >60 years 2.97 268(60) 175(40) Total 12.53 *Data is represented as Frequency (percentage) ASPR=Age Specific Prevalence Rate ASMR= Age Specific Mortality Rate
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3.0
200.0 180.0
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160.0
120.0
1.5
100.0 80.0
1.0
per 100000
140.0
2.0
60.0 40.0
0.5
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per 100,000
2.5
20.0
0.0
0.0
2005
2006
2007
2008
2009
2010
2011
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2004
Co Poisoning Rate
Total Poisoning Rate
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Figure 1- Total and CO poisoning rates in Khorasan Razavi province during 2004-2011
3 2.5
EP
2 1.5 1
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Prevalence rate (per 100,000)
3.5
0.5
0
2004
2005
2006
2007
2008
2009
2010
2011
Year Male
Female
Figure 2- Prevalence rate of CO poisoning in two genders from 2004 to 2011
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35 30 25 20 2005
2006
2007
2008
2009
Years Female
2011
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Male
2010
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2004
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Age
40
3.5
2.5 2 1.5
EP
Per 100,000
3
TE D
Figure 3- Mean (SD) of age in two genders from 2004 to 2011
1
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0.5
0
<10
10-20
20-30
Age Specific Prevalence Rate
30-40
40-50
50-60
>60
Age Specific Mortality Rate
Figure 4- Age specific prevalence and mortality rates in different age groups (2004-2011)
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25.0
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15.0 10.0 5.0 0.0
Female
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Percentage
20.0
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Figure 5-Percentage of admissions in due to CO poisoning in different months of 2004-2011
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CO poisoning rate has been constant in recent years Mean age of CO intoxicated men is rising The highest risk is in >60 years’ age group Proper educational community based interventions could be helpful
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