|Year : 2013 | Volume
| Issue : 6 | Page : 1233-1241
|Nocturnal enuresis among primary school children
Hasan Mohamed Aljefri1, Omer Abdullah Basurreh1, Faisel Yunus2, Amen Ahmed Bawazir3
1 College of Medicine, Hadhramout University for Science and Technology, Hadhramout, Yemen
2 College of Public Health and Health Informatics, King Saud Bin Abdul Aziz University for Health Sciences, Riyadh, Saudi Arabia
3 College of Public Health and Health Informatics, King Saud Bin Abdul Aziz University for Health Sciences, Riyadh, Saudi Arabia; College of Medicine, Aden University, Aden, Yemen
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|Date of Web Publication||13-Nov-2013|
| Abstract|| |
To determine the prevalence and personal and family risk factors for nocturnal enuresis (NE) among primary school children in Al-Mukalla City, Yemen, we conducted a cross-sectional survey using a self-administered, three-part structured questionnaire involving 832 school children aged 6 - 15 years between 2007 and 2008. We assessed participants' socio-demographic factors, family characteristics and factors related to the presence of NE. The mean age of the children was 11.5 (±2.7) years. The overall prevalence of NE was 28.6%, with a predominance of girls, and the prevalence decreased with increasing age (P <0.001). Factors likely to be associated with NE were pattern of sleeping (P <0.001), stressful social and psychological events (P <0.01), positive family history of enuresis (P <0.001), large family size (P >0.002) and a higher number of siblings (P = 0.01). Our findings reveal a high prevalence of NE among children in Al-Mukalla City, Yemen, with a higher prevalence in girls than in boys compared with the other studies. Sleep pattern, stressful life events, family history of NE, large family size and more children in the household may act as a risk factor for NE.
|How to cite this article:|
Aljefri HM, Basurreh OA, Yunus F, Bawazir AA. Nocturnal enuresis among primary school children. Saudi J Kidney Dis Transpl 2013;24:1233-41
|How to cite this URL:|
Aljefri HM, Basurreh OA, Yunus F, Bawazir AA. Nocturnal enuresis among primary school children. Saudi J Kidney Dis Transpl [serial online] 2013 [cited 2020 Jan 24];24:1233-41. Available from: http://www.sjkdt.org/text.asp?2013/24/6/1233/121312
| Introduction|| |
Nocturnal enuresis (NE) is a health problem frequently encountered in childhood, and is defined as an involuntary voiding of urine during sleep with a frequency of at least twice a week in children aged >5 years in the absence of congenital or acquired defects of the central nervous system.  Approximately 10% of all 7-year-old children were reported with NE. However, the annual spontaneous resolution rate ranged from 15 to 16%. , Some recent studies have estimated the prevalence of NE to be around 20% in children of age 5 years and above, with a male predominance and positive family history of enuresis. ,, Population-based studies on the prevalence, determinants and consequences of this disorder are of great concern.  Anecdotal accounts of NE tend to reflect a host of complex issues marked by incomprehension, feelings of humiliation, guilt and shame, avoidance of social activities, a sense of difference from others, victimization and loss of self-esteem.  The resulting distress of the NE to children and their parents shows the public health importance of this problem, and this merits further investigation. Healthcare professionals need to be able to demonstrate knowledge of the causes, assessment and management of NE to provide patients and their families with individualized care.
Data on NE in schoolchildren in Yemen are scarce. However, the only study on NE conducted in Aden (Yemen) reported a prevalence of 17.2% among school children in public schools. 
The aim of this study was to determine the prevalence of NE and its relationship with personal and family characteristics.
| Methods and Patients|| |
A cross-sectional survey was performed in Al Mukalla City (Yemen) during 2007 and 2008. Al Mukalla City is one of the big cities in Yemen with around 144,000 inhabitants.  The research sample was determined using the sample-size formula [n = (z².p.q)/d²] for the main cluster cut-off,  assuming 30% of non-response. The sample size was calculated as 890 school children with 20% expected frequency and 95% confidence interval (Epi Info 6.0).
The sample selection was performed in two stages. Al-Mukalla City is administratively composed of four homogenous districts. In the first stage of the sample selection, two primary schools (one male and one female) were chosen from each district by simple random sampling. In the second stage of the sample selection, the sample size for each school was allocated proportionally according to the total number of students in the primary schools in each district. Then, the required number of school children in each school was obtained by systematic random sampling. All children in our desired age range of 6 - 15 years, i.e. studying in school years 1 - 9 were considered eligible for this study.
This study was approved by the review board at the Faculty of Medicine in Hadhramout University and the Ministry of Education in Hadhramout Governorate.
Data were gathered on paper-based, self-administered questionnaires and were subsequently collated in an electronic format. The questionnaire developed by Robson et al (2005) was used for the study, which was translated in the local language and had already been validated.  The questionnaire consisted of three parts. The first part contained information on socio-demographic factors such as age, school year and gender. The second part included questions related to enuresis, such as sleep pattern, social stressful events, burning micturition, learning performance at school and tea/coffee drinking habit. Finally, the third part included information to assess the family-related factors.
The questionnaire was given to each child who was selected for this study based on the above-mentioned sampling features by the research team and facilitated by the class teacher. The informed consent form and the participant information sheet outlining the study objectives and a note on the voluntary nature of the participation were sent to the child's guardian/parent. The students were also asked to help their parents in filling the questionnaires. The filled questionnaires were submitted to the research team. All those who did not return the questionnaires after 3 weeks of distribution were recorded as "not responders."
Children were divided into three groups based on their ages as follows: Group 1 = 6-8 years old; group 2 = 9-11 years old; group 3 = 12 years or more. The division into the three groups was done to assess the impact of increasing age on the prevalence of NE.
| Statistical Analysis|| |
Statistical analyses were performed using SPSS 19.0 software (IBM Corporation, Armonk, New York, USA). The χ2 test was used to evaluate the relationship between the presence of NE and the socio-demographic and personal and family characteristics. All proposed risk factors (e.g., education level of parents, family history, sleep pattern, tea/coffee consumption, etc.) were compared between the children with and without a history of NE. Univariate analyses were used to calculate the odds ratio (OR). The various factors were then subjected to backward multivariate logistic regression analysis and the adjusted ORs were calculated. All statistical assessments were 2-tailed and the level of significance was set at P = 0.05.
| Results|| |
Of the 890 questionnaires distributed, 872 were returned to the study team. However, 40 questionnaires had extensive missing information and, as a result, were excluded from the study. Therefore, a total of 832 (93.4%) questionnaires were included in the analyses.
The mean age of the children was 11.5 ± 2.7 years, with a range of 6 - 15 years. Fifty-three percent of our sample was girls. History of enuresis was reported from 238 children, giving a prevalence of 28.6%. [Table 1] shows the breakdown of socio-demographic and other personal risk factors in children by their history of enuresis. The younger children (6 -8 years) more frequently reported the problem of enuresis (45.4%) compared with the other age groups (P <0.001). The prevalence of enuresis was higher in girls than in boys (35.1% vs. 21.2%, respectively, P <0.001). School children with a history of NE were hard to awaken, faced stressful social or psychological events, had difficulties in learning, likely to drink at least one cup of tea or coffee and complained of other diseases not related to NE (39.1% vs. 23.5%, 36.7% vs. 23.3%, 53.2% vs. 27.2%, 39.5% vs. 25.8% and 38.0% vs. 27.2%, respectively). All these factors, with the exception of burning micturition, were highly statistically significantly different between the children with and those without a history of NE (P <0.01).
|Table 1: Socio-demographic and personal risk factors of children by history of enuresis.|
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A backward multivariate logistic regression model was built to test for the association between history of NE and various socio-demographic and personal factors. As shown in [Table 2], only three factors were found to be strongly associated with the occurrence of NE among the school children in this study. Difficulties in children's learning performance had a border-line effect with an adjusted odds ratio (AOR) of 1.7 and P = 0.07. We did not find any statistically significant association of the rest of the factors such as the sex, habit of drinking tea or coffee, complaining of other diseases and complaints of burning micturition with NE in the study group.
|Table 2: Socio-demographic and personal factors associated with nocturnal enuresis.|
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[Table 3] shows the factors related to family characteristics of the school children. These include factors related to family history of NE, number of family members, number of siblings, birth order of the child in this study and the education status of the parents. Family history of NE was strongly associated with NE in the children (OR: 5.18, P <0.001). The rate of NE was found to steadily increase with an increase in the size of the family from 19.3% to 29.7% to 38.2% in families with one to two members, three to four members and five or more members, respectively. This finding was also highly statistically significant. However, no statistically significant difference was observed in the rates of NE according to the number of siblings, the birth order of the child in this study and the parental education status. A backward multivariate regression model was built to test for the association between NE and the family characteristics. As highlighted in [Table 4], the past family history of NE, large family size and higher number of siblings (≥5) were associated with the risk of NE.
| Discussion|| |
NE is recognized as a widespread health problem in young children and adolescents, but controversy exists regarding its prevalence among countries and communities. We found the prevalence of NE to be 28% in young school children and adolescents, with a higher prevalence in girls. Our figure is higher than that reported in other countries such as Iran (6.8%),  India (8.6%),  Slovenia (12.4%),  Saudi Arabia (15%),  Australia (18.9%)  and, recently, in Aden (Yemen) (17.2%).  A study from Turkey, however, had quite a similar prevalence of 25.5% to the one found in our study. 
We also found that the prevalence of NE decreases with increasing age, which is consistent with the findings from other studies elsewhere. ,, However, a study from China found no such age trend in children between 6 and 16 years of age.  These reported variations in prevalence are likely due to medical, psychological, socioeconomic, cultural and racial factors. Moreover, differences in the age of the surveyed cohort and data collection instrument (self-administered questionnaire vs. direct interview) are likely to be responsible for the differences in the reported prevalence of NE in each study.
Although NE is prevalent in children and adolescents, many people have a difficulty in understanding the condition and accessing appropriate and timely advice and support. Traditionally, people associate NE in children to immaturity of voiding control, and mostly believe that enuretic children will ultimately acquire normal control with age. A lack of knowledge regarding the nature of enuresis and its negative effects on the children, such as long-term psychosocial hazards, can cause parents to delay seeking medical advice. However, some studies showed that enuretic problems may even persist in 1.5-3% of the adult population.  Therefore, this problem requires medical attention and management.
We found a higher prevalence in girls (35.1%) compared with that in boys (21.2%) (P <0.001). These findings are not in accordance with other studies, e.g., in Turkey,  India  and Iran,  but are more consistent with the findings from a study conducted in Aden (Yemen).  However, no clear explanation is available for this trend in our population.
Our study also found a significant relationship between children who are hard to awaken and prevalence of NE - enuretic children were around two-times more likely to face difficulty in waking up than non-enuretic children. Similar sleep patterns of enuretic children were reported in other studies elsewhere. , Recent findings suggest that poor sleep quality may play a role in the continuation of NE. A vicious cycle of sleep fragmentation is suggested as a reason for an increased arousal threshold, which, in turn, leads to failure to respond to full-bladder signals and continuation of NE. ,,
Stressful events of psychological and social origin form a risk factor of NE in school children in our study. NE was around two-times more prevalent if the child was facing some psychological or social disturbances (OR = 1.91, P <0.001). These findings were consistent with a study performed in Iran and Aden. , Enuretic children are frequently aware of the social and emotional consequences and, in particular, commonly fear being discovered by others. Systematic studies support the notion that enuresis is associated with emotional distress in both children and parents, which is reversible once the children become dry. Joinson et al found a higher rate of parent-reported externalizing and internalizing problems in enuretic children.  This negative feeling probably could have an either positive or negative influence in the school performance of children. Our study showed that school children with NE were three-times more likely at risk of facing difficulties in their school performance. Fergusson et al and Theunis et al have reported that older enuretic children face more psychological consequences of the wetting problem and, as a result, their perceived competence decreases as their age increases. This is opposed to that seen in children without NE, in whom the perceived competence increases with age. , Another study has shown that girls appear more vulnerable to emotional distress, with an increased risk of being more aware of their failing body.  These feelings of failure may have implications on their school performance, where success is very important. However, both the above-mentioned findings were not examined in our study.
Our study also found that the risk of being an enuretic child is five-times higher if a family member had a history of NE (OR = 5.18, P <0.001). This result was consistent with other studies that found high rates of NE in children with a positive family history. ,,,, Family factors such as the number of household members or the number of siblings in the family are also likely to be associated with NE. We found that large family size and/or more than five siblings were the most likely factors associated with the occurrence of NE. Several studies have also reported that enuresis was associated with factors related to family size and child rank in the family. , Mansur et al specified that the child number three in the family was the one to show NE,  while other studies noted that the second ranked child was the one who is likely to develop enuresis.  However, we did not find any such association with birth order in our study.
Although enuresis as a prevalent clinical problem in childhood and adolescence is an old issue, it has not been covered in depth in many countries. Many factors possibly play a role in the development of NE in this age group, such as familial predisposition, which could be a more significant risk factor for enuresis compared with socio-demographic or other personal and family characteristics.  In addition, factors such as hypercalcemia, decreased level of vitamin B 12 , migraine, habitual snoring and changes in brain microstructure have been highlighted as the possible causes for NE. ,,,,, Recently, many studies have suggested different models of educational programs targeting the children and their families with the aim of helping them to quickly alleviate the consequences of this condition. , These programs also need to include the nurses and nurse practitioners working in a primary health care setting to manage children experiencing NE. ,,,
One of the limitations of our study is its cross-sectional design that cannot study the temporal trends in NE with child's increasing age. Therefore, further longitudinal studies are required to evaluate the causal associations between risk factors and NE. Other limitations are the lack of clinical confirmation of the condition, recall bias as the parents filled the questionnaire based on their recollection of the NE-related events and lack of confirmation of children's school performance directly from the school authorities as opposed to relying on self-reported performance for this study. These factors can result in variations in the estimation of the prevalence and the role of various factors. Despite the above-mentioned limitations, the major strength of our study was its very high response rate of 93.4% compared with many other studies conducted elsewhere, where the response rates varied from 35 to 86.3%. ,,
Our findings provide new information on the prevalence of NE among school children in Al-Mukalla City, Yemen, with rates that are different to the ones reported in other studies. The results suggest that the sleeping patters of the children, existence of social or psychological stressful events, family history of NE, large family size and more children in a household may be the risk factors associated with NE. Enuresis management programs employing trained health providers should be implemented with the aim of parental education, advocacy and awareness, accompanied with medical help of enuretic children. The views of the parents on the child wetting problem should be investigated along with the potential causal relationships.
| Acknowledgment|| |
The authors would like to thank Mr. Abdulla Amen for his support in the language revision of this manuscript.
| Conflict of Interests|| |
We declare that we have no conflicts of interest. We certify that neither this manuscript nor one with substantially similar content has been published or is being considered for publication elsewhere, and all the data collected during the study are presented in this manuscript and no data from the study have been or will be published separately.
| References|| |
|1.||Butler RJ, Golding J, Northstone K. Nocturnal enuresis at 7.5 years old: Prevalence and analysis of clinical signs. BJU Int 2005;96: 404-10. |
|2.||Kawauchi A, Naitoh Y, Yoneda K, et al. Refractory enuresis related to alarm therapy. J Pediatr Urol 2006;2:579-82. |
|3.||Hazza I, Tarawneh H. Primary nocturnal enuresis among school children in Jordan. Saudi J Kidney Dis Transpl 2002;13:478-80. |
|4.||Ozkan KU, Garipardic M, Toktamis A, Karabiber H, Sahinkanat T. Enuresis prevalence and accompanying factors in schoolchildren: A questionnaire study from southeast Anatolia. Urol Int 2004;73:149-55. |
|5.||Bayoumi RA, Eapen V, Al-Yahyaee S, Al Barwani HS, Hill RS, Al Gazali L. The genetic basis of inherited primary nocturnal enuresis: A UAE study. J Psychosom Res 2006;61:317-20. |
|6.||Kaneko K. Treatment for nocturnal enuresis: The current state in Japan. Pediatr Int 2012;54:8-13. |
|7.||Safarinejad MR. Prevalence of nocturnal enuresis, risk factors, associated familial factors and urinary pathology among school children in Iran. J Pediatr Urol 2007;3:443-52. |
|8.||Butler R, Heron J. An exploration of children's views of bed-wetting at 9 years. Child Care Health Dev 2008;34:65-70. |
|9.||Yousef KA, Basaleem HO, bin Yahiya MT. Epidemiology of nocturnal enuresis in basic schoolchildren in Aden Governorate, Yemen. Saudi J Kidney Dis Transpl 2011;22:167-73. |
|10.||MOPIC/CS. Population of Yemen: National Census 2004 and its expectations. Sana'a: Ministry of planning and International Cooperation/Central Statistics; 2004. |
|11.||Lwanga SK, Lemeshow S. Sample Size Determination in Health Studies: A Practical Manual. Statistical Methodology. Geneva, Switzerland: World Health Organization 1991. |
|12.||Robson WL, Leung AK, Van Howe R. Primary and secondary nocturnal enuresis: Similarities in presentation. Pediatrics 2005;115: 956-9. |
|13.||eung CK, Sihoe JD, Sit FK, Bower W, Sreedhar B, Lau J. Characteristics of primary nocturnal enuresis in adults: An epidemiological study. BJU Int 2004;93:341-5. |
|14.||Mithani S, Zaidi Z. Bed wetting in school children of Karachi. J Pak Med Assoc 2005;55: 2-5. |
|15.||Karnicnik K, Koren A, Kos N, Marcun Varda N. Prevalence and quality of life of slovenian children with primary nocturnal enuresis. Int J Nephrol 2012;2012:509012. |
|16.||Kalo BB, Bella H. Enuresis: Prevalence and associated factors among primary school children in Saudi Arabia. Acta Paediatr 1996; 85:1217-22. |
|17.||Bower WF, Moore KH, Shepherd RB, Adams RD. The epidemiology of childhood enuresis in Australia. Br J Urol 1996;78:602-6. |
|18.||Carman KB, Ceran O, Kaya C, Nuhoglu C, Karaman MI. Nocturnal enuresis in Turkey: Prevalence and accompanying factors in different socioeconomic environments. Urol Int 2008;80:362-6. |
|19.||Byrd RS, Weitzman M, Lanphear NE, Auinger P. Bed-wetting in US children: Epidemiology and related behavior problems. Pediatrics 1996;98:414-9. |
|20.||Hellstrom AL, Hanson E, Hansson S, Hjalmas K, Jodal U. Micturition habits and incontinence in 7-year-old Swedish school entrants. Eur J Pediatr 1990;149:434-7. |
|21.||Ozden C, Ozdal OL, Altinova S, Oguzulgen I, Urgancioglu G, Memis A. Prevalence and associated factors of enuresis in Turkish children. Int Braz J Urol 2007;33:216-22. |
|22.||Pashapour N, Golmahammadlou S, Mahmoodzadeh H. Nocturnal enuresis and its treatment among primary-school children in Oromieh, Islamic Republic of Iran. East Mediterr Health J 2008;14:376-80. |
|23.||Aloni MN, Ekila MB, Ekulu PM, Aloni ML, Magoga K. Nocturnal enuresis in children in Kinshasa, Democratic Republic of Congo. Acta Paediatr 2012;101:e475-8. |
|24.||Dhondt K, Raes A, Hoebeke P, Van Laecke E, Van Herzeele C, Vande Walle J. Abnormal sleep architecture and refractory nocturnal enuresis. J Urol 2009;182(4 Suppl):1961-5. |
|25.||Neveus T, Hetta J, Cnattingius S, Tuvemo T, Lackgren G, Olsson U, et al. Depth of sleep and sleep habits among enuretic and incontinent children. Acta Paediatr 1999;88:748-52. |
|26.||Thiedke CC. Nocturnal enuresis. Am Fam Physician 2003;67:1499-506. |
|27.||Joinson C, Heron J, Emond A, Butler R. Psychological problems in children with bed-wetting and combined (day and night) wetting: A UK population-based study. J Pediatr Psychol 2007;32:605-16. |
|28.||Fergusson DM, Horwood LJ. Nocturnal enuresis and behavioral problems in adolescence: A 15-year longitudinal study. Pediatrics 1994; 94:662-8. |
|29.||Theunis M, Van Hoecke E, Paesbrugge S, Hoebeke P, Vande Walle J. Self-image and performance in children with nocturnal enuresis. Eur Urol 2002;41:660-7. |
|30.||Chang JW, Yang LY, Chin TW, Tsai HL. Clinical characteristics, nocturnal antidiuretic hormone levels, and responsiveness to DDAVP of school children with primary nocturnal enuresis. World J Urol 2012;30:567-71. |
|31.||Eapen V, Mabrouk AM. Prevalence and correlates of nocturnal enuresis in the United Arab Emirates. Saudi Med J 2003;24:49-51. |
|32.||Akis N, Irgil E, Aytekin N. Enuresis and the effective factors: A case-control study. Scand J Urol Nephrol 2002;36:199-203. |
|33.||Naseri M, Hiradfar M. Abnormal urodynamic findings in children with nocturnal enuresis. Indian Pediatr 2012;49:401-3. |
|34.||von Gontard A, Hollmann E, Eiberg H, Benden B, Rittig S, Lehmkuhl G. Clinical enuresis phenotypes in familial nocturnal enuresis. Scand J Urol Nephrol Suppl 1997;183:11-6. |
|35.||Ozkan S, Durukan E, Iseri E, Gurocak S, Maral I, Ali Bumin M. Prevalence and risk factors of monosymptomatic nocturnal enuresis in Turkish children. Indian J Urol 2010; 26:200-5. |
|36.||Hanafin S. Sociodemographic factors associated with nocturnal enuresis. Br J Nurs 1998; 7:403-8. |
|37.||Mansour A, Saad K, Molokhia T. Evaluation of impact of enuresis on quality of parental reaction towards their enuretic children: A comparison of mothers with fathers. Egypt J Psychiatry 2009;29:65-70. |
|38.||Cher TW, Lin GJ, Hsu KH. Prevalence of nocturnal enuresis and associated familial factors in primary school children in taiwan. J Urol 2002;168:1142-6. |
|39.||Dolgun G, Savaser S, Balci S, Yazici S. Prevalence of nocturnal enuresis and related factors in children aged 5-13 in Istanbul. Iran J Pediatr 2012;22:205-12. |
|40.||Lei D, Ma J, Shen X, et al. Changes in the brain microstructure of children with primary monosymptomatic nocturnal enuresis: A diffusion tensor imaging study. PLoS One 2012;7:e31023. |
|41.||Altunoluk B, Davutoglu M, Garipardic M, Bakan V. Decreased vitamin B12 levels in children with nocturnal enuresis. ISRN Urol 2012;2012:789706. |
|42.||Kim JM. Diagnostic value of functional bladder capacity, urine osmolality, and daytime storage symptoms for severity of nocturnal enuresis. Korean J Urol 2012;53:114-9. |
|43.||Lin J, Rodrigues Masruha M, Prieto Peres MF, et al. Nocturnal enuresis antecedent is common in adolescents with migraine. Eur Neurol 2012;67:354-9. |
|44.||Nikibakhsh A, Poostindooz H, Mahmoodzadeh H, Karamyyar M, Ghareaghaji RR, Sepehrvand N. Is there any correlation between hypercalciuria and nocturnal enuresis? Indian J Nephrol 2012;22:88-93. |
|45.||Sakellaropoulou AV, Hatzistilianou MN, Emporiadou MN, et al. Association between primary nocturnal enuresis and habitual snoring in children with obstructive sleep apnoea-hypopnoea syndrome. Arch Med Sci 2012; 8:521-7. |
|46.||McKillop A, MacKay B, Scobie N. A programme for children with nocturnal enuresis. Nurs Stand 2003;17:33-8. |
|47.||Kiddoo D. Nocturnal enuresis. Clin Evid 2007; 2007:305. |
|48.||Klein NJ. Management of primary nocturnal enuresis. Urol Nurs 2001;21:71-6. |
|49.||Heap JM. Enuresis in children and young people: A public health nurse approach in New Zealand. J Child Health Care 2004;8:92-101. |
|50.||Moulhee N. Effect of the Educational Program upon Parents' knowledge of nocturnal enuretic children. World J Med Sci 2012;7:137-46. |
|51.||Hashem M, Morteza A, Mohammad K, AhmadAli N. Prevalence of nocturnal enuresis in school aged children: The role of personal and parents related socio-economic and educational factors. Iran J Pediatr 2013;23:59-64. |
|52.||Sureshkumar P, Jones M, Caldwell PH, Craig JC. Risk factors for nocturnal enuresis in school-age children. J Urol 2009;182:2893-9. |
Amen Ahmed Bawazir
Community and Environmental Health Department, College of Public Health and Health Informatics, King Saud Bin Abdul Aziz University for Health Sciences, P.O. Box 22490, Riyadh 11426, Kingdom of Saudi Arabia
[Table 1], [Table 2], [Table 3], [Table 4]
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