Prevalence and associated factors of external hernia among adult patients visiting the surgical outpatient department at the University of Gondar Comprehensive Specialised Hospital, Northwest Ethiopia: a cross-sectional study

Abstract

Objectives

This study was aimed to assess the prevalence and associated factors of external hernia among adult patients visiting the surgical outpatient department (OPD) at the University of Gondar Comprehensive Specialised Hospital (UOGCSH), Northwest Ethiopia.

Study design

Institution-based cross-sectional study was conducted from 5 April 2020 to 22 June 2020.

Study setting

UOGCSH.

Participants

All adult patients above 18 years of age who visited the surgical OPD at the UOGCSH.

Outcome

Prevalence of external hernia.

Result

A total of 403 study participants were involved in this study with a response rate of 100%. The prevalence of external hernia was 11.7% (95% CI 8.8% to 15.1%). The epigastric hernia had the highest prevalence 16 (34%), followed by inguinal hernia 14 (29.8%). Old age (adjusted OR (AOR) =2.47, 95% CI 1.06 to 5.78), constipation (AOR 3.67, 95% CI 1.68 to 8.11), chronic cough (AOR 5.18, 95% CI 2.17 to 12.3) and lifting of heavy objects (AOR 7.39, 95% CI 3.36 to 16.2) had a statistically significant association with external hernia.

Conclusion

Regardless of hardly any significant gender difference, the overall prevalence of external hernia was high. Old age, constipation, chronic cough and lifting of heavy objects were found to have a significant association with an external hernia. Patients who have constipation and cough should get appropriate treatment early.

Strengths and limitations of this study.

• The study is comprehensive since it includes most of the external hernia types.

• It could not establish a cause–effect relationship because of the cross-sectional nature of the study design.

• Since the study is institution based, the findings may not be generalised for the entire population.

• The study used only history and physical examination as a means of diagnosis for external hernia.

• Recall bias may have been introduced.

Introduction

Abdominal wall hernia is the most frequently encountered surgical condition that affects all age groups regardless of sex.¹ Globally, the prevalence of abdominal wall hernia was 1.7% for all ages.² Abdominal wall hernias are accounting for 15%–18% of all surgical procedures, and annually more than 20 million hernias are operated worldwide.^3–5 Country-specific studies are demonstrating the prevalence of external hernia. For instance, in the general Russian population, the prevalence of external hernia is 20.9%.⁶ In Arar City, Northern Saudi Arabia, the prevalence of abdominal hernia is 11.5%.¹ A study conducted in Sierra Leone revealed that the prevalence of groin hernia is 7.10%.⁷ Among the external hernias, an inguinal hernia is the most observed type accounting for about 75% of all abdominal wall hernias.⁸ The overall incidence of inguinal hernia in Africa has been estimated to range between 60 and 175 per 100 000.⁹ In sub-Saharan Africa countries, some studies reported the prevalence of inguinal hernia between 7.7%and 30%,^{10 11} incisional hernia ranged between 3% and 15%, femoral hernia between 2.5% and 7.4%, and epigastric hernia between 3.4% and 3.9%.^12–14 A study conducted in Addis Ababa, Ethiopia, indicated that inguinal hernia was found to be the most common form of external hernias which accounted for 66.3% of all the cases, and it is followed by recurrent 28.5% and incisional hernias 21.4%.¹⁵ In previous studies, different factors including muscular weakness, repeated pregnancies, a history of surgery, sex, age, chronic cough, constipation, smoking, strenuous work activities and family history of hernia were identified to have a strong association with external hernia.^{1 16–22} Hernias are among the most common surgical conditions causing a significant number of morbidity and mortality in various parts of Africa.^{23 24} Untreated hernia can lead to life-threatening complications, such as strangulation, incarceration and intestinal obstruction. Of these, strangulation is an acute surgical emergency with significant fatal consequences.²⁵ In Nigeria and Sudan, strangulated external hernia was the most common cause of intestinal obstruction, accounting for 56.9% and 27.7% of cases, respectively.²⁴ Lack of adequate surgical care for inguinal hernia is causing higher rate of mortality in remote rural communities.²⁶

Despite the common occurrence and clinical significance of external hernia, until this study was done, very limited epidemiological studies were done to indicate the magnitude and risk factors for external hernia in the world. Therefore, this study was aimed to assess the prevalence and associated factors of external hernia among adult patients visiting the surgical outpatient department (OPD) at the University of Gondar Comprehensive Specialised Hospital (UOGCSH). Finally, the output of this study will hopefully help clinicians and policy-makers to design a reliable strategy.

Methods

Study design and setting

An institution-based cross-sectional study was conducted from 5 April 2020 to 22 June 2020 among adult surgical patients who visited the surgical OPD at the UOGCSH. The hospital was found in 1954 and it is in the North Gondar administrative zone, Amhara National Regional State, which is about 750 km Northwest of Addis Ababa (the capital city of Ethiopia). According to the 2015 population projection of major cities in Ethiopia, the total population size of Gondar town was estimated to be 323 900. Currently, Gondar town has one Referral Hospital and eight government Health Centres. UOGCSH is a teaching hospital, which serves more than 5 million people of the North Gondar zone and people from the neighbouring zones. It is estimated that around 21 000 patients visit the surgical OPD per year.

Population, sample size determination and sampling procedure

The source and study population of this study were all adult patients above the age of 18 years who visited the surgical OPD and those who were available during the time of data collection in the UOGCSH, respectively. Patients who were not responsive due to severe illness or mental health problems were excluded from the study. The sample size was determined using a single population proportion formula, by using a 95% CI, 0.05 margin of error, 5% non-response rate. Since there was no previous study conducted in the area, we considered expected proportion of external hernia to be 50%. Hence, the final sample size was 403. Participants were selected using a systematic random sampling technique with skipping intervals of three.

Variables and data collection procedures

The dependent variable for this study was having any of the external hernias such as: inguinal, epigastric, umbilical, paraumbilical, femoral and incisional hernias. External hernia was diagnosed by general surgeons based on history and physical examination. Data were collected on the sociodemographic characteristics (age, sex, residence, educational status, occupation and average monthly income), clinical factors (family history of hernia, heavy weightlifting, constipation, straining during urination, body mass index, a history of abdominal surgery, history of abdominal trauma, chronic cough and history of Ascites), behavioural and obstetric factors (smoking, alcohol intake and parity). Chronic cough was defined as current or previous history of cough for more than a month. Besides, straining during urination means difficulty of urination that lasted for three or more months. Constipation was defined as unsatisfactory defecation which is characterised by infrequent stool, difficulty in defecation or both for more than 3 months.²⁷ Interviewer-administered questionnaire which was adapted from different literatures was used to collect data. Five nurses with a bachelorette degree were trained and employed as data collectors. The questionnaire was prepared in English and translated into Amharic and back to English for consistency of the tool. The tool was pre-tested in 10% of a sample size at Debark primary hospital 2 weeks before the main data collection. Necessary adjustments were made based on the pretest result (online supplemental file 1).

Data processing and analysis

The survey data were entered and cleaned using EPI DATA V.3.1 and analysed by STATA V.14 software. Descriptive statistics were used, and the findings were presented using texts, graphs and tables. A logistic regression model was used to identify factors affecting external hernia. Variables with p values of 0.2 or less in the bivariable logistic regression analysis were fitted in the multivariable analysis. Adjusted OR (AOR) with a 95% CI and p<0.05 in the multivariable analysis were used to declare significant association with the outcome variable.

The goodness of fitness of the model was checked by Hosmer and Lemeshow test.

Patient and public involvement

Patients were not involved in this study.

Results

Sociodemographic characteristics

A total of 403 study participants were included in this study with a response rate of 100%. The median age of the participants was 38 years old and the IQR was 24. Both sexes had nearly equal frequency, 207 (51.3%) were female subjects. Of the total participants, 135 (33.5%) were farmers, and almost half of the study participants 200 (49.6%) had an average monthly income of less than US$25 (table 1).

Table 1.

Sociodemographic characteristics of adult patients visiting surgical OPD at the UOGCH, Ethiopia, 2020 (n=403)

Variable	Frequency	%
Sex
Male	196	48.7
Female	207	51.3
Age
19–33	161	40.0
34–48	120	30.0
49–63	81	20.1
64–78	35	8.5
79–84	6	1.5
Residence
Urban	220	54.6
Rural	183	45.4
Occupation
Farmer	135	33.5
Merchant	31	7.7
Civil servant	58	14.4
Housewife	98	24.3
Student	38	9.4
Daily labourer	18	4.6
Others*	25	6.2
Religion
Orthodox	388	96.2
Muslim	11	2.8
Protestant	4	1.0
Educational status
No formal education	210	52.1
Primary education	42	10.4
Secondary education	63	15.7
College or above	88	21.8
Average monthly income in US$
<US$25	200	49.6
US$26–US$185	194	48.1
>US$186 (1)	9	2.3

*Others: unemployed, solider, driver, retire and artist.

OPD, outpatient department; UOGCSH, University of Gondar Comprehensive Specialised Hospital.

Clinical, behavioural and obstetric characteristics

Of the total participants, 19 (4.8%) had a family history of external hernia, and one-fourth (102) had a history of alcohol intake. Among female study participants, the majority 153 (74%) gave at least one birth. About quarter, 96 (24%) of the participants had constipation, and one-fifth had a history of lifting heavy objects 84 (20.9%) (table 2).

Table 2.

Clinical, behavioural and obstetric characteristics of adult patients visiting surgical OPD at the UOGCH, Ethiopia, 2020 (n=403)

Variable	Frequency	%
Family history of hernia
Yes	19	4.8
No	384	95.2
Smoking
No smoking	385	98.0
Previously smoking	6	1.5
Currently smoking	2	0.5
Alcohol intake
No alcohol	301	74.7
Previous alcohol intake	32	8.0
Current alcohol intake	70	17.3
Parity
Nulliparous	54	26.0
Primiparous	22	10.7
Multi parous	68	32.9
Grand multipara	63	30.4
Straining during urination
Yes	64	15.9
No	339	84.1
Constipation
Yes	96	23.9
No	307	76.1
Prolonged cough
Yes	42	10.4
No	361	89.6
Lifting of heavy objects
Yes	84	20.9
No	319	79.1
Previous abdominal surgery
Yes	40	10.0
No	363	90.0
History of abdominal trauma
Yes	13	3.2
No	390	96.8
History of Ascites
Yes	5	1.24
No	398	98.76
BMI
14–17.9	58	14.39
18–24.9	311	77.17
25–29.9	27	6.70
30–34.9	7	1.74

BMI, body mass index; OPD, outpatient department; UOGCSH, University of Gondar Comprehensive Specialised Hospital.

Prevalence of external hernia

Of the total participants, 47 of them had external hernia which makes the overall prevalence of 11.7% (95% CI 8.8% to 15.1%). More than half of external hernia cases, 29 (61.8%), occurred at the age of above 45. The prevalence of external hernia among male and female participants was 11.73% (95% CI 7.59% to 17.09%) and 11.59% (95% CI 7.57% to 16.76%), respectively. Among the total number of hernia cases that were observed in females, 23 (96%) of them were diagnosed from primiparas and multiparous, and 14 (58.4%) of them had a history of more than four deliveries (grand multipara). Of the total cases of external hernia, epigastric and inguinal hernias had nearly equal prevalence of 16 (34%) and 14 (29.8%), respectively (figure 1). About 41 (10.1%) of the participants had a history of abdominal surgery and only 5 (12.2%) of them had an incisional hernia. Only one case of external hernia was present with complications (incarceration) and all external hernia cases were newly diagnosed.

Figure 1.

Bar graph that shows the frequency distribution of types of hernia with the sex of adult patients visiting surgical OPD at the UOGCH, Ethiopia, 2020. OPD, outpatient department; UOGCH, University of Gondar Comprehensive Specialised Hospital.

Factors associated with an external hernia

The multivariable logistic regression analysis revealed that old age, constipation, chronic cough and lifting of heavy objects had a significant association with the occurrence of external hernia. The odds of being diagnosed with external hernia was 2.47 times higher among participants with age groups between 46 and 84 compared with age between 19 and 45 (AOR 2.47, 95% CI 1.06 to 5.78). The odds of having an external hernia was 3.67 times higher among participants who had constipation compared with their counterparts (AOR 3.67, 95% CI 1.68 to 8.11). Patients who had chronic cough had 5.18 times higher odds of having external hernia compared with their counterparts (AOR 5.18, 95% CI 2.17 to 12.3). The odds of having an external hernia was 7.39 times higher among participants lifting heavy objects compared with participants who did not (AOR 7.39, 95% CI 3.36 to 16.2) (table 3).

Table 3.

Multiple logistic regression output for the factors associated with external hernia among adult patients visiting surgical OPD at the UOGCH, Ethiopia, 2020 (n=403)

Variable	External hernia		Crude OR (95% CI)	Adjusted OR (95% CI)	P value
	Yes	No
Age
19–45	18	249	1	1
46–84	29	107	3.74 (1.99 to 7.04)	2.47 (1.06 to 5.78)	0.036
Residence
Urban	16	204	1	1
Rural	31	152	2.6 (1.37 to 4.92)	0.73 (0.30 to1.85)	0.55
Educational status
No formal education	38	172	4.63 (1.60 to 13.4)	2.90 (0.89 to 9.4)	0.07
Primary and  Secondary education	5	100	1.05 (0.27 to 4.03)	1.64 (0.37 to 7.08)	0.50
College or above	4	84	1	1
Staining during urination
Yes	16	48	3.31 (1.68 to 6.50)	0.83 (0.33 to 2.25)	0.712
No	31	308	1	1
Constipation
Yes	26	70	5.05 (2.68 to 9.51)	3.67 (1.68 to 8.11)	0.001
No	21	286	1	1
Prolonged cough
Yes	17	25	7.50 (3.64 to 15.4)	5.18 (2.17 to12.3)	<0.001
No	30	331	1	1
Lifting heavy objects
Yes	29	55	8.81 (4.58 to 16.9)	7.39 (3.36 to 16.2)	<0.001
No	18	301	1	1
BMI
14–17.9	7	51	1.15 (0.48 to 2.7)	1.35 (0.4 to 3.8)	0.56
18–24.9	33	278	1	1
25–34.9	7	27	2.1 (0.82 to 0.17)	3.01 (0.95 to 9.54)	0.06

BMI, body mass index; OPD, outpatient department; UOGCSH, University of Gondar Comprehensive Specialised Hospital.

Discussion

This study assessed the prevalence of external hernia and its associated factors among adult patients visiting the surgical OPD at the UOGCSH, Northwest Ethiopia and found the prevalence of external hernia to be 11.7%. The result is consistent with a study conducted in Arar City, Northern Saudi Arabia 11.5%.¹ In this study, epigastric hernias accounted 34% of the total hernia cases which puts it at the top of all the cases. Nonetheless, proportion of epigastric hernia reported by other studies worldwide is much lower and ranged between 3.4% and 8.1%.^{12 13 28} According to studies conducted in Nigeria, Egypt and India the proportion of inguinal hernia was found to be 70.2%, 56% and 21.8%, respectively.^{12 28 29} However, the proportion of inguinal hernia in this study was found to be 29.8%.

This study indicates that older age participants were more likely to be diagnosed with external hernia compared with younger age groups. This finding is supported by different studies elsewhere.^{6 16 17} The reason could be attributed to the degenerative weakness of abdominal muscles and fibrous tissue in the elderly age group. Loss of abdominal muscle strength and resistance to high intra-abdominal pressure can lead to herniation.^{30 31} Another potential reason could be associated with the age-related decline in blood testosterone level and enhancement of oestrogen via the action of aromatase enzyme. Lower abdominal muscles (LAMs) are sensitive to our body’s oestrogen hormone and tends to express very high levels of oestrogen receptor-α. As a result, the increase in oestrogen level can lead to atrophy and fibrosis of LAM which may result in the occurrence of hernia in males.³² On the other hand, when women reach postmenopausal age, they start to accumulate intra-abdominal adipose tissue which will cause separation of muscle bundle and layers, weakening of aponeurosis and then predisposing to hernia.³³

In this study, the study participants with constipation were more likely to have an external hernia as compared with their counterparts. The same result is obtained by the studies done in America and India.^{18 34} This could be due to prolonged straining during defecation which generates high intra-abdominal pressure and results in weakness of abdominal muscle, which in turn, leads to hernia.³⁵ In this study, the study participants with a chronic cough had higher odds of having external hernia as compared with the corresponding groups. Our finding is strongly supported by the studies done elsewhere.^{17 36 37} This may be due to the repeated occurrence of increased intra-abdominal pressure during coughing which results in weakness of abdominal muscle and followed herniation.³⁸ Our finding showed that lifting heavy objects increased odds of having external hernia. The notion of our study is supported by different studies.^{22 37 39} This could be attributed to increasing intra-abdominal pressure causing breakage in the fibres of transversals fascia, which leads to muscle weakness and results in the occurrence of hernia.⁴⁰

The study is the first of its kind in the study area and in Ethiopia as well. The study is also comprehensive which includes most of the external hernia types. Data were recorded by well-trained data collectors under the close supervision of the investigators. However, there are some limitations of this study such as it could not establish a cause-effect relationship because of the cross-sectional nature of the study design. In addition, this study was institution based, the findings may not fully reflect the entire population. We used only history and physical examination as a means of diagnosis for abdominal hernia, and ultrasound was not used for diagnosis. It is possible that recall bias may have been introduced.

Conclusion

Regardless of hardly any significant gender difference, the overall prevalence of external hernia was high. Old age, constipation, chronic cough and lifting of heavy objects were found to increase the odds of having an external hernia. Health professionals better identify and intervene in external hernias early, especially for high-risk groups. Patients who have constipation and cough should get appropriate treatment in time. Community-based studies should be conducted to reveal the burden of the disease. There is also a need for further studies regarding the burden and risk factors of external hernia in different areas of the country.

Data availability statement

Data are available on reasonable request.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s).

Ethics approval

Ethical approval was obtained from the ethical review committee of the College of Medicine and Health Sciences, University of Gondar (Reference No 1856/12 dated 18 March 2020). Participants gave informed consent to participate in the study before taking part.