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International Journal of Surgery 10 (2012) 364e367

ORIGINAL RESEARCH

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International Journal of Surgery

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Original research

Risk factors for inguinal hernia in adult male Nigerians: A case control study

J.A. Ashindoitiang a, N.A. Ibrahim b,*, O.O. Akinlolu a

aDepartment of Surgery, General Hospital, Ikorodu, Lagos State, NigeriabDepartment of Surgery, Lagos State University College of Medicine and Teaching Hospital, Ikeja, Lagos State, Nigeria

a r t i c l e i n f o

Article history:Received 8 May 2012Received in revised form20 May 2012Accepted 23 May 2012Available online 4 June 2012

Keywords:Inguinal herniaRisk factorsNigerians

* Corresponding author.E-mail address: ibrahimakanmu@yahoo.com (N.A.

1743-9191/$ e see front matter � 2012 Surgical Assohttp://dx.doi.org/10.1016/j.ijsu.2012.05.016

a b s t r a c t

Background: We sought to evaluate selected risk factors for development of inguinal hernia in adult maleNigerians in a hospital based case control study. The aimwas to identify the risks for this condition in ourpopulation. This may assist in instituting appropriate preventive measures towards early detection andtreatment.Methods: All male patients aged 18 years and above who presented with primary inguinal hernia at theGeneral Surgical clinic of Ikorodu General Hospital between April 2009 and March 2011 were enrolledinto the study as cases. Control subjects were selected randomly from the general out-patient clinic.Participants were interviewed during their first clinic attendance using a standardised questionnaire torecord their bio-data and the presence or absence of the risk factors. All study cases had hernia repair andthe type of hernia, whether indirect or direct was determined and documented. SPSS version 15.0 wasused in the statistical analysis and the risk factors among the cases and controls were compared usingunivariate and multivariate logistic regression analysis.Results: A total number of 404 male patients were interviewed. Two hundred and two were the caseswhile the remaining 202 were the controls. Significant risk factors for inguinal hernia were positivefamily history of inguinal hernia (p < 0.001 and strenuous work activities (p < 0.001).Among the cases, 132 (65.3%) had indirect hernia while the remaining 70 (34.7%) had direct hernia.Positive family history (p ¼ 0.011) and straining during urination or defecation (p ¼ 0.047) were thefactors significantly associated with the type of hernia.Conclusion: Family history of inguinal hernia and strenuous work activity are the significant risk factorsfor this condition in our setting. Public health initiatives targeting those at higher risk of hernia devel-opment may help early detection and treatment; thereby reducing morbidity and mortality from thiscondition.

� 2012 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

1. Introduction

Inguinal hernia is one of the most common surgical pathology. Itis the most common form of abdominal wall hernia and occursmore frequently among adult men. Well over one quarter of adultmen in the united states of American would be expected to havea medically recognized inguinal hernia.1 The lifetime risk ofinguinal hernia repair is estimated to be 27% for men and 3% forwomen.2 The incidence and the prevalence of this condition inNigeria are not known. However, it is one of the most commonproblems presenting to surgeons. In a 14-year review ofa secondary level surgical practice in Nigeria, external hernia repairconstituted 56.1% of the surgical procedures undertaken.3 In addi-tion, significant proportion of patients with this disease present

Ibrahim).

ciates Ltd. Published by Elsevier Lt

late for treatment or with complications. Obstructed herniaremains the most common cause of intestinal obstruction inNigeria.4

Certain factors have been implicated in the aetiology of primaryinguinal hernia.5 They include the presence of a patent processusvaginalis, failure of the shutter mechanism and altered metabolismof collagen connective tissue and the extracellular matrix.6

Furthermore, Patient-related factors found to be associated withinguinal hernia in adults include physical exertion and weightlifting,7 constipation,8 straining during urination,9 smoking,10

obesity,11 ageing,1 positive family history of hernia,12 chronicobstructive airway disease (COAD),12 muscle deficiency followingprevious appendectomy and abdominal surgery,13 pelvic fracturesand trauma14 and connective tissue disease.15

Despite the common occurrence and the clinical significance ofthis condition, only few studies carried out largely among Cauca-sians and Asians have investigated the risks for its development. Tothe best of our knowledge, none has been done in an African

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ORIGINAL RESEARCH

population. We therefore evaluated some of the risk factors fordevelopment of inguinal hernia in adult male Nigerians ina hospital based case control study. The aim was to identify theimportant risk factors for the disease in our population. This mayassist in instituting appropriate preventive measures targeted atmodifiable lifestyle and disease-related risk factors and earlydetection of the condition by increasing awareness especiallyamong the groups at higher risk.

2. Methods

All male patients aged 18 years and above who presented with primary inguinalhernia at the general surgical clinic of Ikorodu General Hospital between April 2009and March 2011 were enrolled into the study as cases. The hospital is a secondarylevel care centre serving largely the semi-urban and rural population Ikorodu localGovernment area of Lagos state which has a population of about 0.5 million (2006cencus).

Control subjects were selected randomly from the general out-patient clinic.They were patients with other conditions unrelated to hernia and are not predis-posed to by any of the risk factors being assessed. Patients with history of herniarepair were excluded from the control subjects. Cases and controls were age and sexmatched and informed consent was obtained before enrolment into the study.Participants were interviewed during their first clinic attendance by the attendingphysician among the authors using a standardised questionnaire.

Data recorded included age, body weight, height, body mass index (BMI),smoking habit, presence or absence of chronic cough/COAD, constipation/strainingduring defecation, straining during urination, history of inguinal hernia in a firstdegree relation and obesity. Subjects with BMI >30 were considered obese. Type ofoccupation and level of other regular physical activities were also documented andthesewere used to categorise participants into 2 groups; those involved in strenuousactivities and those who were not. Level of physical activities was determinedemploying the compendium of physical activities by Ainsworth et al.16 as adapted byCenter for Disease Control and prevention (CDC) to categorize general physicalactivities as defined by level of intensity. Activities classified as vigorous (metabolicequivalent of task (MET)> 6.0) were considered strenuous while activities classifiedas moderate (metabolic equivalent of task (MET) between 3.0 and 6.0) wereconsidered non-strenuous. All study cases had hernia repair and the type of hernia,whether indirect or direct was determined and documented.

SPSS version 15.0 was used in the statistical analysis. Risk factors were comparedbetween the cases and controls using univariate and multivariate logistic regressionanalysis. Relative risks for cases compared with controls were estimated by calcu-lating odds ratio (OR) with 95 percent confidence intervals (CI). Association betweenthe risk factors and the type of hernia was also determined by chi-square test.P value of less than 0.05 was regarded as statistically significant.

3. Results

A total number of 404 male patients were interviewed. Twohundred and two who presented with inguinal hernia were thecases while the remaining 202 were the controls. Age range for thecases was from 16 to 80 years with mean age of 47.34 (SD � 16.33).The peak age range was 60e69 years. Age distribution of the casesis as shown in Table 1. For the controls, their ages ranged from 17 to83 and mean age was 45.48 (SD � 16.85).

Distribution of the assessed risk factors for inguinal herniaamong the cases and the controls are as shown in Table 2. Signifi-cant risk factors for inguinal hernia in this study were positivefamily history of inguinal hernia (p ¼ 0.001) and strenuous workactivities (p ¼ 0.001).

Table 1Age distribution of patients with inguinal hernia (N ¼ 202).

Age range (years) Number Percentage

Less than 20 3 1.520e29 32 15.830e39 37 18.340e49 35 17.350e59 33 16.360e69 43 21.370e79 16 7.980 and above 3 1.5Total 202 100

Among the 202 subjects who presented with inguinal hernia,132 (65.3%) had indirect hernia while the remaining 70 (34.7%) haddirect hernia. Age distribution and frequency of risk factorsaccording to the type of hernia is shown in Table 3. Positive familyhistory and straining during urination and defecation were thefactors significantly associated with the type of hernia in this study.Higher percentage of direct hernia (41%) was observed in patientswho strain during urination or defecation (p ¼ 0.047) while three-quarter among patients with positive family history of inguinalhernia developed indirect hernia (p ¼ 0.011).

4. Discussion

Inguinal hernia is predominantly a male disease and the inci-dence increases with age. A national survey of general practices,covering about 1% of the population of England and Wales in1991e1992, found that about 95% of people presenting to primary-care settings with inguinal herniawere males. It also found that theincidence rose from about 11/10,000 person-years in men aged16e24 years to about 200/10,000 person-years in men aged 75years and over.17 A third among patients in this study were aged 60years and above, although, this age group constitutes only 5.5% ofthe Nigerian male population. Increased age results in atrophy ofbody muscles resulting in increased risk of hernia formation.

Positive family history of inguinal hernia is a significant riskfactor for inguinal hernia in this study. Forty-three percent amongpatients in this study had family history of hernia in either theparents or first degree relatives. In addition to being a significantrisk factor for development of inguinal hernia, positive familyhistory also predicts for recurrence of inguinal hernia followingrepair.18 Lau et al.12 reported that family history of hernia was themost important determinant factor for developing inguinal herniain adult males. In addition, a male subject who has a positive familyhistory of hernia is 8 times more likely to develop a primaryinguinal hernia. Genetic factors may play a role in the developmentof hernia. Genes regulating collagen metabolism have been impli-cated and studies on the biology of hernia formation suggest thatdisturbance in collagen metabolism contribute to high recurrencerates following hernia repair.15 A decrease in ratio of type I/IIIcollagen is found in patients with inguinal, incisional and recurrentinguinal hernias.15 A recent study showed that level of matrixmetalloproteinases (MMPs) which are involved in the degradationof collagen are higher in the fascia transversalis of patients withinguinal hernia.19 This may be responsible for weakness of thefascia and development of hernia.

In this study, involvement in strenuous work activity is one ofthe significant risk factors for inguinal hernia development. Studieshave shown that a person whose work activity involves lifting andother strenuous work has higher risk of hernia formation.7,12 Inaddition to the type of weight lifted, the number of years in thisactivity contributes to the risk.7 However, it is also reported that theappearance of inguinal hernia may be attributed to a single stren-uous event. Furthermore, indirect hernias are more likely topresent following such an event.20 It is believed that strenuouswork activities like lifting of heavyweight increase intra-abdominalpressure causing breakage in the fibres of transversalis fascia. Thisleads to weakness and results in the development of inguinalhernia. It has been found that 20% of adults have a patent processusvaginalis (PPV)21 and this predisposes to development of inguinalhernia in the presence of triggering factor such as raised intra-abdominal pressure. In Nigeria, majority among the workforceengage in farming and trading activities which involve carryingheavy objects. Others, however, do not agree that occupation isa factor in the development or aggravation of hernia. They hold thebelief that strenuous physical activity by itself does not cause

Table 2Distribution of risk factors for inguinal hernia among subjects and controls.

Variable Control n ¼ 202No (%)

Cases n ¼ 202No (%)

Univariate analysis Multivariate analysis

OR (CI ¼ 95%) P OR (CI ¼ 95%) P

Strenuous activitiesPresent 429 (21) 116 (57)Absent 160 (79) 86 (43) 5.138 (3.331e7.975) 0.001 5.769 (3.548e9.380) 0.001

Chronic cough/COADPresent 23 (11) 25 (12)Absent 179 (89) 177 (88) 1.099 (0.601e2.009) 0.759 1.286 (0.624e2.649) 0.495

Straining during urination/defecationPresent 29 (14) 42 (21)Absent 173 (86) 160 (79) 1.566 (0.931e2.633) 0.091 1.808 (0.981e3.332) 0.058

Ascites/abdominal massPresent 3 (1) 1 (0.5)Absent 199 (99) 201 (99.5) 0.330 (0.034e3.200) 0.339 0.208 (0.021e2.062) 0.179

Family history of inguinal herniaPresent 27 (13) 97 (48)Absent 175 (87) 105 (52) 5.988 (3.667e9.777) 0.001 7.018 (4.091e12.038) 0.001

ObesityPresent 21 (10) 14 (7)Absent 181 (90) 188 (93) 0.642 (0.317e1.301) 0.219 0.442 (0.183e1.066) 0.069

SmokingPresent 11 (5.4) 10 (5)Absent 191 (94.6) 192 (95) 0.904 (0.375e2.179) 0.823 0.754 (0.261e2.173) 0.601

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ORIGINAL RESEARCH

primary or recurrent inguinal herniation. It is also reported thatthere is seldom any subjective association between muscle strainand the onset of groin hernia.22,23 vanWessem et al.24 reported thatthe prevalence of PPV does not increase significantly with age andconcluded that the aetiology of indirect inguinal hernia in adults, asin infants, is congenital. Studies conducted among Israelis andAmericans did not find significant association between physicalactivities and inguinal hernia occurrence.1,9

Straining during defecation or urination causes increase in intra-abdominal pressure and predisposes to inguinal hernia formation.This factor did not significantly increase the risk of inguinal herniain our study population. This is similar to findings in a study among

Table 3Age distribution and frequency of risk factors according to the type of hernia(n ¼ 202).

Variable Type of hernia

Indirect (n ¼ 132)Number (%)

Direct (n ¼ 70)Number (%)

Chi-square p-value

Age�60 years 20 (15) 14 (20)

0.768 0.381<60 years 112 (85) 56 (80)Strenuous activitiesPresent 69 (52) 47 (67)

4.137 0.381Absent 63 (48) 23 (33)Chronic cough/COADPresent 13 (10) 12 (17)

2.244 0.134Absent 119 (90) 58 (83)Straining during

urination/defecationPresent 22 (17) 20 (29)

3.936 0.047Absent 110 (83) 50 (71)Ascites/abdominal massPresent 1 (0.8) 0 (0)

0.533 0.465Absent 131(99.2) 70 (100)Family history of

inguinal herniaPresent 72 (55) 25 (36)

6.499 0.011Absent 60 (45) 45 (64)ObesityPresent 8 (6) 6 (9)

0.447 0.504Absent 124 (94) 64 (91)SmokingPresent 8 (6) 2 (3)

0.998Absent 124 (94) 68 (97)

Asian population.12 Abramson et al.9 found higher risk for inguinalhernia in patients with features of benign prostatic hypertrophyand not in those who had constipation. Ruhl et al.1 also reportedthat constipation or bowelmovement frequencywas not associatedwith higher risk of inguinal hernia. Chronic cough from COAD isbelieved to be one of the causes of raised intra-abdominal pressureand has been associated with increased risk of inguinal hernia.12

This was not a significant risk factor in this study. Our finding issimilar to the report from a survey in Israel.9

Obesity and overweight were not significant risk factors fordeveloping inguinal hernia in this study. Lower incidence ofinguinal hernia among overweight and obese men as comparedwith normal-weight men was reported by Ruhl et al.1 This findingwas supported by studies in Israel9 and Netherlands.25 It is sug-gested that among heavier men, abdominal wall musculature maybe strengthened by the excess adipose tissue which providesa stronger barrier against hernia formation. Our findings showedthat cigarette smoking was not a significant risk factor for inguinalhernia. This is in support of reports from similar studies amongChinese12 and Americans.1 Smoking is reported to have adverseeffect on connective tissue metabolism and has been proposed asa risk factor for inguinal hernia development and reoccurrence.10

However, Jansen et al.18 reported that smoking could be identi-fied as an additional risk factor for early onset of hernia disease butnot for hernia recurrence.

5. Conclusion

Inguinal hernia remains a common disease among adult men.Family history of inguinal hernia and strenuous work activity werethe significant risk factors for this condition in our setting.Morbidity from inguinal hernia is still relatively high among ourpopulation compared to what obtains in more affluent societies.Many with the disease in our environment would not come fortreatment until complications arise.26 Public health initiatives tar-geting those at higher risk of hernia development may help earlydetection and treatment; thereby reducingmorbidity andmortalityfrom this condition.

Ethical approvalWritten informed consent was obtained and assurance of

confidentiality of responses was given to each respondent. Ethical

J.A. Ashindoitiang et al. / International Journal of Surgery 10 (2012) 364e367 367

ORIGINAL RESEARCH

approval given by the relevant authorities of the hospital where thestudy was carried out.

FundingFunding for the research was by the authors.

RCTNot applicable.

Author contributionJAAe study design, data collection, data analysis andwrite up of

manuscript.NAI e study design, data analysis and final write up of

manuscript.OOA e study design, data collection and write up of manuscript.

Conflict of interestNo conflict of interest to be declared.

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