Literature Review
The prevalence of hernias is greater in obesity. Obesity is suspected to impact the success rate of inguinal hernia repairs as the recurrence rate is higher. The higher recurrence rate was identified as a result of surgical and postoperative complications affecting the success rate of surgery. Certain factors decrease how successful the surgery is and increase the risk of a recurrence. Factors such as surgical complications and post-operative complications and surgical procedure type reduce the success rate.
The aim is to investigation the impact of obesity on the success rate of inguinal hernia repair, by identifying the amount of recurrences, surgical and postoperative complications.
A study by Y El-Dhuwaib tested this using, 125,342 non-obese patients who underwent either one of the inguinal hernia surgical procedures and revealed that laparoscopic surgery had a reoperation rate of 4%, whereas open repair shown 2.1%. (Y El-Dhuwaib et al., 2012) As the non-obese individuals undergoing open repair had less abdominal fat, it meant the surgeon could easily access the hernia through the small incisional line, making open repair more effective. (Y El-Dhuwaib et al., 2012)
A study by Froylich reviewed 186 obese patients, 35 underwent laparoscopy repair and 151 underwent open surgery inguinal hernia repair between 2004 and 2012. (Froylich et al., 2016) Throughout the 58 months’ the patients were monitored, a higher recurrence rate was found in open repair with 27.1%. Laparoscopic was more effective and shown a recurrence rate of 20.0% (Froylich et al., 2016)
The most effective surgery in non-obese patients with a BMI between 18.5-24.9 was least effective in obese patients with a BMI over 30 representing the effect of factors within the studies. Therefor limitations and risk factors are prevented within the study proposal to ensure accurate results are obtained and allow evaluation on whether obesity has an impact on the success rate of inguinal hernia repair.
Introduction
A protrusion of an organ or fatty tissue through the surrounding fascia is known as a hernia (Jenkins, & O’Dwyer, 2008).The most common are inguinal hernias present within two thirds of adults and located mainly in the lower abdomen. (ETHICON, 2015) Inguinal hernias are formed when an abdominal organ protrudes into and through the inguinal canal. (Willacy, 2017) The categorisation of hernias are spilt into 2 types, direct hernias, caused by a weakness of abdominal muscles and indirect hernias caused by a problem within the closure of the inguinal ring. (Roland, 2018) If the internal inguinal ring doesn’t seal accordingly, the defect causes indirect inguinal hernias as shown in figure 1.(ETHICON, 2015)
Successfully performed surgery removes the hernia completely, but complications during surgery impact the repair. If the repair is affected there is a higher risk the hernia will return. (Froylich et al., 2016)Therefore an increased rate of hernia’s recurrences represents the repair wasn’t successful. Certain factors decrease how successful the surgery is and increase the risk of a recurrence. Factors such as surgical complications and post-operative complications and surgical procedure type and obesity reduce the success rate.
Over 600,000 inguinal hernia repairs occur each year in the United States. (Edward, Leanne, & Karl, 2013) Identification of the hernia type allows suitable surgical procedures to be performed. Repair is traditionally performed by an open surgical method but recent advancement has introduced laparoscopic repair. (Pahwa, et al., 2015) Open repair is performed by cutting a single long incision and pushing the direct hernia bulge back inside. Indirect hernias that are moving down the inguinal canal, are repaired by tying and removing the hernia or pushing it back in. (Kulacoglu, 2011) However in laparoscopic repair, two to four incisions are made. Surgical instruments and a laparoscope are passed through the incisions to repair the hernia by stapling or covering it with mesh. (McCormack, 2005) As the two surgical procedures are performed differently, the effectiveness is varied throughout patients. Therefore, if one procedure used is more successful than the opposing one, the recurrence rate will be lowered in the patients. Similarly if the procedure is less successful, the recurrence rate will increase.( Dehn, 2009)
Obesity, characterised by an excessive fat accumulation has increased by 50% worldwide since 1980, with 1.4 billion overweight adults in 2008.(EASO, 2017) The highest obesity prevalence is from 12% to 23% within America. (Menifield, Doty, & Fletcher, 2008) This shows an 11% increase as a consequence of fast food availability and absence of exercise. (Wile, 2015) The excessive fat builds up mainly around the abdominal area, but also the limbs and face are affected ( Ofei, 2005) As obesity affects the abdomen it increases the intra-abdominal pressure, producing weakened abdominal muscles which increase the recurrence of inguinal hernias. (Wint & Higeura, 2015). As obesity increases the surgical and postoperative complications, it has a significant effect on the increase of recurrences, as the successfulness of the surgery is disrupted.
In obesity, treatment is more difficult and inefficient due to hernias being deep within the body. The extra abdominal fat layers cause difficulties in accessing hernias. Obesity increases both surgical and post-operative complications by increasing the risk of infections and open wounds, as it is affected by the extra weight producing a downward pressure. Overall obesity is suspected to increase the risk of recurrences. (Pierpont, 2014)
As obese patients are known to have an increased risk of surgical and post-operative complications, the recurrence rate of inguinal hernias are suspected to be higher. Successful hernia repair is evaluated based on the rate of recurrence. The more recurrences, the less successful the repair was in fully removing the hernia. (Kavic, 2013) The aim is to investigate the impact of obesity on the success rate of inguinal hernia repair, by identifying the amount of recurrences, surgical and postoperative complications.
Figure 1 represents an inguinal hernia protuised through a defective inguinal canal obtained from: http://www.mayoclinic.org/diseases-conditions/inguinal-hernia/home/ovc-20206354
Discussion
A study by Y El-Dhuwaib tested this using, 125,342 non-obese patients who underwent either one of the inguinal hernia surgical procedures. (Y El-Dhuwaib et al., 2012) This study used HES (hospital episode statistics) from the NHS information centre to analysis the patients. Only patients with matching ICD (International classification disease) diagnostic codes were involved in the final analysis in order to prevent the involvement of different factors which can affect the patient’s results. (Thorn, 2016) The types of hernias repaired were spilt into, primary or recurrent then unilateral or bilateral. (Conze, 2001)
Y El-Dhuwaib’s study was eventually based on non-obese patients who underwent repair between 2002 and 2004. The first criteria analysed in the study were complications such as, infection, bleeding and any organ injuries, in order to identify the postoperative complications. Then the study used HESID to follow up the patients and record if any required more hernia surgery, allowing a calculation of the amount of recurrences.
However, factors that affect success rate weren’t removed. As the two different surgical procedures were involved it was difficult to conclude an accurate recurrence rate. The study revealed that laparoscopic surgery had a reoperation rate of 4%, whereas open repair shown 2.1%. (Y El-Dhuwaib et al., 2012) As the non-obese individuals undergoing open repair had less abdominal fat, it meant the surgeon could easily access the hernia through the small incisional line, making open repair more effective. Different repair methods impacted the recurrence rate, as fewer recurrences were identified in open compared to laparoscopic. Therefor the comparison between non-obese and obese patients was invalid, disallowing a conclusion to be produced. . (Y El-Dhuwaib et al., 2012)
Three other studies shown that laparoscopic repair had less postoperative complications and lower recurrence rates compared against open. These studies found laparoscopy to be the most effective and successful surgical procedure because they found using open surgery increased the risk of infections. (Willoughby et al., 2016) (Sajid,M.S et al., 2015)(Tadaki et al., 2016) However, the three studies performed randomised trails meaning the BMI levels weren’t taken into consideration. The study performed by Willoughby, only analysed the success rate of open repair in obese patients, but the success rate of laparoscopic surgery was analysed in non-obese patients. As surgical procedures and BMI affect the success rate differently, the same surgeon, BMI category and procedure should be used to maintain accuracy. (Willoughby et al., 2016)
The above method maintained accuracy by ensuring that only patients with matching ICD diagnostic codes were included in the study. ICD is a medical classification list which provides codes for specific symptoms, diseases and illnesses. Using this means that each patient within the sample had the same condition. (Stiender, 2010) The above study looked for specific factors to identify if postoperative complications had occurred, allowing the postoperative complication assessment to be carried out similarly. Then the rate of recurrence was calculated using HESID, a hospital episode statistics but with the person’s identification hidden, effective in preventing ethical issues. (NHS, 2009)
However, including recurrent inguinal hernias in the sample possibly produced anomalous results as the study was based on the amount of recurrences, so by analysing an already recurred hernia it objects against it. A more effective method is including only primary hernias so a recurrence rate can be calculated from the first time it recurred. The surgeon wasn’t mentioned, so it is unknown whether the surgical procedures were performed by the same person, this can limit the results as they may be different depending on the surgeon characteristics. Including one type of repair reduces factors which affect the validity of results.
A study by Froylich reviewed 186 obese patients, 35 underwent laparoscopy repair and 151 underwent open surgery inguinal hernia repair between 2004 and 2012. (Froylich et al., 2016) Patients of the same sex, obese BMI category and age were tested on and hernias were categorised into small, medium and large.
Throughout the 58 months’ the patients were monitored, a higher recurrence rate was found in open repair with 27.1%. Laparoscopic was more effective and shown a recurrence rate of 20.0%. (Froylich et al., 2016) As two different surgical procedures were used it affected the validity of the results, as both produced different success rates. A study by Eker, involved two surgical procedures and found that the recurrence rate was instead higher in laparoscopy surgery at 18% and lower within open repair at 14%. This supports the theory that different surgical procedures affect the rate of recurrences. (Eker, et al., 2013)
The study involved a limited sample of patients, using a larger patient sample would have shown more results, allowing more recurrences to be identified. More results could also have indicated different effects within the surgeries. The surgical procedure time scale was too large, decreasing the accuracy of results as advancements in treatment would create difficulty in ensuring the patients underwent the same surgery. Using a shorter time scale and one surgeon to perform the same procedure would improve the research, as a comparison on just the recurrence rate can be made as the same procedures occurred. Only identifications on the hernia size were made, meaning that patients with recurring hernias couldn’t be eliminated.
Figure 2 shows the recurrence rate of inguinal hernias after repair in obese and non-obese patients.
Figure 2 represents that hernia repair is less successful in obese patients with recurrence rates 16% and 25% higher than in non-obese patients. A higher recurrence rate indicates less success within repair.
Although this study shown that obese patients had a higher recurrence rate, four other studies concluded that as BMI increases the recurrence rate decreases. (Zendejas et al., 2014) (Froylich et al., 2016) (Zheng et al., 2016) (Sarkhosh et al., 2017) However these studies state at the end that further research needs to be performed in order to investigate the long term effects, as they were only based on short term effects.
Furthermore two other studies had shown that there was no correlation between the BMI and the recurrence rate. (Tadaki et al., 2016) (Park et al., 2011) However in these two studies, there was a small sample size, limiting the results and analysis.
The studies performed aim to analyse the impact of obesity on the success rate of inguinal hernia repair, but fail to as factors and limitations affect the methods. To evaluate the hypothesis, the limitations and factors within the study need to be eliminated so accurate results can be produced.
Performing all repairs within 5 years with one surgeon would be most effective because using a variety of surgeons with different characteristics such as age. Aging decreases the cognitive and physical ability of an individual. The cognitive and physical decline during aging was analysed by a study and shown that older surgeons created higher surgical risk factors. If surgeons of different ages were used, their ability would be different therefor effecting how successful the surgery goes, which would increase the recurrence rate (Blasier,2009) .Including one surgical procedure eliminates a factor, which affects the recurrence rate of hernias, from disrupting the results. Also by comparing and categorising the hernia types, patients who have previously undergone hernia surgery are removed from the sample. This allows analysis of only primary hernias and prevents the risk of miscounting already reoccurred hernias. By ensuring there are no limitations, the recurrence rate of inguinal hernia repair within obese patients can be identified and compared against non-obese patients to investigate whether obesity impacts the success rate.
In conclusion, the prevalence of obesity impacts successful hernia repairs as the recurrence rate increased. The higher recurrence rate was identified as a result of surgical and postoperative complications affecting the success rate of surgery. The most effective surgery in non-obese patients with a BMI between 18.5-24.9 was least effective in obese patients with a BMI over 30 representing the effect of factors within the studies. Therefor eliminating limitations and risk factors ensure accurate results are obtained. Accurate results would allow evaluation on whether obesity has an impact on the success rate of inguinal hernia repair.
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