Proportion of more complex inguinal and incisional hernias in the total collective
To date, no data have been published showing the proportion of patients with inguinal or incisional hernia exhibiting one or more characteristics of a complex hernia. Therefore, an analysis of data from the Herniamed Registry was performed and the findings are presented below.
In the last data analysis up to February 1, 2019, of the total 612,830 prospectively documented cases in the Herniamed Registry, there were 401,446 inguinal hernias in the database. There were 394,088 patients with complete data entry and 392,035 with an age of ≥ 16 years. The proportion of emergency inguinal hernia procedures was n = 10,350 (2.64%). 46,720 (11.92%) of patients had an inguinal hernia recurrence. 69,200 (17.65%) had undergone bilateral repair. The proportion of women was n = 46.369 (11.83%). 13,166 (3.36%) cases were classified as scrotal hernia. 60,613 (17.76%) had undergone previous surgery of the lower abdomen.
41,501 (10.63%) of patients had a BMI ≥ 30 kg/ m2. 64,102 (16.35%) patients with inguinal hernia had been classified as ASA III/IV. The number of patients > 80 years of age was n = 27,961 (7.13%). At least n = 27,961 (7.13%) patients possessed one recorded risk factor (chronic obstructive pulmonary disease, diabetes, aortic aneurysm, immunosuppression, corticosteroid treatment, smoking, coagulopathy, antiplatelet medication and anticoagulation therapy).
On summation of all the characteristics and factors related to inguinal hernia repair that demonstrated an unfavorable influence on the outcome, n = 280,593 (71.57%) patients had a recorded characteristic and/or factor. This resulted in n = 111,442 (28.43%) patients who were not at high risk of more negative outcomes. These cases represented elective, primary, unilateral, non-scrotal inguinal hernias in men who had no other risk factors.
Examining the number of influencing factors leading to a more negative outcome, n = 136,444 (34.80%) patients had one factor, n = 85,482 (21.80%) two, n = 40,160 (10.24%) three, n = 14,260 (3.64%) four, n = 3657 (0.93%) five, n = 553 (0.14%) six, n = 36 (0.001) seven and n = 1 (0.00%) eight.
Of the 612,830 patients in the Herniamed Registry database, 70,748 had a defined incisional hernia. Of these, 68,923 had a complete data set and 68,812 an age of ≥ 16 years.
For incisional hernia the proportion of emergency procedures was
n = 3582 (5.21%) and the proportion of incisional hernia recurrence
n = 14.482 (21.05%). The proportion of patients with a hernia defect width of > 10 cm (European Hernia Society classification W3) [
24] was
n = 11,809 (17.16%). The number of patients with ASA score III/IV was
n = 23,179 (33.68%).
The number of patients aged > 80 years was n = 4660 (6.77%). In the incisional hernia collective group n = 28,787 (41.83%) patients had at least one risk factor (chronic obstructive pulmonary disease, diabetes, aortic aneurysm, immunosuppression, corticosteroid treatment, smoking, coagulopathy, antiplatelet medication and anticoagulation therapy).
On summation of all the factors and characteristics related to incisional hernia repair that increased the risk of a negative outcome applied to n = 48,722 (70.80%) of patients. Therefore, only n = 20,090 (29.20%) of cases with incisional hernia were not at an increased predisposition of possible negative outcome. These related to elective, primary, small to medium-sized incisional hernias in patients with no other risk factors.
On summation of the complex influencing factors related to incisional hernia repair, n = 22,582 (32.82%) had one factor, n = 16,767 (24.37%) two factors, n = 7343 (10.67%) three factors, n = 1810 (2.63%) four factors, n = 206 (0.30%) five factors with n = 14 (0.02%) six factors.
In summary, approximately 70% of all patients with inguinal and incisional hernia had negative influencing factors on the outcome. Of these 70% of patients, in turn around 36% with inguinal hernia and around 38% with incisional hernia had several factors that exerted a possible negative effect on the outcome.
As the Herniamed database is voluntary and only covers around 20% of German hernia patients there is a possible inclusion bias. Many dedicated German hernia surgeons include their patients, probably involving a higher rate of complex cases that have been referred to them. Relatively large numbers of easy cases are possibly treated by surgeons not enrolled in the database. Their results are unknown. Despite this bias the Herniamed database has huge power and relevance in this study. It is the largest database that includes all the relevant risk factors and patient characteristics.
General surgery training and hernia repair
“The American Board of Surgery has designated 132 procedures as being core to the practice of general surgery” [
16]. “General surgery residents are expected to be able to safely and independently perform those designated procedures by the time they graduate/are board certified” [
16]. “There is increasing concern though that perhaps some general surgery residents are not competent to enter independent practice” [
16]. In a study from a US university hospital approximately 40% of the faculty members expressed that trainees were not independently capable of performing inguinal hernia repair at any stage of their training [
55]. This is reflected in the fact that “US General Surgery residents are reported to be not universally ready to independently perform core procedures (appendectomy, inguinal hernia repair, cholecystectomy) by the time they complete residency training” [
16]. “Eighty percent of US general surgery residents do undertake a period of post-residency fellowship training which is mirrored with 77% of general surgery trainees in the UK also pursuing additional clinical fellowship periods, in addition to their standard specified training” [
56,
57]. “This comprehensively suggests that the majority of trainees in both countries do feel the need to extend their clinical training before independent practice” [
56,
57].
What is apparent in contemporary training was demonstrated by a meta-analysis of 12 studies that reported the actual numbers of inguinal hernia repairs performed by general surgery trainees [
15]. Two of these studies were from the UK, one from Thailand and nine from the USA [
58‐
69]. The mean figure reported for general surgery training in the USA was 53–71 inguinal hernia repairs [
15].
One US study did report a greater number of repairs with a mean of 113 hernia repairs per trainee [
15]. UK studies overall reported a mean of 90 inguinal hernia repairs by the residents during their general surgery training.
A further study from the UK, which was published after the meta-analysis, reported a mean of 117 repairs for the index procedure inguinal hernia repair for 311 trainees [
56]. By contrast, 69 trainees from a single UK Deanery had performed only a mean of 64 inguinal hernia repairs [
70].
“Guidance for the award of a certificate of completion of training in the UK also stipulates that, among the competences defined in the general surgery curriculum, trainees should be able to demonstrate that they have performed a minimum number of logged surgical procedures” [
71]. This minimum number of operative procedures for inguinal hernia was given as 60 procedures [
71]. But no further information is provided for ventral incisional hernia repair procedures [
71]. In Germany there is a requirement for evidence to be provided of having conducted at least 50 hernia repairs during 6 years of general surgery training [
72].
In Switzerland, general surgery trainees need to have performed at least 40 inguinal or umbilical hernia repairs and 25 abdominal wall hernia repairs over a 6-year period [
73].
Only very few studies have calculated what proportion of the total number of procedures performed during general surgery training were laparo-endoscopic inguinal hernia repairs. For a mean total number of 71.2 inguinal hernia repairs undertaken by graduating general surgery residents in 2010/2011, McCoy et al. [
60] reported a mean of 23.3 repairs using a laparo-endoscopic technique. For a mean total number of 67.4 inguinal hernia repairs conducted by graduating surgical residents in 2010, Unawane et al. [
61] reported a mean of 20.4 repairs using again a minimally invasive technique. Fryer et al. [
62] reported on the number of procedures undertaken by 15 general surgery program graduates of a single institution, with on average a higher than previously reported numbers; 92.0 open inguinal hernia repairs with the general surgery program graduates performing a mean number of 21.1 laparo-endoscopic inguinal hernia repairs. Carson et al. [
64] analyzed the number of individual cases performed by all graduating chief residents from all general surgery residency programs in the United States. Of the total mean number of 62,462 inguinal hernia repairs performed in the years 2007/2008, 25.8% were conducted using a laparo-endoscopic technique. This value corresponds to a mean number of 16 minimally invasive procedures. Bell et al. [
65] reported on 1022 US general surgery residents who graduated in 2005 and who, in addition to an average of 45.9 open inguinal hernia repairs, performed 12.7 by a laparo-endoscopic technique. In a retrospective review of the Accreditation Counsel for Graduate Medical Education the average number of laparo-endoscopic inguinal hernia repairs performed by graduating surgical residents was not greater than 34.1 during the period of 2015–2018 [
75]. There is though disappointingly a noted paucity of data available in the literature on the role of ventral and incisional hernia repair in general surgery training, Malangoni et al. [
59] reported on 1923 residents who completed their general surgery training in 2010–2011 with the residents performing on average 43.5 ventral hernia repairs during their training. Fryer et al. [
62] did report a mean number of 48.9 ventral hernia repairs for 15 residents in a single institution during 5 years of general surgery training, which was not too dissimilar to other findings.