Furthermore, the investigated main variable was shown to be a significant risk factor for
reoperation for recurrence. More specifically, hernia repairs performed with LWM were associated with an increased risk of reoperation for recurrence, compared to those repaired with HWM (Table 3, Figure 9).
Figure 9. Kaplan Meier curve illustrating the significant (p < 0.001) lower rate of reoperation for recurrence for HWM compared to LWM during the time following a TEP hernia repair on men..
Hernia repairs with a defect > 3 cm appeared to be associated with an increased risk of recurrence, compared to smaller hernias that were repaired in the cohort. However, this result was not
significant in the multivariate analysis (Table 3).
Subgroup analysis demonstrated that in smaller (HR 1.31, CI 0.83-2.11) and in indirect (HR 1.33, CI 1.01-1.76) hernia repairs, the risk of reoperation rate for recurrence with the use of LWM were more comparable to HWM.
5.2 PAPER II
A total of 94,601 hernia repairs were eligible from the SHR during the study period. After excluded meshes and other exclusion criteria, 76,495 hernia repairs remained for the statistical analysis, of which 1676 were reoperated on for recurrence. 38,729 hernia repairs were repaired with HWM, 13,002 with regular LWM-PP, 17,029 with LWM-PP/PGC and 7735 with LWM-PP/PG. The median follow-up time was 7.4 years for repairs with HWM, 4.8 years for regular LWM-PP, 5.5 years for LWM-PP/PGC and 8.2 years for LWM-PP/PG. The cumulative overall reoperation rate for recurrence in the cohort was only 1.2 %.
The main findings in Paper II were that regular-LWM-PP were not associated with an increased risk of reoperation for recurrence compared to HWM-PP (Figure 10, Figure 11). However, the other two LWM-groups, LWM-PP/PGC and LWM-PP/PG, were associated with a significant increased risk of reoperation for recurrence compared to HWM (Figure 10, Figure 11).
Figure 10. Forrest plot illustrating hazard ratios and confidence intervals with p-values of the different variables in the multivariate Cox´s proportional analysis of the outcome of reoperation for recurrence. The reference variable of each variable group is presented in the plot with hazards ratio 1. * Stands for significant p-values.
Figure 11. Kaplan Meier curve illustrating the rate of reoperation for recurrence during the time after the OAM repair in male hernia repairs.
Other variables that were shown to be associated with an increased risk of reoperation for
recurrence were repairs for a direct or a larger hernia, and a recurrent hernia (Figure 10). The hernia repairs in older patients were in this cohort not associated with an increased risk of recurrence compared to younger patients that had their hernia repaired.
The subgroup analysis demonstrated no significant increased rate of reoperation for recurrence for LWM-PP/PGC and regular LWM compared to HWM in the repair of smaller hernia defects.
(Figure 12).
Figure 12. Kaplan Meier curve illustrating the rate of reoperation for recurrence for the four mesh groups in the repair of smaller hernia defects following the OAM inguinal hernia repair on men.
5.3 PAPER III
A total number of 43,303 hernia repairs were registered in the SHR during the study period of Paper III. Of these, 30,577 provided answers to the pain questionnaire with a response rate of 70.6
%. After exclusion, a total of 23,259 hernia repairs performed with three different mesh types (HWM-PP, regular LWM-PP and LWM-PP/PGC) remained for the statistical analysis.
The main finding in this study was the high chronic pain rate following an OAM inguinal hernia repair on men, particularly of young age. The significant persistent pain 1 year after surgery was reported as 15.9 % by the entire study population and 19.4 % among patients aged less than 50 years, making young age in this cohort the most evident risk factor for the assessed outcome (Figure 13).
Adjusted multiple logistic regression analyses demonstrated that the estimated risk of developing pain 1 year after an OAM hernia repair were similar for the three different mesh types (Figure 13).
Figure 13. Forrest plot of the adjusted multiple logistic regression analyses of the included variables for the outcome of pain 1 year after surgery with estimated odds ratios and confidence intervals. Hence, the reference variable of each variable group is not presented in the plot. The reference variables are; > 70 y, ASA 1-2, Indirect hernias, <1.5 cm hernias, HWM-PP, No recurrent hernia and Consultant (yes).
The most interesting subgroup analysis was to investigate if the risk of developing pain 1 year after surgery in the younger age group (of less than 50 years old) were influenced by the type of mesh.
The results showed no significant difference in the risk of chronic pain between the mesh groups (Figure 14).
Figure 14. Forrest plot of the subgroup analyses of the included meshes for the outcome of pain 1 year after surgery with estimated odds ratios and confidence intervals in the young ages group < 50 years old. Reference was HWM-PP and not presented in the plot.
5.4 PAPER IV
In total, 253 umbilical hernia repairs were eligible from Södertälje Hospital’s surgical database (using ICD codes) during the study period. After exclusion of suture repairs and mesh repairs with a sublay positioning and a laparoscopic approach, 115 hernia repairs remained for further investigation. Thereafter, a total of 80 small elective umbilical hernias ≤ 2 cm (Figure 15), repaired with a 4 x 4 cm (± 1 cm) onlay-mesh (Figure 16) remained for the final statistical analysis.
The follow-up of the patients (n = 80) in the outpatient clinic documentation after surgery was 29 (4.3-50.1) months in median (range). The patients were middle aged (46 years old in median) and predominantly males (67 %). Furthermore, the median (range) BMI was 28 kg/m2 (19-38) and all the patients were mostly healthy (ASA I-II nearly 90 %). Among the registered risk factors, smoking was the most frequently observed in over 20 % of the patients.
The main findings in Paper IV were the low frequency of surgical site complications. Only 4 out of 80 (5 %) patients were found, from the outpatient clinic documentation, to have had a seroma (3 patients) and a superficial wound infection (1 patient). All the patients with a treatment
outcome healed well within the follow-up without the need for a re-operation. There were no registered cases of recurrences during the follow-up period.
Figure 15. A small umbilical hernia with a defect < 2 cm.
Figure 16. A small 4x4 cm lightweight mesh was being prepared to be placed above the aponeurosis on the sutured hernia defect.