Hernia surgery : evaluation of the clinical impacts and interactions of mesh and mesh fixation

<p dir="ltr">AIMS</p><p dir="ltr">The project underlying this thesis aimed to identify and quantify relative risk differences in reoperation rate (Papers I and II) and chronic postoperative inguinal pain (CPIP) following surgical repair of groin hernias, depending on diverse types of mesh implants and modes of mesh fixation.</p><p dir="ltr">Paper III was a preparatory study to identify relevant preoperative effect modifiers, to streamline an upcoming CPIP study on mesh/fixation combinations in laparoscopic groin hernia repair.</p><p dir="ltr">METHODS</p><p dir="ltr">The 3 individual studies were each based on large, nationwide cohorts from the Swedish Hernia Registry (SHR). For statistical analysis, Papers I and II used multivariable Cox regression. Paper III used multivariable logistic regression. P- values are 2-tailed with 95% confidence intervals (CI).</p><p dir="ltr">The predictors of interest were:</p><p dir="ltr">Paper I: Fixation suture material in the Lichtenstein repair: permanent vs long- term absorbable vs short-term absorbable sutures.</p><p dir="ltr">Paper II: Mesh/fixation combinations in laparoscopic repairs. Standard polypropylene mesh (StdPPM) vs lightweight mesh (LWM); and metal tacks vs absorbable tacks vs fibrin glue vs no fixation.</p><p dir="ltr">Paper III: Preoperative risk factors in laparoscopic repairs.</p><p dir="ltr">RESULTS</p><p dir="ltr">Paper I: 82,015 Lichtenstein repairs were included. With permanent sutures as reference (HR = 1) · long-term absorbable sutures (HR 1.1; CI 0.8-1.6; P = 0.49) were not associated with an increased risk for reoperation . short-term absorbable sutures associated with a more than doubled reoperation risk (HR, 2.2; CI 1.7-3.0; P <0.001).</p><p dir="ltr">Paper II: Of 25,190 repairs, 924 (3.7%) were later reoperated for recurrence. The lowest, mutually equivalent, reoperation risks were associated with:</p><p dir="ltr">· StdPPM without fixation (reference = HR, 1) · StdPPM + metal tacks (HR, 0.8; CI 0.4 - 1.4; P = 0.39), · StdPPM + fibrin glue (HR, 1.1; CI 0.7 - 1.6; P = 0.63) · LWM + fibrin glue (HR, 1.2; CI 0.95 - 1.6; P = 0.11) All other LWM options correlated with increased risk:</p><p dir="ltr">· LWM + metal tacks (HR, 1.6; CI 1.02 - 2.6; P = 0.040) · LWM + absorbable tacks (HR, 2.4; CI 1.5 - 3.8; P <0.001) · LWM without fixation (HR, 2.0; CI 1.5 - 2.5; P <0.001).</p><p dir="ltr">Paper III: From 82 surgical centers, 15,363 patients (33% female) were eligible, with mean age 57 years. Of 10,524 (69%) questionnaire respondents, 3,026 (29%) had CPIP according to our primary definition used for the main analysis, and 1,614 (15%) according to our secondary definition. The response rate varied significantly across some variables, particularly age.</p><p dir="ltr">Preoperative predictors significantly associated with CPIP were:</p><p dir="ltr">· female sex (OR, 1.2; CI, 1.1-2.3) · younger age (eg, <45 vs ≥65 years; OR, 1.4; CI, 1.2-1.6) · overweight (OR 1.3; CI 1.2-1.5) and obesity (OR, 1.6; CI, 1.3-1.9) · ASA 2 (OR, 1.1; CI, 1.01-1.2), and ASA ≥3 (OR, 1.4; CI, 1.2-1.7) · recurrent hernia (OR, 1.3; CI, 1.2-1.5) · femoral hernia (OR, 1.3, ;CI, 1.1-1.6) vs lateral and/or medial hernias · small (<1.5cm) vs large (>3cm) hernia defect Ø (OR, 1.2; C,I 1.03-1.4)</p><p dir="ltr">CONCLUSIONS</p><p dir="ltr">Paper I:</p><p dir="ltr">· Regarding recurrence risk, long-term absorbable sutures are an excellent alternative to permanent sutures for mesh fixation in Lichtenstein inguinal hernioplasty.</p><p dir="ltr">. Short-term absorbable sutures entail an independent risk factor for recurrence and should therefore be avoided.</p><p dir="ltr">Whether there is a difference in impact on CPIP between these 2 suture alternatives needs to be explored.</p><p dir="ltr">Paper II:</p><p dir="ltr">· With StdPPM, neither mechanical nor glue fixation associated with improved outcomes. Thus, for this mesh category, we recommend no fixation. This is also, by far, the least expensive option.</p><p dir="ltr">· With LWM, we recommend fibrin glue fixation, which was the only LWM alternative on par with non-affixed StdPPM.</p><p dir="ltr">Paper III:</p><p dir="ltr">. This study identified relevant preoperative CPIP risk factors and quantified their relative impact.</p><p dir="ltr">The results can be useful in designing and interpreting other studies.</p><p dir="ltr">. It also highlights selection bias, which appears to be a major general issue in CPIP studies but has not been satisfactorily addressed in prior reports. Future CPIP research should incorporate strategies to mitigate selection bias further.</p><h3>List of scientific papers</h3><p dir="ltr">I. <b>Novik B,</b> Nordin P, Skullman S, Dalenbäck J, Enochsson L. More recurrences after hernia mesh fixation with short-term absorbable sutures: A registry study of 82 015 Lichtenstein repairs. Arch Surg. 2011;146:12-17. <a href="https://doi.org/10.1001/archsurg.2010.302" rel="noreferrer" target="_blank">https://doi.org/10.1001/archsurg.2010.302</a></p><p dir="ltr">II. <b>Novik B,</b> Sandblom G, Ansorge C, Thorell A. Association of mesh and fixation options with reoperation risk after laparoscopic groin hernia surgery: A Swedish Hernia Registry study of 25,190 totally extraperitoneal and transabdominal preperitoneal repairs. J Am Coll Surg 2022;234:311-325. <a href="https://doi.org/10.1097/XCS.0000000000000060" rel="noreferrer" target="_blank">https://doi.org/10.1097/XCS.0000000000000060</a></p><p dir="ltr">III. <b>Novik B,</b> Sandblom G, Thorell A. Preoperative risk factors for chronic pain after laparoscopic groin hernia repair: A Swedish Hernia Registry study. 2024. [Submitted]</p>