SUTURE TYPE AND RECURRENCE RISK AFTER INCISIONAL HERNIA REPAIR

A detailed descpription of the study is presented in the attached study protocol.

Background and Rationale Incisional hernia is a frequent postoperative complication associated with pain, impaired physical capacity and diminished quality of life. Complex abdominal wall reconstruction has substantial morbidity and recurrence risk. Minimally invasive retromuscular repair (laparoscopic or robot-assisted) has become increasingly used, combining biomechanical advantages of Rives-Stoppa principles with minimally invasive benefits. A key knowledge gap concerns the optimal suture material for fascial closure. Non-absorbable sutures provide permanent mechanical support but remain as lifelong foreign material. Slowly absorbable sutures may reduce suture-related complications but lose strength over time. Evidence from open laparotomy cannot be directly transferred to minimally invasive retromuscular procedures. No randomized multicentre trials have directly compared these suture strategies in laparoscopic or robot-assisted retromuscular incisional hernia repair. The TAFAR trial aims to address this gap, focusing on CT verified recurrence as a robust, objective measure of long-term outcome.

Objectives and Hypotheses Primary Objective

To determine whether suture material (non-absorbable vs slowly absorbable) influences the risk of CT verified incisional hernia recurrence at 2 years after minimally invasive retromuscular repair. A hierarchical hypothesis framework is applied:

1. Superiority of non-absorbable sutures.
2. If not met, non inferiority of slowly absorbable sutures within a pre specified margin.

Secondary Objectives Comparison of postoperative complications (30 days), patient-reported outcomes (pain, function, quality of life), long-term clinical outcomes (reoperations, mesh-related events, bulging), perioperative variables, and exploratory health-economic measures.

Trial Design:

A prospective, randomized, parallel-group, multicentre clinical trial with 1:1 allocation. Hierarchical testing of recurrence at 2 years (superiority → non inferiority). Structured follow up at baseline, 30 days, 1, 2, and 3 years, with CT at 2 years.

Study Setting:

National Swedish multicentre trial conducted at hospitals experienced in minimally invasive retromuscular incisional hernia surgery. Clinical practices follow local routines, with standardized follow-up and CT protocol.

Sample Size:

Superiority analysis assumed recurrence rates of 10% vs 5%; required n≈435/group. Non inferiority (margin 5 percentage points) required n≈446/group. The stricter requirement (NI) was adopted. With \~10% expected attrition at 2 year CT, total enrollment target is 980 participants.

Participant Timeline \& Assessments:

Data collection at baseline, intraoperatively, 30 days, 1 year, 2 years (including CT), and 3 years. A SPIRIT compliant schedule outlines enrolment, interventions, and assessments.

Randomization and Blinding:

Computer generated 1:1 randomization, stratified by centre, hernia width (W3 yes/no), and lateral location (yes/no). Allocation concealed until induction of anesthesia.

Blinding: Surgeons are unblinded; participants are blinded to suture type until 3 year follow up. Radiological assessment is blinded.

Data Collection, management, and quality assurance:

Data collected prospectively via paper or electronic CRFs, later consolidated in an electronic database. Baseline, perioperative, and follow up variables are standardized. Data pseudonymization, role based access, secure storage and encrypted transfers are implemented. Data retained for 10 years.

Statistical Method:

Primary analysis: Intention to treat (primary) and per protocol (sensitivity) approaches. Logistic regression adjusted for stratification variables (centre, W3, lateral hernia). Results expressed as risk difference and relative measures with 95% CI.

Secondary analysis: Includes logistic regression for complications, mixed models for PROMs, and descriptive or time to event analyses for long-term outcomes.

Subgroup and exploratory analyses Pre specified subgroups: hernia width (W3 vs W1 2) and location (lateral vs medial). Exploratory evaluation of non randomized factors (robotic vs laparoscopic, closure of posterior fascia). Missing data handled via complete case analysis, with multiple imputation sensitivity analyses.

Ethics and dissemination The trial adheres to the Declaration of Helsinki and Swedish regulations. Both suture types are standard medical products; risk is considered low. Radiation exposure from CT is minimized. Participation is voluntary with informed consent. Results will be published in peer reviewed journals and presented at scientific meetings. Lay summaries available to participants

Trial governance and monitoring Steering committee and lead investigators oversee study conduct. No planned interim analysis or independent DSMB; safety events graded ≥III are reported. Targeted monitoring may occur. Protocol amendments documented and submitted to ethics authority as required.