Kristoffer Andresen | University of Copenhagen (original) (raw)

Papers by Kristoffer Andresen

Updates in Surgery, 2017

The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use.

Springer eBooks, 2018

Introduction-Aim: The Open New Simplified Totally Extra-Peritoneal (ONSTEP) inguinal hernia repai... more Introduction-Aim: The Open New Simplified Totally Extra-Peritoneal (ONSTEP) inguinal hernia repair involves placing the greater part of a pre-shaped mesh in the preperitoneal space covering all hernia defects and the rest of it in the inguinal canal. Its advantages over the existing techniques include shorter operative time, faster learning curve, less postoperative pain, speedier return to normal activities, better cosmetic result and a lower recurrence rate. The purpose of this study is to present our initial experience of this novel method. Patients-Methods: Adult patients underwent inguinal hernia repair with the ONSTEP procedure. Patients were followed up for one year for pain, wound complications and recurrence. The pre-shaped mesh used for repairing the hernia defect was the Polysoft TM hernia patch. Results: During a 1.5-year period (between the 1 st January 2013 and the 30 th June 2014) thirty three (33) patients underwent inguinal hernia repair with the ONSTEP procedure. The mean operative time was 33.28 (± 11.69) minutes, the time to discharge was 24h for all patients and the return to normal activity was between three and seven days. The overall wound complication rate was minimal and the overall recurrence rate was zero. No patient experienced residual or chronic pain at six months. Three patients had mild discomfort related to the memory ring; however, the pain subsided and did not necessitate its removal. The cosmetic result was very good immediately postoperatively, as well as at one and six months. All patients were very satisfied owing to minimal discomfort, good cosmetic result, no chronic pain and speedy return to normal activity. Conclusions: ONSTEP repair of inguinal hernia is a new technique which is fast to learn and perform, with a low complication rate and minimal recurrence rate. The overall cosmetic result and patient satisfaction is excellent. It is a safe alternative to other open and laparoscopic techniques.

Hernia : the journal of hernias and abdominal wall surgery, 2015

Purpose: The anterior cutaneous nerve entrapment syndrome (ACNES) is a frequently overlooked enti... more Purpose: The anterior cutaneous nerve entrapment syndrome (ACNES) is a frequently overlooked entity and is hardly ever considered in the differential diagnosis of chronic abdominal pain. Treatment is usually conservative. However, symptoms are often recalcitrant and surgical resection of the end twigs of the intercostal nerve( s) (neurectomy) may be considered. We wanted to clarify the role of a surgical neurectomy on chronic pain levels in patients who failed on conservative treatment of ACNES.

Hernia, Apr 9, 2021

Previous studies have shown a correlation between surgeons with high annual volume and better out... more Previous studies have shown a correlation between surgeons with high annual volume and better outcomes after various surgical procedures. However, the preexisting literature regarding groin hernia repair and annual surgeon volume is limited. The aim was to investigate how annual surgeon volume affected the reoperation rates for recurrence after primary groin hernia repair. This nationwide cohort study was based on data from the Danish Hernia Database and the Danish Patient Safety Authority’s Online Register. Patients ≥ 18 years undergoing laparoscopic or Lichtenstein primary groin hernia repair between November 2011 and January 2020 were included. Annual surgeon volume was divided into five categories: ≤ 10, 11–25, 26–50, 51–100, and > 100 cases/year. We included 25,262 groin hernia repairs performed in 23,088 patients. The risk of reoperation for recurrence after Lichtenstein repair was significantly higher for the volume categories of ≤ 10 (HR 4.02), 11–25 (HR 3.64), 26–50 (HR 3.93), or 51–100 (HR 4.30), compared with the > 100 category. The risk of reoperation for recurrence after laparoscopic repair was significantly increased for the volume categories of ≤ 10 (HR 1.89), 11–25 (HR 2.08), 26–50 (HR 1.80), and 51–100 (HR 1.58) compared with the > 100 category. The risk of reoperation for recurrence was significantly higher after Lichtenstein and laparoscopic repairs performed by surgeons with < 100 cases/year compared with > 100 cases/year. This indicates that higher surgeon volume minimizes the risk of reoperation for recurrence after groin hernia repair.

PubMed, Nov 10, 2022

Introduction: The most common laparo-endoscopic groin hernia repair techniques are TEP (total ext... more Introduction: The most common laparo-endoscopic groin hernia repair techniques are TEP (total extraperitoneal) and TAPP (transabdominal preperitoneal) repair. Despite geographic proximity, Swedish surgeons distinctively favour TEP, whereas Danish surgeons prefer TAPP. The aim of this study is to analyse the risk of reoperation for recurrence after TAPP, TEP and Lichtenstein repair using data from two nationwide registers. We also aim to discuss advantages of international collaboration between nationwide registers. Methods: All groin hernia operations registered as TEP, TAPP or Lichtenstein repair in the Swedish Hernia Register and the Danish Hernia Database between January 2004 and December 2020 will be included. Cumulative hazard rate of reoperation for recurrence will be estimated using Cox-regression analyses adjusted for age and anatomy. Conclusion: Approximately 400,000 operations are estimated to have been registered prospectively in the inclusion period in the registers. The merging of two nationwide registers was made possible owing to close cooperation between the register steering committees and by obtaining the necessary approvals. This unique collaboration between nationwide registers will make it possible to compare the risk of reoperation for recurrence after TAPP, TEP and Lichtenstein repair on an international level. In future, similar collaboration may be established to explore other outcomes such as complication rates and chronic pain. Funding: This study protocol is financed by grants generated from Sahlgrenska University Hospital (ALF grant ALFGBG-733561, an agreement concerning research and education of doctors) and the Swedish Society of Medicine (SLS-784551). Trial registration: not relevant.

The Cochrane library, Jun 24, 2022

This is a protocol for a Cochrane Review (intervention). The objectives are as follows: Main obje... more This is a protocol for a Cochrane Review (intervention). The objectives are as follows: Main objective To assess the benefits and harms of mesh compared with non-mesh in emergency groin hernia repair in adult patients with an inguinal or femoral hernia. Secondary objective To assess whether the e ects of mesh versus non-mesh in emergency groin hernia repair di er according to the degree of contamination.

Hernia, May 4, 2016

Purpose Inguinal hernia repairs should have few complications and a short learning curve. A new o... more Purpose Inguinal hernia repairs should have few complications and a short learning curve. A new operation called Onstep has promising results, but still some recurrences. The aim of the study was to find reasons for recurrence, by studying the re-operations. Methods The study is a case series, where 565 patients operated with Onstep at six hospitals between December 2011 and April 2015 were identified. If a recurrence had occurred, the description of the re-operation was studied and compared to the primary Onstep operation. Results We found 26 inguinal hernia recurrences, giving a recurrence rate of 4.6 %. The reasons for recurrence were a cranial displacement of the mesh in five patients, a caudal displacement in three patients, a folded mesh in one patient, and broken sutures in the mesh laterally in six patients. We found indications of a learning curve, since 70 % of the recurrences had their primary operation among the first half of the total Onstep procedures. Another finding was that 30 patients had complaints from the ring in the mesh, and most of these patients were slender. Fifteen patients have had the ring removed, and for six patients with a follow-up, the complaints have been reduced or disappeared. Conclusions The main reasons for recurrence may be broken sutures in the mesh laterally or a suboptimal size of the opening in fascia transversalis medially, enabling the mesh to displace. Furthermore, the results suggest a learning curve. These findings may guide further improvement in the Onstep method for inguinal hernia repair.

Langenbeck's Archives of Surgery, May 26, 2023

Purpose The best operative management of groin hernia in adolescents is uncertain. The aim of thi... more Purpose The best operative management of groin hernia in adolescents is uncertain. The aim of this systematic review was to assess recurrence and chronic pain after mesh versus non-mesh repair for groin hernia in adolescents. Methods A systematic search was done in PubMed, EMBASE, and Cochrane CENTRAL in May 2022 for studies reporting postoperative chronic pain (≥6 months) or recurrence after groin hernia repair in adolescents aged 10-17 years. We included randomized controlled trials and observational studies on primary unilateral or bilateral groin hernia repair. Risk of bias was assessed with the Cochrane risk-of-bias tool and Newcastle-Ottawa Scale. Meta-analysis of the incidence of recurrence was conducted. This review is reported according to PRISMA guideline. Results A total of 21 studies including 3,816 adolescents with groin hernias were included comprising two randomized controlled trials, six prospective, and 13 retrospective cohort studies. For non-mesh repairs, the weighted mean incidence proportion of recurrence was 1.6% (95% CI 0.6-2.5) after 2,167 open repairs and 1.9% (95% CI 1.1-2.8) after 1,033 laparoscopic repairs. For mesh repairs, it was 0.6% (95% CI 0.0-1.4) after 406 open repairs while there were no recurrences after 347 laparoscopic repairs (95% CI 0.0-0.6). Across all surgical techniques, the rate of chronic pain after 1,153 repairs ranged from 0 to 11%. Follow-up time varied and was reported in various ways. Conclusion The incidences of recurrence after groin hernia repair in adolescents were low for both open and laparoscopic mesh and non-mesh repairs. Rates of postoperative chronic pain were low. Trial registration PROSPERO: CRD42022130554.

Surgical Endoscopy and Other Interventional Techniques, Mar 13, 2019

Background Regarding groin hernia repair in children, guidelines do not favor open or laparoscopi... more Background Regarding groin hernia repair in children, guidelines do not favor open or laparoscopic repair. Even so, most surgeons prefer an open technique. The aim of this systematic review was to compare short-and long-term outcomes after laparoscopic and open groin hernia repair in children. Methods Systematic searches were conducted in three databases, and all randomized controlled trials comparing laparoscopic and open groin hernia repair in children under 18 years were included. Outcomes were postoperative complications, intraoperative complications, operative time, length of hospital stay, time to recovery, and wound appearance. The outcomes were compared between open and laparoscopic repairs in meta-analyses. Results We included ten studies with 1270 patients involving 1392 hernias. We found no differences in recurrence rate, testicular atrophy, hydrocele, hematoma, seroma, infection, pain, length of hospital stay, or time to full recovery. Laparoscopic repair was superior regarding wound appearance. Laparoscopic repair had shorter operative time than open repair for bilateral groin hernias. For unilateral groin hernias, extraperitoneal laparoscopic repair was faster than open repair, but open repair was faster than intraperitoneal laparoscopic repair. Conclusion Our results indicate similar outcome after laparoscopic and open techniques for groin hernia repair in children. The surgeon's preference as well as the wishes of the patient and parents should therefore determine the surgical approach.

British Journal of Surgery, Dec 11, 2017

Background: Ventral hernia repairs are common and have high recurrence rates. They are usually re... more Background: Ventral hernia repairs are common and have high recurrence rates. They are usually repaired laparoscopically with an intraperitoneal mesh, which can be fixed in various ways. The aim was to evaluate the recurrence rates for the different fixation techniques. Methods: This systematic review included studies with human adults with a ventral hernia repaired with an intraperitoneal onlay mesh. The outcome was recurrence at least 6 months after operation. Cohort studies with 50 or more participants and all RCTs were included. PubMed, Embase and the Cochrane Library were searched on 22 September 2016. RCTs were assessed with the Cochrane risk-of-bias assessment tool and cohort studies with the Newcastle-Ottawa scale. Studies comparing fixation techniques were included in a network meta-analysis, which allowed comparison of more than two fixation techniques. Results: Fifty-one studies with a total of 6553 participants were included. The overall crude recurrence rates with the various fixation techniques were: absorbable tacks, 17⋅5 per cent (2 treatment groups); absorbable tacks with sutures, 0⋅7 per cent (3); permanent tacks, 7⋅7 per cent (20); permanent tacks with sutures, 6⋅0 per cent (25); and sutures, 1⋅5 per cent (6). Six studies were included in a network meta-analysis, which favoured fixation with sutures. Although statistical significance was not achieved, there was a 93 per cent chance of sutures being better than one of the other methods. Conclusion: Both crude recurrence rates and the network meta-analysis favoured fixation with sutures during laparoscopic ventral hernia repair.

JAMA Surgery, Feb 1, 2023

Hernia, Dec 9, 2019

Purpose Performing two anterior or two posterior inguinal hernia repairs in the same groin contra... more Purpose Performing two anterior or two posterior inguinal hernia repairs in the same groin contradict guidelines. Nevertheless, there can be indications for using the same approach at reoperation, and information on complications other than the risk of a third repair and chronic pain is lacking in the literature. The aim was to assess intraoperative events and postoperative complications after two Lichtenstein repairs or laparoscopic inguinal hernia repairs in the same groin. Methods This nationwide cohort study included patients that had received two Lichtenstein repairs (Lichtenstein-Lichtenstein) or two laparoscopic (Laparoscopy-Laparoscopy) inguinal hernia repairs in the same groin. Patients were identified in the Danish Hernia Database and outcomes were identified in medical records during a period of 6 years. Outcomes were intraoperative events that deviated from a standard repair and 1-year postoperative complications classified according to the Clavien-Dindo classification. Outcomes were reported separately for the two cohorts. Results Among the included 102 Lichtenstein reoperations, 27% of the repairs had intraoperative events, with drain placement being most common (10%). Half of the reoperations resulted in complications where infection (15%) and hematoma (12%) were most frequent. Among the 58 laparoscopic reoperations, 16% had an intraoperative event where bleeding requiring clips was most common (10%). Half of the reoperations resulted in a complication with surgery in general anesthesia in the same groin area being the most frequent complication (9%). Conclusions Intraoperative events and 1-year postoperative complications were high for both Lichtenstein-Lichtenstein and Laparoscopy-Laparoscopy, and the results therefore support guidelines that recommend another approach at reoperation.

PubMed, Feb 3, 2023

Aim: We aimed to investigate how celestial phenomena like zodiac signs, lunar phases, and Friday ... more Aim: We aimed to investigate how celestial phenomena like zodiac signs, lunar phases, and Friday the 13th impacted the risk of reoperation after groin hernia repair. Methods: We conducted a nationwide register-based study based on the Danish Hernia Database and Danish Patient Safety Authority's Online Register between 2000-2019. We included patients ≥18 years undergoing open Lichtenstein or laparoscopic groin hernia repair. The main outcomes were risk of reoperation after groin hernia repair in relation to patient and surgeon zodiac sign, lunar phase at the time of the repair, and Friday the 13th vs other Fridays. Results: 151,901 groin hernias were included in the analysis of patient zodiac sign, and 25,075 groin hernias were included in the analysis of surgeon zodiac sign. Compared with the Sagittarius, there was a significantly higher risk of reoperation (HR [95% CI]) if the performing surgeon was born under the Capricorn (1.93 [1.16-3.12]); Pisces (1.68 [1.09-2.57]); Aries (1.61 [1.07-2.38]); Taurus (1.62 [1.04-2.54]); Cancer (2.21 [1.48-3.28]); or Virgo (1.71 [1.13-2.59]). Repairs performed under the waxing (1.23 [1.03-1.46]) and the new moon (1.54 [1.11-2.13]) had significantly higher risk of reoperation (HR [95% CI]) compared with the waning moon. Neither patient zodiac sign nor Friday the 13th affected risk of reoperation after groin hernia repair. Conclusions: Surgeons' zodiac sign and lunar phase significantly affected the risk of reoperation after groin hernia repair. Neither patients' zodiac sign nor Friday the 13th influenced on the risk of reoperation after groin hernia repair. This indicates why significant findings should be considered carefully to distinguish between random statistical association and cause-and-effect relations.

PubMed, Nov 4, 2022

A rapid review is a synthesis of available evidence in which some components of the review proces... more A rapid review is a synthesis of available evidence in which some components of the review process are modified slightly to shorten the process. This will require tight control as well as day-to-day scientific mentoring. The typical rapid review has a focused research question covering a narrow and well-defined clinical problem. With a continuous focus on some elements in the planning and production phases, it is realistic to produce a rapid scoping or systematic review with or without meta-analysis within three months without compromising on scientific quality.

Updates in surgery series, 2017

Hernia, 2016

The aim of this study was to assess the extent of reoperations after hernia repair in Denmark tha... more The aim of this study was to assess the extent of reoperations after hernia repair in Denmark that are being performed at a different facility than the primary repair and thereby investigate whether or not reoperation is a reliable basis for assessment of personal-or facility recurrence rates. Methods On a national level, we included all groin hernia repairs that had been reoperated a least once from January 1, 1998, to August 19, 2015. Results A total of 14,264 hernia repairs were included comprising a total of 7371 reoperations. We found that 26 % (n = 1883) of all reoperations were performed at a different healthcare facility. Time to reoperation, age at time of repair and having the primary repair performed at a private facility were all independent risk factors for being reoperated at a different facility in a logistic regression model. Conclusion One in four patients underwent repair for recurrent hernia at a different facility than the prior repair. Having the primary repair performed at a private hospital increased the risk of being reoperated at a different facility compared to having it performed at a public facility. This indicates that personal or institutional reoperation rates are underestimating the true reoperation rates, unless they can be followed in central registries or personal contact is made to all patients.

Scientometrics

The Cochrane Database of Systematic Reviews is internationally recognized as one of the best sour... more The Cochrane Database of Systematic Reviews is internationally recognized as one of the best sources of evidence within medical research. Nevertheless, a considerable amount of Cochrane reviews in the Cochrane Database of Systematic Reviews (CDSR) have not been updated for more than 5.5 years and are therefore considered inactive. This study’s aim was to evaluate if these are still used in academia. The study included 7,729 Cochrane reviews from the CDSR. Their Digital Object Identifiers (DOIs) were linked with citation data from the search engine The Lens. The citation pattern of 3,735 inactive reviews in the CDSR were analyzed and the results were adjusted for inflation in citation. A subgroup analysis of citing motives was performed for the most recent citations of the 20 most outdated reviews. In 2020, 41% of all citations of Cochrane reviews, were of reviews that had not been updated for more than 5.5. years. 5 years after last update, Cochrane reviews were on average cited 8.6...

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Ugeskrift for laeger, 2020

This case report presents a 34-year-old surgeon, who had a six-hour faecal digital smell after 96... more This case report presents a 34-year-old surgeon, who had a six-hour faecal digital smell after 96 minutes of manual disimpaction. The surgeon used a double layer of sterile latex gloves and an additional layer of gynaecological gloves. He noted a distinct faecal digital smell on several occasions, and a colleague also confirmed the odour two hours after the disimpaction. Currently, surgeons tend to use the same pair of gloves during surgery, as long as they are visibly intact. This case report emphasises the need for glove change during long contaminated procedures in order to maintain glove integrity.

British Journal of Surgery, 2019

Background Urinary retention and mortality after open repair of inguinal hernia may depend on the... more Background Urinary retention and mortality after open repair of inguinal hernia may depend on the type of anaesthesia. The aim of this study was to investigate possible differences in urinary retention and mortality in adults after Lichtenstein repair under different types of anaesthesia. Methods Systematic searches were conducted in the Cochrane, PubMed and Embase databases, with the last search on 1 August 2018. Eligible studies included adult patients having elective unilateral inguinal hernia repair by the Lichtenstein technique under local, regional or general anaesthesia. Outcomes were urinary retention and mortality, which were compared between the three types of anaesthesia using meta-analyses and a network meta-analysis. Results In total, 53 studies covering 11 683 patients were included. Crude rates of urinary retention were 0·1 (95 per cent c.i. 0 to 0·2) per cent for local anaesthesia, 8·6 (6·6 to 10·5) per cent for regional anaesthesia and 1·4 (0·6 to 2·2) per cent for ...