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Chronic postoperative pain: the case of inguinal herniorrhaphy

2004; Elsevier BV; Volume: 95; Issue: 1 Linguagem: Inglês

10.1093/bja/aei019

1471-6771

Eske Kvanner Aasvang, Henrik Kehlet,

Anesthesia and Pain Management

That surgical injury can lead to chronic pain is now well established.8Bruce J Drury N Poobalan AS et al.The prevalence of chronic chest and leg pain following cardiac surgery: a historical cohort study.Pain. 2003; 104: 265-273Abstract Full Text Full Text PDF PubMed Scopus (169) Google Scholar21Jung BF Ahrendt GM Oaklander AL et al.Neuropathic pain following breast cancer surgery: proposed classification and research update.Pain. 2003; 104: 1-13Abstract Full Text Full Text PDF PubMed Scopus (332) Google Scholar29Macrae WA Chronic pain after surgery.Br J Anaesth. 2001; 87: 88-98Crossref PubMed Scopus (530) Google Scholar41Perkins FM Kehlet H Chronic pain as an outcome of surgery. A review of predictive factors.Anesthesiology. 2000; 93: 1123-1133Crossref PubMed Scopus (1087) Google Scholar50Sharma AD Parmley CL Sreeram G et al.Peripheral nerve injuries during cardiac surgery: risk factors, diagnosis, prognosis, and prevention.Anesth Analg. 2000; 91: 1358-1369Crossref PubMed Scopus (74) Google Scholar From these reviews and studies using a systematic collection of data, the estimated incidences of chronic pain after various procedures are: leg amputation about 60%, thoracotomy about 50%, breast surgery about 30%, cholecystectomy 10–20%, and inguinal herniorrhaphy about 10%. Predictive risk factors for chronic postoperative pain are: preoperative pain, repeat surgery, psychological vulnerability, workers compensation, a surgical approach with risk of nerve damage, moderate or severe intensity of acute postoperative pain, radiation therapy, neurotoxic chemotherapy, depression, neuroticism, and anxiety.29Macrae WA Chronic pain after surgery.Br J Anaesth. 2001; 87: 88-98Crossref PubMed Scopus (530) Google Scholar41Perkins FM Kehlet H Chronic pain as an outcome of surgery. A review of predictive factors.Anesthesiology. 2000; 93: 1123-1133Crossref PubMed Scopus (1087) Google Scholar All these factors should be assessed in any study of chronic postoperative pain; however, this has rarely been the case. Thus, a detailed understanding of the relative role of the mechanisms responsible for the development of chronic postoperative pain is not available and further complicated by the many possible pathogenic mechanisms. As patients undergoing inguinal hernia repair do not have a number of the risk factors such as cancer, a severe preoperative pain state, chemotherapy or radiation therapy, or predominant psychosocial characteristics, this surgical model may be suitable for a detailed analysis of the pathogenic mechanisms involved in development of a chronic postoperative pain state. Thus, this review will focus on the study of chronic pain after inguinal hernia repair, which is one of the most common surgical procedures with an annual rate of 2800 per million population in Europe and the USA.3Bay-Nielsen M Perkins FM Kehlet H Pain and functional impairment 1 year after inguinal herniorrhaphy: a nationwide questionnaire study.Ann Surg. 2001; 233: 1-7Crossref PubMed Scopus (482) Google Scholar Poobalan and colleagues published a review in 200144Poobalan AS Bruce J Smith WC et al.A review of chronic pain after inguinal herniorrhaphy.Clin J Pain. 2003; 19: 48-54Crossref PubMed Scopus (413) Google Scholar where data on chronic pain after inguinal herniorrhaphy until 2000 were analysed, and found that chronic pain was observed in about 10% of patients undergoing inguinal herniorrhaphy. The conclusions and risk factors are summarized in Table 1.Table 1Factors related to development of a chronic post-herniorrhaphy pain state, based upon a literature review up to 200044Poobalan AS Bruce J Smith WC et al.A review of chronic pain after inguinal herniorrhaphy.Clin J Pain. 2003; 19: 48-54Crossref PubMed Scopus (413) Google ScholarPain reported in 0–53% patients.Moderate to severe pain in about 10%.Pain restricted daily activity in up to 25% of patients.No conclusion on differences between laparoscopic vs open-hernia repair.Higher risk of pain after operation for a recurrent hernia.Less pain after mesh than non-mesh repair.Chronic pain related to numbness in surgical area after surgery.Chronic pain related to intensity of acute postoperative pain. Open table in a new tab This review considers, in addition to the findings by Poobalan and co-workers,44Poobalan AS Bruce J Smith WC et al.A review of chronic pain after inguinal herniorrhaphy.Clin J Pain. 2003; 19: 48-54Crossref PubMed Scopus (413) Google Scholar the literature from 2000 to April 2004, as there has been an increased focus on post-herniorrhaphy pain more recently, thereby providing a better understanding of the pathogenic mechanisms of chronic postoperative (post-herniorrhaphy) pain. A special emphasis is placed on the role of nerve damage in order to outline strategies for prevention and treatment of chronic postoperative pain. The term ‘chronic post-herniorrhaphy pain’ has a wide variety of interpretations in the literature. The International Association for the Study of Pain has defined chronic pain as pain lasting more than 3 months.20International Association for the Study of Pain Classification of chronic pain. Descriptions of chronic pain syndromes and definitions of pain terms. Prepared by the International Association for the Study of Pain, Subcommittee on Taxonomy.Pain Suppl. 1986; 3: S1-226PubMed Google Scholar However, with the modern use of synthetic mesh for hernia repair, an inflammatory response may last a couple of months as a result of a reaction against the foreign material. The criteria for inclusion in this review were therefore: studies of pain more than/equal to 6 months after hernia surgery and including more than/equal to 100 patients. A search was made using the PUBMED search engine (National Centre for Biotechnology Information, US National Library of Medicine, USA), and the Ovid search engine (Ovid Technologies, Wolters Kluwer, Amsterdam, The Netherlands). We searched both databases in May 2004 and covered the period January 2000 through to April 2004. The term ‘pain’ was combined with the term ‘hernia, inguinal’. Other words associated with pain were explored, such as ‘neuropathy’, ‘discomfort’, ‘complications’, ‘consequences’, and ‘results’. The search was restricted to ‘adult 19+’ and ‘English language’. In addition, some articles published during the review process after April 2004 were included, as were articles known by the authors, but not found in the databases. References were crosschecked for literature not found in the database search. Reviews were checked for additional studies. Letters to the editor and abstracts were not included. Data extracted from each study were: number of patients included in the original study, follow-up rate and period, frequency and severity of pain at a given time, method of pain assessment, pain descriptors, and type of surgery (mesh vs non-mesh vs laparoscopic repair). If available, data on preoperative and early postoperative pain were extracted, as were any data regarding impairments in physical, social, psychological, or sexual functions. To calculate the incidence of pain, we analysed the number of patients responding at the time of data collection. If more than one follow-up date was noted, data from the follow up closest to 1 yr were extracted, and we only included studies where the data had been collected systematically. Exclusion criteria were: articles already included in the previous review,44Poobalan AS Bruce J Smith WC et al.A review of chronic pain after inguinal herniorrhaphy.Clin J Pain. 2003; 19: 48-54Crossref PubMed Scopus (413) Google Scholar although studies relevant to pathogenic mechanisms are quoted in the section on interpretation and future strategies; studies with less than 6 months follow up; and studies with unclear definitions of pain and its assessment. Our search yielded 111 articles, of which 62 articles were not identified beyond the abstract as they had a follow up of less than 6 months or less than 100 patients. The remaining 59 articles were studied for full critical review, and 35 articles fulfilled the inclusion criteria by evaluating postoperative pain beyond 6 months in more than/equal to 100 patients. The studies fell into two major categories: randomized controlled trials and non-randomized studies. There was no correlation between study type and frequency of pain reported, but a significantly lower incidence of pain in single centre studies compared with multicentre studies in open surgery (χ2=72, P<0.01), and laparoscopic surgery (χ2= 15, P<005). The incidence of pain was not correlated to study size. Pain was the primary outcome in only 16 studies,3Bay-Nielsen M Perkins FM Kehlet H Pain and functional impairment 1 year after inguinal herniorrhaphy: a nationwide questionnaire study.Ann Surg. 2001; 233: 1-7Crossref PubMed Scopus (482) Google Scholar6Bozuk M Schuster R Stewart D et al.Disability and chronic pain after open mesh and laparoscopic inguinal hernia repair.Am Surg. 2003; 69: 839-841PubMed Google Scholar10Courtney CA Duffy K Serpell MG et al.Outcome of patients with severe chronic pain following repair of groin hernia.Br J Surg. 2002; 89: 1310-1314Crossref PubMed Scopus (200) Google Scholar13Douek M Smith G Oshowo A et al.Prospective randomised controlled trial of laparoscopic versus open inguinal hernia mesh repair: five year follow up.Br Med J. 2003; 326: 1012-1013Crossref PubMed Scopus (105) Google Scholar17Haapaniemi S Nilsson E Recurrence and pain three years after groin hernia repair. Validation of postal questionnaire and selective physical examination as a method of follow-up.Eur J Surg. 2002; 168: 22-28Crossref PubMed Scopus (94) Google Scholar24Kumar S Wilson RG Nixon SJ et al.Chronic pain after laparoscopic and open mesh repair of groin hernia.Br J Surg. 2002; 89: 1476-1479Crossref PubMed Scopus (224) Google Scholar25Lau H Patil NG Yuen WK et al.Prevalence and severity of chronic groin pain after endoscopic totally extraperitoneal inguinal hernioplasty.Surg Endosc. 2003; 17: 1620-1623Crossref PubMed Scopus (59) Google Scholar27Liem MS van Duyn EB van der GY et al.Recurrences after conventional anterior and laparoscopic inguinal hernia repair: a randomized comparison.Ann Surg. 2003; 237: 136-141Crossref PubMed Scopus (152) Google Scholar30Miedema BW Ibrahim SM Davis BD et al.A prospective trial of primary inguinal hernia repair by surgical trainees.Hernia. 2004; 8: 28-32Crossref PubMed Scopus (25) Google Scholar31Mikkelsen T Werner MU Lassen B et al.Pain and sensory dysfunction 6 to 12 months after inguinal herniotomy.Anesth Analg. 2004; 99: 146-151Crossref PubMed Scopus (133) Google Scholar39Paajanen H Do absorbable mesh sutures cause less chronic pain than nonabsorbable sutures after Lichtenstein inguinal herniorraphy?.Hernia. 2002; 6: 26-28Crossref PubMed Scopus (71) Google Scholar40Page B Paterson C Young D et al.Pain from primary inguinal hernia and the effect of repair on pain.Br J Surg. 2002; 89: 1315-1318Crossref PubMed Scopus (108) Google Scholar42Picchio M Palimento D Attanasio U et al.Randomized controlled trial of preservation or elective division of ilioinguinal nerve on open inguinal hernia repair with polypropylene mesh1.Arch Surg. 2004; 139: 755-758Crossref PubMed Scopus (97) Google Scholar43Poobalan AS Bruce J King PM et al.Chronic pain and quality of life following open inguinal hernia repair.Br J Surg. 2001; 88: 1122-1126Crossref PubMed Scopus (356) Google Scholar51Sondenaa K Nesvik I Breivik K et al.Long-term follow-up of 1059 consecutive primary and recurrent inguinal hernias in a teaching hospital.Eur J Surg. 2001; 167: 125-129Crossref PubMed Scopus (30) Google Scholar54Tsakayannis DE Kiriakopoulos AC Linos DA Elective neurectomy during open, ‘tension free’ inguinal hernia repair.Hernia. 2004; 8: 67-69Crossref PubMed Scopus (35) Google Scholar and there was a significantly higher incidence of chronic pain in these studies (25 vs 7%, χ2=611, P<0.01) (range 0–76%), compared with studies with chronic pain as a secondary outcome. Similarly, Poobalan and co-workers44Poobalan AS Bruce J Smith WC et al.A review of chronic pain after inguinal herniorrhaphy.Clin J Pain. 2003; 19: 48-54Crossref PubMed Scopus (413) Google Scholar found a 15–53% incidence of chronic pain in four studies with pain as the primary outcome. There was no correlation between the incidence of pain in relation to follow up. However, the literature does not contain data from a large patient cohort studied in detail and prospectively over a prolonged period. In a study10Courtney CA Duffy K Serpell MG et al.Outcome of patients with severe chronic pain following repair of groin hernia.Br J Surg. 2002; 89: 1310-1314Crossref PubMed Scopus (200) Google Scholar of 120 patients, from an earlier study18Hair A Duffy K McLean J et al.Groin hernia repair in Scotland.Br J Surg. 2000; 87: 1722-1726Crossref PubMed Scopus (173) Google Scholar of 4076 patients, that reported severe or very severe pain 3 months after the operation, 71% still reported pain after 2.5 yr, but only 26% of the 120 patients then described the pain as severe or very severe, suggesting a ‘burn out’ effect of the pain complaints. In a prospective randomized trial26Leibl BJ Daubler P Schmedt CG et al.Long-term results of a randomized clinical trial between laparoscopic hernioplasty and shouldice repair.Br J Surg. 2000; 87: 780-783Crossref PubMed Scopus (64) Google Scholar in 102 patients comparing Shouldice's procedure to laparoscopy, no patients complained of pain in the laparoscopic group, but 46% in the Shouldice had complaints after 1 yr, and 16% after 6 yr. However, there was no clear definition of the terms ‘pain’ or ‘complaints’, making interpretation difficult. Two other studies55Tschudi JF Wagner M Klaiber C et al.Randomized controlled trial of laparoscopic transabdominal preperitoneal hernioplasty vs shouldice repair.Surg Endosc. 2001; 15: 1263-1266Crossref PubMed Scopus (38) Google Scholar59Wright D Paterson C Scott N et al.Five-year follow-up of patients undergoing laparoscopic or open groin hernia repair: a randomized controlled trial.Ann Surg. 2002; 235: 333-337Crossref PubMed Scopus (164) Google Scholar with more than 1 yr follow up, described declining pain incidences when patients were seen at 6, 12, 24, or 60 months after surgery, but again the specific time-course data on frequency and intensity were not presented from the same group of patients. In a study36Neumayer L Giobbie-Hurder A Jonasson O et al.Open mesh versus laparoscopic mesh repair of inguinal hernia.N Engl J Med. 2004; 350: 1819-1827Crossref PubMed Scopus (773) Google Scholar of 1983 patients assigned to either laparoscopy or open-mesh hernia repair, most cases of long-term pain (about 12%) persisted from the early postoperative period, but in others it was a new phenomenon observed at a long-term visit, but without presentation of specific data. An earlier study11Cunningham J Temple WJ Mitchell P et al.Cooperative hernia study. Pain in the post repair patient.Ann Surg. 1996; 224: 598-602Crossref PubMed Scopus (314) Google Scholar found an incidence of moderate or severe pain in 55% of 276 patients in the immediate postoperative period, which was reduced to 12% after 1 yr and 11% after 2 yr, but the study had a low follow-up rate of only 38%. In a recent study42Picchio M Palimento D Attanasio U et al.Randomized controlled trial of preservation or elective division of ilioinguinal nerve on open inguinal hernia repair with polypropylene mesh1.Arch Surg. 2004; 139: 755-758Crossref PubMed Scopus (97) Google Scholar of 391 patients treated with hernia mesh-repair, 28% complained of mild pain, 17% of moderate pain, and 6% of severe pain at the 1-month follow up. After 6 months, the numbers were 25, 9, and 3%, and after 1 yr 18, 4, and 2%, respectively. Pain was assessed by a four-point verbal scale, but was not corrected for age or activity level. These studies suggest that some patients improve over time, but overall there is a lack of well-designed prospective studies in well-defined groups of patients to assess and quantify the time course of chronic post-herniorrhaphy pain. Only four studies compared patient age with the occurrence of chronic pain,3Bay-Nielsen M Perkins FM Kehlet H Pain and functional impairment 1 year after inguinal herniorrhaphy: a nationwide questionnaire study.Ann Surg. 2001; 233: 1-7Crossref PubMed Scopus (482) Google Scholar10Courtney CA Duffy K Serpell MG et al.Outcome of patients with severe chronic pain following repair of groin hernia.Br J Surg. 2002; 89: 1310-1314Crossref PubMed Scopus (200) Google Scholar43Poobalan AS Bruce J King PM et al.Chronic pain and quality of life following open inguinal hernia repair.Br J Surg. 2001; 88: 1122-1126Crossref PubMed Scopus (356) Google Scholar59Wright D Paterson C Scott N et al.Five-year follow-up of patients undergoing laparoscopic or open groin hernia repair: a randomized controlled trial.Ann Surg. 2002; 235: 333-337Crossref PubMed Scopus (164) Google Scholar and found that the risk of chronic pain decreased with increasing age, from 39 to 58% in patients less than 40 yr to 14–17% in patients more than 65 yr. The fraction of patients with severe or very severe pain was also higher in the younger group. However, an overall interpretation of the data is hindered by the lack of data on physical activities, which may be different between the age groups, and consequently for their complaints. Disappointingly, few studies had data on preoperative pain frequency and intensity. In a study of 300 patients,59Wright D Paterson C Scott N et al.Five-year follow-up of patients undergoing laparoscopic or open groin hernia repair: a randomized controlled trial.Ann Surg. 2002; 235: 333-337Crossref PubMed Scopus (164) Google Scholar 88% of patients that developed chronic pain had pain at the preoperative assessment, compared with 59% of patients without chronic pain (P<0.001). Another study43Poobalan AS Bruce J King PM et al.Chronic pain and quality of life following open inguinal hernia repair.Br J Surg. 2001; 88: 1122-1126Crossref PubMed Scopus (356) Google Scholar also found a significant predictive value (P<0.005) between preoperative pain, and chronic pain. A study of 323 patients40Page B Paterson C Young D et al.Pain from primary inguinal hernia and the effect of repair on pain.Br J Surg. 2002; 89: 1315-1318Crossref PubMed Scopus (108) Google Scholar showed that herniorrhaphy reduced the preoperative global pain score for the patient population but that some of the patients (numbers not shown) without a history of preoperative pain developed pain at the hernia repair site 1 yr after surgery. In contrast, a large randomized study27Liem MS van Duyn EB van der GY et al.Recurrences after conventional anterior and laparoscopic inguinal hernia repair: a randomized comparison.Ann Surg. 2003; 237: 136-141Crossref PubMed Scopus (152) Google Scholar of 994 patients found no significant relation between the development of chronic and preoperative pain (P=0.2). The MRC study found that 30% of patients reported no change in pain from before to after surgery, but that 5% felt worse than before the herniorrhaphy.53The MRC Laparoscopic Groin Hernia Trial Group Laparoscopic versus open repair of groin hernia: a randomised comparison. The MRC Laparoscopic Groin Hernia Trial Group.Lancet. 1999; 354: 185-190Abstract Full Text Full Text PDF PubMed Scopus (334) Google Scholar Preoperative chronic pain conditions such as headache, back pain, irritable bowel syndrome, pain from scars elsewhere in the body, and peptic ulcer were found to be significantly correlated with the development of chronic pain in two studies.10Courtney CA Duffy K Serpell MG et al.Outcome of patients with severe chronic pain following repair of groin hernia.Br J Surg. 2002; 89: 1310-1314Crossref PubMed Scopus (200) Google Scholar59Wright D Paterson C Scott N et al.Five-year follow-up of patients undergoing laparoscopic or open groin hernia repair: a randomized controlled trial.Ann Surg. 2002; 235: 333-337Crossref PubMed Scopus (164) Google Scholar However, there is a lack of detailed information on the type of chronic preoperative pain and psychological factors, hindering proper interpretation. In conclusion, the available data suggest that preoperative pain may increase the risk of developing chronic pain but more studies are required with a detailed analysis of the history and type of pain complained of in other parts of the body than the inguinal area. Studies that had gender-specific data showed the highest pain incidence in women. Thus, a nationwide study3Bay-Nielsen M Perkins FM Kehlet H Pain and functional impairment 1 year after inguinal herniorrhaphy: a nationwide questionnaire study.Ann Surg. 2001; 233: 1-7Crossref PubMed Scopus (482) Google Scholar of 1071 patients with a follow up of 81%, found a 38% incidence of chronic pain in female patients compared with 28% in males (χ2=3.87, P<0.05). Similarly, in a study where 15% of 224 patients undergoing mesh hernia repair were women, three of the four patients with continuous pain were women resulting in an incidence of chronic pain of 0.5% in males vs 8.8% in females.34Mori T Souda S Nezu R et al.Results of performing mesh plug repair for groin hernias.Surg Today. 2001; 31: 129-132Crossref PubMed Scopus (13) Google Scholar In a retrospective study of 594 men and 56 women, 3% of males and 11% of female patients developed chronic pain.51Sondenaa K Nesvik I Breivik K et al.Long-term follow-up of 1059 consecutive primary and recurrent inguinal hernias in a teaching hospital.Eur J Surg. 2001; 167: 125-129Crossref PubMed Scopus (30) Google Scholar Contrary to these findings, a non-significant (P=0.84) odds ratio of 0.9 for chronic pain in females were found in a study of 994 patients.27Liem MS van Duyn EB van der GY et al.Recurrences after conventional anterior and laparoscopic inguinal hernia repair: a randomized comparison.Ann Surg. 2003; 237: 136-141Crossref PubMed Scopus (152) Google Scholar In conclusion, these findings suggest that females are at a higher risk of developing chronic pain than males. These results are in accordance with studies after other surgical procedures, which demonstrate that females may report increased intensity of acute postoperative pain.28Logan DE Rose JB Gender differences in post-operative pain and patient controlled analgesia use among adolescent surgical patients.Pain. 2004; 109: 481-487Abstract Full Text Full Text PDF PubMed Scopus (65) Google Scholar52Taenzer AH Clark C Curry CS Gender affects report of pain and function after arthroscopic anterior cruciate ligament reconstruction.Anesthesiology. 2000; 93: 670-675Crossref PubMed Scopus (79) Google Scholar Two studies found no significant relation between BMI and complications.43Poobalan AS Bruce J King PM et al.Chronic pain and quality of life following open inguinal hernia repair.Br J Surg. 2001; 88: 1122-1126Crossref PubMed Scopus (356) Google Scholar49Schmedt CG Daubler P Leibl BJ et al.Simultaneous bilateral laparoscopic inguinal hernia repair: an analysis of 1336 consecutive cases at a single center.Surg Endosc. 2002; 16: 240-244Crossref PubMed Scopus (52) Google Scholar Four other studies measured weight as a preoperative variable but the articles did not report whether this was a predisposing factor.27Liem MS van Duyn EB van der GY et al.Recurrences after conventional anterior and laparoscopic inguinal hernia repair: a randomized comparison.Ann Surg. 2003; 237: 136-141Crossref PubMed Scopus (152) Google Scholar35Muldoon RL Marchant K Johnson DD et al.Lichtenstein vs anterior preperitoneal prosthetic mesh placement in open inguinal hernia repair: a prospective, randomized trial.Hernia. 2004; 8: 98-103Crossref PubMed Scopus (49) Google Scholar55Tschudi JF Wagner M Klaiber C et al.Randomized controlled trial of laparoscopic transabdominal preperitoneal hernioplasty vs shouldice repair.Surg Endosc. 2001; 15: 1263-1266Crossref PubMed Scopus (38) Google Scholar57Vrijland WW van den Tol MP Luijendijk RW et al.Randomized clinical trial of non-mesh versus mesh repair of primary inguinal hernia.Br J Surg. 2002; 89: 293-297Crossref PubMed Scopus (129) Google Scholar In most of the studies reviewed, the study population was a combination of patients undergoing herniorrhaphy for either primary or recurrent hernia, and the data on chronic pain were not specified for primary or recurrent herniorrhaphy. Only five studies compared the risk of chronic pain in these two groups. One prospective, randomized trial27Liem MS van Duyn EB van der GY et al.Recurrences after conventional anterior and laparoscopic inguinal hernia repair: a randomized comparison.Ann Surg. 2003; 237: 136-141Crossref PubMed Scopus (152) Google Scholar and two retrospective questionnaire studies10Courtney CA Duffy K Serpell MG et al.Outcome of patients with severe chronic pain following repair of groin hernia.Br J Surg. 2002; 89: 1310-1314Crossref PubMed Scopus (200) Google Scholar17Haapaniemi S Nilsson E Recurrence and pain three years after groin hernia repair. Validation of postal questionnaire and selective physical examination as a method of follow-up.Eur J Surg. 2002; 168: 22-28Crossref PubMed Scopus (94) Google Scholar found no correlation between surgery for recurrent hernia and a risk of chronic pain. In contrast, a study of 351 patients found that an operation for a recurrent hernia significantly increased the risk of chronic pain 4-fold (P=0.005).43Poobalan AS Bruce J King PM et al.Chronic pain and quality of life following open inguinal hernia repair.Br J Surg. 2001; 88: 1122-1126Crossref PubMed Scopus (356) Google Scholar Also, a detailed prospective study9Callesen T Bech K Kehlet H Prospective study of chronic pain after groin hernia repair.Br J Surg. 1999; 86: 1528-1531Crossref PubMed Scopus (358) Google Scholar of 419 patients of which 21% were operated on for a recurrent hernia found a significant higher incidence of moderate or severe chronic pain 12 months after operation compared with primary herniorrhaphy (14 vs 3%, P<0.01). Based on these two latter studies of high quality it may be concluded that surgery for a recurrent hernia increases the risk for development of chronic pain, probably related to a technically more difficult operation with a higher risk of nerve damage. Employment was found to be a risk factor for chronic pain when employed patients where compared with their retired counterparts.43Poobalan AS Bruce J King PM et al.Chronic pain and quality of life following open inguinal hernia repair.Br J Surg. 2001; 88: 1122-1126Crossref PubMed Scopus (356) Google Scholar However, this finding was not corrected for patient age or physical activity. An earlier study found that patients receiving workers' compensation for work-related injury had a higher risk of developing chronic pain after 6 months.48Salcedo-Wasicek MC Thirlby RC Postoperative course after inguinal herniorrhaphy. A case-controlled comparison of patients receiving workers' compensation vs patients with commercial insurance.Arch Surg. 1995; 130: 29-32Crossref PubMed Scopus (108) Google Scholar Studies that fulfilled the inclusion criteria for calculation of the overall incidence of pain yielded 7658 patients that had been treated by open procedures and 7998 that had been treated by laparoscopic surgery, all of whom had been questioned or examined for pain at the time of data collection.3Bay-Nielsen M Perkins FM Kehlet H Pain and functional impairment 1 year after inguinal herniorrhaphy: a nationwide questionnaire study.Ann Surg. 2001; 233: 1-7Crossref PubMed Scopus (482) Google Scholar4Bell RC Price JG Laparoscopic inguinal hernia repair using an anatomically contoured three-dimensional mesh.Surg Endosc. 2003; 17: 1784-1788Crossref PubMed Scopus (28) Google Scholar6Bozuk M Schuster R Stewart D et al.Disability and chronic pain after open mesh and laparoscopic inguinal hernia repair.Am Surg. 2003; 69: 839-841PubMed Google Scholar7Bringman S Ramel S Heikkinen TJ et al.Tension-free inguinal hernia repair: TEP versus mesh-plug versus Lichtenstein: a prospective randomized controlled trial.Ann Surg. 2003; 237: 142-147Crossref PubMed Scopus (182) Google Scholar10Courtney CA Duffy K Serpell MG et al.Outcome of patients with severe chronic pain following repair of groin hernia.Br J Surg. 2002; 89: 1310-1314Crossref PubMed Scopus (200) Google Scholar13Douek M Smith G Oshowo A et al.Prospective randomised controlled trial of laparoscopic versus open inguinal hernia mesh repair: five year follow up.Br Med J. 2003; 326: 1012-1013Crossref PubMed Scopus (105) Google Scholar17Haapaniemi S Nilsson E Recurrence and pain three years after groin hernia repair. Validation of postal questionnaire and selective physical examination as a method of follow-up.Eur J Surg. 2002; 168: 22-28Crossref PubMed Scopus (94) Google Scholar19Heikkinen T Bringman S Ohtonen P et al.Five-year outcome of laparoscopic and Lichtenstein hernioplasties.Surg Endosc. 2004; 18: 518-522Crossref PubMed Scopus (92) Google Scholar23Khajanchee YS Urbach DR Swanstrom LL et al.Outcomes of laparoscopic herniorrhaphy without fixation of mesh to the abdominal wall.Surg Endosc. 2001; 15: 1102-1107Crossref PubMed Scopus (57) Google Scholar, 24Kumar S Wilson RG Nixon SJ et al.Chronic pain after laparoscopic and open mesh repair of groin hernia.Br J Surg. 2002; 89: 1476-1479Crossref PubMed Scopus (224) Google Scholar, 25Lau H Patil NG Yuen WK et al.Prevalence and severity of chronic groin pain after endoscopic totally extraperitoneal inguinal hernioplasty.Surg Endosc. 2003; 17: 1620-1623Crossref PubMed Scopus (59) Google Scholar, 26Leibl BJ Daubler P Schmedt CG et al.Long-term results of a randomized clinical trial between laparoscopic hernioplasty and shouldice repair.Br J Surg. 2000; 87: 780-783Crossref PubMed Scopus (64) Google Scholar, 27Liem MS v