Background: Chronic postoperative inguinal pain (CPIP) is the most common long-term complication of inguinal hernia repair. As such procedures are routinely performed, CPIP can be considered a significant burden to global health care. Therefore, adequate preventative measures relevant to surgical practice are investigated. However, as no gold standard research approach is currently available, study and outcome measures differ between studies. The current review aims to provide a qualitative analysis of the literature to seek out if outcomes of CPIP are valid and comparable, facilitating recommendations on the best approach to preventing CPIP. Methods: A systematic review of recent studies investigating CPIP was performed, comprising studies published in 2007-2015. Study designs were analyzed regarding the CPIP definitions applied, the use of validated instruments, the availability of a baseline score, and the existence of a minimal follow-up of 12 months. Results: Eighty eligible studies were included. In 48 studies, 22 different definitions of CPIP were identified, of which the definition provided by the International Association for the Study of Pain was applied most often. Of the studies included, 53 (66%) used 33 different validated instruments to quantify CPIP. There were 32 studies (40%) that assessed both pain intensity (PI) and quality of life (QOL) with validated tools, 41% and 4% had a validated assessment of only PI or QOL, respectively, and 15% lacked a validated assessment. The visual analog scale and the Short Form 36 (SF36) were most commonly used for measuring PI (73%) and QOL (19%). Assessment of CPIP was unclear in 15% of the studies included. A baseline score was assessed in 45% of the studies, and 75% had a follow-up of at least 12 months. Conclusion: The current literature addressing CPIP after inguinal hernia repair has a variable degree of quality and lacks uniformity in outcome measures. Proper comparison of the study results to provide conclusive recommendations for preventive measures against CPIP therefore remains difficult. These findings reaffirm the need for a uniform and validated assessment with uniform reporting of outcomes to improve the burden that CPIP poses to a significant surgical patient population.

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Keywords Chronic pain, Hernia, Outcome definition, Quality of life, Uniform assessment
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Journal European Surgical Research: clinical and experimental surgery
Molegraaf, M.J, Lange, J.F, & Wijsmuller, A.R. (2017). Uniformity of Chronic Pain Assessment after Inguinal Hernia Repair: A Critical Review of the Literature. European Surgical Research: clinical and experimental surgery (Vol. 58, pp. 1–19). doi:10.1159/000448706