Surgical management of chronic inguinal pain syndromes - Liespijn

INTRODUCTIONThe introduction of mesh techniques in groin hernia surgery has reduced recurrencerates but has rekindled interest in postherniorrhaphy pain syndromes. Several tools forassessment of pain severity are currently utilized. The McGill Pain Questionnaire 1 and theWisconsin Brief Pain Questionnaire 2 are multidimensional pain questionnaires assessingsensory, affective and evaluative aspects of pain. In contrast, the Visual Analogue Scale(VAS), Verbal Rating Scale (VRS) and Numerical Rating Scale (NRS) are simple unidimensionaltests which only rate sensory components of pain and omit affective andpsychosocial pain aspects. Researchers often rely on unidimensional systems 3 as multidimensionalquestionnaires are generally considered too long and too complicated.The widely used VAS represents a 100 mm horizontal line with on the one end written‘no pain’ (score 0) and on the other end ‘unbearable pain’ (score 100). Individuals areinstructed to put a mark along this line at a position that is currently reflecting theirintensity of pain. A VAS test may allow for rapid completion and harbours a high sensitivity.However, its conceptual complexity may result in a high non-compliance rate orscale failure, particularly in elderly patients with cognitive and psychomotor impairments4 . In contrast, a VRS exists in several versions ranging from a simple 4-point(no pain, mild, moderate or severe pain) to a more complex 15-point list. A VRS excels insimplicity but may lack sensitivity due to its ordinal character 4 .Author Year Unidimensional Multidimensional1. Cunningham 8 1996 NRS/ VRS (4-point)2. Callesen 9 1999 VRS (4-point)3. Bay-Nielsen 10 2001 VRS (4-point)4. Poobalan 11 2001 McGill 45. Courtney 12 2002 SF-36 5 / Wisconsin 66. Page 5 2002 VAS 37. Kumar 13 2002 Presence of pain/discomfort?8. Lau 14 2003 VRS (4-point)9. Mikkelsen 18 2004 McGill10. Grant 15 2004 VRS (5-point)11. Nienhuijs 6 2005 VAS12. O’Dwyer 16 2005 VAS/ VRS (5-point)13. Franneby 17 2006 DIBS 714. Loos 7 2007 VASTable 1 Pain measurement tools used in postherniorrhaphy groin pain literature.NRS = Numerical Rating Scale, VRS = Verbal Rating Scale, VAS = Visual Analogue Scale, McGill = McGill Pain questionnaire,SF-36 = Short-Form 36, Wisconsin = Wisconsin Brief Pain questionnaire, DIBS = Duration-Intensity-Behavior-Scale.The ideal pain assessment tool should be determined by type of pain and the settingin which it is measured. Unidimensional scales have routinely been employed in theevaluation of postherniorrhaphy groin pain syndromes. Which pain rating scale servesbest under these circumstances is unknown since a gold standard is lacking. A randomlist of groin pain studies and employed pain assessment tools is depicted in Table 1 5-8 .Some investigators used VAS tests to investigate groin pain intensity 5,6 . To convert VASinto VRS scores, cut-off points are mandatory. These investigators introduced VAS cutoffpoints on arbitrary grounds (0 mm = no pain, 50 mm = severe pain) 5 while other general pain researchers suggested differentcut-off points 19-22 .Aim of this study was to evaluate two frequently used pain rating scales (VAS and4-point VRS) for scale failure, and to determine which test performs better in patientsfollowing groin hernia repair.PATIENT AND METHODSThe present study was based on pain data obtained from a questionnaire among postherniorrhaphycases 7 . Patients with a groin hernia repair between January 2000 andAugust 2005 in the Máxima Medical Center received a postal questionnaire in February2006. The Máxima Medical Center is a teaching hospital serving a total population ofapproximately 175,000 inhabitants. Each individual was asked to grade their presentgroin pain intensity on a 4-point VRS (no pain, mild, moderate or severe pain) followedby a VAS (0-100 mm). Brief written instructions regarding the VAS were providedwhereas VRS instructions were deemed unnecessary. Results were analyzed for scalefailure, which was defined as a situation in which the patient did not complete the painrating scale, or if the response could not be coded to a unique score.Statistical analysis was carried out using the Statistical Package for the Social Sciences(SPSS), Windows version 12.0.1. An ‘outlier’ in Figure 1 was defined as a position between1.5 and 3 box lengths from the upper or lower interquartile range. Similarly, an ‘extremecase’ was defined as a position more than 3 box lengths removed from the upper orlower interquartile range. Mean and median VAS scores per VRS category with standarddeviation and range were calculated. Frequency distribution of paired VAS-VRS datausing different cut-off points for VAS classification was evaluated by means of squarecontingency tables. Optimal VAS cut-off points were identified in such a way that theVAS-classification concurred optimally with VRS-answers creating the optimal kappacoefficient. Using these optimal cut-off points, a subgroup analysis for sex and age wascarried out to detect any difference in kappa. Kappa coefficients were compared afterapplication of Page’s cut-off points 5 (0 mm= no pain, 50 mm = severe pain) on the current data set.54 Chapter 4Evaluating postherniorrhaphy groin pain: Visual Analogue or Verbal Rating Scale? 55