UNIVERSITY OF CALGARY How do we measure vulvar pain? Objective measurement of a subjective parameter by Magali Berthe Marie Therese Colette Robert A THESIS SUBMITTED TO THE FACULTY OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF COMMUNITY HEALTH SCIENCES CALGARY, ALBERTA JUNE, 2012 Magali Berthe Marie Therese Colette Robert 2012
UNIVERSITY OF CALGARY FACULTY OF GRADUATE STUDIES The undersigned certify that they have read, and recommend to the Faculty of Graduate Studies for acceptance, a thesis entitled "How do we measure vulvar pain? Objective measurement of a subjective parameter" submitted by Magali Berthe Marie Therese Colette Robert in partial fulfilment of the requirements of the degree of Master of Science. Supervisor, Dr. Sue Ross, Department of Obstetrics and Gynecology, Surgery, Family Medicine, and Community Health Sciences Dr. Misha Eliasziw, Department of Community Health Sciences Dr. Paul Taenzer, Department of Medicine, Psychiatry and Oncology Dr. Kathleen Oberle, Faculty of Nursing May, 2012 ii
Abstract Objectives The objective of the research was to explore the possible relationships of commonly used pain measures in women suffering from vulvar pain. Methods Characterization of the pain profiles of a twenty women cohort presenting with vulvar pain was undertaken. Descriptive analysis was used to describe the cohort. Scatter plots were used to explore the relationships between the vulvalgesiometer pain thresholds, the McGill Pain Questionnaire responses and modified visual analogue scale scores. Spearman s correlation coefficient of Rho greater than eight was considered important. Results The cohort was representative of the spectrum of women suffering from vulvar pain. There was no correlation between the different pain measures. This was seen on scatter plots and confirmed with Spearman correlation coefficients less than eight. Conclusion There is no correlation between the commonly used pain measures in women presenting with vulvar pain. Better characterization and understanding of women suffering from vulvar pain is required. iii
Acknowledgements This thesis is the collective work of many individuals: Thank you especially to Dr. Sue Ross for her guidance, energy and eternal patience. The valuable input from Drs. Misha Eliasziw and Paul Taenzer was much appreciated. Thank you to Drs. Kim Fisher, John Jarrell and Ann Carlson for the preliminary study which led to this thesis. iv
Dedication To my children, Jasmine and Darya, and my husband Farshad: just for being. v
Table of Contents Approval Page... ii Abstract... iii Acknowledgements... iv Dedication...v Table of Contents... vi List of Tables...x List of Figures and Illustrations... xii Chapter 1: Introduction 1 1.0 Background 1 2.0 Vulvodynia 1 3.0 Measurement of the pain experience 9 3.1 Chronic pain 9 3.1.1 Quantifying pain 10 3.1.2 Qualifying pain 10 3.1.3 Beyond pain measures 12 3.2 Pain measurement in vulvodynia 15 3.2.1 Quantifying pain in vulvodynia 17 3.2.2 Measuring pain experience in vulvodynia 17 4.0 Synthesis 19 Chapter 2: Research objectives 21 1.0 The relationship amongst pain measures 21 2.0 Objective of the research 21 3.0 Specific questions 22 vi
Chapter 3: Methods 23 1.0 Primary trial: 2002 23 1.1 Objectives 23 1.2 Participants 23 1.3 Study protocol 24 1.3.1 Initial study visit 24 1.3.2 Assessment 24 1.3.2.1 Multidimentional inventory 25 1.3.2.2 Physical examination 26 1.4 Sample size 27 1.5 Publication 27 2.0 Thesis research: 2009 28 2.1 Objectives 28 2.2 Rational 28 2.3 Ethics approval 29 2.4 Population 29 2.5 Protocol 30 2.6 Sample size justification 30 2.7 Data entry and management 30 2.8 Analysis 31 2.9 Null hypothesis 32 3.0 Summary 32 vii
Chapter 4: Results 33 1.0 Descriptive analysis 33 1.1 Pain characteristics 36 1.2 McGill Pain Questionnaire 36 1.3 Pain intensity 39 2.0 Correlation of pain measures 40 2.1 Scatter diagram 40 2.2 Spearman correlation calculation 45 2.3 Summary 47 3.0 Removing outliers 48 4.0 Summary 51 Chapter5: Discussion 52 1.0 Importance of vulvar pain measurement 52 2.0 Summary of findings 52 2.1 Expected findings 53 2.1.1 McGill pain questionnaire 53 2.2 Unexpected findings 54 2.2.1 VAS 54 2.2.1.1 Vas reported pain in past month 54 2.2.1.2 VAS reported pain at moment 55 2.2.1.3 VAS reported pain with intercourse 55 2.2.2 VAS general 55 viii
2.2.3 Vulvalgesiometer 56 2.2.4 McGill pain questionnaire 57 2.2.5 Outliers 58 3.0 Epidemiological and clinical relevance 59 4.0 Pain measurement 60 4.1 Sampling error 60 4.2 Measures 63 4.2.1 Reliability 63 4.2.2 Validity 63 4.2.3 Confounders 64 5.0 Pain measures in general 65 6.0 Study appraisal 67 6.1 Strengths of the study 67 6.2 Weaknesses 68 6.3 Limitations 69 7.0 Implications of the study 70 8.0 Future direction 71 References 74 Appendix A: Illustration of vulvar vestibule 83 Appendix B: Physician evaluation 84 ix
List of Tables Table 1: Report of outcome measures of published studies on vulvodynia from 1999 to April 2011 5 Table 2: Pain descriptors with pain threshold testing (Pukall et al., 2004) 17 Table 3: Demographics of cohort 34 Table 4: General pain characteristics of cohort 35 Table 5: Distribution of responses to the MPQ 37 Table 6: Distribution of PRI scores of MPQ 38 Table 7: Distribution of VAS responses 40 Table 8: Spearman s correlation comparing minimum average pain thresholds (g), MPQ measures and VAS scores to average of total pain thresholds (g) 45 Table 9: Spearman s correlation comparing MPQ measures and VAS scores to minimum pain threshold (g) 46 Table 10: Spearman s correlation of the McGill pain descriptor numbers and pain measured by VAS 46 Table 11: Spearman s correlation of pain assessment by VAS at different times 47 Table 12: Spearman s correlation of average of total pain thresholds (g) to outcome measures (outliers removed) 50 Table 13: Spearman s correlation of minimum pain threshold (maximum pain) (g) and other measures of pain (outliers removed) 50 Table 14: Spearman s correlation of the McGill pain descriptor numbers and pain measured by VAS (outliers removed) 50 x
Table 15: Spearman s correlation of pain assessment by VAS at different times (outliers removed) 51 xi
List of Figures and Illustrations Figure 1: Common pain descriptors of MPQ 36 Figure 2: Pain intensity profiles as described on modified VAS 39 Figure 3: Scatter plot of average of total pain thresholds (g) and average of hymenal pain thresholds (g) as defined in appendix B 41 Figure 4: Scatter plot of average of total pain thresholds (g) and minimum pain threshold (g) 42 Figure 5: Scatter plot of average of total pain thresholds (g) and number of descriptors of McGill pain questionnaire 43 Figure 6: Scatter plot of average of total pain thresholds (g) and VAS pain at moment 44 Figure 7: Scatter plot of number of descriptors of McGill pain questionnaire and VAS pain at the moment 45 Figure 8: Scatter plot of average of total pain thresholds (g) and average of hymenal pain thresholds (g) (outliers removed) 48 Figure 9: Scatter plot of number of descriptors of McGill pain questionnaire and VAS pain at the moment (outliers removed) 49 xii