UNIVERSITY OF CALGARY. How do we measure vulvar pain? Objective measurement of a subjective parameter. Magali Berthe Marie Therese Colette Robert

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1 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

2 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

3 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

4 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

5 Dedication To my children, Jasmine and Darya, and my husband Farshad: just for being. v

6 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 Background Vulvodynia Measurement of the pain experience Chronic pain Quantifying pain Qualifying pain Beyond pain measures Pain measurement in vulvodynia Quantifying pain in vulvodynia Measuring pain experience in vulvodynia Synthesis 19 Chapter 2: Research objectives The relationship amongst pain measures Objective of the research Specific questions 22 vi

7 Chapter 3: Methods Primary trial: Objectives Participants Study protocol Initial study visit Assessment Multidimentional inventory Physical examination Sample size Publication Thesis research: Objectives Rational Ethics approval Population Protocol Sample size justification Data entry and management Analysis Null hypothesis Summary 32 vii

8 Chapter 4: Results Descriptive analysis Pain characteristics McGill Pain Questionnaire Pain intensity Correlation of pain measures Scatter diagram Spearman correlation calculation Summary Removing outliers Summary 51 Chapter5: Discussion Importance of vulvar pain measurement Summary of findings Expected findings McGill pain questionnaire Unexpected findings VAS Vas reported pain in past month VAS reported pain at moment VAS reported pain with intercourse VAS general 55 viii

9 2.2.3 Vulvalgesiometer McGill pain questionnaire Outliers Epidemiological and clinical relevance Pain measurement Sampling error Measures Reliability Validity Confounders Pain measures in general Study appraisal Strengths of the study Weaknesses Limitations Implications of the study Future direction 71 References 74 Appendix A: Illustration of vulvar vestibule 83 Appendix B: Physician evaluation 84 ix

10 List of Tables Table 1: Report of outcome measures of published studies on vulvodynia from 1999 to April 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

11 Table 15: Spearman s correlation of pain assessment by VAS at different times (outliers removed) 51 xi

12 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