A scoring system for the assessment of bowel and lower urinary tract symptoms in women

Transcription

1 BJOG: an International Journal of Obstetrics and Gynaecology April 2002, Vol. 109, pp A scoring system for the assessment of bowel and lower urinary tract symptoms in women L. Hiller a, H.D. Bradshaw b, S.C. Radley b, S. Radley c, * Objective To develop a simple scoring system for a validated 22-item questionnaire used to assess bowel and urinary dysfunction in women. Setting A urogynaecology clinic, a functional bowel clinic, a district general hospital and a general practice. Population One hundred and one women referred with functional bowel and/or urinary symptoms and 131 asymptomatic controls. Methods A user manual has been prepared. Individual responses to questions are categorised into normal and abnormal and odds ratio tests applied to reflect their sensitivity. Results Scoring methods have been detailed, and appropriate and sensitive cutoff points defined. Conclusions The use of this validated questionnaire is now aided by a user manual, facilitating health care evaluation research into the effects of pelvic surgery on pelvic floor symptomatology. A simple scoring system is provided, making the questionnaire a valuable and accessible research tool. INTRODUCTION Patient self-completed questionnaires provide a valuable method for symptom assessment in both clinical and research arenas. Such instruments may be used as a screening tool to identify normal or abnormal symptoms, but can also be used to generate scores for specific groups of symptoms thus allowing symptom severity to be assessed in specific areas or domains. Symptom scores for a variety of differing conditions and quality of life assessments are currently used both in clinical practice and research. Some of these are clinically based 1,2, whereas others are generated by self-completed assessments 3 5. The calculation of a valid score also allows comparisons to be made between differing patient groups and to assimilate longitudinal data. We have demonstrated previously the robust psychometric properties of a 22-item bowel and urinary tract symptoms questionnaire 6, encompassing all aspects of pelvic floor function in women and separating into four domains, that individually cover constipation, evacuation, incontinence and urinary symptoms. In this paper we present a user manual for the questionnaire, documenting a simple scoring system to aid its use as a clinical and research tool. a Cancer Research UK, Institute for Cancer Studies, Edgbaston, Birmingham, UK b Central Sheffield University Hospitals Department of Obstetrics and Gynaecology, UK c University of Birmingham Department of Surgery, Queen Elizabeth Hospital, UK * Correspondence: Mr S. Radley, University of Birmingham Department of Surgery, Queen Elizabeth Hospital, Birmingham B15 2TH, UK. D RCOG 2002 BJOG: an International Journal of Obstetrics and Gynaecology PII: S (02) The Birmingham Bowel and Urinary Symptoms Questionnaire (BBUSQ-22) was designed to be used in a clinic or other hospital setting or as a postal questionnaire. Recommendation is only for the instrument to remain as a patient-completed one to curb any unnecessary bias in the reporting of the symptoms, and for the allowance of as much time as required for completion of the instrument. Calculation of the domain scores For all individual questions, responses are coded as 1 to 4 from top to bottom of the response sets, with the exception of question one being coded as 1 to 6 and question 14 as 1 for yes and 2 for no (see Appendix 1). All missing responses are coded as 0. Except for a stand-alone binary constipation question (question 14), the questionnaire is composed entirely of multi-item domains with the composition of these domains shown in Table 1. Each domain score ranges from 0 to 100 where a high score is indicative of more severe symptoms. The procedure used for creating these domain scores is as follows: 1. Linearly transform all answered questions responses so that scores are standardised ranging from 0 to 100. This involves, for the majority of questions, subtracting one from the response so the range of possible values runs from 0 to 3 instead of 1 to 4, then dividing by three and multiplying by 100. There are two exceptions to this rule: 1. For question 1 it is necessary to divide by five instead of three (there are six responses available); 2. Question 14 requires no transformation as it does not contribute to any domain score.

2 A SCORING SYSTEM FOR BOWEL AND URINARY TRACT SYMPTOMS 425 Table 1. Composition of domains. Domain No. of Questions Question nos. Constipation 2 Q1, Q2 Evacuation 8 Q7 Q13 and Q15 Incontinence 4 Q3 Q6 Urinary 7 Q16 Q22 Q14 is not included within the four domains. 2. Provided that at least half the questions have been answered, calculate the average of the transformed values of all answered questions in each domain. If more than half are missing in any one domain, then the domain score must be set to missing. Therefore individual domain scores cannot be calculated for patients with two responses missing in the constipation domain, five or more missing in the evacuation domain, three or more in the incontinence domain or four or more in the urinary domain. This setting of domain scores to missing is an infrequent occurrence; experience with this instrument has found that less than 5% of questionnaires have two or more questions with missing responses. Interpretation of the domain scores After creating the four domain scores ranging from 0 to 100, it is important to attach some clinical meaning to these transformed scores. General population averages can provide a norm against which various subgroups may be compared (previously published for this questionnaire 6 ). This is known as the normative approach. Another method of assigning clinical meaning is by the identification of clinically relevant cutoff points to distinguish between normal and abnormal domain scores. A gynaecologist, urogynaecologist and coloproctogist identified clinically relevant cutoff points for each question to distinguish between the normal and abnormal (see Appendix 1). After this categorisation, the highest possible normal score for each domain was calculated and used as the cutoff. Using this approach, the resulting abnormal scores for the four principle domains are defined as: constipation score 64%; evacuation score 17%; incontinence score 17%; urinary symptoms score 20%. In order to assess the appropriateness of these cutoff points, the questionnaire was administered to two different populations who were asked to record symptoms suffered over the previous month. One hundred and thirty-one controls not consulting their doctor for bowel or urinary symptoms were recruited from a general practitioner s practice and from healthcare workers. A group of 101 symptomatic patients were recruited in two sites: a urogynaecology clinic and a functional bowel clinic. All participants gave consent to take part in the study, which received local ethics committee approval. The patient characteristics are summarised in Table 2. The 101 symptomatic patients with valid domain scores and diagnoses from objective clinical assessments fall into three groups: 1. Constipation/evacuatory dysfunction (n ¼ 19) 2. Anal incontinence (n ¼ 18) 3. Lower urinary tract symptoms (n ¼ 64) For each domain, the relevant symptomatic patients scores were compared with controls who had a valid score for that domain to assess the sensitivity of the predictions made by the cutoff points. Odds-ratios and their confidence intervals were calculated for each of the two by two tables in turn (Table 3). The cutoff points provided correct identification 81% of the time for the symptomatic patients and 85% of the time for controls ( P 0.01 for all domains). A patient with an abnormal constipation score is four times more likely to be symptomatic than non-symptomatic; with an abnormal evacuation score 14 times more likely, with an abnormal incontinence score 53 times more likely and with an abnormal urinary symptoms score 61 times more likely. This demonstrates the clinically chosen cutoffs as sensitive for detecting abnormal levels of symptoms thus validating the accuracy of the scoring system. DISCUSSION Some questionnaires, such as the generic Nottingham Health Profile 7 previously used in this area 8, record merely whether a symptom was suffered (yes/no). Domain scores are then calculated by attributing to these responses preassigned weights, determined from another population s view on the impact these symptoms have on general life. In our questionnaire, data are collected on the severity of Table 2. Patient characteristics. Values are n (%) unless otherwise shown. Grouping Age (years) Median 44 IQR Range Unknown 18 Parity 0 20 (9) (61) 4þ 18 (8) Unknown 52 (22) Previous surgery Anorectal 4 (2) Prolapse surgery 5 (2) Urological 2 (1) Colonic 1 (0.5) None specified 220 (94.5)

3 426 L. HILLER ET AL. Table 3. Cut-point predictions. Bold numbers indicate correct predictions. Within each domain, 130 controls from the 131 samples had valid domain scores. Patients Predicted OR (95% CI) P Abnormal Normal n % n % Constipation (<64, 64) Symptomatic (n ¼ 19) ( ) 0.01 Controls (n ¼ 130) Evacuation (<17, 17) Symptomatic (n ¼ 19) ( ) Controls (n ¼ 130) Incontinence (<17, 17) Symptomatic (n ¼ 18) ( ) Controls (n ¼ 130) Urinary (<20, 20) Symptomatic (n ¼ 64) ( ) Controls (n ¼ 130) symptoms suffered by the individual patient, allowing the patient s own view on the impact of the symptom to be used in the calculation of the domain scores. Such simple linear scoring systems have been shown to be robust 9 and are commonly applied to questionnaires despite the necessity for equi-interval scaling. We do not believe that the response sets in this questionnaire are sufficiently nonlinear to raise concerns with regards to generating domain scores in such a manner. No individual weightings have been applied to questions before calculating domain scores. This was on the clinical premise that the areas covered by the individual questions were of equal importance within the domains. Furthermore, the introduction of weighting would add undue complexity to the calculations, outweighing any possible benefit and reducing the accessibility of the questionnaire for general use. The use of a total, global score based on either the average of all questions, or of all domains, is a measure sometimes used to obtain a single score to sum up patients symptom suffering. However, we advise against the use of such a summary measure for this instrument. Although content coverage is deemed complete within each domain, the domains were not designed to collectively cover all aspects as a whole. A single score calculated from all four domains is not considered to represent an adequate global symptom score. In this paper the scores generated have been dichotomised into normal and abnormal groups and symptomatic patients compared with controls. This exercise has demonstrated each of the four domains clear ability to discriminate. The use of such cutoff values will allow clinicians to make simple and meaningful comparisons between different patient groups and also provide useful information when determining the impact of specific interventions alongside conventional clinical assessment and physiological investigations. Further work is needed in order to define the minimal clinically important difference by comparing changes in domain scores over time with a separate criterion measuring patient s view of improvement or worsening in their health status. This would enable changes over time to be represented in terms of the linearly transformed data while still guaranteeing clinical relevance. CONCLUSION The recommended use of this instrument in health care assessment research, to determine the effects of pelvic surgery on bowel and urinary symptoms, is now aided by a user manual and simple scoring system making it both a valuable and accessible research tool. A user pack including a copy of the full instrument for use in such research may be obtained from the authors. Acknowledgements The authors gratefully acknowledge the help of Mr R. Callender and Mr J. Jordan in facilitating the study. The authors would also like to thank the Worcester Street General Practice, Stourbridge, for recruiting control patients into this study. The authors would also like to thank all the women who participated in the study. References 1. Agachan F, Chen T, Pfeifer J, Reissman P, Wexner SD. A constipation scoring system to simplify evaluation and management of constipated patients. Dis Colon Rectum 1996;39:

4 A SCORING SYSTEM FOR BOWEL AND URINARY TRACT SYMPTOMS American Fertility Society. Revised American Fertility Society classification of endometriosis. Fertil Steril 1985;43: Lamping DL, Rowe P, Clarke A, Black N, Lessof L. Development and validation of the menorrhagia outcomes questionnaire. Br J Obstet Gynaecol 1998;105: Kelleher CJ, Cardozo LD, Khullar V, Salvatore S. A new questionnaire to assess the quality of life of urinary incontinent women. Br J Obstet Gynaecol 1997;104: Reilly WT, Talley NJ, Pemberton JH, Zinsmeister AR. Validation of a questionnaire to assess fecal incontinence and associated risk factors: fecal incontinence questionnaire. Dis Colon Rectum 2000;43: Hiller L, Radley S, Mann CH, et al. Development and validation of a questionnaire for the assessment of bowel and urinary tract symptoms in women. Br J Obstet Gynaecol 2002;109: Hunt SM, McEwan J, McKenna SP. Measuring health-status: a new tool for clinicians and epidemiologists. J R Coll Gen Prac 1985;35: Grimby A, Milsom I, Molander U, Wiklund I, Ekelund P. The influence of urinary incontinence on the quality of life of elderly women. Age Ageing 1993;22: Dawes RM. The robust beauty of improper linear models. Am Psychol 1979;34: Accepted 5 February 2002

5 428 L. HILLER ET AL. Appendix 1. Bowel and Urinary Symptoms Questions (" indicating an abnormal response).

6 A SCORING SYSTEM FOR BOWEL AND URINARY TRACT SYMPTOMS 429

7 430 L. HILLER ET AL.