- Email: [email protected]
Objective Assessment of Urinary Incontinence in Women: Comparison of the One-Hour and 24-Hour Pad Tests
European Urology
European Urology 45 (2004) 208–212
Objective Assessment of Urinary Incontinence in Women: Comparison of the One-Hour and 24-Hour Pad Tests Gurminder S. Matharua,*, R. Philip Assassab, Kate S. Williamsc, Madeleine Donaldsonc, Ruth Matthewsc, Douglas G. Tincellod, Christopher J. Maynea The Leicestershire MRC Incontinence Study Team a
Department of Obstetrics & Gynecology, Leicester General Hospital, Gwendolen Road, Leicester, LE5 4PW, UK Pinderfields and Pontefract Hospitals, Pinderfields Hospital, Aberford Road, Wakefield WF1 4DG, UK c Department of Epidemiology, University of Leicester, Princess Road West, Leicester LE1 6TP, UK d Department of Obstetrics & Gynaecology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, P.O. Box 65, Leicester LE2 7LX, UK b
Accepted 9 September 2003 Published online 2 October 2003
Abstract Objective: To compare the performance and clinical usefulness of the one-hour and 24-hour pad tests in terms of the relationship with reported symptoms and urodynamic diagnosis. Methods: 341 women aged 40 years and over reporting lower urinary tract symptoms who were recruited to a nurse led continence service, and went on to receive urodynamics, a one-hour and a 24-hour pad test and completed a urinary diary. Results: For both pad tests, there was a significant difference in the amount of urine leaked between the different urodynamic diagnoses ( p < 0:0001, for the one-hour and p ¼ 0:001 for the 24-hour test). Women with sphincter incompetence leaked significantly more than women with detrusor instability, or those with no abnormality. There was a significant difference between the proportion of women dry on a one-hour pad test and those dry on a 24-hour pad test (26.0% versus 38.4%, difference 12.4%; CI 5.5; 19.4). There is a positive relationship between amount of urine leakage and symptom severity expressed in terms of number of incontinent episodes for both pad tests. Conclusion: Both pad tests bore little relationship to the underlying urodynamic diagnosis but there was a positive relationship with symptom severity. The 24-hour pad test appears to be clinically a more useful too than the one-hour test. The two types of pad test are probably assessing incontinence in different ways. We suggest that the minimum data set should include structured questions, diaries and the 24-hour pad test. # 2003 Elsevier B.V. All rights reserved. Keywords: Urinary incontinence; Pad test; Urodynamics; Investigation; Symptom severity 1. Introduction Leakage of urine is probably the most troublesome of all lower urinary tract symptoms in women. It has always been considered important to obtain information about the severity of leakage. The simplest instrument with which to measure urine loss objectively is the pad test. Two of the most commonly used types of *
Corresponding author. Tel. þ44-116-249-0490; Fax: þ44-116-273-1620. E-mail address: [email protected] (G.S. Matharu).
pad tests in use today are the one-hour test, as recommended by the International Continence Society [1] and the 24-hour test. Although the one-hour test is an investigation recommended by the ICS, a number of studies have reported poor reproducibility for both types of pad test [2–5]. In the most recent study the test-retest reliability of the one-hour pad test was shown to be inadequate, with the first and second tests differing by 44 to þ66 g, despite the women having similar bladder volumes [5]. There appears to be no consensus in practical terms on which pad test provides the most reliable and useful
0302-2838/$ – see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.eururo.2003.09.006
G.S. Matharu et al. / European Urology 45 (2004) 208–212
measure of urinary leak. The aims of this study were (i) to compare the urine loss in women undergoing each pad test by urodynamic abnormality and (ii) to assess the clinical usefulness of each pad test in terms of the relationship between objective urine loss and the subjective measure of incontinent episodes reported in a urinary diary.
2. Subjects and methods Women aged 40 years and over, reporting a variety of lower urinary tract symptoms were recruited via a postal questionnaire and home interview to a nurse led service [6], which was part of the Leicestershire MRC Incontinence Study. The service entailed delivery of care by a group of trained continence nurse practitioners (CNPs) using a set of pre-defined evidence-based protocols. All women were seen by a CNP at three planned visits over an eight-week period, together with additional visits depending on the interventions provided and the degree of support deemed necessary by the nurse. Details of these interventions can be found elsewhere [6]. At the end of two-month period, each woman underwent a complete assessment including taking a structured history, a threeday urinary diary, a 24-hour pad test and a scan of the bladder to estimate the post-void residual volume of urine. At the end of this phase, women were invited to undergo urodynamic evaluation of their condition if they satisfied any one of the following criteria: any episode of incontinence in the three-day diary; a loss of 5 g or more on the 24-hour pad test; an average daytime voiding frequency of eight or more times; at least two episodes of nocturia; urgency which was reported to be present most of the time. Each woman performed an ICS one-hour pad test [1] before undergoing urodynamic investigation, which comprised uroflowmetry, subtracted dual channel cystometry with provocation tests, and a voiding study, in accordance with ICS standards [1]. For cystometry, the bladder was filled transurethrally with sterile water at a continuous rate of 100 ml/min with the patient in the supine position. Pressure measurement was via fluid-filled catheters. Separate filling and pressure measurement catheters were used (10FR MED5200 and 4.5FR MED5100 Medi Plus respectively). Rectal pressure was measured using a fluid filled rectal balloon catheter (4.5FR MED5415 Medi Plus). Urodynamic investigation was performed by appropriately trained medical and nursing staff. Climbing a flight of stairs, which is part of the ICS one-hour pad test schedule [1], was omitted as a proportion of the study population was elderly or frail and would have had difficulty climbing stairs. Each woman was given one of the following diagnoses according to ICS terminology [7]: detrusor overactivity (DO),
209
urodynamic stress incontinence (USI), mixed urinary incontinence (DO & USI), no abnormality or ‘other’. Both pad tests were performed at home using Tena Lady pads (SCA Hygiene Products, Gothenburg, Sweden). The pads were weighed on digital scales by the continence nurse practitioner on the ward both before and within 24 hours after each test and the weight gain calculated. In addition to examining the actual values obtained at each pad test we categorised the women as either ‘‘wet’’ or ‘‘dry’’. A patient was classified as being dry if there was a gain in pad weight of less than 1 g for the one-hour test and less than 4 g for the 24-hour test [8]. All other women were classified as wet, regardless of the actual magnitude of pad loss. We also compared the average number of incontinent episodes per day recorded in the urinary diary with urine loss on each pad test. Continuous data were analysed by Mann–Whitney U test, or a Kruskal–Wallis test. Data are presented as the median (inter-quartile range). Differences between proportions were calculated according to Altman [9] and presented as a difference (95% confidence intervals).
3. Results 2421 women were recruited to the nurse-led service. Having completed the nursing intervention, 1003 women were eligible for and offered urodynamic investigation and 490 completed the investigation. Pad test data was either missing or incomplete for 149 of these women. One-hour and 24-hour pad test data was available for 341 women. The median urine loss for the whole sample was 1.7 g (IQR 0.4 to 13.9) for the one-hour test and 5.0 g for the 24-hour test (IQR 2.1 to 15.0) respectively. There was a moderate correlation of r ¼ 0:443 ( p < 0:001) between the two types of pad test (Spearman’s rank correlation). At urodynamic investigation, 83 women (24.3%) had DO, 132 (38.7%) had USI 79 (23.2%) had mixed incontinence and 47 (13.8%) had no abnormality. Median urine loss for each pad test according to diagnostic group is shown in Table 1. For both pad tests, there was a significant difference in the amount of urine leaked between the different urodynamic groups ( p < 0:0001, for the one-hour test and p ¼ 0:002 for the 24-hour test, Kruskal-Wallis test). Women with USI (alone or with DO) leaked more than women with DO alone, or those with no
Table 1 Median urine loss (interquartile range) for each pad test by urodynamic diagnosis Urodynamic diagnosis
1-hour pad loss (g) 24-hour pad loss (g) a
DO (n ¼ 83)
USI (n ¼ 132)
Mixed (n ¼ 79)
No abnormality (n ¼ 47)
pa
0.8 (0.2 to 7.0) 4.8 (1.9 to 19.0)
4.0 (1.0 to 15.7) 6.0 (2.7 to 15.9)
4.1 (0.5 to 18.0) 6.0 (2.4 to 21.1)
0.3 (0.0 to 1.6) 2.8 (1.0 to 6.0)
<0.0001 0.002
Kruskal–Wallis test for difference between urodynamic diagnosis groups.
210
G.S. Matharu et al. / European Urology 45 (2004) 208–212
Table 2 Proportions of patients dry on each pad test Urodynamic diagnosis
Dry on 24-hour pad test % (n)
Dry on one-hour pad test % (n)
% Difference between pad tests (95% CI)
GSI (n ¼ 132) DI (n ¼ 83) Mixed (n ¼ 79) No abnormality (n ¼ 47)
32.6 43.4 36.7 63.8
17.4 50.6 30.4 59.6
15.2 7.2 6.3 4.3
Total (341)
40.5 (138)
(43) (36) (29) (30)
34.3 (117)
Average numberof incontinent episodes/24 hours
urodynamic abnormality. There was considerable overlap in the amount of urine lost between the different urodynamic groups and the amount of loss was not discriminatory of urodynamic diagnosis (data not shown). The simplified pad test data is shown in Table 2. There was a difference between the proportion of
(a) 15.00
10.00
5.00
0.00 Minimal (<4g)
Moderate (20.1-50g) Minor (4.1-20g)
Severe (>50g)
Severity of leakage from 24 hour pad test
Average number of incontinent episodes/24 hours
(23) (42) (24) (28)
(b)
(5.9 to 24.4) (20.9 to 6.5) (5.5 to 18.1) (10.1 to 18.7)
6.2 (0.1 to 12.2)
women dry on a 24-hour pad test and those dry onehour pad test (difference 6.2%; CI 0.1% to 12.2%). According to urodynamic diagnosis, 32.6% of women with GSI were dry on the 24-hour pad test compared to 17.4% on the one-hour pad test (difference 15.2%, CI 5.9% to 24.4%). 36.7% of women with mixed incontinence were dry on the 24-hour test, compared to 30.4% on the one-hour test (difference 6.3%, CI 5.5% to 18.1%). 40.4% and 36.2% of those with no urodynamic abnormality were wet on the one-hour and 24-hour pad tests, respectively. No episodes of incontinence were recorded in the diaries of 61 women of whom 44.3% (27) were wet on the one-hour pad test and 34.4% (21) on the 24-hour pad test. Fig. 1a and b show the relationship between the average number of incontinent episodes reported in the three-day diary and the severity of urine loss for each pad test. The results are for 314 women. Twentyseven patients had incomplete data in their urinary diaries and were not included in this analysis. Both graphs show that there is a gradual increase in the severity of urine loss with increasing number of incontinent episodes. Although there was a statistically significant difference ( p < 0:0001, Kruskal–Wallis test) between the different severity groups for both pad tests, there was considerable overlap between the groups.
15.00
4. Discussion 10.00
5.00
0.00 Minimal (<1g)
Moderate (5.1-20g) Minor (1-5g)
Severe (>20g)
Severity of leakage from 1 hour pad test
Fig. 1. (a) Total number of incontinent episodes by severity of urine loss on the 24-hour pad test. (b) Total number of incontinent episodes by severity of urine loss on the one-hour pad test.
The International Continence Society recommends a perineal pad test to be performed as part of the evaluation of the incontinent woman to provide an objective assessment of urine loss. A recent review article demonstrated that the only test with adequate reproducibility was a 24-hour pad test [10], but there are no data directly comparing the results of pad tests to patient reported symptoms or severity measures. More recently the variation of repeated one-hour pad tests in the same patient was shown to be 44 to þ66 g [5], a finding that renders the interpretation of the actual figures obtained meaningless.
G.S. Matharu et al. / European Urology 45 (2004) 208–212
This study compares the one-hour and 24-hour pad tests from the largest cohort of women to date. Despite the significant differences in urine loss between the different urodynamic groups, recorded volumes of urine loss were not helpful in diagnosing the underlying urodynamic abnormality. We found that women with USI leaked more than those with DO on both pad tests, whereas Fantl et al. [11] reported the opposite for the one-hour test. We agree with their comment that the considerable between patient variability makes the test impractical as a diagnostic tool. The large variability of results also obtained from the one-hour test by Simons et al. [5] suggests that the pad test should perhaps be assessed more simply in terms of ‘‘wet’’ or ‘‘dry’’. We have analysed our data on this basis. Firstly, comparison of the one-hour and 24-hour pad tests showed that there were significant differences in the results obtained. The negative pad rate amongst women complaining of urinary incontinence was higher overall for the 24-hour pad test, and most marked in women with USI. However, of those patients without any incontinent episodes in their urinary diaries, more were ‘‘wet’’ on the one-hour pad test than the 24-hour test. When one considers that the volumes lost in the two tests were very similar, this finding of differences in the positive test frequency suggests that the two tests are assessing incontinence in very different ways. The 24-hour pad test is almost certainly more representative of the patients’ day-to-day experiences and is more likely to correlate with reported symptoms [12]. A number of studies have reported conflicting results of the correlation between the one-hour pad test and symptoms. It would seem logical for a pad test to be performed whilst the woman is performing her normal day-today activities rather than ‘provoke’ incontinence by asking her to perform tasks or exercises that she would not normally do, which may happen with the one-hour pad test. The 24-hour test would be much more appropriate for the elderly or those with physical disability who may not be able to perform some of the exercises of the one-hour test. Furthermore, amount of urine leakage on the 24-hour test is a good predictor of outcome of conservative therapy (unpublished data). One factor, which may explain the large numbers of women not leaking with either pad test, is non-compliance. It is difficult to judge patient compliance for either test when they are performed at home. Versi and colleagues [13] have reported 83% compliance with a 48-hour pad test. In interpreting one’s results, it is worth remembering that standard cystometry has a false negative rate, particularly in terms of detecting DO and our data reflect the underlying difficulty with
211
all of the currently available techniques for assessing bladder function. Until more reliable and accurate methods of performing cystometry are developed this uncertainty will remain. It must be borne in mind that there are significant false negative and false positive rates in the pad tests and the validated questionnaires now available are likely to be more informative in evaluating the degree of ‘‘bother’’ of an individual patient’s symptoms. A recent survey of continence workers (doctors and nurses) and patients in the UK demonstrated remarkable concordance between them in what outcomes were regarded as important [14]. Improvements in subjective symptoms and quality of life were most important and the role of the pad test was poorly rated. This may be a reflection of the uncertainty surrounding the way pad tests should be used in clinical practice. The recent report from a working party to address the state of research into pelvic floor disorders recommended a minimum dataset for research studies [15]. Pad testing was not listed among the required minimum dataset and the working party commented that ‘‘further research is needed to clarify the role of pad tests in quantifying symptom severity’’. Our data contribute to this process and suggest that there does appear to be a positive relationship between pad tests and symptom severity as assessed by the number of incontinent episodes reported in a urinary diary. We have demonstrated that even when analysed in basic terms, the performance of the pad test in any form is a poor predictor of underlying abnormality but they may be helpful in assessing symptom severity. The fact that symptoms and pad loss only show a mild correlation and that sometimes pad tests can be ‘positive’ and symptoms ‘negative’ (and vice versa) suggests that in trials you need both. The one-hour pad test appears to be less useful than the 24-hour test. However, to detect all cases of incontinence, the minimum data set should include structured questions, diaries and 24-hour pad tests.
Acknowledgements This study was part of a programme grant funded by the MRC. We thank all the participants in the study and the GPs of Leicester who gave support to the study; the Continence Nurse Practitioners who carried out the nursing intervention; Lesley Harris for administrative support; Jennie Lucas for data management; Peter Marsh and Chris Sanders for IT support; and Nigel Smith and Usman Azam who contributed to the clinical interventions.
212
G.S. Matharu et al. / European Urology 45 (2004) 208–212
References [1] Abrams P, Blaivas JG, Stanton SL, Andersen JT. The standardisation of terminology of lower urinary tract function. The International Continence Society Committee on Standardisation of Terminology. Scand J Urol Nephrol 1988;114(Suppl):5–19. [2] Jorgensen L, Steen A, Bagger PV, Fisher-Rasmussen W. The onehour pad-weighing test for assessment of the result of female incontinence surgery. In: Proceedings of the 15th Annual Meeting of the International Incontinence Society; London. 1985. p. 392–3. [3] Lose G, Gammelgaard J, Jorgensen TJ. The one-hour pad weighing test: reproducibility and the correlation between the test result, the start volume in the bladder and the diuresis. Neurourol Urodyn 1986;5:17–21. [4] Lose G, Jorgensen L, Thunedborg P. 24-hour home pad weighing test versus 1-hour ward test in the assessment of mild stress incontinence. Acta Obstet Gynecol Scand 1989;68:211–5. [5] Simons AM, Yoong WC, Buckland S, Moore KH. Inadequate repeatability of the one-hour pad test: the need for a new incontinence outcome measure. Br J Obstet Gynaecol 2001;108:315–9. [6] Williams KS, Assassa RP, Smith NGK, Jagger C, Perry S, Shaw C, et al. Development, implementation and evaluation of a new nurseled continence service: a pilot study. J Clin Nurs 2000;9:566–73. [7] Abrams P, Cardozo L, Fall M, Griffiths D, Rosier P, Ulmsten U, et al. The standardisation of terminology of lower urinary tract function: Report from the standardisation sub-committee of the International Continence Society. Neurourol Urodyn 2002;21:167–78.
[8] Artibani W, Andersen JT, Gajewski JB, Ostergard DR, Raz S, Tubaro A, et al. Imaging and other investigations. In: Abrams P, Cardozo L, Khoury S, Wein A, editors. 2nd International Consultation on Incontinence. Plymouth: Health Publications Ltd.; 2001. p. 425–77. [9] Altman DG. Principles of statistical analysis. In: Altman DG, editor. Practical statistics for medical research, 1st ed. London: Chapman & Hall; 1991. p. 152–78. [10] Siltberg H, Victor A, Larsson G. Pad weighing tests: the best way to quantify urine loss in patients with incontinence. Acta Obstet Gynecol Scand 1997;76:28–32. [11] Fantl JA, Harkins SW, Wyman JF, Choi SC, Taylor JR. Fluid loss quantitation test in women urinary incontinence: a test-retest analysis. Obstet Gynecol 1987;70:739–43. [12] Mouritsen L, Berild G, Hertz J. Comparison of different methods for quantification of urinary leakage in incontinent women. Neurourol Urodyn 1989;8:579–87. [13] Versi E, Orrego G, Hardy E, Seddon G, Smith P, Anand D. Evaluation of the home pad test in the investigation of female urinary incontinence. Br J Obstet Gynaecol 1996;103:162–7. [14] Tincello DG, Alfirevic Z. Important clinical outcomes in urogynecology: views of patients, nurses and medical staff. Int Urogynecol J 2002;13:96–8. [15] Weber A, Abrams P, Brubaker L, Cundiff G, Davis G, Dmochowski RR, et al. The standardization of terminology for researchers in female pelvic floor disorders. Int Urogynecol J 2001;12:178–86.
European Urology 45 (2004) 208–212
Objective Assessment of Urinary Incontinence in Women: Comparison of the One-Hour and 24-Hour Pad Tests Gurminder S. Matharua,*, R. Philip Assassab, Kate S. Williamsc, Madeleine Donaldsonc, Ruth Matthewsc, Douglas G. Tincellod, Christopher J. Maynea The Leicestershire MRC Incontinence Study Team a
Department of Obstetrics & Gynecology, Leicester General Hospital, Gwendolen Road, Leicester, LE5 4PW, UK Pinderfields and Pontefract Hospitals, Pinderfields Hospital, Aberford Road, Wakefield WF1 4DG, UK c Department of Epidemiology, University of Leicester, Princess Road West, Leicester LE1 6TP, UK d Department of Obstetrics & Gynaecology, University of Leicester, Robert Kilpatrick Clinical Sciences Building, P.O. Box 65, Leicester LE2 7LX, UK b
Accepted 9 September 2003 Published online 2 October 2003
Abstract Objective: To compare the performance and clinical usefulness of the one-hour and 24-hour pad tests in terms of the relationship with reported symptoms and urodynamic diagnosis. Methods: 341 women aged 40 years and over reporting lower urinary tract symptoms who were recruited to a nurse led continence service, and went on to receive urodynamics, a one-hour and a 24-hour pad test and completed a urinary diary. Results: For both pad tests, there was a significant difference in the amount of urine leaked between the different urodynamic diagnoses ( p < 0:0001, for the one-hour and p ¼ 0:001 for the 24-hour test). Women with sphincter incompetence leaked significantly more than women with detrusor instability, or those with no abnormality. There was a significant difference between the proportion of women dry on a one-hour pad test and those dry on a 24-hour pad test (26.0% versus 38.4%, difference 12.4%; CI 5.5; 19.4). There is a positive relationship between amount of urine leakage and symptom severity expressed in terms of number of incontinent episodes for both pad tests. Conclusion: Both pad tests bore little relationship to the underlying urodynamic diagnosis but there was a positive relationship with symptom severity. The 24-hour pad test appears to be clinically a more useful too than the one-hour test. The two types of pad test are probably assessing incontinence in different ways. We suggest that the minimum data set should include structured questions, diaries and the 24-hour pad test. # 2003 Elsevier B.V. All rights reserved. Keywords: Urinary incontinence; Pad test; Urodynamics; Investigation; Symptom severity 1. Introduction Leakage of urine is probably the most troublesome of all lower urinary tract symptoms in women. It has always been considered important to obtain information about the severity of leakage. The simplest instrument with which to measure urine loss objectively is the pad test. Two of the most commonly used types of *
Corresponding author. Tel. þ44-116-249-0490; Fax: þ44-116-273-1620. E-mail address: [email protected] (G.S. Matharu).
pad tests in use today are the one-hour test, as recommended by the International Continence Society [1] and the 24-hour test. Although the one-hour test is an investigation recommended by the ICS, a number of studies have reported poor reproducibility for both types of pad test [2–5]. In the most recent study the test-retest reliability of the one-hour pad test was shown to be inadequate, with the first and second tests differing by 44 to þ66 g, despite the women having similar bladder volumes [5]. There appears to be no consensus in practical terms on which pad test provides the most reliable and useful
0302-2838/$ – see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.eururo.2003.09.006
G.S. Matharu et al. / European Urology 45 (2004) 208–212
measure of urinary leak. The aims of this study were (i) to compare the urine loss in women undergoing each pad test by urodynamic abnormality and (ii) to assess the clinical usefulness of each pad test in terms of the relationship between objective urine loss and the subjective measure of incontinent episodes reported in a urinary diary.
2. Subjects and methods Women aged 40 years and over, reporting a variety of lower urinary tract symptoms were recruited via a postal questionnaire and home interview to a nurse led service [6], which was part of the Leicestershire MRC Incontinence Study. The service entailed delivery of care by a group of trained continence nurse practitioners (CNPs) using a set of pre-defined evidence-based protocols. All women were seen by a CNP at three planned visits over an eight-week period, together with additional visits depending on the interventions provided and the degree of support deemed necessary by the nurse. Details of these interventions can be found elsewhere [6]. At the end of two-month period, each woman underwent a complete assessment including taking a structured history, a threeday urinary diary, a 24-hour pad test and a scan of the bladder to estimate the post-void residual volume of urine. At the end of this phase, women were invited to undergo urodynamic evaluation of their condition if they satisfied any one of the following criteria: any episode of incontinence in the three-day diary; a loss of 5 g or more on the 24-hour pad test; an average daytime voiding frequency of eight or more times; at least two episodes of nocturia; urgency which was reported to be present most of the time. Each woman performed an ICS one-hour pad test [1] before undergoing urodynamic investigation, which comprised uroflowmetry, subtracted dual channel cystometry with provocation tests, and a voiding study, in accordance with ICS standards [1]. For cystometry, the bladder was filled transurethrally with sterile water at a continuous rate of 100 ml/min with the patient in the supine position. Pressure measurement was via fluid-filled catheters. Separate filling and pressure measurement catheters were used (10FR MED5200 and 4.5FR MED5100 Medi Plus respectively). Rectal pressure was measured using a fluid filled rectal balloon catheter (4.5FR MED5415 Medi Plus). Urodynamic investigation was performed by appropriately trained medical and nursing staff. Climbing a flight of stairs, which is part of the ICS one-hour pad test schedule [1], was omitted as a proportion of the study population was elderly or frail and would have had difficulty climbing stairs. Each woman was given one of the following diagnoses according to ICS terminology [7]: detrusor overactivity (DO),
209
urodynamic stress incontinence (USI), mixed urinary incontinence (DO & USI), no abnormality or ‘other’. Both pad tests were performed at home using Tena Lady pads (SCA Hygiene Products, Gothenburg, Sweden). The pads were weighed on digital scales by the continence nurse practitioner on the ward both before and within 24 hours after each test and the weight gain calculated. In addition to examining the actual values obtained at each pad test we categorised the women as either ‘‘wet’’ or ‘‘dry’’. A patient was classified as being dry if there was a gain in pad weight of less than 1 g for the one-hour test and less than 4 g for the 24-hour test [8]. All other women were classified as wet, regardless of the actual magnitude of pad loss. We also compared the average number of incontinent episodes per day recorded in the urinary diary with urine loss on each pad test. Continuous data were analysed by Mann–Whitney U test, or a Kruskal–Wallis test. Data are presented as the median (inter-quartile range). Differences between proportions were calculated according to Altman [9] and presented as a difference (95% confidence intervals).
3. Results 2421 women were recruited to the nurse-led service. Having completed the nursing intervention, 1003 women were eligible for and offered urodynamic investigation and 490 completed the investigation. Pad test data was either missing or incomplete for 149 of these women. One-hour and 24-hour pad test data was available for 341 women. The median urine loss for the whole sample was 1.7 g (IQR 0.4 to 13.9) for the one-hour test and 5.0 g for the 24-hour test (IQR 2.1 to 15.0) respectively. There was a moderate correlation of r ¼ 0:443 ( p < 0:001) between the two types of pad test (Spearman’s rank correlation). At urodynamic investigation, 83 women (24.3%) had DO, 132 (38.7%) had USI 79 (23.2%) had mixed incontinence and 47 (13.8%) had no abnormality. Median urine loss for each pad test according to diagnostic group is shown in Table 1. For both pad tests, there was a significant difference in the amount of urine leaked between the different urodynamic groups ( p < 0:0001, for the one-hour test and p ¼ 0:002 for the 24-hour test, Kruskal-Wallis test). Women with USI (alone or with DO) leaked more than women with DO alone, or those with no
Table 1 Median urine loss (interquartile range) for each pad test by urodynamic diagnosis Urodynamic diagnosis
1-hour pad loss (g) 24-hour pad loss (g) a
DO (n ¼ 83)
USI (n ¼ 132)
Mixed (n ¼ 79)
No abnormality (n ¼ 47)
pa
0.8 (0.2 to 7.0) 4.8 (1.9 to 19.0)
4.0 (1.0 to 15.7) 6.0 (2.7 to 15.9)
4.1 (0.5 to 18.0) 6.0 (2.4 to 21.1)
0.3 (0.0 to 1.6) 2.8 (1.0 to 6.0)
<0.0001 0.002
Kruskal–Wallis test for difference between urodynamic diagnosis groups.
210
G.S. Matharu et al. / European Urology 45 (2004) 208–212
Table 2 Proportions of patients dry on each pad test Urodynamic diagnosis
Dry on 24-hour pad test % (n)
Dry on one-hour pad test % (n)
% Difference between pad tests (95% CI)
GSI (n ¼ 132) DI (n ¼ 83) Mixed (n ¼ 79) No abnormality (n ¼ 47)
32.6 43.4 36.7 63.8
17.4 50.6 30.4 59.6
15.2 7.2 6.3 4.3
Total (341)
40.5 (138)
(43) (36) (29) (30)
34.3 (117)
Average numberof incontinent episodes/24 hours
urodynamic abnormality. There was considerable overlap in the amount of urine lost between the different urodynamic groups and the amount of loss was not discriminatory of urodynamic diagnosis (data not shown). The simplified pad test data is shown in Table 2. There was a difference between the proportion of
(a) 15.00
10.00
5.00
0.00 Minimal (<4g)
Moderate (20.1-50g) Minor (4.1-20g)
Severe (>50g)
Severity of leakage from 24 hour pad test
Average number of incontinent episodes/24 hours
(23) (42) (24) (28)
(b)
(5.9 to 24.4) (20.9 to 6.5) (5.5 to 18.1) (10.1 to 18.7)
6.2 (0.1 to 12.2)
women dry on a 24-hour pad test and those dry onehour pad test (difference 6.2%; CI 0.1% to 12.2%). According to urodynamic diagnosis, 32.6% of women with GSI were dry on the 24-hour pad test compared to 17.4% on the one-hour pad test (difference 15.2%, CI 5.9% to 24.4%). 36.7% of women with mixed incontinence were dry on the 24-hour test, compared to 30.4% on the one-hour test (difference 6.3%, CI 5.5% to 18.1%). 40.4% and 36.2% of those with no urodynamic abnormality were wet on the one-hour and 24-hour pad tests, respectively. No episodes of incontinence were recorded in the diaries of 61 women of whom 44.3% (27) were wet on the one-hour pad test and 34.4% (21) on the 24-hour pad test. Fig. 1a and b show the relationship between the average number of incontinent episodes reported in the three-day diary and the severity of urine loss for each pad test. The results are for 314 women. Twentyseven patients had incomplete data in their urinary diaries and were not included in this analysis. Both graphs show that there is a gradual increase in the severity of urine loss with increasing number of incontinent episodes. Although there was a statistically significant difference ( p < 0:0001, Kruskal–Wallis test) between the different severity groups for both pad tests, there was considerable overlap between the groups.
15.00
4. Discussion 10.00
5.00
0.00 Minimal (<1g)
Moderate (5.1-20g) Minor (1-5g)
Severe (>20g)
Severity of leakage from 1 hour pad test
Fig. 1. (a) Total number of incontinent episodes by severity of urine loss on the 24-hour pad test. (b) Total number of incontinent episodes by severity of urine loss on the one-hour pad test.
The International Continence Society recommends a perineal pad test to be performed as part of the evaluation of the incontinent woman to provide an objective assessment of urine loss. A recent review article demonstrated that the only test with adequate reproducibility was a 24-hour pad test [10], but there are no data directly comparing the results of pad tests to patient reported symptoms or severity measures. More recently the variation of repeated one-hour pad tests in the same patient was shown to be 44 to þ66 g [5], a finding that renders the interpretation of the actual figures obtained meaningless.
G.S. Matharu et al. / European Urology 45 (2004) 208–212
This study compares the one-hour and 24-hour pad tests from the largest cohort of women to date. Despite the significant differences in urine loss between the different urodynamic groups, recorded volumes of urine loss were not helpful in diagnosing the underlying urodynamic abnormality. We found that women with USI leaked more than those with DO on both pad tests, whereas Fantl et al. [11] reported the opposite for the one-hour test. We agree with their comment that the considerable between patient variability makes the test impractical as a diagnostic tool. The large variability of results also obtained from the one-hour test by Simons et al. [5] suggests that the pad test should perhaps be assessed more simply in terms of ‘‘wet’’ or ‘‘dry’’. We have analysed our data on this basis. Firstly, comparison of the one-hour and 24-hour pad tests showed that there were significant differences in the results obtained. The negative pad rate amongst women complaining of urinary incontinence was higher overall for the 24-hour pad test, and most marked in women with USI. However, of those patients without any incontinent episodes in their urinary diaries, more were ‘‘wet’’ on the one-hour pad test than the 24-hour test. When one considers that the volumes lost in the two tests were very similar, this finding of differences in the positive test frequency suggests that the two tests are assessing incontinence in very different ways. The 24-hour pad test is almost certainly more representative of the patients’ day-to-day experiences and is more likely to correlate with reported symptoms [12]. A number of studies have reported conflicting results of the correlation between the one-hour pad test and symptoms. It would seem logical for a pad test to be performed whilst the woman is performing her normal day-today activities rather than ‘provoke’ incontinence by asking her to perform tasks or exercises that she would not normally do, which may happen with the one-hour pad test. The 24-hour test would be much more appropriate for the elderly or those with physical disability who may not be able to perform some of the exercises of the one-hour test. Furthermore, amount of urine leakage on the 24-hour test is a good predictor of outcome of conservative therapy (unpublished data). One factor, which may explain the large numbers of women not leaking with either pad test, is non-compliance. It is difficult to judge patient compliance for either test when they are performed at home. Versi and colleagues [13] have reported 83% compliance with a 48-hour pad test. In interpreting one’s results, it is worth remembering that standard cystometry has a false negative rate, particularly in terms of detecting DO and our data reflect the underlying difficulty with
211
all of the currently available techniques for assessing bladder function. Until more reliable and accurate methods of performing cystometry are developed this uncertainty will remain. It must be borne in mind that there are significant false negative and false positive rates in the pad tests and the validated questionnaires now available are likely to be more informative in evaluating the degree of ‘‘bother’’ of an individual patient’s symptoms. A recent survey of continence workers (doctors and nurses) and patients in the UK demonstrated remarkable concordance between them in what outcomes were regarded as important [14]. Improvements in subjective symptoms and quality of life were most important and the role of the pad test was poorly rated. This may be a reflection of the uncertainty surrounding the way pad tests should be used in clinical practice. The recent report from a working party to address the state of research into pelvic floor disorders recommended a minimum dataset for research studies [15]. Pad testing was not listed among the required minimum dataset and the working party commented that ‘‘further research is needed to clarify the role of pad tests in quantifying symptom severity’’. Our data contribute to this process and suggest that there does appear to be a positive relationship between pad tests and symptom severity as assessed by the number of incontinent episodes reported in a urinary diary. We have demonstrated that even when analysed in basic terms, the performance of the pad test in any form is a poor predictor of underlying abnormality but they may be helpful in assessing symptom severity. The fact that symptoms and pad loss only show a mild correlation and that sometimes pad tests can be ‘positive’ and symptoms ‘negative’ (and vice versa) suggests that in trials you need both. The one-hour pad test appears to be less useful than the 24-hour test. However, to detect all cases of incontinence, the minimum data set should include structured questions, diaries and 24-hour pad tests.
Acknowledgements This study was part of a programme grant funded by the MRC. We thank all the participants in the study and the GPs of Leicester who gave support to the study; the Continence Nurse Practitioners who carried out the nursing intervention; Lesley Harris for administrative support; Jennie Lucas for data management; Peter Marsh and Chris Sanders for IT support; and Nigel Smith and Usman Azam who contributed to the clinical interventions.
212
G.S. Matharu et al. / European Urology 45 (2004) 208–212
References [1] Abrams P, Blaivas JG, Stanton SL, Andersen JT. The standardisation of terminology of lower urinary tract function. The International Continence Society Committee on Standardisation of Terminology. Scand J Urol Nephrol 1988;114(Suppl):5–19. [2] Jorgensen L, Steen A, Bagger PV, Fisher-Rasmussen W. The onehour pad-weighing test for assessment of the result of female incontinence surgery. In: Proceedings of the 15th Annual Meeting of the International Incontinence Society; London. 1985. p. 392–3. [3] Lose G, Gammelgaard J, Jorgensen TJ. The one-hour pad weighing test: reproducibility and the correlation between the test result, the start volume in the bladder and the diuresis. Neurourol Urodyn 1986;5:17–21. [4] Lose G, Jorgensen L, Thunedborg P. 24-hour home pad weighing test versus 1-hour ward test in the assessment of mild stress incontinence. Acta Obstet Gynecol Scand 1989;68:211–5. [5] Simons AM, Yoong WC, Buckland S, Moore KH. Inadequate repeatability of the one-hour pad test: the need for a new incontinence outcome measure. Br J Obstet Gynaecol 2001;108:315–9. [6] Williams KS, Assassa RP, Smith NGK, Jagger C, Perry S, Shaw C, et al. Development, implementation and evaluation of a new nurseled continence service: a pilot study. J Clin Nurs 2000;9:566–73. [7] Abrams P, Cardozo L, Fall M, Griffiths D, Rosier P, Ulmsten U, et al. The standardisation of terminology of lower urinary tract function: Report from the standardisation sub-committee of the International Continence Society. Neurourol Urodyn 2002;21:167–78.
[8] Artibani W, Andersen JT, Gajewski JB, Ostergard DR, Raz S, Tubaro A, et al. Imaging and other investigations. In: Abrams P, Cardozo L, Khoury S, Wein A, editors. 2nd International Consultation on Incontinence. Plymouth: Health Publications Ltd.; 2001. p. 425–77. [9] Altman DG. Principles of statistical analysis. In: Altman DG, editor. Practical statistics for medical research, 1st ed. London: Chapman & Hall; 1991. p. 152–78. [10] Siltberg H, Victor A, Larsson G. Pad weighing tests: the best way to quantify urine loss in patients with incontinence. Acta Obstet Gynecol Scand 1997;76:28–32. [11] Fantl JA, Harkins SW, Wyman JF, Choi SC, Taylor JR. Fluid loss quantitation test in women urinary incontinence: a test-retest analysis. Obstet Gynecol 1987;70:739–43. [12] Mouritsen L, Berild G, Hertz J. Comparison of different methods for quantification of urinary leakage in incontinent women. Neurourol Urodyn 1989;8:579–87. [13] Versi E, Orrego G, Hardy E, Seddon G, Smith P, Anand D. Evaluation of the home pad test in the investigation of female urinary incontinence. Br J Obstet Gynaecol 1996;103:162–7. [14] Tincello DG, Alfirevic Z. Important clinical outcomes in urogynecology: views of patients, nurses and medical staff. Int Urogynecol J 2002;13:96–8. [15] Weber A, Abrams P, Brubaker L, Cundiff G, Davis G, Dmochowski RR, et al. The standardization of terminology for researchers in female pelvic floor disorders. Int Urogynecol J 2001;12:178–86.