Correlation of urodynamic measures of urethral resistance with clinical measures of incontinence severity in women with pure genuine stress incontinence

Correlation of urodynamic measures of urethral resistance with clinical measures of incontinence severity in women with pure genuine stress incontinence James P. Theofrastous, MD,” Richard C. Bump, MD,“, b Denise M. Elser, MD,b Jean F. Wyman, RN, PhD,” Donna K. McClish, PhD,d and the Continence Program Women Research Group

Durham, North

Carolina,

and Richmond,

for

Virginia

OBJECTIVE: Our aim was to correlate multiple measures of urethral resistance with five clinical measures of incontinence severity in women with pure genuine stress incontinence. STUDY DESIGN: Seventy-five women with pure genuine stress incontinence underwent passive and dynamic urethral pressure profilometry and Valsalva leak point pressure determinations. The standardized and validated measures of incontinence severity included (1) the number of incontinent episodes, (2) the number of continence pads used recorded in a prospective 1 -week urinary diary, (3) grams of fluid loss on a pad quantitation test, and (4) two condition-specific quality-of-life scales, the urogenital distress inventory and the incontinence impact questionnaire. The urodynamic and severity measures were compared with Pearson product-moment correlation analysis. RESULTS: There were no significant correlations between dynamic urethral pressure profile pressure transmission ratios and any measure of incontinence severity. Passive urethral pressure profile variables correlated significantly with incontinence episodes and pad use. Valsalva leak point pressures correlated significantly with pad use and quantitation testing. None of the urodynamic measurements was significantly correlated with either of the quality-of-life scales, but our power to demonstrate a correlation was limited. CONCLUSIONS: Both passive urethral pressure profile measures and Valsalva leak point pressures correlate with some severity measures of genuine stress incontinence. Although inefficient pressure transmission during stress is critical to the pathogenesis of genuine stress incontinence, the severity of the pressure transmission defect is not related to clinical severity. Conversely, impairment of intrinsic urethral resistance is not essential to the pathogenesis of genuine stress incontinence, but the degree of sphincteric impairment is related to severity once the condition exists. (AM J OBSTET GYNECOL 1995;173:407-14.)

Key words: Urodynamics, genuine stress incontinence, urethral profilometry, urethral resistance

Urinary continence with physical stress is the result of a rise in urethral pressure, simultaneous with the rise in abdominal and vesical pressure, of sufficient magnitude to maintain a positive pressure gradient in the urethra. Maintenance of a positive urethral pressure gradient with stress results from the interaction of three primary determinants: (1) the resting resistance of the multifacFrom the Department of Obstetrics and Gynecology Duke University Medical Center,’ and the Departments of Obstetrics and Gynecology,’ Adult Health Nursing,‘ and Biostatistics,” Virginia Commonwealth University. Supported by grant No. lJOlAGO5170-06 from the National Institute on Aging. Presented as Invited Guest at the Fifiv-seventh Annual Meetiw of The South Atlantic Association of 6b;tetricians and Gynecolog”titi, Hot Springs, Virginia, January 28-31, 1995. Reprint requests: Richard C. Bump, MD, Department of Obstetrics and Gynecology, Box 3609, Duke University Medical Center, Durham, NC 27710. Copyright 0 1995 by Mosby-Year Book, Inc. 0002-9378/95 $3.00 + 0 6/6/65369

quality

of life, leak point

pressures,

torial urethral sphincteric mechanism, (2) the relative efficiency of the urethral pressure rise compared with the vesical pressure rise with stress (quantified as a pressure transmission ratio), which is predominately related to the stability of urethral anatomic support, and (3) the magnitude of the physical stress itself. When the magnitude of the physical stress times the inefficiency of pressure transmission (100% minus the pressure transmission ratio) exceeds the force of urethral closure, genuine stress incontinence results. Pressure transmission < 100% associated with urethral hypermobility is the essential pathophysiologic mechanism for most genuine stress incontinence, although a small fraction of genuine stress incontinence does result from an intrinsic failure of the sphincteric mechanism to maintain mucosal coaptation during negligible stress in spite of normal anatomic support and essentially equal pressure transmission.’ Overall, groups of patients with genuine stress incontinence 407

408

Theofrastous

et al.

i\ugLlst 1995 Am J Obstet Gynecol

The purpose of our study was to compare how well these two competing measures of urethral resistance, urethral pressure profile and Valsalva leak point pressure, correlate with five standardized, reproducible, validated measures of incontinence severity in women with

pure

genuine

stress

incontinence.

Subjects and methods

Fig. 1. Measurement of Valsalva leak point pressure. thral area is swabbed dry, after which patient is asked down progressively while holding her breath. Precise that fluid is observed at external urethral meatus is on vesical pressure record with remote event marker point a). Rise in vesical pressure (Pves) over baseline measured at instant leakage begins and represents leak point pressure.

have

significantly

lower

pressure

transmission

Periureto bear instant recorded (arrou at (line b) is Valsalva

ratios

than do groups of normal women’ and groups of patients with other forms of incontinence.3 Although inefficient pressure transmission is a prerequisite for most genuine stress incontinence, the magnitude of this inefficiency (i.e., the severity of pressure transmission ratio depression) does not correlate significantly with the severity of any resulting stress incontinence.” Conversely, there is evidence that the closure force of the urethral sphincteric mechanism is significantly correlated with the severity of incontinence once inefficient pressure transmission has allowed the development of genuine stress incontinence.” ’ Urogynecologists have traditionally assessed urethral resistance with the urethral pressure profile. An alternative measurement, more favored by urologists, is the leak point pressure, which is the vesical pressure at which urethral resistance is overcome and leakage of fluid is observed. In the case of women with genuine stress incontinence, the vesical pressure increase that causes fluid leakage results from an increase in abdominal pressure with a prompted Valsalva maneuver (Valsalva leak point pressure or Valsalva leak point pressure). Previous studies by Hilton and Stanton’ and by McGuire et al.” are contradictory with respect to the value of the urethral pressure profile in predicting the severity of genuine stress incontinence, with the former authors showing a significant association between lower maximum urethral closure pressure and worsening incontinence and the latter showing no correlation between maximum urethral closure pressure and severity of incontinence. In contrast, McGuire et al.’ did show an association between lower Valsalva leak point pressures and increasing severity of incontinence. However, both of these studies used a single (although different) subjective, nonstandardized, nonvalidated method for assessing the clinical severity of genuine stress incontinence in their study subjects.

Seventy-five women referred for evaluation of urinary incontinence and found to have urodynamically confirmed pure genuine stress incontinence underwent passive and dynamic urethral pressure profilometry and Valsalva leak point pressure determinations. Specific details of the urethral pressure profile methods and calculations have been described previously.“, ’ Variables from the urethral pressure profiles included the functional urethral length, maximum urethral closure pressure, total profile area, mean urethral closure pressure (profile area in millimeters X cm H,O/functional urethral length in millimeters) from the passive urethral pressure profile, and pressure transmission ratios from the dynamic urethral pressure profile. Valsalva leak point pressure determinations were performed with an 8F microtop transducer catheter at maximum cystometric capacity with the patient in the 45degree upright position. The periurethral area was swabbed dry, after which the subject was asked to bear down while holding her breath, as if she were trying to push something out of the vagina. The precise instant that

fluid

was

observed

at the

external

urethral

meatus

was recorded on the vesical pressure record with a handheld remote event marker. The increase in vesical pressure over resting vesical pressure at the instant leakage began was measured and designated the vesical Valsalva leak point pressure (Fig. 1). The diagnosis of genuine stress incontinence was made if the patient had the symptom of stress incontinence and had observable leakage produced by stress without concurrently demonstrable detrusor activity during urethrocystometry or had a positive direct visualization test immediately after the catheters were removed in the total absence of detrusor instability during urethrocystometry. Urodynamic techniques and measurements, terms, and diagnostic criteria conform to the recommendations of the International Continence Society.6 The five standardized and validated measures of incontinence severity included (1) the number of incontinence

episodes

experienced

per

week,

(2) the

number

of continence pads used per week, both recorded prospectively on a ‘i-day urinary diary,’ (3) the amount of fluid

lost

on

a

quantitative

pad

test,*

and

(4)

two

condition-specific quality-of-life scales, the urogenital distress inventory and the incontinence impact questionnaire.’ Composite scores of the urogenital distress inventory

(range

0 to

300)

and

incontinence

impact

Volume 173, Number Am J Obstet Gynecol

Theofrastous

2

Table I. Passive and dynamic urethral pressure profilometry variables and Valsalva leak point correlations with measures of incontinence severity in 75* women with pure genuine stress incontinence IEW

Passive UPP FUL MUCP MnUCP Area Dynamic UPP PTR VLPP?

CPW

Quant.

Correlation coeficient

Significance

Correlation coeficient

- 0.341 -0.258 - 0.285 -0.300

p p p p

0.006 0.04 0.03 0.02

-0.303 -0.157 -0.215 -0.252

p = 0.02 ii p = 0.05

0.179 -0.116 - 0.086 -0.061

NS NS

~0.010 - 0.425

NS p = 0.002

-0.011 -0.277

- 0.235 - 0.205

IEW, Incontinent quantitation pad pressure profile; urethral closure *Correlations TValsalva leak

= = = =

Si&icance

Correlation coefficient

NS NS NS NS

NS p = 0.04

Correlation coejkient

409

pressure

lJDP+

Significance

et al.

II@

Signzjkance

Correlation coeficient

Significance

0.122 0.056 0.122 0.174

NS NS NS NS

0.252 - 0.050 0.078 0.203

NS NS NS NS

- 0.030 - 0.076

NS NS

0.245 - 0.244

NS NS

episodes per week; CPW, continence pads per week; Quant., grams of fluid lost on standardized fluid loss test; UDI, score on urogenital distress inventory; 114, score on incontinence impact questionnaire; UPP, urethral FUL, functional urethral length; NS, not significant; MUCP, maximum urethral closure pressure; MnUCP, mean pressure; PTR, mean pressure transmission ratio; VLPP, Valsalva leak point pressure. were calculated with 33 subjects who completed quality-of-life scales. point pressure correlations were calculated with 61 subjects who had leakage with Valsalva maneuver.

questionnaire (range 0 to 400) were used for analysis; lower scores reflect a higher quality of life for both scales. Only 33 of the 75 subjects (44%) completed the quality-of-life questionnaires. Pearson product-moment correlation analysis was used to assess the relationships between urodynamic measures of urethral resistance and the five severity measures. A two-tailed Student t test was used to compare various urethral pressure profile and severity variables between women who had leakage and those who had no leakage with the Valsalva maneuver. Continuous variables are expressed as the mean + SD and range. Results The 75 subjects had a mean age of 56 years (? 11 years, range 33 to 84 years), parity of 2.5 ( 2 2.0, range 0 to 1 l), and weight of 75 kg ( f 15 kg, range 47 to 134 kg). Twenty-nine (39%) had undergone prior continence surgery (17 with one, nine with two, and two with three procedures). The study population reported an average of 42 incontinent episodes per week ( f 79, range 0 to 409) and used an average of 22 continence pads per week ( + 20, range 0 to 105). The average amount of fluid lost on a pad test at maximum cystometric capacity was 50 gm (+ 86 gm, range 0 to 410 gm). The mean urogenital distress inventory score was 136 (+ 62, range 7 to 260) and the mean incontinence impact questionnaire score was 119 ( f 98, range 4 to 336). On urodynamic testing the study population had an average cystometric capacity of 520 ml ( f 138 ml, range 200 to 919 ml), maximum urethral closure pressure of 35 cm Ha0 (+ 2 1 cm H20, range 3 to 126 cm H,O), mean urethral closure pressure of 20 cm Ha0 ( f 12 cm I&O, range 3 to 67 cm H,O), stress urethral axis of 39

degrees (+-23 degrees, range - 20 to +90 degrees), and mean pressure transmission ratio of 85% ( * 12%, range 62% to 124%). The Valsalva leak point pressure averaged 50 cm Ha0 ( ? 2 1 cm H,O, range 24 to 72 cm H,O) in the 61 (81%) subjects who demonstrated leakage with Valsalva maneuver. Fourteen subjects (19%) did not experience leakage with the Valsalva maneuver in spite of an average increase in vesical pressure of 79 cm H,O ( ? 34 cm H,O, range 26 to 148 cm H,O). Thus the failure of these subjects to experience leakage was not simply related to a less intense Valsalva effort. There were no significant differences in age, parity, weight, urethral mobility, functional urethral length, or mean pressure transmission ratio between subjects who experienced leakage with Valsalva maneuver and those who did not, but the latter did have significantly higher maximum urethral closure pressures (50 vs 32 cm H,O, p = 0.004), mean urethral closure pressures (27 vs 18 cm H,O, $ = 0.005), and urethral pressure profile areas (671 vs 425, p = 0.01). They also tended to lose less fluid on quantitation testing (30 vs 54 gm), have fewer incontinent episodes (26 vs 45), and have better (lower) quality-of-life scores (96 vs 141 for urogenital distress inventory, 75 vs 125 for incontinence impact questionnaire), although these differences were not statistically significant. Table I demonstrates the correlations between the urodynamic variables and the measures of incontinence severity. Overall, the data demonstrate that decreasing measures of urethral resistance were associated with increasing severity of stress incontinence. All variables from the passive urethral pressure profile and the Valsalva leak point pressure demonstrated significant, although weak, negative correlations with one or both

410

Theofrastous

et al.

of the urinary diary severity variables; only the Valsalva leak point pressure showed a significant correlation with the results of the fluid loss quantitation test. There were no significant correlations between the pressure transmission ratios (from any quartile or from the mean of all quartiles) calculated from the dynamic urethral pressure profile with any of the severity measures. None of the urodynamic measurements were significantly correlated with either of the condition-specific qualityof-life scales, but the power of this observation is limited by the large SDS of these scores and by our relatively small sample size.

Comment The traditional aim of urodynamic testing of an incontinent woman has been to identify the physiologic condition causing the incontinence. In most instances this involves differentiating incontinence caused by pure genuine stress incontinence from that caused by detrusor instability or mixed incontinence (genuine stress incontinence + detrusor instability). Genuine stress incontinence is usually diagnosed by demonstrating loss of urine from the urethra simultaneous with a physical stress when vesical pressure exceeds urethral pressure in the absence of a detrusor contraction.6 Depression of pressure transmission < 100% and urethral hypermobility of 2 30 degrees typify patients with genuine stress incontinence, having sensitivities of 97% and 70%, respectively.3 However, these defects in pressure transmission and support do not define genuine stress incontinence, and many women with such defects remain stress continent because their resting force of urethral closure is great enough or their increases in abdominal pressure during daily physical exertions are small enough to allow them to maintain a positive, although diminished, pressure gradient with stress. Thus inefficient pressure transmission ratios and urethral hypermobility have specificities of only 56% and 66%, respectively.’ In contrast, the observation of leakage during the dynamic urethral pressure profile is 93% specific for genuine stress incontinence.“’ In this study we have shown that the visualization of leakage with a Valsalva maneuver is 81% sensitive for genuine stress incontinence, a figure comparable to the 77% sensitivity we reported for Valsalva leak point pressures in another population of incontinent women.” In our urodynamic testing of 293 consecutive incontinent women over the past 24 months we have yet to demonstrate fluid leakage with Valsalva maneuver in a woman who did not have the diagnosis of genuine stress incontinence established by the independent criteria noted in the Subjects and Methods section of this article. Thus in our hands leakage with Valsalva maneuver is 100% specific for genuine stress incontinence, although it does not exclude the possibility of coexisting detrusor instability. On the basis of these observations we conclude that

August 1995 Am J Obstet Gynecol

both dynamic urethral pressure profile and Valsalva leak point pressure determinations are tests that can be used to substantiate the diagnosis of genuine stress incontinence, although the diagnosis can be and usually is made independent of the results of these tests. A second aim of urodynamic testing is to establish the severity of urethral sphincteric dysfunction once the diagnosis of genuine stress incontinence has been established. It is reasonable to assume that the magnitude of the compromise in urethral resistance is correlated with both the severity of the individual woman’s incontinence”. 4 and her response to various therapeutic interventions, including surgery.‘, ” Clinicians have attempted to correlate objective laboratory testing with the clinical severity of stress incontinence since Bonney’s13 observation in 1923 that minimal pressure was required to overcome the urethral resistance of one woman with severe stress incontinence compared with women with less severe incontinence. However, the subjective, nonvalidated, nonstandardized systems for stratifying patients according to the severity of their incontinence have been an impediment to correlating clinical severity with urodynamic findings. In 1983 Hilton and Stanton” concluded that pressure transmission ratio values are an “all or none” phenomenon, in that an inefficient ratio was essential to the pathophysiologic features of genuine stress incontinence but that the level of inefficiency was not associated with the severity of the incontinence. In their study severity was graded into four levels by a composite system based on their Urilos nappy test, videocystourethrography, and clinical examination. A recent study that stratified women into “slight” and “severe” genuine stress incontinence on the basis of the results of a l-hour pad test noted no correlations between pressure transmission ratios and severity.‘4 The current study, which used five standardized, reproducible, validated continuous severity variables supports the conclusions of both of these studies regarding pressure transmission ratios. Hilton and Stanton’ also suggested that passive urethral pressure profile measures reflect the severity of stress incontinence. In contrast, Meyer et aLI4 noted no significant relationship between functional urethral length or maximum urethral closure pressure with severity. Recently McGuire et al4 stated that leak point pressures, but not urethral pressure profile measures, define the qualitative and quantitative defect in urethral sphincter function in women with genuine stress incontinence. These authors reported that Valsalva leak point pressures, but not maximum urethral closure pressure, have an inverse relationship with the clinical severity of incontinence, as measured retrospectively and subjectively by the patient according to a fourgrade system. Our data, derived from more objective, prospective, and continuous severity measures, provide

Volume 173, Number Am J Obstet Gynecol

2

evidence that both urethral pressure profile measures and Valsalva leak point pressures correlate inversely with the clinical severity of genuine stress incontinence. Although the Valsalva leak point pressure has been proposed as a more reproducible urodynamic measure of urethral resistance that may correlate better with the severity of genuine stress incontinence than do urethral pressure profile measures,4’ ” our data do not support this contention in the baseline assessment of subjects with the disorder. The quality-of-life instruments used in this study are self-administered patient questionnaires that have been developed during the Continence Program for Women clinical trials in an attempt to quantitatively describe the impact of urinary incontinence on a woman’s life. The urogenital distress inventory includes irritative, obstructive/discomfort, and stress subscales and is designed to evaluate a woman’s perception of the severity of her symptoms, whereas the incontinence impact questionnaire addresses the impact of incontinence on domestic, physical, and social relationships and emotional function. Both instruments have been shown to be significantly correlated with urinary diary and quantitation testing results, and their reliability and validity have been determined in a clinical population of incontinent women.’ Although a previous study has noted a heterogeneous correlation between quality-of-life scores and incontinence severity on the basis of urinary diary data,‘” this study is the first to examine the relationship between urodynamic variables and quality-of-life assessments. The lack of a significant correlation between our urodynamic variables and quality-of-life measures is likely related both to our relatively small sample size and to the fact that, although the quality-of-life measures are condition specific, they have a large SD because of the multifactorial and subjective perception of the impact of incontinence on the life of an individual woman. At opposite ends of this perceptual spectrum are the fastidious woman who finds the infrequent loss of a single drop of urine intolerable and the imperturbable woman who is stoically resigned to constantly wearing a pad because of frequent leakage. Our data suggest that urodynamic variables and quality-oflife measures reflect largely independent domains of clinical severity of genuine stress incontinence. In summary, our data demonstrate that urethral pressure profilometry and Valsalva leak point pressures provide similar diagnostic (qualitative) and severity (quantitative) information about genuine stress incontinence during the baseline assessment of incontinent women. Urethral profilometry provides the information only if both a passive and dynamic urethral pressure profile are performed and requires two transducers with a high-frequency response (usually expensive cathetermounted microtransducers), a mechanical profilometer arm, and a multichannel recording system.” The Val-

Theofrastous

et at.

411

salva leak point pressure can potentially provide this information at considerably less cost during one Valsalva maneuver by use of one inexpensive external pressure transducer and a single-channel recording device. However, the techniques for determining Valsalva leak point pressures need to be standardized, and each variation of technique should be validated before its widespread clinical use can be advocated.” This is especially true if the Valsalva leak point pressure is to be used for making critical therapeutic decisions such as choosing between traditional urethropexy, a pubovesical sling procedure, or periurethral injections for the treatment of genuine stress incontinence. Further studies are needed to assess whether changes in urethral pressure profile or Valsalva leak point pressure parameters better reflect clinical improvement after various therapeutic interventions. The Continence Program for Women Research Group includes J. Andrew Fantl, Jean F. Wyman, Richard C. Bump, Donna K. McClish, and Denise M. Elser from Virginia Commonwealth University; Curt D. Furberg, Samuel F. Lentz, Timothy M. Morgan, Deirdre Robinson, and Sally A. Shumaker from Bowman Gray School of Medicine, Winston-Salem, North Carolina; and Richard C. Bump and James P. Theofrastous from Duke University Medical Center. REFERENCES

1. Agency for Health Care Policy and Research Urinary Incontinence Guideline Panel. Urinary incontinence in adults: clinical practice guideline. Rockville, Maryland: U.S. Department of Health and Human Services, 1992:111. 2. Hilton P, Stanton SL. Urethral pressure measurement by microtransducer: the results in symptom-free women and in those with genuine stress incontinence. Br J Obstet Gynaecol 1983;90:919-33. 3. Bump RC, Copeland WE Jr, Hurt WG, Fantl JA. Dynamic urethral pressure profilometry pressure transmission ratio determinations in stress incontinent and stress continent subjects. AM J OBS~T GYNECOL 1988;159:749-55. 4. McGuire EJ, Fitzpatrick CC, Wan J, et al. Clinical assessment of urethral sphincter function. J Urol 1993;150: 1452-4. 5. Bump RC, Hurt WG, Fantl FA, Wyman JF. Assessment of Kegel pelvic muscle exercise performance following brief verbal instruction. AM J OBSTET GYNECOL 1991;165:322-9. 6. Abrams P, Blaivas JG, Stanton SL, Anderson JT. The International Continence Society Committee on Standardisation of Terminology: the standardisation of terminology of lower urinary tract function. Stand J Urol Nephrol 1988;114S:5-19. 7. Wyman JF, Choi SC, Harkins SW, Wilson MS, Fantl JA. The urinary diary in evaluation of incontinence in women: a test-retest analysis. Obstet Gynecol 1988;71:812-7. 8. Fantl JA, Harkins SW, Wyman JF, Choi SC, Taylor JR. Fluid loss quantitation test in women with urinary incontinence: a test-retest analysis. Obstet Gynecol 1987; 70:739-73. 9. Shumaker SA, Wyman JF, Uebersax J, McClish DK, Fantl JA. Health-related quality of life measures for women with urinary incontinence: urogenital distress inventory and incontinence impact questionnaire. Qua1 Life Res 1994;3: 291-306. 10. Richardson DA. Value of the cough pressure profile in

412

Theofrastous

et al.

August 1995 Am J Obstet

the evaluation of patients with stress incontinence. AM J GYNECOL 1986;155:808-11. Bump RC, Elser DM, Theofrastous JP, McClish DK, Continence Program for Women Research Group. Valsalva leak point pressures in women with genuine stress incontinence: reproducibility, effect of catheter caliber, and correlations with other measures of urethral resistance. AM J OBSTET GYNECOL 1995;173:551-7. Bowen LW, Sand PK, Ostergard DR, Franti CE. Unsuccessful Burch retropubic urethropexy: a case-controlled urodynamic study. AM J OBSTET GYNECOL 1989;160:452-8. Bonney V. On diurnal incontinence of urine in women. J Obstet Gynaecol Br Emp 1923;30:358-65. Meyer S, De Granti P, Schmidt N, Sanzeni W, Spinosa JP. Urodynamic parameters in patients with slight and severe genuine stress incontinence: is the stress profile useful? Neurourol Urodyn 1994;13:21-8. Wan.1, McGuire El, Bloom DA, Ritchey ML. Stress leak point-pressure: a d
11.

12 13. 14.

15. 16.

17.

Discussion ANNE WISKIND, Atlanta, Georgia (Invited Guest). The authors have performed a well-designed study to further clarify our ability to diagnose the severity of urethral sphincter dysfunction in women with pure genuine stress incontinence. This is an important subject, because genuine stress incontinence is the most common form of incontinence in women of reproductive age. The better we are able to understand a particular patient’s disorder, the better we are able to predict her response to therapy and to recommend the most appropriate therapy for her. This study is the first to use objective, validated, standardized systems to compare Valsalva leak point pressure and urethral pressure profile variables with the severity of incontinence and thereby (presumably) determine the severity of the urethral sphincter dysfunction. They found that passive urethral pressure profile variables inversely correlate with incontinent episodes per week and continence pads per week, whereas Valsalva leak point pressure inversely correlates with continence pads per week and quantitative urine loss on pad test. There was no correlation with dynamic urethral pressure profile variables and incontinence severity and no correlation with any of the urodynamic parameters and the quality-of-life scales. This is a clear, well-done study. My only criticism with the method is that so few patients (44%) completed the quality-of-life scale questionnaires. Because three centers are listed as being involved with the study (Duke, Virginia Commonwealth, and Bowman Gray), what measures were taken to ensure that all patients were studied in a consistent manner (i.e., size catheter, urodynamic equipment, and computer software)? How much interobserver variation do you think there is in determining Valsalva leak point pressure, and what measures were taken to minimize this variation? Another interesting finding in this study was the DR.

Gynecol

comparison of the urethral pressure profile variables and measures of incontinence severity between those patients who leaked with Valsalva maneuver (n = 61) and those who did not (n = 14). Those who did not leak had higher passive urethral pressure profile variables, less fluid loss on pad test, fewer incontinence episodes per week, and better scores on quality-of-life scales. Although these differences were not statistically significant, the numbers are rather small. It would be interesting to compare a larger series of appropriate power to see if simply having a positive Valsalva leak point pressure is prognostic of significant urethral sphincter dysfunction. Because passive urethral pressure profile variables are associated with resting urethral resistance and Valsalva leak point pressure is a reflection of urethral resistance under stress, it is not surprising that both of these measures correlate inversely with objective measures of incontinence severity. Therefore, although they do so in different ways, it seems that both tests reflect the severity of urethral sphincter dysfunction. However, because neither urethral pressure profile measurements nor Valsalva leak point pressure are necessary to make the diagnosis of genuine stress incontinence according to the criteria of the International Continence Society and because dynamic urethral pressure profile variables have no correlation with the severity of urethral sphincter dysfunction, are dynamic urethral pressure profiles ever necessary outside an academic research setting? Furthermore, because Valsalva leak point pressures are easier and more inexpensive to perform than even passive urethral pressure profile, is Valsalva leak point pressure going to replace urethral pressure profile measurements altogether? In addition, are either urethral pressure profile or Valsalva leak point pressure valid measures of urethral sphincter dyshmction in patients with significant anterior wall vaginal prolapse (where urethral kinking may give falsely elevated results), and was the amount of uterovaginal prolapse considered in this series of patients? How should we standardize Valsalva leak point pressure measurement (i.e., position of the patient, measurement of abdominal or vesical pressure, microtip vs fluid-filled pressure catheters, catheter size, and bladder volume)? Valsalva leak point pressure was initially described by McGuire et al.’ as the measure of the total abdominal pressure to initiate urinary leakage demonstrated on vesicocystourethrogram with the patient in the upright position with a 10F catheter and 150 ml in the bladder. In this study Valsalva leak point pressure was defined as the change in vesical pressure required to cause leakage observed at the perineum in a patient in the 45-degree upright position at cystometric capacity with an SF catheter in the bladder. How significant are these differences in technique? Miklos and Karram’ found no difference in the intravesical versus intravaginal measure of Valsalva leak point pressure. However, they did find that there was a significant decrease in the Valsalva leak point pressure as the bladder volume at testing increased. They also

Volume 173, Number Am J Obstet Gynecol

2

found a significantly lower Valsalva leak point pressure if no intravesical catheter was ‘placed and only the intravaginal pressure was measured. On the other hand, Bump et al3 found no difference in Valsalva leak point pressure measurement with a 3F versus an 8F catheter, but they did find intravesical measurements to be significantly higher than intravaginal measurements. What are your recommendations for Valsalva leak point pressure measurement? REFERENCES

McQuire EJ, Fitzpatrick CC, Wan J, et al. Clinical assessment of urethral sphincter function. J Urol 1993;150: 1452-4. Miklos JR, Karram MM. Leak point pressures: initial observations. In: Proceedings of the fifteenth annual meeting of the American Uro-Gynecologic Society, Toronto, Ontario, Canada, September 1994. Toronto: American UroGynecologic Society, 1994. Bump RC, et al. Correlation of vesical Valsalva leak point pressures (VLPP), vaginal VLPP, and cough leak point pressures in women with genuine stress incontinence. In: Proceedings of the fifteenth annual meeting of the American Uro-Gynecologic Society, Toronto, Ontario, Canada, September 1994. Toronto: American Uro-Gynecologic Society, 1994. DR. DAVID SOPER, Richmond, Virginia. Do your measurements add anything to the clinical evaluation of patients who may be surgical candidates? Would you comment on the relationship of your measurements and to the surgical candidacy of a given patient as opposed to clinical observations that most clinicians would do in their office if they do not have the sophisticated testing equipment that you have? DR. JOHN THORP, Chapel Hill, North Carolina. We recently took nulliparous women with no bladder dysfunction and did an array of simpler tests and then retested the women. With that work, our correlation coefficients were similarly small and barely reached statistical significance. Can you hypothesize why the correlations you find are so small? DR. THEOFRASTOLJS (Closing). I thank Dr. Wiskind and the others for such a thoughtful discussion, and I will try to address the points somewhat in order. The 33 women who completed the quality-of-life instruments did so as part of their participation in an ongoing Continence Program for Women clinical trial. The instruments were part of a 39-page questionnaire that requires about 45 minutes for the woman to complete; thus women not in the trial did not complete it. There were no differences in any of the demographic, clinical, urodynamic, or quality-of-life measures between the women who completed quality-of-life instruments and those who did not complete the questionnaire. In reference to the consistency between the centers, all of the studies were performed by one of three physicians using identical equipment and a standardized technique. We are relatively software impaired, and all the data were measured by hand, in some cases in triplicate. The reproducibility of the Valsalva leak point pressure was established in our previous study, which indicated that the intraobserver variation is very small with an r value

Theofrastous et al.

413

close to 1.0, a slope of 0.83, and a y intercept of 5.3 on regression analysis.’ Is dynamic profilometry a research tool? We see it as one method among many to establish the diagnosis of genuine stress incontinence according to International Continence Society criteria. It is also useful for describing populations of patients or the effects of intervention. Pelvic organ prolapse can affect both active and passive measures of urethral resistance.2 None of the patients in this study had significant pelvic organ prolapse, defined as descent of any part of the vagina lower than 1 cm above the hymenal ring during a Valsalva maneuver. I think these discussions outline the need for standardization of this technique. The confusion is epitomized by recent Medicare guidelines for the diagnosis of intrinsic sphincteric deficiency before periurethral injection of collagen for the treatment of incontinence, which lists a leak point of 65 cm Ha0 with no specifics of how that number is obtained. With those criteria 60% to 70% of the patients in our study would have that diagnosis, but we believe that the proportion of true intrinsic sphincteric deficiency is much lower, closer to 20%. In the study by McGuire et al.’ that Dr. Wiskind mentioned, the pressure resulting in leakage during straining was noted as total intraabdominal pressure, but the catheters were zeroed at the level of the bladder. This would make the measurement equivalent to our measuring technique. I would note that most urologists determine leak points with contrast in the bladder, documenting leakage radiographically. There is as yet no comparison of that technique in which larger catheters are used with the method outlined in this study, we suspect that the former technique results in higher leak point pressures. We also have noted that there is a variable effect of having a catheter in the urethra during measurement of a leak point pressure. Patients with impaired urethral function seem to have lower leak points with a catheter in place. We postulate that this phenomenon may be because of splinting of the urethra by the catheter and disruption of mucosal coaptation. Conversely, in women who have higher measures of urethral resistance, the catheter seems to obstruct the urethra and increase the leak point. We are in the midst of examining both of these issues, as well as the effect of intravesical volume on Valsalva leak point pressures. We wholeheartedly agree that standardization of this technique is vital, and we would encourage any practitioners who are not using a standardized or published technique to mention the details of the technique including the equipment they are using, patient position, type of fluid, intravesical volume, provocative maneuvers, method of assessing leakage, and reproducibility. Dr. Soper asked an excellent clinical question. We see this study as establishing the criterion-related validity of the Valsalva leak point pressure compared with other clinical and urodynamic measures of incontinence severity and diagnosis. There is no doubt that a woman without complications and with straightforward symptoms and definitive findings on examination and with

Barrett

et al.

August 1995 Am J Obstet Gynecol

simple urodynamics does not require complicated testing. The leak point is a very attractive measure in that it is relatively simple to perform and does not require overly sophisticated and expensive equipment. I suggest that the utility of this test at this point is mainly as an aid for establishing the diagnosis of genuine stress incontinence and for follow-up of women after intervention to assess efficacy of therapy. Ultimately, it is possible that the Valsalva leak point pressure may identify women who may be at increased risk for failure after conventional continence surgery, as has been suggested for critical values of urethral closure pressure+’ and hypermobility.”

In answer to Dr. Thorp’s question, I think it is tempting to oversimplify and to imply that what we are seeing at a given moment in the relatively unnatural setting of the laboratory is an accurate reflection of what a woman experiences during her daily activities. It is a further leap of faith to hope that these artificial constructs will have a consistent and understandable relationship with each other. The best that we can hope for is to standardize our measuring techniques and to validate these measures clinically. Beyond scientific interest, the ultimate purpose of our testing is to establish the right diagnosis and to help us to choose the most successful method of therapy.

Endometrial cancer: Stage at diagnosis and associated factors in black and white patients Rolland J. Barrett II, MD,” Linda C. Harlan, PhD,b Margaret N. Wesley, PhD, Holly A. Hill, MD, PhD,d Vivien W. Chen, PhD,’ Linda A. Clayton, MD, MPH, Herbert L. Katz, MD,g J. William Eley, MD, MPH,d Stanley J. Robboy, MD,b and Brenda K. Edwards, PhDb Winston-Salem and Durham, North Carolina, Atlanta, Georgia, Shreveport, Louisiana, New

Bethesda and Silver Spring, York,

New

York,

and

Maryland,

Washington,

D.C.

OBJECTIVE: This study examined the relationship of clinicopathologic, health status, medical system, and socioeconomic factors to differences in stage at diagnosis of endometrial cancer in black and white patients. STUDY DESIGN: A population-based study of 130 black and 329 white patients with invasive endometrial cancer was conducted as part of the National Cancer Institute’s Black/White Cancer Survival Study. Logistic regression was used to determine the relative importance of factors thought to be related to stage at diagnosis after age and geographic location were adjusted for. RESULTS: High-grade (poorly differentiated) lesions increased the risk for stage Ill or IV disease (odds ratio 8.3, 95% confidence interval 3.4 to 20.3) as did serous histologic subtype (odds ratio 3.5, 95% confidence interval 1.4 to 8.8) and no usual source of care (odds ratio 5.5, 95% confidence interval 1.4 to 20.9). In the final statistical model these three factors also accounted for the majority of the excess risk of advanced stage for blacks. CONCLUSION: Black-white racial disparities in stage at diagnosis appear to be related to higher-grade lesions and more aggressive histologic subtypes occurring more frequently in black patients with endometrial cancer. (AM J OBSTET GYNECOL 1995;173:414-23.)

Key words:

Endometrial

cancer, stage, risk factors, race

From the Department of Obstetrzcs and Gynecology, Bowman Gray School ofMedicine of Wake Forest University,” the Division of Cancer Prevention and Control, National Cancer Institute,” Information Management Services, Inc.,’ the Department of Epidemiology, Rollins School of Public Health of Emory lJniversity,d the Department of Pathology, Louisiana State University Medical Center,’ Neu York City Health and Hospitals Corporation,’ the Department of Obstetrics and Gynecology, George Washington University Hospital,” and the Department of Pathology Duke University Medical Center.” Presented as Oficial Guest at the Fi$y-seventh Annual Meeting of The South Atlantic Association of Obstetricians and Gynecologists, Hot Springs, Virginia, Januav 28-31, 1995. Reprint requests: Rolland J. Barrett II, MD, 1900 S. Hawthorne Road, Suite 712, Winston-Salem, NC 27103. 6/6/66197

Cancer of the uterine corpus is the most common malignancy of the female genital tract, with an estimated 31,000 new cases in the United States in 1994, with 5900 deaths projected.’ The difference in survival rates between black and white patients with cancer of the corpus uteri is well established. The most recent data from the Surveillance, Epidemiology and End Results Program of the National Cancer Institute show an overall difference of 30% between the races, with higher survival among white patients.‘, ’ A number of important factors have been identified related to sur-