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NO RELATIONSHIP BETWEEN SUBJECTIVE ASSESSMENT OF URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN IN A RANDOM POPULATION SAMPLE OF MENOPAUSAL WOMEN
Vol. 159,800-803,March 1998 Printed in U.S&
NO RELATIONSHIP BETWEEN SUBJECTIW ASSESSMENT OF URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN IN A RANDOM P O P U T I O N SAMPLE OF MENOPAUSAL WOMEN ALLAN MALTHA RYHAMMER,* S0REN LAURBERG, JENS CHRISTIAN DJURHUUS ANNE PERNILLE H E R M A "
AND
From the Surgical Research Unit, Department of Surgery L and University Department of Endocrinology and Metabolism, Amtssygehuset, University Hospital of Aarhus and Institute of Experimental Clinical Research, university of Aarhus, Aarhus, Denmark
ABSTRACT
Purpose: We studied the association between urinary incontinence and pad weight gain during a 24-hour pad test in healthy menopausal women. Materials and Methods: Menopausal women 45 to 58 years old were randomly sampled from the national register. Information on self-reported urinary incontinence was collected at patient interview using a structured questionnaire. A 24-hour home pad test was performed and episodes of urinary incontinence during the pad test were noted. Results: A total of 144 women 45 to 57 years old (mean age 50) were included in the study. At the interview 99 subjects (69%)reported urinary continence and 45 (31%) reported incontinence. Of the continence group 78 women (80%) performed the pad test and the mean weight gain was 3.1 gm.(range 0 to 9).Of the incontinence group 38 women (84%) performed the pad test and the mean weight gain was 3.3 gm.(range 0 to 8,not significant). Of the 38 women in the incontinence group 16 reported 1 or more episodes of urinary incontinence, whereas the remaining 22 reported no incontinence during the pad test. There was no difference in pad weight gain between these 2 groups (mean gain 3.3 gm.,range 0 to 8). Conclusions: The subjective assessment of urinary incontinence was frequent but it was not associated with the objective findings of the 24-hour pad test. KEYWORDS:urinary incontinence,questionnaires,menopause
The prevalence of urinary incontinence in middle-aged effect of postmenopausal replacement therapy with estrogen women in the normal population has been estimated in sev- on fracture risk. The study comprises 2,015 menopausal eral questionnaire studies at 9 to 60%.1-9 The volume of urine women with a planned followup of 20 years. Of the particileakage is generally reported to be minor, ranging from drop- pants 595 are followed at our center. Study participants were lets to volumes that wet the garments or pads.3-5.9-11 How- recruited through a mailed questionnaire. Between October ever, to our knowledge the objective assessment of leakage 1990 and February 1993 this questionnaire was mailed to has never been studied in these epidemiologicalpopulations women 45 to 58 years old who were randomly selected from using quantitative methods. We evaluate 24-hour pad test the national register according to civil registration number weight gain, and compare the results of self-reported conti- and who resided in 1 of the 4 geographical areas where the nence and incontinence in menopausal women based on a centers are located. Women who met the inclusion criteria random population sample drawn from the national register. (see Appendix)and desired to participate were invited to visit the nearest center for further information and a clinical SUBJECTS AND METHODS examination. At our center 16,000 letters were mailed and The results are baseline values from an ongoing random- 60% of those invited returned the questionnaire. Of the 157 women who were invited to participate in the ized study of the effect of postmenopausal estrogen treatment on pelvic floor function. Participants were consecutively present study 144 (92%)accepted. Mean subject age was 50 accrued between April 1992 and February 1993 from the years (range 45 to 571, mean height plus or minus standard Aarhus Centre of the multicenter Danish Osteoporosis Pre- deviation was 165 t 5.3 cm. and mean weight was 67 2 12.1 vention Study. All participants were menopausal women 45 kg. None of the participants had undergone abdominal or to 58 years old (see Appendix). Results of the anorectal tests gynecological surgery within the 12 months before the investigation. Previously 6 subjects had undergone bladder surhave been described previously.12 Danish Osteoporosis Prevention Study. The Danish Osteo- gery, including a vaginal procedure (Kelly plasty) in 2 and an porosis Prevention Study is a multicenter study of which the abdominal procedure (Burch operation) in 4. Complete abdepartment of endocrinologyand metabolism at our hospital dominal hysterectomy had been performed in 34 participants is 1 of the 4 centers. The aim of the prevention study is to (24%)and supravaginal hysterectomy in 1.The median numevaluate demographic, biochemical and osteodensitometric ber of births was 2 (range 0 to 6). T w o women were receiving variables as predictors of future fractures, and assess the diuretics at the time of the study. All background information was obtained by interviewing the participants and it was not checked with hospital files. Accepted for publication August 1, 1997. Supported by a grant from Institute of Experimental Clinical Participants were interviewed using a structured questionResearch, University of Aarhus, K. E. Jensen Foundation. naire on the symptoms of urinary incontinence and relevant * Requests for reprints: Surgical Research Unit, Department of S ery L, University Hospital of Aarhus, Amtssygehuset,DK-8000 background variables. All interviews were performed by 1 of a u s , Denmark. us (A. M.R.).Questions on urinary incontinence referred to 800
SUBJECTIVE URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN
80 1
the 12 months before the interview. Urge incontinence was incontinent: yes or no) to 0.35 (social or hygienic problem: recorded if the proband positively responded to the questions, yes or no) (see table). A valid pad test was performed by 116 “Have you, within the last twelve months, experienced a women (81%) in which mean pad weight gain was 3.2 gm. sudden, very strong urge to void,” and “If you have, did you :range 0 to 9) (fig. 1). Pad test results were excluded in 8 ever lose any urine before reaching the toilet.” Stress incon- :ases due to missing pads in 3,late return of the pads in 3 tinence was defined as a positive response to the question, and fecal soiling of the pads in 2. “Have you, within the last twelve months lost any urine Of the continence group 78 subjects (79%) and of the inwhen you coughed, laughed, sneezed, lifted heavy things, Icontinence group 38 (84%)performed the pad test. A total of etc.” Mixed incontinence was defined as a positive response 16 incontinent subjects reported at least 1 episode (range 1 to to both types of incontinence. Thus, each of the 3 types is 3) of urinary leakage during the pad test, whereas the remutually exclusive of the others. The reproducibility of the maining 22 had no incontinence during that time. Mean questionnaire was tested by having the same interviewer weight gain in the 3 groups was similar and in the same again interview the participants randomized to the control range (fig. 1). There was a 0.2 gm. mean difference (95%CI group after 3 months using the same structured question- -0.9 to 1.3)in weight gain between the continence group and naire. The interviewer and participants were blinded to the the 16 women who were incontinent during the pad test. A mean of 2.5 days (range 0 to 4) elapsed from the time of answers of the first interview. Participants were given 8 electronically pre-weighed pads finishing the pad test until the pads were weighed aRer the and a resealable plastic bag. They wore the pads as long as test. There was no difference in the fractions of continent and they chose and changed them as needed. While wearing the incontinent women who performed the pad test (78 of 99 continent, 79%, versus 38 of 45 incontinent, 84%, chi-square pads, they noted any episodes of urinary incontinence. &r finishing the test the pads were mailed to the hospital in a 0.63,p >0.3). Of the participants 41 performed the pad test stamped envelope and the pads were weighed. A maximum twice and the mean difference between the 2 tests was interval of 4 days from finishing the pad test to weighing the -0.3 ? 2 standard deviations 4.1gm. (95% CI -0.95 to 0.35, pads was tolerated. At the interview written instructions and 65% coefficient of variation) (fig. 2). In the laboratory no a thorough oral explanation were given. To establish the evaporation was demonstrated in the pads in the sealed bags repeatability of the pad test participants who had not started after 2 weeks. In the nonsealed bags a consistent weight loss treatment with estrogen (control group) were asked to repeat was present from day 4 ranging from 1 gm.in the set with 5 ml. of Ringer‘s lactate to 2 gm.with 15 ml. of solution added. the pad test. Evaporation from the pads was assessed in the laboratory using 6 pad test sets with 8 pads per set. Three volumes (5, DISCUSSION 10 and 15 ml.) of Ringer’s lactate in duplicate were added and We found that nearly a third of the normal menopausal the pads were put in the used plastic bags. In 1 of the 4 pad women reported urinary incontinence at interview. This essets the plastic bags were sealed but they remained open in timated prevalence is in accordance with the findings of the remaining 3. Wilson et al previously showed that the several epidemiological studies.1-9 However, urine leakage evaporation effects of urine and Ringer’s lactate are simi- was not demonstrated objectively using the 24-hour home lar.13 The pads remained in the laboratory at 21 to 25C and pad test. In women who reported incontinence at the interthey were weighed daily for 2 weeks. AU definitions con- view pad weight gains were the same range as those in formed to International Continence Society standards unless continent women, suggesting that self-reported continence otherwise stated. Participants received a financial reim- status does not correlate with the magnitude of pad weight bursement of 300 dKr. The study was performed in accor- gain. More strikingly, episodes of incontinence during the dance with the Helsinki Declaration I1 and was approved by pad test did not influence pad weight gain, which indicates the Ethical Committee of Aarhus County. All women pro- that the amount of urine lost was too small to be detected, or vided fully informed written consent. the pad test or reporting of incontinence was not fully valid. Statistical analysis. The precision of the estimated differ- The 95% CI for the estimated difference in pad weight gain ence in pad weight gain between the continent and inconti- between the continent and incontinent women suggests that nent groups was calculated using the formula, mean differ- the difference was probably no greater than 1 gm.The measence ? 95% confidence interval (CI), and the repeatability of urement error of weight was ‘1 gm. and, provided the the pad test was calculated according to the principles de- measurement error did not systematically depend on contiscribed by Bland and Altman.14 Bias is the mean difference nence status, it has not afFected the estimate of the differbetween the 2 test results (test 1 - test 2) and the corre- ence. sponding 95% CI indicates the precision of the estimated The validity of pad test results is highly dependent on difference. The calculated standard deviation of the differ- participant compliance. In our study 80% of the women perence expresses the variation between 2 consecutive meas- formed the pad test, and the fractions of incontinent and urements and 95% of the differences are expected to be less continent women who performed the tests were the same. than 2 standard deviations, termed the repeatability coeffi- Before performing the test thorough oral and written instruccient.14.15 The coefficient of variation is expressed as a per- tions were given. Compared with results from other studies, centage.16 All data were double keyed in a blinded fashion. in which healthy volunteers were studied, pad weight gains in the present study were in a similar range17.18 and testretest repeatability was the same.18 Compliance was moniRESULTS tored by noting the time from finishing the test to weighing At the interview 45 participants (31%)reported urinary the pads, and checking that no pads were missing upon incontinence, while the remaining 99 reported continence. There was stress incontinence in 26 subjects, urge incontinence in 10 and mixed incontinence in 9. Daily incontinence, Reproducibility of questions describing incontinence incontinence a t least once weekly and less than weekly incontinence were reported by 5, 12 and 28 women, respecVariable Kappa tively. A total of 24 women (53%of all those incontinent) wore Incontinence (yeelno) 0.78 sanitary pads for incontinence and 7 (16%) considered it a Type (streselurge/mixed) 0.65 Social or hygienic problem. Mean duration of incontinence Frequency (dailyhveeklyflessthan weekly) 0.60 Use of pads (yeelno) 0.47 was 6.8 years (range 1 to 37).Reproducibility was evaluated Social or hveienic nroblem (vedno) n RF. by calculating kappa coefficients, which ranged from 0.78
802
SUBJECTIVE URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN
L
I16 (87%) 3.2 (0-9)g
though 45 (31%)self-reported incontinence at interview. The 24-hour pad test results suggest that self-reported inconti. nent women had a similar amount of leakage in the pads as self-reported continent women. Pads were supplied by Molnlycke, Allered, Denmark. APPENDIX: INCLUSION AND EXCLUSION CRITERIA
Patient age 45 to 58 years and last menses 3 to 24 months ago or irregular periods, hot flushes and elevated serum FSH Patient age 45 to 52 years, hysterectomy and elevated serum FSH Exclusion criteria Anorectal incontinence Treatment with estrogens presently or previously for more than 3 months, or present treatment with corticosteroids Present or previous malignant disease, or metabolic bone disease
Inclusion criteria
REFERENCES
1. Elving, L. B., Foldspang, A., Lam, G. W. and Mommsen, S.: Descriptive epidemiology of urinary incontinence in 3,100 women age 30-59. Scand. J. Urol. Nephrol., suppl., 1 2 5 37, 1989. 2. Sommer, P., Bauer, T. and Nielsen, K. R:Voiding patterns and Drevalence of incontinence in women. A auestionnaire survev. brit. J. Urol., 66:12, 1990. 3. Yarnell. J. W.. Vovle. G. J., Sweetnam, P. M., Milbank. J.. Richards, C:J. &d Stephenson, T. P.: The prevalence and severity of urinary incontinence in women. J . Epidemiol. Community Health, 36: 71, 1981. 4. Brocklehurst, J. C.: Urinary incontinence in the communityanalysis of a MORI poll. Brit. Med. J., 306: 832, 1993. 0 5. LagroJanssen, T. L. M., Smits, A. J. and van Weel, C.: Women with urinary incontinence: self-perceived worries and general I I I I I I I , , , practitioners' knowledge of problem. Brit. J . Gen. Pract., 4 0 0 1 2 3 4 5 6 7 8 9 331, 1990. 6. Milsom, I., Ekelund, P., Molander, U., Amidsson, L. and Mean weight gain for the two tests (9) Areskoug, B.: The influence of age, parity, oral contraception, hysterectomy and menopause on the prevalence of urinary FIG.2. Test-retest repeatability of 2 4 h o y home pad test with incontinence in women. J. Urol., 1 4 9 1459, 1993. mean difference (test 1 - test 2) plotted a g w t mean (test 1 + test 7. Simeonova, Z. and Bengtsson, C.: Prevalence of urinary inconti2)2. nence among women at a Swedish primary health care centre. Scand. J. Pr. Health Care, 8: 203, 1990. return to the hospital. However, pad test results were not 8. Thomas, T. M., Plymat, K. R., Blannin, J . and Meade, T. W.: discussed with the participants after the test, since this sePrevalence of urinary incontinence. Brit. Med. J., 281: 1243, 1980. ries was part of a prospective study in which the investigator 9. Jolleys, J. V.: Reported prevalence of urinary incontinence in is blinded and, therefore, admission to previous results was women in a general practice. Brit. Med. J., 296. 1300, 1988. avoided. To obtain the highest possible validity of the information 10. Fall, M., Frankenberg, S., Frisen, M., Larsson, B. and Petren, M.: 456,000 Swedes may have urinary incontinence. Only evon the self-recarted continence status a structured ouestionerv fourth Derson seekshelo for the disorder. Ldcartidnineen. - . naire was d e d for the interview and all interviews were si: 2054, iwi. performed by 1interviewer. Testing the reproducibilityof the 11. Fenelev, R. C., SheDherd. A. M., Powell. P. H. and Blannin. J.: questionnaire revealed that reproducibility was good (kap Urin-& incontin&ce: prevalence and needs. Brit. J. Urol.,.Sl: pa = 0.78) regarding the question on incontinence,whereas it 493, 1979. was only fair (kappa = 0.35)regarding the question on social 12. Ryhammer, A. M., Laurberg, S. and Hermann, A. P.: Long-term effect of vaginal deliveries on anorectal function in normal or hygienic problems in relation to incontinence. However, it perimenopausal women. Dis. Colon Rect., 3 9 852, 1996. is also likely that the perception of continence status and reporting of leakage episodes were modulated by differences 13. Wilson, P. D., Al Samarrai, M. T. and Brown, A. D.: Quantifying female incontinence with particular reference to the Urilos in personality characteristics.19-22 Some women who are inSystem. Urol. Int., 3 5 298, 1980. continent may believe that urinary leakage represents vagi- 14. Bland, J. M. and Altman, D. G.: Statistical methods for assessing nal discharge or perspiration, and some who are continent agreement between two methods of clinical measurement. may report &continence episodes, although the perception of Lancet, 1: 307, 1986. pelvic floor stressing or a sensation of urgency did not result 15. Precision of Test Methods. Guide for the Determination of Repeatability and Reproducibility for a Standard Test Method by in actual leakage. Inter-laboratory Tests. Part 1. London: British Standards Institution, 1987 (unpublished data). CONCLUSIONS 16. Armitage, P. and Berry, G.: Statistical Methods in Medical ReIn our study of middle-aged women based on a random search. Oxford Blackwell Scientific publications, 1987. population sample no major incontinence was present, al- 17. Mouritsen, L., Berild, G. and Hertz, J.: Comparison of different
SUBJECTIVE URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN methods for quantification of urinary leakage in incontinent women. Neurourol. Urodyn., 8: 579, 1989. 18. Lose, G., Jorgensen, L. and Thunedborg, P.: 24Hour home pad weighing test versus 1-hour ward test in the assessment ofmild stress incontinence. Acta Obst. Gynec. Scand., 68: 211, 1989. 19. Wyman, J . F., Harkins, S. W., Choi, S. C., Taylor, J . R. and Fantl, J. A.: Psychosocial impact of urinary incontinence in women. Obst. Gynec., 7 0 378, 1987.
803
20. Frazer, M. I., Haylen, B. T. and Sutherst, J. R.: The severity of urinary incontinence in women. Comparison of subjective and objective tests. Brit. J. Urol., g3: 14, 1989. 21. Herzog, A. R. and Fultz, N. H.: Prevalence and incidence of urinary incontinence in communitydwelling populations. J. h e r . Geriatr. Soc., 38:273, 1990. 22. Fultz, N. H. and Herzog, A. R.: Measuring urinary incontinence in surveys. Gerontologist, 33:708, 1993.
NO RELATIONSHIP BETWEEN SUBJECTIW ASSESSMENT OF URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN IN A RANDOM P O P U T I O N SAMPLE OF MENOPAUSAL WOMEN ALLAN MALTHA RYHAMMER,* S0REN LAURBERG, JENS CHRISTIAN DJURHUUS ANNE PERNILLE H E R M A "
AND
From the Surgical Research Unit, Department of Surgery L and University Department of Endocrinology and Metabolism, Amtssygehuset, University Hospital of Aarhus and Institute of Experimental Clinical Research, university of Aarhus, Aarhus, Denmark
ABSTRACT
Purpose: We studied the association between urinary incontinence and pad weight gain during a 24-hour pad test in healthy menopausal women. Materials and Methods: Menopausal women 45 to 58 years old were randomly sampled from the national register. Information on self-reported urinary incontinence was collected at patient interview using a structured questionnaire. A 24-hour home pad test was performed and episodes of urinary incontinence during the pad test were noted. Results: A total of 144 women 45 to 57 years old (mean age 50) were included in the study. At the interview 99 subjects (69%)reported urinary continence and 45 (31%) reported incontinence. Of the continence group 78 women (80%) performed the pad test and the mean weight gain was 3.1 gm.(range 0 to 9).Of the incontinence group 38 women (84%) performed the pad test and the mean weight gain was 3.3 gm.(range 0 to 8,not significant). Of the 38 women in the incontinence group 16 reported 1 or more episodes of urinary incontinence, whereas the remaining 22 reported no incontinence during the pad test. There was no difference in pad weight gain between these 2 groups (mean gain 3.3 gm.,range 0 to 8). Conclusions: The subjective assessment of urinary incontinence was frequent but it was not associated with the objective findings of the 24-hour pad test. KEYWORDS:urinary incontinence,questionnaires,menopause
The prevalence of urinary incontinence in middle-aged effect of postmenopausal replacement therapy with estrogen women in the normal population has been estimated in sev- on fracture risk. The study comprises 2,015 menopausal eral questionnaire studies at 9 to 60%.1-9 The volume of urine women with a planned followup of 20 years. Of the particileakage is generally reported to be minor, ranging from drop- pants 595 are followed at our center. Study participants were lets to volumes that wet the garments or pads.3-5.9-11 How- recruited through a mailed questionnaire. Between October ever, to our knowledge the objective assessment of leakage 1990 and February 1993 this questionnaire was mailed to has never been studied in these epidemiologicalpopulations women 45 to 58 years old who were randomly selected from using quantitative methods. We evaluate 24-hour pad test the national register according to civil registration number weight gain, and compare the results of self-reported conti- and who resided in 1 of the 4 geographical areas where the nence and incontinence in menopausal women based on a centers are located. Women who met the inclusion criteria random population sample drawn from the national register. (see Appendix)and desired to participate were invited to visit the nearest center for further information and a clinical SUBJECTS AND METHODS examination. At our center 16,000 letters were mailed and The results are baseline values from an ongoing random- 60% of those invited returned the questionnaire. Of the 157 women who were invited to participate in the ized study of the effect of postmenopausal estrogen treatment on pelvic floor function. Participants were consecutively present study 144 (92%)accepted. Mean subject age was 50 accrued between April 1992 and February 1993 from the years (range 45 to 571, mean height plus or minus standard Aarhus Centre of the multicenter Danish Osteoporosis Pre- deviation was 165 t 5.3 cm. and mean weight was 67 2 12.1 vention Study. All participants were menopausal women 45 kg. None of the participants had undergone abdominal or to 58 years old (see Appendix). Results of the anorectal tests gynecological surgery within the 12 months before the investigation. Previously 6 subjects had undergone bladder surhave been described previously.12 Danish Osteoporosis Prevention Study. The Danish Osteo- gery, including a vaginal procedure (Kelly plasty) in 2 and an porosis Prevention Study is a multicenter study of which the abdominal procedure (Burch operation) in 4. Complete abdepartment of endocrinologyand metabolism at our hospital dominal hysterectomy had been performed in 34 participants is 1 of the 4 centers. The aim of the prevention study is to (24%)and supravaginal hysterectomy in 1.The median numevaluate demographic, biochemical and osteodensitometric ber of births was 2 (range 0 to 6). T w o women were receiving variables as predictors of future fractures, and assess the diuretics at the time of the study. All background information was obtained by interviewing the participants and it was not checked with hospital files. Accepted for publication August 1, 1997. Supported by a grant from Institute of Experimental Clinical Participants were interviewed using a structured questionResearch, University of Aarhus, K. E. Jensen Foundation. naire on the symptoms of urinary incontinence and relevant * Requests for reprints: Surgical Research Unit, Department of S ery L, University Hospital of Aarhus, Amtssygehuset,DK-8000 background variables. All interviews were performed by 1 of a u s , Denmark. us (A. M.R.).Questions on urinary incontinence referred to 800
SUBJECTIVE URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN
80 1
the 12 months before the interview. Urge incontinence was incontinent: yes or no) to 0.35 (social or hygienic problem: recorded if the proband positively responded to the questions, yes or no) (see table). A valid pad test was performed by 116 “Have you, within the last twelve months, experienced a women (81%) in which mean pad weight gain was 3.2 gm. sudden, very strong urge to void,” and “If you have, did you :range 0 to 9) (fig. 1). Pad test results were excluded in 8 ever lose any urine before reaching the toilet.” Stress incon- :ases due to missing pads in 3,late return of the pads in 3 tinence was defined as a positive response to the question, and fecal soiling of the pads in 2. “Have you, within the last twelve months lost any urine Of the continence group 78 subjects (79%) and of the inwhen you coughed, laughed, sneezed, lifted heavy things, Icontinence group 38 (84%)performed the pad test. A total of etc.” Mixed incontinence was defined as a positive response 16 incontinent subjects reported at least 1 episode (range 1 to to both types of incontinence. Thus, each of the 3 types is 3) of urinary leakage during the pad test, whereas the remutually exclusive of the others. The reproducibility of the maining 22 had no incontinence during that time. Mean questionnaire was tested by having the same interviewer weight gain in the 3 groups was similar and in the same again interview the participants randomized to the control range (fig. 1). There was a 0.2 gm. mean difference (95%CI group after 3 months using the same structured question- -0.9 to 1.3)in weight gain between the continence group and naire. The interviewer and participants were blinded to the the 16 women who were incontinent during the pad test. A mean of 2.5 days (range 0 to 4) elapsed from the time of answers of the first interview. Participants were given 8 electronically pre-weighed pads finishing the pad test until the pads were weighed aRer the and a resealable plastic bag. They wore the pads as long as test. There was no difference in the fractions of continent and they chose and changed them as needed. While wearing the incontinent women who performed the pad test (78 of 99 continent, 79%, versus 38 of 45 incontinent, 84%, chi-square pads, they noted any episodes of urinary incontinence. &r finishing the test the pads were mailed to the hospital in a 0.63,p >0.3). Of the participants 41 performed the pad test stamped envelope and the pads were weighed. A maximum twice and the mean difference between the 2 tests was interval of 4 days from finishing the pad test to weighing the -0.3 ? 2 standard deviations 4.1gm. (95% CI -0.95 to 0.35, pads was tolerated. At the interview written instructions and 65% coefficient of variation) (fig. 2). In the laboratory no a thorough oral explanation were given. To establish the evaporation was demonstrated in the pads in the sealed bags repeatability of the pad test participants who had not started after 2 weeks. In the nonsealed bags a consistent weight loss treatment with estrogen (control group) were asked to repeat was present from day 4 ranging from 1 gm.in the set with 5 ml. of Ringer‘s lactate to 2 gm.with 15 ml. of solution added. the pad test. Evaporation from the pads was assessed in the laboratory using 6 pad test sets with 8 pads per set. Three volumes (5, DISCUSSION 10 and 15 ml.) of Ringer’s lactate in duplicate were added and We found that nearly a third of the normal menopausal the pads were put in the used plastic bags. In 1 of the 4 pad women reported urinary incontinence at interview. This essets the plastic bags were sealed but they remained open in timated prevalence is in accordance with the findings of the remaining 3. Wilson et al previously showed that the several epidemiological studies.1-9 However, urine leakage evaporation effects of urine and Ringer’s lactate are simi- was not demonstrated objectively using the 24-hour home lar.13 The pads remained in the laboratory at 21 to 25C and pad test. In women who reported incontinence at the interthey were weighed daily for 2 weeks. AU definitions con- view pad weight gains were the same range as those in formed to International Continence Society standards unless continent women, suggesting that self-reported continence otherwise stated. Participants received a financial reim- status does not correlate with the magnitude of pad weight bursement of 300 dKr. The study was performed in accor- gain. More strikingly, episodes of incontinence during the dance with the Helsinki Declaration I1 and was approved by pad test did not influence pad weight gain, which indicates the Ethical Committee of Aarhus County. All women pro- that the amount of urine lost was too small to be detected, or vided fully informed written consent. the pad test or reporting of incontinence was not fully valid. Statistical analysis. The precision of the estimated differ- The 95% CI for the estimated difference in pad weight gain ence in pad weight gain between the continent and inconti- between the continent and incontinent women suggests that nent groups was calculated using the formula, mean differ- the difference was probably no greater than 1 gm.The measence ? 95% confidence interval (CI), and the repeatability of urement error of weight was ‘1 gm. and, provided the the pad test was calculated according to the principles de- measurement error did not systematically depend on contiscribed by Bland and Altman.14 Bias is the mean difference nence status, it has not afFected the estimate of the differbetween the 2 test results (test 1 - test 2) and the corre- ence. sponding 95% CI indicates the precision of the estimated The validity of pad test results is highly dependent on difference. The calculated standard deviation of the differ- participant compliance. In our study 80% of the women perence expresses the variation between 2 consecutive meas- formed the pad test, and the fractions of incontinent and urements and 95% of the differences are expected to be less continent women who performed the tests were the same. than 2 standard deviations, termed the repeatability coeffi- Before performing the test thorough oral and written instruccient.14.15 The coefficient of variation is expressed as a per- tions were given. Compared with results from other studies, centage.16 All data were double keyed in a blinded fashion. in which healthy volunteers were studied, pad weight gains in the present study were in a similar range17.18 and testretest repeatability was the same.18 Compliance was moniRESULTS tored by noting the time from finishing the test to weighing At the interview 45 participants (31%)reported urinary the pads, and checking that no pads were missing upon incontinence, while the remaining 99 reported continence. There was stress incontinence in 26 subjects, urge incontinence in 10 and mixed incontinence in 9. Daily incontinence, Reproducibility of questions describing incontinence incontinence a t least once weekly and less than weekly incontinence were reported by 5, 12 and 28 women, respecVariable Kappa tively. A total of 24 women (53%of all those incontinent) wore Incontinence (yeelno) 0.78 sanitary pads for incontinence and 7 (16%) considered it a Type (streselurge/mixed) 0.65 Social or hygienic problem. Mean duration of incontinence Frequency (dailyhveeklyflessthan weekly) 0.60 Use of pads (yeelno) 0.47 was 6.8 years (range 1 to 37).Reproducibility was evaluated Social or hveienic nroblem (vedno) n RF. by calculating kappa coefficients, which ranged from 0.78
802
SUBJECTIVE URINARY INCONTINENCE AND PAD TEST WEIGHT GAIN
L
I16 (87%) 3.2 (0-9)g
though 45 (31%)self-reported incontinence at interview. The 24-hour pad test results suggest that self-reported inconti. nent women had a similar amount of leakage in the pads as self-reported continent women. Pads were supplied by Molnlycke, Allered, Denmark. APPENDIX: INCLUSION AND EXCLUSION CRITERIA
Patient age 45 to 58 years and last menses 3 to 24 months ago or irregular periods, hot flushes and elevated serum FSH Patient age 45 to 52 years, hysterectomy and elevated serum FSH Exclusion criteria Anorectal incontinence Treatment with estrogens presently or previously for more than 3 months, or present treatment with corticosteroids Present or previous malignant disease, or metabolic bone disease
Inclusion criteria
REFERENCES
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20. Frazer, M. I., Haylen, B. T. and Sutherst, J. R.: The severity of urinary incontinence in women. Comparison of subjective and objective tests. Brit. J. Urol., g3: 14, 1989. 21. Herzog, A. R. and Fultz, N. H.: Prevalence and incidence of urinary incontinence in communitydwelling populations. J. h e r . Geriatr. Soc., 38:273, 1990. 22. Fultz, N. H. and Herzog, A. R.: Measuring urinary incontinence in surveys. Gerontologist, 33:708, 1993.