Keywords
obesity - urinary incontinence - bariatric surgery
Palavras-chave
obesidade - incontinência urinária - cirurgia bariátrica
Introduction
Obesity is a chronic disease with high prevalence that is difficult to manage.[1] It is a public health problem, and up to 1.9 billion people are affected by obesity
or overweightness.[2] The prevalence of obesity has doubled since the 1980s.[3] By 2016, 39% and 13% of adults over 18 years of age were overweight and obese respectively.[2] In the past, obesity was considered a problem found in developed countries; however,
obesity and overweightness are currently drastically increasing in low- and middle-income
countries, particularly in urban centers.[2]
[3]
Obesity is responsible for several adverse health effects, including increased morbidities
and greater mortality.[4] Elevated risks are already observed for overweight individuals, and increase progressively
with the development of obesity.[3] Obesity causes functional disabilities, reduced quality of life and reduced life
expectancy, and is known to contribute to increases in chronic diseases, including
cerebrovascular and cardiovascular diseases, diabetes, sleep apnea and pelvic floor
dysfunctions.[5]
[6] The negative effects of obesity on health include a strong association between obesity
and urinary incontinence (UI).[7]
Obesity is the best established and most potentially modifiable risk factor in the
development of UI.[8] A positive association between UI and body mass index (BMI) has already been confirmed
in certain studies.[7]
[8] There is a clear dose effect of weight on incontinence, with each 5-unit increase
in BMI associated with a 20 to 70% increase in incontinence risk.[7] Compared with normal-weight patients, obese patients have approximately twice the
risk of presenting with UI.[9]
[10] Increased weight may aggravate or cause pelvic floor disorders by increasing both
intra-abdominal pressure and chronic pressure on ligaments and nerves, leading to
excessive stretching.[11]
[12]
In addition, there are other recognized risk factors for UI. There is an increase
in the prevalence of UI during the perimenopausal period.[9] Most studies show a peak prevalence of UI, particularly stress UI (SUI), between
the ages of 40 and 60.[13]
[14] Parity is another factor that is clearly associated with increased UI.[10]
[15]
[16]
[17] Cesarean sections appear to have a protective effect; nevertheless, UI often presents
during pregnancy, and this manifestation is a predictive factor for postpartum UI
regardless of the delivery method.[18]
[19] Fetal weight and advanced maternal age also appear to be risk factors for UI.[20] A previous hysterectomy has been positively associated with the appearance of UI,
although the only available data regarding this association are from observational
studies.[21]
The aim of this study was to analyze the prevalence of UI in female patients with
an indication for bariatric surgery and investigate potential risk factors.
Methods
The present study was conducted in a reference center for morbid obesity. Ethical
and research approvals were obtained from the applicable local committee.
An informed consent form was offered to patients who satisfied the study criteria.
To the patients it was promised that all data would remain confidential, and that
the obtained results would only be used for scientific purposes. The participants
were recruited between June 2016 and September 2017. A total of 221 female patients
aged over 18 years old who had been assessed for bariatric surgery were enrolled in
the present study.
The initial evaluation was performed using a structured interview and a specific study
form. Symptoms and quality of life were assessed based on the interview, and the results
of the validated Portuguese version of the International Consultation on Incontinence
Questionnaire - Short Form (ICIQ-SF) and Kings Health Questionnaire.[22] The patients who reported episodes of UI once a week or less were considered symptomatic.
The anthropometric data, bioimpedance results, and medical histories were obtained
from the medical records.
Statistical analyses were performed using the Statistical Package for the Social Sciences
(SPSS, IBM Corp., Armonk, NY, US) software, version 21. Descriptive statistics (mean,
median, standard deviation, and range) were used to present numerical variable values.
Numbers and absolute and relative percentage frequencies were used to present categorical
variables. The Mann-Whitney U test was used to assess the statistical significance
of differences between median values. Continuous data were analyzed using the Student
t-test for related samples, and categorical variables were compared using chi-squared
tests. Poisson regression was performed to identify independent risk factors related
to UI. In the model, variables with p-values lower than 0.20 were included, and those with p-values lower than 0.10 were excluded. Multicollinear factors such as weight, excess
weight, BMI, and waist circumference were incorporated into different models to improve
the fit of the final model.
Results
During the study period, a total of 325 patients were identified as eligible subjects;
221 of these patients consented to participate and completed the baseline assessment.
The patients were divided into 2 groups (Group 1, patients with UI; Group 2, patients
without UI). A total of 118 patients (53.4%) reported UI episodes.
The patients in Group 1 were significantly older than the patients in Group 2 (41.1 ± 12.1years
versus 37.0 ± 9.1years, p = 0.006). Regarding the parameters used to evaluate the body composition of the patients,
BMI, abdominal circumference and excess of weight were significantly higher in Group
1 than in Group 2. Menopause was more frequent in Group 1 than in Group 2 (23/116
(19.8%) subjects versus 8/102 (7.8%) subjects). These data are summarized in [Table 1].
Table 1
Baseline demographic and clinical characteristics of the patients according to urinary
incontinence status
|
Variables
|
Patients with UI
(n = 118)
|
Patients without UI (n = 103)
|
p-value
|
|
Age (years)*
|
41.1 ± 12.1
|
37.0 ± 9.1
|
0.006
|
|
Weight (kg)*
|
118.7 ± 19.0
|
114.8 ± 17.5
|
0.121
|
|
BMI*
|
45.9 ± 7.6
|
44.0 ± 6.3
|
0.043
|
|
Waist circumference*
|
126.5 ± 13.1
|
122.8 ± 12.9
|
0.030
|
|
Waist-to-hip ratio*
|
0.93 ± 0.07
|
0.93 ± 0.19
|
0.704
|
|
Fat mass*
|
51.9 ± 3.5
|
51.5 ± 4.1
|
0.317
|
|
Excess weight (kg)*
|
53.8 ± 18.3
|
48.9 ± 16.0
|
0.041
|
|
Basal metabolic rate*
|
1583 ± 151
|
1565 ± 183
|
0.439
|
|
Hypertension
|
54/118 (45.8)
|
38/102 (37.3)
|
0.255
|
|
Diabetes
|
24/118 (20.3)
|
14/103 (13.6)
|
0.251
|
|
Asthma
|
11/118 (9.3)
|
7/103 (6.8)
|
0.661
|
|
Dyslipidemia
|
23/118 (19.5)
|
22/103 (21.4)
|
0.860
|
|
Smoking history
|
32/114 (28.1)
|
19/102 (18.6)
|
0.161
|
|
Hysterectomy
|
9/116 (7.8)
|
4/101 (4.0)
|
0.374
|
|
Menopause
|
23/116 (19.8)
|
8/102 (7.8)
|
0.020
|
|
Sexual activity
|
81/116 (69.8)
|
81/101 (80.2)
|
0.111
|
|
Parity
|
|
0
|
31/116 (26.7)
|
39/103 (37.9)
|
0.208
|
|
1–3
|
75 (64.7)
|
57 (55.3)
|
|
4–7
|
10 (8.6)
|
7(6.8)
|
|
Mode of delivery
|
|
Vaginal
|
30 (25.9)
|
17 (16.5)
|
0.088
|
|
Cesarean section
|
35 (30.2)
|
36 (35.0)
|
|
None
|
31 (26.7)
|
39 (37.9)
|
|
Both
|
20 (17.2)
|
11 (10.7)
|
Abbreviations: BMI, body mass index; UI, urinary incontinence.
Note: *Data presented as mean ± standard deviation; p-value calculated with the chi-squared test. All other data presented as number/total
of patients (%); p-value calculated with the chi-squared test.
A Poisson regression was performed to identify the independent risk factors related
to UI ([Table 2]). After an adjustment, the following factors were associated with UI: vaginal delivery
(p = 0.044) and menopause (p = 0.031). Among women who had given birth vaginally and women who had entered menopause,
the prevalence of UI was increased by 47% and 34% respectively. Smoking, excess weight
and having delivered both vaginally and via caesarean section exhibited borderline
associations with UI after the adjustment.
Table 2
Multivariate analysis
|
Variables
|
PR (95%CI)
|
p-value
|
|
Smoking history
|
1.28 (0.98–1.66)
|
0.071
|
|
Mode of delivery
|
|
None
|
1.00
|
|
|
Cesarean section
|
1.22 (0.83–1.79)
|
0.301
|
|
Vaginal
|
1.47 (1.01–2.12)
|
0.044
|
|
Both
|
1.41 (0.94–2.10)
|
0.095
|
|
Menopause
|
1.34 (1.03–1.76)
|
0.031
|
|
Weight excess
|
1.00 (0.99–1.01)
|
0.073
|
Abbreviations: 95%CI, 95% confidence interval; PR, prevalence ratio.
With respect to the patients with UI (Group 1), 40 (33.9%), 16 (13.5%), 62 (52.5%),
of these patients presented with SUI only, urgency UI (UUI) only, and mixed UI (MUI)
respectively. The median urinary frequencies during the day and at night were 6 (5–8)
voids and 2 (1–3) voids respectively, and 35/112 (31.2%), of the patients used pads
due to UI. Coital incontinence was reported by 12/111 (10.4%). A total of 75/111 (67.6%)
of the patients wanted a specific treatment for UI ([Table 3]).
Table 3
Data related to urinary incontinence
|
Patients with UI (N = 118)
|
|
SUI only
|
40 (33.9)
|
|
UUI only
|
16 (13.5)
|
|
MUI
|
62 (52.5)
|
|
Coital UI
|
12/111 (10.4)
|
|
Frequency*
|
6.0 (5–8)
|
|
Nocturia*
|
2 (1–3)
|
|
Use of incontinence pads
|
35/112 (31.2)
|
|
Desire for a specific treatment
|
75/111 (67.6)
|
Abbreviations: MUI, mixed urinary incontinence; SUI, stress urinary incontinence;
UI, urinary incontinence; UUI urgency urinary incontinence.
Note: *Median (range); other data presented as number/total of patients (%).
The results of the ICIQ-SF are described in [Table 4]. The mean ICIQ-SF score was 9.36 ± 4.9. The severity of symptoms was considered
moderate in 53.3% (63) of the Group 1 patients. Most of these patients believed that
they leaked small quantities: 79 (70.5%) of urine. The highest scores of the 9 domains
of the Kings Health Questionnaire were in the domains “Impact of Urinary Incontinence,”
“Measures of Gravity” and “General Perception of Health”, with mean scores and standard
deviations of 44.3 ± 33.3, 41.2 ± 26.9, and 43.2 ± 21.5 respectively.
Table 4
ICIQ-SF scores
|
Patients with UI (N = 118)
|
|
Total score *
|
9.36 ± 4.9
|
|
Severity
|
|
Slight (1–5)
|
29 (24.5)
|
|
Moderate (6–12)
|
63 (53.3)
|
|
Severe (13–18)
|
19 (16.1)
|
|
Very severe(19–21)
|
7 (5.9)
|
|
Frequency of urine leakage
|
|
Once a week or less
|
37 (31.5)
|
|
Twice to three times a week
|
31 (26.1)
|
|
Once a day
|
14 (11.8)
|
|
Several times a day
|
24 (20.3)
|
|
All the time
|
7 (5.9)
|
|
Amount of urine leaked
|
|
Small
|
79 (70.5)
|
|
Moderate
|
26 (23.2)
|
|
Large
|
7 (6.3)
|
|
Leaks before patient can get to the toilet
|
70 (62.5)
|
|
Leaks when patient coughs or sneezes
|
85 (75.9)
|
|
Leaks when patient is asleep
|
20 (17.9)
|
|
Leaks when patient is exercising
|
31(27.7)
|
|
Leaks after patient urinates
|
34 (30.4)
|
|
Leaks for no obvious reason
|
23 (20.5)
|
|
Leaks all the time
|
4 (3.6)
|
Abbreviations: ICIQ-SF, International Consultation on Incontinence Questionnaire -
Short Form; UI, urinary incontinence.
Note:*Total score = sum of questions 1, 2 and 3; other data presented as number/total
of patients (%).
Discussion
Urinary incontinence impacts quality of life negatively, and the prevalence of UI
is high in patients with obesity. In the present study, UI affected more than half
(53.4% (118)) of the patients with obesity; this finding was in agreement with previously
reported results.[23]
Urinary incontinence was more prevalent in patients after menopause. The patients
in Group 1 were older than those in Group 2, and this was statistically significant,
although the difference was not a marked one. Since the tissues involved in the female
urinary continence mechanism are sensitive to estrogen, estrogen deficiency after
menopause may be an etiological factor in the development or progression of UI.[24] This effect did not appear to be attenuated by the peripheral conversion of estrogen,
which is particularly common in patients with obesity.[25]
Vaginal delivery was the other independent factor associated with a higher prevalence
of UI. As it has been observed in other studies, this effect was most evident in the
third and fourth decades of life, but was attenuated in middle age and absent for
elderly subjects.[13]
[26]
[27] Thus, the aforementioned finding could be explained by the fact that the mean ages
of the examined subjects were 41.1 ± 12.1 years versus 37.0 ± 9.1 years for Group
1 and Group 2 respectively.
Urinary incontinence was more common in patients with higher BMIs, excess of weight
and waist circumference. In most studies, a strong association is observed between
increasing weight and UI. Each 5-unit increase in BMI was associated with ∼ 20 to
70% increase in the risk of daily incontinence.[7] However, in our sample, in which all of the patients had obesity, none of those
parameters were independently related to UI.
The most prevalent type of UI observed in the present study was MUI, followed by SUI.
The association between UI and obesity is known to be stronger for SUI and MUI and
more modest for UUI.[9]
[28]
[29]
[30] Cohort studies have also suggested that an earlier appearance of obesity is associated
with a higher probability of developing UI in middle age.[31] There is evidence that obesity increases the incidence of SUI, but increases in
metabolic syndrome are more strongly associated with IUU.[32] Increased weight may aggravate or cause pelvic floor disorders by increasing intra-abdominal
pressure and chronic pressure on ligaments and nerves, leading to excessive stretching.[11]
[12]
This study benefits from the use of a validated incontinence questionnaires, which
enable the differentiation of incontinence type, frequency, and severity based on
the self-reports of the patients. The use of this type of questionnaire allows for
better interpretation of the impact that patients' symptoms have on their quality
of life.
Another strength of our study is the number of obese patients who were enrolled. In
many studies, an obese population is compared with a normal BMI population. Our data
are from patients with a mean BMI of class III obesity.
An important limitation is the lack of an objective outcome to compare with subjective
measures. Our data could be stronger had we performed a pad test and/or an urodynamic
assessment.
Obesity is known to be associated with many medical issues. Recently, the association
between obesity and UI, which impacts quality of life, has been widely researched.
The impact of obesity on pelvic floor function and consequently UI cannot be underestimated.
This effect is particularly relevant at the present time, given the increasing prevalence
of obesity and, therefore, UI. Urinary incontinence is more than twice as prevalent
as diabetes and dyslipidemia, and is more prevalent than hypertension. In this study,
most of the patients with UI stated that they wanted a specific treatment for their
symptoms; such treatment needs to be offered by health professionals.
Conclusion
In our sample of patients with obesity, UI was highly prevalent and greatly impacted
quality of life. In the present study, vaginal delivery and menopause were independently
associated with a higher prevalence of UI.
