Prevalence of Urinary Incontinence in a Random Sample of the Urban Population of Pouso Alegre, Minas Gerais, Brazil

Correspondencia: Claudia Regina de Souza Santos Universidade de São Paulo. Escola de Enfermagem. Departamento de Enfermagem Médico-Cirúrgica (ENC). Av. Dr. Enéas de Carvalho Aguiar, 419 Bairro: Cerqueira Cesar CEP: 05403-000 São Paulo, SP, Brasil E-mail:claudiasantos8@hotmail.com 1 Enfermera, Maestría en Enfermería, Profesor Adjunto, Universidade de Lavras, MG, Brasil. E-mail: claudiasantos8@hotmail.com. 2 Enfermera, Libre docente, Profesor Asociado, Escola de Enfermagem, Universidade de São Paulo, SP, Brasil. E-mail: veras@usp.br. El estudio tiene por objetivo conocer la prevalencia de la incontinencia urinaria (IU), de los factores de predicción demográficos y clínicos de la presencia de IU. Se trata de un estudio epidemiológico de corte transversal, aprobado por el Comité de Ética de la Escuela de Enfermería de la Universidad de Sao Paulo. Muestreo estratificado por conglomerado compuesto de 519 individuos con edad ≥18 años, residentes en 341 domicilios del área urbana, sorteados aleatoriamente. Las pruebas utilizadas fueron Chi-cuadrado, Hosmer Lemeshow y regresión logística multivariante (stepwise). Las prevalencias de IU fueron estandarizadas por sexo y edad, en una muestra de 519 personas, siendo 20,1% en la población general 32,9% eran mujeres y 6,2% hombres. Los factores más fuertemente asociados a la IU fueron: mayor tiempo de pérdidas (OR=29,3; p<0,001), diabetes mellitus (OR=17,7; p<0,001), accidente vascular encefálico (OR=15,9; p<0,001) y cistocele (OR=12,5; p<0,001). El estudio permitió conocer la epidemiologia de la IU y puede contribuir para el desarrollo de políticas públicas para su prevención primaria y secundaria, su tratamiento, inclusive considerando su inicio en el ámbito municipal.


Introduction
The International Continence Society (ICS) defines Urinary Incontinence (UI) as "any involuntary urine loss" and classifies it into the following basic categories: Stress Urinary Incontinence (SUI), Urge Incontinence (UUI), Mixed Incontinence (MUI), Continuous Urinary Incontinence (CUI) and Post Micturition Symptoms (PMS) (1) .According to these concepts, the terms 'urinary incontinence' and 'urinary loss' are interchangeable and are so used by ICS researchers and specialists.UI has a multi-factor origin; studies have shown that its occurrence is associated with gynecological surgeries and the female sex (2) , advanced age and multiple births (3) , hypertension, diabetes mellitus, childbirth carried out at home, and infections in the urinary tract (4) .Some Santos CRS, Santos VLCG.
Given the epidemiological relevance of UI among women, several international studies specifically addressing this population in different age ranges and situations have been carried out in various countries.A prevalence of UI of 31% was found in Bergen, Norway in women six months after birth (7) , with an increased risk in the cases of vaginal birth and perineal laceration (8) .
A longitudinal study also investigated an elderly female population over the course of nine years and found a UI incidence of 14%, showing that associated factors are pelvic organ prolapse, urinary tract infection, obesity, multiple births and surgery such as a hysterectomy (9) .
In addition to these conditions, studies have also shown that UI might also be associated with gynecological surgeries and advanced age, infection in the urinary tract, being female (2) , hypertension, diabetes mellitus, childbirths carried out at home (4) , multiple births, and obesity (3) .
There are few population studies in Brazil (4) , using different methodologies and in general addressing specific groups such as women during pregnancy or in distinct periods postpartum (10) , elderly individuals (11) or institutionalized chronic patients (12) , and patients in the postoperative phase of radical retropubic prostatectomy; this last group has an incidence of 62% of UI in 13 studied patients (13) .These facts confirm the need and relevance of this study (13) .
Therefore, this study identifies and analyzes the prevalence of urinary incontinence and verifies the following demographic (age, ethnicity, gender, schooling, family income) and clinical factors (pregnancy/multiple births, urogynecologic and rectal surgery, rectal and genital prolapse, medication, menopause, urinary infection, dysuria and nocturia symptoms, diabetes mellitus and hypertension), predictors of UI in adults residing in the urban area of Pouso Alegre, MG, Brazil.The sample, composed of 341 houses distributed over five regions, with the level of precision at 5%, was established from a stratified cluster sampling in a single stage.The houses were randomly selected.The selected individuals had to meet the following criteria in order to be included in the study: being 18 years old or older, being of a physical and mental condition to answer the interview questions and to give consent to participate in the study.Finally, 519 people composed the sample.About 30.3% of the male individuals refused to participate.The study was limited to the urban area of the city due to the difficulties in obtaining addresses in the rural area.Two instruments were used to collect data (2) .

Method
The first addressed socio-demographic data (gender,

Results
The Even though almost all demographic and clinical factors were significantly associated with the occurrence of UI in the final logistic regression (Table 2), a longer duration of loss, (OR=29.3;p<0.001), diabetes mellitus (OR=17.7;p<0.001), stroke (OR=15.9;p<0.001) and cystocele (OR=12.5;p<0.001) were the factors most strongly associated with UI.Other factors such as frequent urinary infections can be also included.

Discussion
Among all types of incontinence, UI is the one with largest number of studies though most studies address only specific groups such as women, older or institutionalized individuals.In this study, the standardized prevalence of UI was 21.1% in the population in general; 32.9% in women and 6.2% in www.eerp.usp.br/rlae Rev. Latino-Am.Enfermagem 2010 Sep-Oct;18(5):903-10.
men, adults residents in the urban area of Pouso Alegre.
A lower prevalence in women and similar in men was found in Portugal with 21.4% and 7.6%, respectively, in people 40 years old or older (14) .
In Brazil, only two studies addressed groups from the population in general.A study carried out in Porto Alegre, RS, Brazil, identified detrusor overactivity in 18.9% among 448 individuals 15 to 55 years old.The authors verified that the highest prevalence was found in the same age groups for both men and women, though women were most affected (15) .The second national study verified a prevalence of 10.7% in a randomized community sample of 657 respondents, in a Family Health Program in the district Cidade Dutra, SP, Brazil.
Several and high BMI were associated with UUI (3) .
A study conducted in Western Turkey with a sample of 1,585 women 20 years old or older reported a prevalence of 49.5% and the following associated factors: frequent urinary infections, diabetes mellitus, diuretic medication and advanced age (16) .
In Europe, a multi-center study (17) carried out in France, Germany, Spain and the United Kingdom sent 29,500 questionnaires by mail and found that 2,953 women had UI.Another important study EPINCONT (18) also carried out in Europe, with  (4) .In 2006, also with a female population, half of the 340 women presented SUI in the third trimester of pregnancy in Campinas, state of São Paulo (10) .Finally, in 2008, a study addressing the prevalence of overactive bladder (OAB) in women older than 15 years of age and using a stratified cluster sample (368 visited households), in Sorocaba, state of São Paulo, a total index of 10.1% was found: 6.1% had wet OAB and 4% dry OAB.In this study, women with lower educational levels, lower income, older than 20 years of age, sedentary and smokers had a greater probability of developing OAB.Additionally, at each increase in the BMI unit, this probability increased by 6.6% (19) .
Even though the identified studies have methodologies that differ among them and in relation to this study, a high predominance of women with UI, which varied according to age, was observed in most of the studies.These were also associated factors or predictors in this study.However, some other predictors such as duration of UI, which was the most important according to the final model of multivariate regression, were characterized in only some of the studies found (20)(21) .Diabetes mellitus was also one of the most important factors in the occurrence of UI, which is also confirmed in other studies (22)(23) .
Relatedly, hypertension and stroke, which were also factors significantly associated with UI in this study, are confirmed in some other reviews (24) .The same occurred with cystocele, which was revealed to be one of the most important factors explaining UI (25) , corroborating the intrinsic relation between pelvic organ prolapse and UI.
The only factor of reproductive life significantly associated with UI was the number of vaginal deliveries, which was also found in a study carried out in China with women 20 years old or older, also associated with SUI (26) .
Since most of the older individuals use medication that may increase urinary frequency, increasing the need to go to the bathroom, many end up reducing their consumption of water and food, which may result in increased dysuria and urinary infections, ultimately worsening a UI condition.Hence, educating and supporting older individuals, whether they are institutionalized or not, as well as their family members and caregivers, are essential measures in reducing such occurrences.
Another recommendation that results from this study is the targeting of women, a group badly affected by UI, compose another risk population, to whom prevention programs, both primary and secondary, addressing pregnancy, childbirth and postpartum.
This is an epidemiological, exploratory, descriptive, and cross-sectional study, population-based where correlations are tested.The study was developed in Pouso Alegre, MG, Brazil.The target population was composed of people 18 years old or older, resident of the urban area of Porto Alegre.The city's population was estimated at 120,467 in 2007* for the purpose of sampling.
The project was approved by the Research Ethics Committee at the University of São Paulo (process 673/2007/CEP/EEUSP) and complied with the requirements of Resolution nº 196/96 of the National Council of Health.
ethnicity, schooling, marital status, occupation and family income) and clinical information (previous urogynecologic surgery, number and type of childbirths, dysuria, previous urinary infection, anal and genital disorders, medications, menopause, hypertension, diabetes mellitus, e UI); the second instrument included UI characteristics (duration and condition, urge leakages, waking up during the night to urinate, UI during sexual intercourse, frequency and quantity of urinary leakage, use and frequency external collection devices were changed).UI prevalence was adjusted by gender and age range using the population of Pouso Alegre as the standard.Hence, the standardized prevalence of UI was obtained in this study.Variables were analyzed through the Chisquare test before the logistic regression process and only those with statistically significant differences were included in the multivariate regression model (stepwise method).The verification of model adjustment was performed using the Chi-square test and the Hosmer Lemeshow test.In relation to the logistic regression procedure, the univariate model was used to identify any association between each of the independent variables and the dependent variable (the presence of UI or not).* http://www.ibge.gov.br/cidadesat/topwindow.htm?1 www.eerp.usp.br/rlaeRev. Latino-Am.Enfermagem 2010 Sep-Oct;18(5):903-10. Independent variables were incorporated into the multivariate models when significant (p<0.05).The models 1, 2, 3 and 4 were used to model, respectively, the relation between socio-demographic, clinical and reproductive life variables, and characteristics of urinary leakage with urinary incontinence .Model 5, considered the final model, was used to model the relation between all the significant variables that were kept in the models 1 through 4. The level of statistical significance adopted was 5% (p≤0.05).

Table 1 -
Characteristics of UI in residents of Pouso

Table 2 -
Demographic and clinical factors associated with the occurrence of UI in residents of Pouso Alegre, MG, studies have been carried out specifically