Urinary Incontinence in Older Hong Kong Women: A Cross-sectional Study

This study is a cross-sectional observational study designed in accordance with the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. A total of 1,000 female patients with urinary incontinence and 100 healthy controls will be enrolled.

Both urinary incontinence group and healthy group will be recruited through a combination of online publicity (via social media platforms) and offline community outreach. Each participant will be scheduled for a visit, during which the research staff will introduce the study's objectives, procedures, nature, and data privacy policy. Informed consent will be obtained. Socio-epi-demographic information (including age, educational level, marital status, occupation, income, reproductive history, medical history, comorbidities, medication history, diagnosis and treatment for urinary incontinence) and the type, frequency and severity of lower urinary tract symptoms will be collected.

Then, eligible participants with symptoms of urinary incontinence will undergo a 1-hour pad test, bladder capacity and post-void residual volume measurements, and a 1-week bladder diary to confirm the subtype of urinary incontinence (SUI, MUI, UUI) and its severity (mild, moderate, severe). Standardized questionnaires will be administered to assess the cognitive level regarding urinary incontinence (UIQ), quality of life (IIQ-7 and ICIQ-UI-SF), and barriers to care seeking (Barriers to Incontinence Care Seeking Questionnaire). Hand grip strength test will be conducted to evaluate the muscle strength. The first 300 urinary incontinence patients (100 with SUI, 100 with UUI, and 100 with MUI) enrolled in the study, who do not have chronic comorbidities (except for well-controlled hypertension or hyperlipidemia) and are not taking medications that affect urination or gut microbiota, will proceed to TCM syndrome differentiation and bio-sample collection. TCM syndrome differentiation related symptoms and signs will be collected for Delphi consensus research and cluster analysis. Blood, urine, stool routine lab tests (including metabolic and inflammatory markers such as fasting blood glucose, fasting triglycerides, albumin, creatinine, glucose, C-reactive protein, white blood cell count, etc.) and biological sample collection will also be performed for these patients.

Eligible participants who have never experienced symptoms of urinary incontinence and have no chronic comorbidity (expect for well-controlled hypertension and hyperlipidemia) and are not taking medications that affect urination or gut microbiota will serve as healthy controls. For healthy group, only blood, urine, stool routine lab tests and bio-sample will be conducted.

All data will be independently collected and cross-verified by two researchers, and entered into the electronic data management system (REDCap).

Diagnostic Criteria:

• Urinary Incontinence (UI)：Urinary incontinence will be diagnosed according to the definition of the International Continence Society (ICS), that is, 'any involuntary leakage of urine'. In addition, participants must have experienced this symptom continuously for at least six months to exclude cases of transient urinary incontinence.

• Stress Urinary Incontinence (SUI)：The clinical diagnosis of SUI will be made with reference to the guidelines of the European Association of Urology (EAU) and the International Continence Society (ICS):

• Symptoms: Involuntary leakage of urine during activities that increase intra-abdominal pressure, such as physical exertion, laughing, coughing, or walking; urine leakage stops immediately when the activity ceases.
• Signs: Positive result on the cough stress test or a positive 1-hour pad test (the procedure will follow the standardized ICS protocol; leakage >1g is considered positive).
• Pure urge incontinence and mixed urinary incontinence will be excluded. This subtype will be preliminarily identified using the Chinese version of the "3 Incontinence Questions" (3IQ): "During the past three months, in which of the following situations did you most often experience urine leakage? (single choice) A. During physical activities such as coughing, sneezing, lifting, or exercise; B. When you had the urge to urinate or felt the need to empty your bladder but could not reach the toilet in time; C. Without physical activity or urge; D. Equally during physical activity and urgency." (Selection of option A) SUI will be finally confirmed by a one-week bladder diary (showing only stress-related leakage) and a positive 1-hour pad test.

• Urge Urinary Incontinence (UUI)：The clinical diagnosis of UUI will follow the guidelines of the European Association of Urology (EAU) and the International Continence Society (ICS):

• Symptoms: Involuntary leakage of urine accompanied by or immediately preceded by urgency (a sudden, compelling desire to void that is difficult to defer).
• Cases of pure stress urinary incontinence and mixed urinary incontinence will be excluded.

This subtype will be preliminarily identified using the Chinese version of the "3 Incontinence Questions" (3IQ): "During the past three months, in which of the following situations did you most often experience urine leakage? (single choice) A. During physical activities such as coughing, sneezing, lifting, or exercise; B. When you had the urge to urinate or felt the need to empty your bladder but could not reach the toilet in time; C. Without physical activity or urge; D. Equally during physical activity and urgency." (Selection of option B) Final confirmation will be based on a one-week bladder diary recorded by the participant (showing only urgency-related leakage).

• Mixed Urinary Incontinence (MUI)：The clinical diagnosis of MUI will follow the guidelines of the European Association of Urology (EAU) and the International Continence Society (ICS):

• Symptoms: The presence of stress urinary incontinence symptoms, such as involuntary leakage of urine during activities that increase intra-abdominal pressure (e.g., exercise, laughing, coughing, walking), with urine flow ceasing immediately upon stopping the activity; and, at the same time, the presence of urge urinary incontinence symptoms, such as urgency (a sudden, compelling desire to void that is difficult to defer) accompanied by or immediately followed by involuntary leakage of urine.
• Signs: Positive result on the cough stress test or a positive 1-hour pad test (the procedure will follow the standardized protocol of the ICS; leakage >1g is considered positive).
• Cases of pure urge urinary incontinence and pure stress urinary incontinence will be excluded.

This subtype will be preliminarily identified using the Chinese version of the "3 Incontinence Questions" (3IQ): "During the past three months, in which of the following situations did you most often experience urine leakage? (single choice) A. During physical activities such as coughing, sneezing, lifting, or exercise; B. When you had the urge to urinate or felt the need to empty your bladder but could not reach the toilet in time; C. Without physical activity or urge; D. Equally during physical activity and urgency." (Selection of option D) Final confirmation will be based on a one-week bladder diary recorded by the participant (showing both urgency- and stress-related leakage) and a positive 1-hour pad test.

• Inclusion Criteria for Patients with Urinary Incontinence

• Females aged ≥55 years
• Has been living in Hong Kong for one year or more.
• Meet the diagnostic criteria for SUI, UUI, or MUI, and the symptoms of urinary incontinence have persisted for at least 6 months.
• Able to understand and follow written and verbal instructions in Chinese or English.
• Provide informed consent voluntarily after being fully informed

• Exclusion Criteria for Patients with Urinary Incontinence

• Diagnosed with types of urinary incontinence other than stress, urge, or mixed urinary incontinence, including those secondary to neurological or systemic diseases (such as post-stroke, post-spinal cord injury, multiple sclerosis, Alzheimer's disease, Parkinson's disease, or uncontrolled diabetic peripheral neuropathy), as well as the overflow incontinence.
• Active or structural urogenital diseases (such as unrepaired vesicoureteral reflux, congenital urethral malformations, urogenital fistula, urethral diverticulum, or active pelvic malignancies).
• Deemed by researchers to be unable to cooperate with assessments due to severe mental or physical illness.

• Eligible Urinary Incontinence Patients for Bio-Sample Collection

• The first 300 urinary incontinence patients (100 each with SUI, UUI, and MUI) enrolled in the study.
• No chronic comorbidities (except for well-controlled hypertension, defined as systolic blood pressure below 140 mmHg and diastolic blood pressure below 90 mmHg, and hyperlipidemia), including neurological disorders (central nervous system injury, motor neuron diseases, neurodegenerative diseases), diabetes, connective tissue diseases, psychiatric disorders, severe cardiovascular or cerebrovascular diseases, and severe liver or kidney diseases.
• Not using medications that affect urination or gut microbiota (including but not limited to thiazolidinediones, sodium-glucose cotransporter-2 inhibitors, anticholinergics, α- and β-adrenergic blockers, α- and β-adrenergic agonists, diuretic antihypertensives, antihistamines, muscarinic receptor antagonists, calcium channel blockers, angiotensin-converting enzyme inhibitors, hormone medications, neurotransmitter-related drugs, gut microbiota modulators, etc.).

• Inclusion Criteria for Healthy Volunteers

• Female, aged ≥55 years;
• Has been living in Hong Kong for one year or more;
• Able to understand and follow written and verbal instructions in Chinese or English;
• Fully informed and voluntarily signs the informed consent form.

• Exclusion Criteria for Healthy Volunteers

• Meet the diagnostic criteria for urinary incontinence;
• Has a history of involuntary urine leakage, or has sought medical consultation for symptoms related to urinary incontinence;
• Has chronic comorbidities (except for well-controlled hypertension, defined as systolic blood pressure below 140 mmHg and diastolic blood pressure below 90 mmHg, and hyperlipidemia).
• Uses medications that affect urination or gut microbiota (including but not limited to thiazolidinediones, sodium-glucose cotransporter-2 inhibitors, anticholinergics, α- and β-adrenergic blockers, α- and β-adrenergic agonists, diuretic antihypertensives, antihistamines, muscarinic receptor antagonists, calcium channel blockers, angiotensin-converting enzyme inhibitors, hormone medications, neurotransmitter-related drugs, and gut microbiota modulators, etc.).
• Deemed by researchers to be unable to cooperate with assessments due to severe mental or physical illness.