In the sham electroacupuncture group, Hwato brand disposable sterile acupuncture needles (Suzhou Medical Appliance Factory) of φ0.30×25mm and φ0.30×40mm are used. The electroacupuncture apparatus is Hwato SDZ-V. Control points corresponding to Ciliao (BL32), Zhongliao (BL33), Shenshu (BL23), and Sanyinjiao (SP6) as main acupoints, with with adjunct control points selected by syndrome differentiation. After needle insertion, electrodes of the electroacupuncture device are connected horizontally to bilateral Ciliao, Zhongliao, and Sanyinjiao respectively. Continuous wave at a frequency of 2 Hz is applied, with current intensity 0.1-0.3 mA to produce slight tingling tolerated by the patient. Stimulation is delivered for 30 seconds then turned off. Each session lasts 30 minutes over 6-month period. During the first month, treatment is administered 3 times weekly (once every other day); the second month, 2 times weekly (once every 2-3 days); and the 3-6 month, once monthly.

Total number of cumulative lower urinary tract infections in all patients within 1 year

The number and proportion of patients with 0, 1, 2, 3, 4, and ≥5 lower urinary tract infection episodes within 6 months and 12 months.

It was defined as the time interval from randomization to the first occurrence of acute lower urinary tract infection, recorded in days. For participants without recurrence during the follow-up period, the data were censored at the end of the study.

It was defined as the time interval between two consecutive episodes of acute lower urinary tract infection during the observation period, recorded and calculated in days. Patients with only one episode or no recurrence were not included in the calculation.

It refers to the time from the onset to remission of each acute lower urinary tract infection episode, documented in days. The mean value was calculated as the average duration of all such episodes.

It refers to the average score of the Urinary Tract Infection Symptoms (UTIS) questionnaire completed by patients during each acute lower urinary tract infection episode, which reflects the severity of symptoms during each episode. The UTIS is used to assess the severity of urinary tract infection-related symptoms. Scores were calculated based on the frequency and severity of symptoms. UTIS comprises 4 dimensions: none, mild, moderate, and severe. Each dimension is rated on 4 levels (none = 0, mild = 1, moderate = 2, severe = 3). Lower scores indicate milder urinary symptoms and a better outcome, while higher scores indicate more severe symptoms.

It was defined as the difference between the urinary tract infection symptom score (UTIs) score at follow-up time points without acute lower urinary tract infection and the baseline score, used to evaluate the improvement of persistent urinary symptoms. The UTIS is used to assess the severity of urinary tract infection-related symptoms. Scores were calculated based on the frequency and severity of symptoms. UTIS comprises 4 dimensions: none, mild, moderate, and severe. Each dimension is rated on 4 levels (none = 0, mild = 1, moderate = 2, severe = 3). Lower scores indicate milder urinary symptoms and a better outcome, while higher scores indicate more severe symptoms.

It was defined as the difference between the EQ-5D-5L score at each follow-up time point and the baseline score, to assess the improvement in patients' quality of life. The EQ-5D-5L comprises 5 dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is rated on 5 levels (1 = no problems, 2 = slight problems, 3 = moderate problems, 4 = severe problems, 5 = extreme problems). Higher scores indicate better health-related quality of life.

It was defined as the difference between the Hospital Anxiety and Depression Scale (HADS) total score, anxiety subscale score, and depression subscale score at each follow-up time point and the baseline score, used to evaluate the effect of the intervention on anxiety and depression. The HADS consists of two subscales: anxiety and depression, with 7 items each. Each item is scored from 0 to 3. Anxiety subscale: 0-21, depression subscale: 0-21. Higher scores indicate more severe anxiety and depression, while lower scores reflect better emotional state.

It was defined as the difference between post-void residual urine volume at each follow-up time point and the baseline value, to evaluate the effect of the intervention on patients' urinary function. Post-void residual urine volume was measured by abdominal ultrasound. After the patient completely emptied the bladder, the superior-inferior, left-right, and anterior-posterior diameters of the bladder were measured, and the volume was calculated using the built-in formula of the ultrasound machine.

It was defined as the difference between the maximum urinary flow rate, average urinary flow rate at each follow-up time point and the baseline values, to assess the effect of the intervention on patients' urinary function. Maximum urinary flow rate and average urinary flow rate were measured by uroflowmetry. With a natural desire to void, patients urinated freely and independently into the uroflowmeter device, which automatically recorded and calculated the maximum and average urinary flow rates in mL/s.

Patient-Reported Response Rate assessed by the Patient Global Impression of Change (PGIC) scale, defined as the percentage of patients with at least mild improvement (including very much improved, much improved, and minimally improved) after intervention among all valid cases. PGIC: patients rated their overall change after treatment based on subjective feelings, using a 7-point scale: 1 = very much improved, 2 = much improved, 3 = minimally improved, 4 = no change, 5 = minimally worse, 6 = much worse, 7 = very much worse. Lower scores indicate better patient-reported response rate.

Patients' expectation of the therapeutic effect of acupuncture was assessed using a questionnaire before treatment. Patients were asked: "In general, how do you think your lower urinary tract infection will be 6 months from now?" The response options included: much better, better, do not know, no change, and worse.

Patients' trust in acupuncture therapy was assessed using a questionnaire before treatment. Patients were asked: "Do you think acupuncture is helpful for treating your lower urinary tract infection?" The response options included: ineffective, poorly effective, uncertain, moderately effective, and highly effective. This index was used to evaluate patients' trust in acupuncture for urinary tract infection.

After treatment, patients were asked: "Do you think the treatment you received was indistinguishable, electroacupuncture, or sham electroacupuncture?" The response options were: do not know, electroacupuncture, and sham electroacupuncture. This was used to assess patients' guesses regarding treatment allocation and to evaluate the success of blinding.

It refers to the actual number of days of antibiotic treatment during each acute lower urinary tract infection (LUTI) episode

It refers to the proportion of enrolled patients who received at least one course of antibiotic treatment during the entire observation follow-up period.

It refers to the cumulative number of days of antibiotic treatment received by each participant during the entire follow-up observation period.