A total of 40 studies were identified, including 2,751 participants (Figure 1). Most trials were published between 2010 and 2019 (n=21 studies) and were conducted in Europe (n=18 studies). Pelvic floor muscle training (PFMT) associated with electrical stimulation (EStim) (n=9 studies) and tibial nerve stimulation (TNS) (n=8 studies) were the most frequently investigated conservative management interventions. UI episodes (n=17 studies) and UI symptom questionnaires (n=17 studies) were the most frequently reported outcomes. Adverse events were reported in 19 studies. Only 2/40 (5%) trials were classified as having an overall low risk of bias.
Brain disorders
22 studies involved participants with brain disorders, including stroke (n=14 studies), Parkinson’s disease (n=5 studies) and memory/cognitive impairment (n=3), totaling 1,745 participants with a mean age of 69 (±6.5), of which 52% were women. Among these studies, 14/22 reported no data on adverse events. In those that did, six reported no adverse events and two reported adverse events. Adverse events included residual urine volume > 150 ml, minor skin irritation, ankle cramping, falls, urinary tract infection and bladder catheterization. Overall, the number of adverse events was small and similar across groups.
TNS vs. no active treatment
Based on data available, TNS probably makes no difference for the relief of UI symptoms at the end of treatment (RR 1.12, 95% CI 0.55 to 2.27, p=0.76; I2 = 36%; moderate certainty of evidence) and intermediate follow-up (RR 1.12, 95% CI 0.54 to 2.33, p=0.75; I2 = 0%; moderate certainty of evidence) (Table 1). The evidence supporting TNS is very uncertain on UI episodes over 24 hours (MD -1.14, 95% CI -2.80 to 0.53, p=0.18; I2 = 88%; very-low certainty of evidence) and UI-specific QoL measures (MD -6.66, 95% CI -16.54 to 3.23, p=0.19; I2 = 68%; very low certainty of evidence) (Table 1).
EStim vs. no active treatment
EStim may improve UI symptom measures (SMD -0.84, 95% CI -1.17 to -0.51, p<0.00001; I2 = 0%; moderate certainty of evidence). The evidence supporting EStim is very uncertain regarding UI episodes over 24h (MD -4.13, 95% CI -7.94 to -0.32, p=0.03; I2 = 97%; very-low certainty of evidence) (Table 1).
Toilet assistance vs usual care
Based on data available, toilet assistance probably improves neuro-urological QoL (MD -3.17, 95% CI -6.01 to -0.33, p=0.03; I2 = 0%; moderate certainty of evidence) (Table 1). However, this intervention is not likely to affect UI symptom measures at the end of treatment (SMD -0.16, 95% CI -0.48 to 0.17, p=0.35; I2 = 0%; low certainty of evidence) and intermediate follow-up (SMD -0.00, 95% CI -0.38 to 0.38, p=0.99; I2 = 0%; low certainty of evidence) (Table 1).
SC disorders
Three RCTs involved participants with SC disorders: two RCTs included participants with an SC injury, and one RCT included subjects with spina bifida, totaling 422 participants with mean age of 42 (±10.5), of which 39% were women. All studies reported data on adverse events, two studies reported no adverse events, and one study participant reported soreness of the pelvic floor area in the PFMT group 1/17 (5.9%). There were not enough RCTs to report on the certainty of evidence of conservative interventions for the treatment of UI symptoms in SC disorders.
MS
Thirteen trials included participants with MS, totaling 545 participants with a mean age of 45 (±7.1), of which 72% were women. Among these studies, seven reported no data on adverse events, five reported no adverse events, and in one study, 1/10 (10%) participants reported that the protocol was physically and psychologically demanding, and 1/10 (10%) reported tingling in the posterior right thigh, both in the PFMT with EStim group.
PFMT with EStim vs. PFMT
Based on available data, PFMT with EStim probably decreases UI episodes over 24h at the end of treatment (MD -0.62, 95% CI -1.15 to -0.10, p=0.02; I2 = 0%; moderate certainty of evidence), but probably makes no difference at intermediate follow-up (MD -0.19, 95% CI -0.6 to 0.22, p=0.36; I2 = 0%; moderate certainty of evidence) (Table 1). PFMT with EStim probably has the same effect as PFMT alone on neuro-urological QoL (MD -0.21, 95% CI -0.52 to 0.11, p=0.2; I2 = 0%, low certainty of evidence). The evidence is very uncertain regarding UI-specific QoL (SMD -0.45, 95% CI -1.15 to 0.26, p=0.21; I2 = 58%, very-low certainty of evidence) (Table 1).
Mixed neurological disorders
Two trials included participants with mixed neurological disorders, totaling 39 participants with a mean age of 54 (±1.4) of which 56% were women. Both studies reported no adverse events. There were not enough RCTs to report on the certainty of evidence of conservative interventions for the treatment of UI symptoms in patients with mixed neurological disorders.