A number of prospective observational studies show the effectiveness and safety of vaginal Er:YAG SMOOTH® in treatment of women patients with stress urinary incontinence (SUI), confirmed by randomized sham-controlled data [1]. Long term studies demonstrate that the effects of Er:YAG SMOOTH® treatment are comparable to local hormone treatment [2]. Head to head study [3] showed that Er:YAG SMOOTH® therapy in women improved urinary incontinence as effectively as the tension-free vaginal tape (TVT) and transobturator tape (TOT) procedures. Clinical evidence and effectiveness of Er:YAG SMOOTH® treatment should not be ignored as possible harms induced by completely different and more invasive laser technologies are not uniform. However, prediction of outcome is needed. Aim of the of study was to find the pre-intervention predictors of a short-term Er:YAG outcome. The second objective was to identify patients segments with the best ER:YAG laser treatment short-term outcome.

A prospective cohort study at Ob/Gyn Clinic, Zagreb, Croatia, recruited 85 female patients suffering from SUI. The intervention was performed with 2940 nm wave length Er:YAG laser (XS Dynamis, Fotona, Slovenia). Study outcomes were absolute change in International Consultation on Incontinence Questionnaire –Short Form (ICIQ-UI), and the relative ICIQ-UI score decrease of ≥30% six months  after the intervention. Tested predictors were patients’ age, body mass index calculated as body weight in kilograms divided by body height in square meters, number of births, average birth weight, the last delivery weight, menopausal status, muscle strength of pelvic diaphragm indicated by average pressure (mmHg) measured by and Apimedis perineometer (EXTT-101, Korea), adequacy of anatomic support to the bladder neck and urethro-versical angle measured by Q-tip elevation, and ICIQ-UI baseline, pre-intervention value.

After power analysis we analyzed the sample of 84 patients. Range of their age was 30-70.
ICIQ-UI six months after the intervention decreased significantly for median (IQR) 45% (-93%-0%))
Overall predictor of a clinically relevant reduction in ICIQ-UI decrease (MID) (≥30%) was attained using a model containing: age ≤47.5 years (83% MID; 70% decrease; P=0.009); body mass index ≤23.3 (87% MID; 69% decrease; P<0.001); average birth weight >3.6 kg (78% MID; 66% decrease; P=0.217); ICIQ-UI at baseline ≤10 (85% MID; 65% decrease; P=0.013); perineometer squeeze duration at baseline ≥3.51 (87% MID; 77% decrease; P=0.001). Of the patients with ≤1 positive predictor (n=14), 36% achieved a clinically relevant reduction (MID) in ICIQ-UI. The mean (SD) reduction in ICIQ-UI was 14% (26%). All patients with four or five positive predictors achieved a clinically relevant reduction in ICIQ-UI (MID) of ≥30%. Positive predictive value was 0.97 (95% CI 0.87-0.99), and negative predictive value was 0.53 (95% CI 0.45-0.55).

Relevant decreases in ICIQ-UI (minimum important difference) of ≥30% can be predicted based on age, body mass index, average birth weight, perineometer squeeze duration, and ICIQ-UI scores prior to intervention. The best results should be expected in younger women with a body mass index of ≤23.3, an average birth weight of >3.6 kg, ICIQ-UI at a baseline of ≤10, and a baseline squeeze duration of ≥3.51 seconds. The critical age for Er:YAG laser effect is 47.5. Although the study sample is not representative, the results are indicative. The authors believe that the predictive model presented here will help practitioners identify which patients can expect desirable positive outcomes from Er:YAG laser treatment for SUI.

The improvement after Er:YAG SMOOTH® laser treatment was more effective in younger and normal weight patients. The findings and conclusions presented are limited due to the study’s reduced sample size, short term follow-up, and the lack of a control group. 
Long term well designed prospective studies are still needed to disclose effectiveness of laser and other EBDs in SUI and GSM treatment

Blaganje M, Šcepanovic D, Žgur L, Verdenik I, Pajk F, Lukanovic A. Non-ablative Er:YAG laser therapy effect on stress urinary incontinence related to quality of life and sexual function: A randomized controlled trial. Eur J Obstet Gynecol Reprod Biol 2018;224:153-158.
Gambacciani M, Levancini M, Russo E, Vacca L, Simoncini T, Cervigni M. Long-term effects of vaginal erbium laser in the treatment of genitourinary syndrome of menopause. Climacteric 2018;21:148-152.
Okui N. Comparison between erbium-doped yttrium aluminum garnet laser therapy and sling procedures in the treatment of stress and mixed urinary incontinence. World J Urol. 2018 Aug 16. doi: 10.1007/s00345-018-2445-x. [Epub ahead of print]