2. Patient population

Following internal departmental ethics approval, patients with ED were prospectively enrolled from January 2018 to January 2019 (Fig. 1). Inclusion criteria included patient age ≥18 years, has a poor response to medical therapy, a minimum 6-month history of ED, International Index of Erectile Function (IIEF)-5 score ≥12, and is in a stable sexual relationship for more than 3 months. Poor response to medical therapy is defined as a lack of adequate penile erection for sexual intercourse with the aids of oral phosphodiesterase type-5 inhibitors and/or intracavernosal therapy, with an IIEF-5 score less than 21. Patients who developed ED following prostate cancer treatment such as prostatectomy or radiation, or pre-existing anatomical or neurological conditions were excluded. Patient demographics including comorbid conditions and vascular risk factor and pre-treatment IIEF-5, Erection Hardness Score (EHS) and Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) scores were recorded. The IIEF-5 questionnaire is the abridged five-item version of the IIEF with a scale from 0 to 25, where a score of 0 to 5 is awarded to each of the 5 questions, where 0 denotes no sexual activity while 5 means almost always or always. On the other hand, the EHS is a validated single-item patient-reported outcome on the hardness of erection ranging from 0 (penis does not enlarge) to 4 (completely hard and fully rigid). The exclusion criteria were patients who have a history of coagulopathy, pelvic (or prostate) surgery, received radiation therapy or androgen deprivation therapy for prostate cancer, uncontrolled diabetes (glycosylated haemoglobin >7%), and those with penile deformity and neurological disorders. The primary outcome of this study was improvement in EF based on IIEF-5 and EHS, while secondary endpoints were safety profile and patient satisfaction rates with LIESWT.