Determining the feasibility of randomising infants, children and young people to invasive and non-invasive urine sampling techniques

Background Obtaining uncontaminated urine samples from children can be difficult. Clean catch urine (CCU) is non-invasive but may be slow and lead to a contaminated sample, whereas transurethral bladder catheterisation (TUBC) and suprapubic aspiration (SPA) are invasive. We assessed the feasibility of randomising children to a definitive trial. Methods FROG was a multicentre, randomised feasibility trial with a mixed-methods perspectives study, health-economic analysis and stakeholder consensus meeting. Children under 16 years requiring urine testing for suspected urinary tract infection (UTI) who could not provide a midstream sample were eligible for the feasibility trial. Parents, children and healthcare professionals were eligible for the perspectives study and consensus meeting. Results Of 703 children screened, 170 were offered the study and 99 were recruited. Overall, 64/170 (37.6%) consented to randomisation, exceeding the feasibility threshold (33%); 32 were allocated to CCU and 32 to TUBC. The allocated method was received by 46/64 (71.9%); delays, unsuccessful collection and distress contributed to non-receipt. Among participants with available cultures, contamination occurred in 2/12 (16.7%) allocated CCU and 0/6 allocated TUBC. No participants consented to randomisation involving SPA. The perspectives study included 14 parent interviews, 89 parent questionnaires and 28 staff across 5 focus groups and 1 interview. CCU and TUBC were considered acceptable, although participants balanced speed and accuracy against pain and distress. SPA availability and acceptability were limited. A total of 19 stakeholders attended the consensus meeting; 94% supported recruiting children aged under 18 months and 100% supported comparing CCU with TUBC, without SPA. Accuracy was the highest-ranked outcome. Conclusions A definitive trial comparing CCU-first with TUBC-first in children aged under 18 months is feasible. Its primary outcomes should reflect diagnostic accuracy and clinical consequences of contamination, with successful collection, collection time, pain and distress assessed as key secondary outcomes.