Table 2

Definitions of UTI for primary and secondary analyses. As the UTI definitions are combinations of two or more components, the start of the risk period is defined as the date of the earliest component

	UTI-related read code in GP data (online supplemental material B)	Antibiotic prescription in GP data (online supplemental material C)	UTI-related ICD-10 code in PEDW (online supplemental material D)	Urine culture results in WRRS	Time frame	Clinical scenario
Primary analysis	Yes	Yes	No	Yes, showing bacterial growth of ≥1x10⁸ CFU/L and WCC ≥1x10⁸ /L	Three codes occur within a 7-day window	GP clinically suspected and microbiologically confirmed UTI
Secondary analysis 1	Yes	Yes	No	Yes, showing mixed bacterial growth (any descriptor for ‘mixed growth’ or >3 organisms).	Three codes occur within a 7-day window	GP clinically suspected UTI with mixed growth
Secondary analysis 2	Yes	Yes	No	No	Same day	GP clinically diagnosed and treated UTI. It is important to consider this group as not all individuals with suspected UTI have urine culture, and limiting to those with culture is subject to selection bias.
Secondary analysis 3	Yes	Yes	No	Yes, showing bacterial growth of <1x10⁷ CFU/L.	Three codes occur within a 7- day window	UTI is clinically suspected but not supported by microbiology. This group is important to understand if early symptoms and signs of acute MI or stroke are attributed to UTI.
Secondary analysis 4	No	No	Yes	Yes, showing bacterial growth of ≥1x10⁸ CFU/L and WCC ≥1x10⁸ /L	Two codes occur within a 7-day window	UTI diagnosed and/or treated in hospital
Secondary analysis 5	Yes, OR ICD-10 code	Yes, OR ICD-10 code	Yes, OR: UTI Read code AND antibiotic Read code	Yes, showing bacterial growth of ≥1x10⁸ CFU/L and WCC ≥1x10⁸ /L	Two/three codes occur within a 7-day window	GP clinically suspected and microbiologically confirmed UTI or UTI diagnosed and/or treated in hospital

GP, General Practice; ICD-10, International Classification of Disease version 10; PEDW, Patient Episode Database for Wales; UTI, urinary tract infection; WCC, white cell count; WRRS, Welsh Results Reporting Service .