Defining recurrent urinary tract infection and reinfection risk: electronic health record study.

BACKGROUND: There is limited evidence to support the current standard recurrent urinary tract infection (rUTI) definition of ≥2 UTIs within 6 months or ≥3 within 12 months. Information about reinfection risk after meeting criteria for rUTI may aid decisions on the value of prophylactic approaches. AIM: To estimate the risk of subsequent UTI associated with different rUTI definitions. DESIGN & SETTING: Electronic health record study using Infections in Oxfordshire Research Database (IORD, 2008-2019) and the Clinical Practice Research Datalink (CPRD, 2009-2019). METHOD: We identified community-acquired UTIs, separated by 28 days, in non-pregnant women aged 16+years. We created candidate rUTI definitions varying the time window from 3-9 months, and the number of UTIs required to meet the definition from 2-3 episodes. For each definition, we calculated Kaplan-Meier risk estimates of subsequent UTIs within 6 and 12 months after meeting rUTI criteria. RESULTS: Of eligible women with at least one UTI, 18% (15,617/84,809) in IORD and 20% (334,487/1,703,088) in CPRD experienced ≥1 rUTI (current definition). The risk of at least two subsequent UTIs within 12 months after meeting the current rUTI definition rose from 17% (IORD) and 16% (CPRD) to 33% (IORD) and 32% (CPRD) under a rUTI definition of ≥3 UTIs within 6 months. Risk of subsequent UTI also increased with age. CONCLUSION: Risk estimates of subsequent UTIs after a rUTI vary according to the definition of rUTI adopted. Estimates provided here could support shared decision making around UTI prophylaxis and stratification of populations included in future rUTI research.