Risk of adverse outcomes following urinary tract infection in older people with renal impairment: Retrospective cohort study using linked health record data

Abstract

Background

Few studies have investigated the risk of adverse outcomes in older people with renal impairment presenting to primary care with a urinary tract infection (UTI). The aim of this study was to determine the risk of adverse outcomes in patients aged ≥65 years presenting to primary care with a UTI, by estimated glomerular filtration rate (eGFR) and empirical prescription of nitrofurantoin versus trimethoprim.

Methods and findings

This was a retrospective cohort study using linked health record data from 795,484 patients from 393 general practices in England, who were aged ≥65 years between 2010 and 2016. Patients were entered into the cohort if they presented with a UTI and had a creatinine measurement in the 24 months prior to presentation. We calculated an eGFR to estimate risk of adverse outcomes by renal function, and propensity-score matched patients with eGFRs <60 mL/minute/1.73 m ² to estimate risk of adverse outcomes between those prescribed trimethoprim and nitrofurantoin. Outcomes were 14-day risk of reconsultation for urinary symptoms and same-day antibiotic prescription (proxy for treatment nonresponse), hospitalisation for UTI, sepsis, or acute kidney injury (AKI), and 28-day risk of death. Of 123,607 eligible patients with a UTI, we calculated an eGFR for 116,945 (95%). Median age was 76 (IQR, 70–83) years and 32,428 (28%) were male. Compared to an eGFR of >60 mL/minute/1.73 m ², patients with an eGFR of <60 mL/minute/1.73 m ² had greater odds of hospitalisation for UTI (adjusted odds ratios [ORs] ranged from 1.14 [95% confidence interval (CI) 1.01–1.28, p = 0.028], for eGFRs of 45–59, to 1.68 [95% CI 1.01–2.82, p < 0.001] for eGFRs <15) and AKI (adjusted ORs ranged from 1.57 [95% CI 1.29–1.91, p < 0.001], for eGFRs of 45–59, to 4.53 [95% CI 2.52–8.17, p < 0.001] for eGFRs <15). Compared to an eGFR of >60 mL/minute/1.73 m ², patients with an eGFR <45 had significantly greater odds of hospitalisation for sepsis, and those with an eGFR <30 had significantly greater odds of death. Compared to trimethoprim, nitrofurantoin prescribing was associated with lower odds of hospitalisation for AKI (ORs ranged from 0.62 [95% CI 0.40–0.94, p = 0.025], for eGFRs of 45–59, to 0.45 [95% CI 0.25–0.81, p = 0.008] for eGFRs <30). Nitrofurantoin was not associated with greater odds of any adverse outcome. Our study lacked data on urine microbiology and antibiotic-related adverse events. Despite our design, residual confounding may still have affected some of our findings.

Conclusions

Older patients with renal impairment presenting to primary care with a UTI had an increased risk of UTI-related hospitalisation and death, suggesting a need for interventions that reduce the risk of these adverse outcomes. Nitrofurantoin prescribing was not associated with an increased risk of adverse outcomes in patients with an eGFR <60 mL/minute/1.73 m ² and could be used more widely in this population.

Abstract

In this retrospective study, Haroon Ahmed and colleagues investigate associated risks between common urinary tract infection and impaired kidney function in older adults, as well as outcomes related to nitrofurantoin prescription.

Author summary

Why was this study done?

• It is not known if older adults with impaired kidney function are at increased risk of hospitalisation or death following a urinary tract infection (UTI).

• Nitrofurantoin is an antibiotic used to treat UTI but is not recommended in people with impaired kidney function. However, the evidence supporting this recommendation is limited.

What did the researchers do and find?

• This study used linked health record data from general practices and hospitals in England and estimated risk of hospitalisation and death for older adults with impaired kidney function presenting to primary care with a suspected UTI.

• Older adults with impaired kidney function had greater risk of a UTI-related hospitalisation and death in the 14–28 days following a UTI.

• Older adults with impaired kidney function who were treated with nitrofurantoin were not at greater risk of an adverse outcome and were less likely to experience a hospital admission for worsening kidney function.

What do these findings mean?

• There is a need for strategies that prevent UTIs and reduce the risk of UTI-related hospitalisations and death in older adults with impaired kidney function.

• Nitrofurantoin was not associated with worse outcomes and could be used more widely in this population.