Abstract
BACKGROUND: Risk factors for poor prognosis in outpatient urinary tract infection (UTI) vary across studies and clinical guidelines. AIM: To review the evidence on risk factors for poor prognosis in adults' UTI. DESIGN & SETTING: Systematic review and meta-analysis of observational studies performed in the outpatient setting. METHOD: Five databases and citations of included studies were searched. Two reviewers independently screened studies, abstracted data, and assessed risk of bias (RoB). Random-effects meta-analysis of relative risks (RR) and adjusted odds ratios (aORs) were performed for risk factors reported by ≥3 studies. RESULTS: Thirty-five cohort studies including 1 532 790 adults with cystitis or pyelonephritis (PN) were included. Ten were at moderate to high RoB. Increasing age was the only independent predictor of re-consultation (aOR 1.18 per decade). Hospitalisation was associated with high procalcitonin (PCT) (aOR 5.12), increasing age (aOR 3.51 if aged ≥65 years; aOR 1.27 per decade), hypotension (aOR 3.29), fever >38°C (aOR 2.08), elevated C-reactive protein (CRP) (aOR 1.62), creatinine ≥1.2 mg/dl (aOR 1.56), male sex (aOR 1.41), and diabetes (aOR 1.34). In the only study on mortality, among patients aged ≥65 years with cystitis, this outcome was associated with no antibiotics; older age; hospitalisation or antibiotics in prior month; higher comorbidity index; and smoking. CONCLUSION: Older age, male sex, elevated CRP, and diabetes are predictors of adverse outcomes in both patients with cystitis and PN. Elevated PCT, creatinine, hypotension, and fever predict hospitalisation in patients with PN only. These findings support risk stratification and patient management, but further studies are needed to consolidate knowledge on risk factors, especially for patients with cystitis.