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Table 1 Candidate predictors of bacteriuria measured (a) once at admission (constant throughout one hospital stay; time independent) and (b) multiple times throughout a patient’s hospital stay (time-dependent)

From: Development of risk prediction models to predict urine culture growth for adults with suspected urinary tract infection in the emergency department: protocol for an electronic health record study from a single UK university hospital

Candidate predictor Definition Units/categories
(a) Measured at admission
Demographic
 Age Recorded age at hospital admission in 10-year age bands (continuous age is unavailable due to privacy regulations) 18–24, 25–34,…, 95–104
 Sex As recorded in the admission notes Male/female
 Social deprivation Index of Multiple Deprivation (IMD) 2015 quintile Deciles (1–10)
 Ethnicity As recorded in the admission notes; collapsed into 5 major categories Asian, Black, Mixed, other, White
Co-morbidity
 Charlson Co-morbidity Index Numeric comorbidity score based on the presence of relevant ICD-10 codes in the entire hospital record* Count (1–33)
 Underlying renal disease Presence of a relevant ICD-10 code in the previous 5 years* Yes/no
 Underlying urological condition Presence of a relevant ICD-10 code in the previous 5 years* Yes/no
 Renal or urological surgery Presence of a relevant OPCS code in the previous 5 years* Yes/no
 Immunosuppression Presence of a relevant ICD-10 code in the prior year* Yes/no
 Cancer Presence of a relevant ICD-10 code in the prior year* Yes/no
Previous healthcare contact   
 Discharge from hospital in prior 7 days Most recent discharge date from QEHB within 7 days of index attendance date Yes/no
 Number of previous admissions Number of hospital spells at QEHB in the prior year Count (≥ 0)
 Number of days spent in hospital Number of days spent as an inpatient at QEHB in the prior year Count (≥ 0)
 Number of previous ED attendances Number of ED attendances at QEHB in the prior year Count (≥ 0)
Factors predisposing to UTI   
 Previous admission for UTI Admission to QEHB with an ICD-10 code of UTI on discharge in the prior year* Yes/no
 Previous ED attendance for UTI ED attendance at QEHB with ED diagnosis of lower UTI, pyelonephritis or urosepsis in the prior year Yes/no
 Number of previous admissions for UTI Number of hospital spells at QEHB with an ICD-10 code of UTI on discharge in the prior 2 years* Count (≥ 0)
Number of previous ED attendances for UTI Number of ED attendances at QEHB with ED diagnosis of lower UTI, pyelonephritis or urosepsis in the prior year* Count (≥ 0)
 Previous urine culture Urine sample submitted at QEHB for microbiological diagnosis in prior year Yes/no
 Previous bacteriuria Urinary pathogen identified at QEHB from blood or urine in prior year Yes/no
 Previous resistant pathogen Drug-resistant pathogen identified at QEHB from blood or urine in prior year Yes/no
 Prior antibiotic consumption Total antibiotic consumption in QEHB in prior year Defined daily doses (DDDs) (≥ 0) [18]
Characteristics of the admission
 Admitted from care home As recorded Yes/no
 Month of admission As recorded January,…, December
 Day of year of admission As recorded Count (1–366)
 Day of week of admission As recorded Monday,…, Sunday
Investigations in the ED
 Suspected diagnosis in the ED ED impression of clinical syndrome as recorded by the ED clinician Lower UTI, pyelonephritis, urosepsis
 Positive urinalysis Presence of leucocytes and/or nitrates in urinalysis Yes/no
Urinalysis  
 Leucocytes As recorded by the clinician (dipstick test) Positive/negative
 Nitrates As recorded by the clinician (dipstick test) Positive/negative
 White blood cells As recorded by the laboratory (flow cytometry) Count/μL
 Red blood cells As recorded by the laboratory (flow cytometry) Count/μL
 Epithelial cells As recorded by the laboratory (flow cytometry) Count/μL
 Small round cells As recorded by the laboratory (flow cytometry) Count/μL
 Bacteria As recorded by the laboratory (flow cytometry) Count/μL
 Yeast As recorded by the laboratory (flow cytometry) Count/μL
 Conductivity As recorded by the laboratory (flow cytometry) mS/cm
 Casts As recorded by the laboratory (flow cytometry) Count/μL
 Crystals As recorded by the laboratory (flow cytometry) Count/μL
(b) Measured multiple times throughout hospital stay
Clinical observations
 Heart rate As recorded Beats per minute
 Respiratory rate As recorded Breaths per minute
 Body temperature As recorded
 Oxygen saturation As recorded Percent
 Systolic blood pressure As recorded mmHg
 AVPU As recorded Alert, verbal, pain, unresponsive
 SEWS Standardised Early Warning Score as recorded or calculated based on heart rate, respiratory rate, body temperature, oxygen saturation and AVPU Count (0–18)
Clinical investigations
 White cell count (blood) As recorded 103/mL
 C-reactive protein As recorded mg/L
 Creatinine As recorded μmol/L
 Acute kidney injury score Defined as the change in serum creatinine compared to an approximate baseline measure (i.e. average creatinine in previous 6 months) Stage 0 (1.0–1.5 × baseline), stage 1 (1.5–1.9), stage 2 (2.0–2.9) stage 3 (≥ 3.0)
 Alkaline phosphatase As recorded IU/L
 Bilirubin As recorded μmol/L
 Platelets As recorded 109/L
Antibiotic treatment
 Antibiotic treatment Recorded administration of any systemic antibiotic (British National Formulary chapter 5.1.) Yes/no
 Broad-spectrum antibiotic Recorded administration of any of the following antibiotics: co-amoxiclav, piperacillin-tazobactam, carbapenems, cephalosporins (except 1st generation), quinolones, colistin, fosfomycin, aminoglycosides Broad-spectrum, narrow-spectrum, none
 Route of administration Recorded route of administration, giving precedence to intravenous (IV) antibiotics (i.e. if multiple antibiotics are prescribed with ≥ 1 IV, treatment is classified as IV) IV, oral, none
 Dosage As recorded DDDs (≥ 0) [18]
  1. *Detailed code lists available in the appendix
  2. For each time-dependent variable, we will also consider the change in value compared to the last observed measurement
  3. Excluding anti-tuberculosis and anti-leprosy medication