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Table 1 List of risk factors for acute kidney injury selected and defined for the study

From: Diagnosis of acute kidney injury and its association with in-hospital mortality in patients with infective exacerbations of bronchiectasis: cohort study from a UK nationwide database

Risk factors proposed in NICE guidance for AKI

Definition in the current study

- Chronic kidney disease (eGFR < 60 mL/min/1.73 m2)

- Outpatient eGFRa categorised into groups: > 60, 45–60, 30–45, and 15–30 mL/min/1.73 m2, and “No measurement” allocated if serum creatinine had not been measured for the past 2 years prior to the hospitalisation for LRTI.

- Heart failure

- Diagnosis of heart failure, recorded in CPRD before the hospitalisation for LRTI

- Liver disease

- Diagnosis of cirrhosis in CPRD, as a representative code for liver disease

- Diabetes

- Diagnosis of diabetes in CPRD

- History of AKI

- Diagnosis of AKI in CPRD or any hospitalisations with diagnosis of AKI in HES

- Oliguria (urine output < 0.5 mL/kg/h)

(Not obtained in the database)

- Neurological or cognitive impairment or disability, which may mean limited access to fluids because of reliance on a carer

- Diagnosis of dementia in CPRD, as a representative condition

- Hypovolaemia

(Not obtained in the database)

- Use of drugs with nephrotoxic potential (such as NSAIDs, aminoglycosides, ACEI, ARBs, and diuretics)

- NSAIDs, aminoglycosides (products for injection and nebuliser), ACEI or ARBs, and diuretics (loop, thiazide, and potassium-sparing diuretics), prescribed for the past 3 months prior to the hospitalisation for LRTI

- Use of iodinated contrast agents

(Not obtained in the database)

- Symptoms or history of urological obstruction or conditions that may lead to obstruction

- Diagnosis of prostatic hypertrophy in CPRD, as a representative condition

- Sepsis

- Sepsis identified as an additional diagnosis code of sepsis in HES during the hospitalisation for LRTI

- Deteriorating early warning scores

(Not obtained in the database)

- Age (≥ 65 years)

- Age categorised into groups: < 65, 65–74, 75–84, and > 85

  1. ACEI, angiotensin converting enzyme inhibitor; AKI, acute kidney injury; ARB, angiotensin II receptor blocker; CPRD, Clinical Practice Research Datalink; eGFR, estimated glomerular filtration rate; LRTI, lower respiratory tract infection; HES, Hospital Episode Statistics; NICE, National Institute for Health and Care Excellence; NSAIDs, non-steroidal anti-inflammatory drugs
  2. aBased on the most recent creatinine measurement, excluding those just before admission (within 28 days)