Table 2.

Case-finding algorithms for hospitalization for acute liver injury and severe complications of urinary tract infection in CPRD, the HIRD, and Medicare

Outcome	Case-finding algorithm
	CPRD	HIRD and Medicare
Hospitalization for acute liver injury	(1) Any Read code for acute liver injury in which the definition of hospitalizationa was met within 30 days before or after the Read code OR (2) Hospital record in HES with acute liver injury as the first diagnosisb (ICD-10 code) in the first episodec of the hospitalization stay	(1) An inpatient hospitalization with an ICD-9-CM or ICD-10-CMf diagnosis code for acute liver injury OR (2) An inpatient hospitalization with a procedure codeg for liver transplantation
Severe complication of urinary tract infection (pyelonephritis or urosepsis)	Pyelonephritis	Pyelonephritis
	(1) Hospital record in HES with pyelonephritis as the first diagnosisb in the first episodec of the hospitalization stay OR (2) Any Read code for pyelonephritis with consultation type = ED visit OR (1) Any Read code for pyelonephritis with consultation type = GP plus hospitalizationa	An inpatient hospitalization or ED visith with an ICD-9-CM diagnosis code or ICD-10-CMf diagnosis code for pyelonephritis
	Urosepsis	Urosepsis
	(1) Urosepsis diagnosis defined as either (a) GP diagnosis of urosepsis plus hospitalizationa or (b) Read code for urosepsis with ED visitc OR (2) Sepsis diagnosis (hospitalization or ED visit for sepsis)d AND urinary tract infection diagnosis (within 7 days before or after the sepsis hospitalization date)e	(1) Sepsis diagnosisi: An inpatient hospitalization or ED visith with an ICD-9-CM or ICD-10-CMf diagnosis code for sepsis AND (2) Urinary tract infection diagnosis: A visit to any place of service with an ICD-9-CM diagnosis code or ICD-10-CMf diagnosis code for urinary tract infection with a visit date during the sepsis hospitalization or ED visit, or within 7 days before or after the sepsis datei

CPRD Clinical Practice Research Datalink, ED emergency department, GOLD General Practitioner Online Database of the CPRD, GP general practitioner, HCPCS Healthcare Common Procedure Coding System, HES Hospital Episode Statistics, HIRD HealthCore Integrated Research Database, ICD-9-CM International Classification of Diseases, 9th Revision, Clinical Modification, ICD-10 International Statistical Classification of Diseases and Related Health Problems, 10th Revision, ICD-10-CM International Classification of Diseases, 10th Revision, Clinical Modification, ICD-10-PCS International Classification of Diseases, 10th Revision, Procedure Coding System

^aIn CPRD GOLD, hospitalization (within 30 days before or after the Read code of interest) was defined as (1) a Read code for a hospitalization with an accompanying code indicating that no death occurred; OR (2) a reported Clinical or Referral record with a consultation type of discharge details, hospital admission, hospital inpatient report, or initial post discharge review, as reported in the “Consultation” data set; OR (3) an inpatient referral type was indicated in the “Referral” data set

^bIn CPRD HES, the first ordered diagnosis code for a given hospital episode represents the primary purpose of the hospital episode

^cIn CPRD HES, the data are structured such that multiple “episodes” may be recorded for a single hospitalization, with one episode for each encounter within the hospital made by the patient (e.g., one episode may be the initial ED visit, one episode from another ward to which the patient is admitted, etc.). The first episode of the hospitalization stay is the first encounter that the patient has during the hospitalization

^dIn CPRD, a sepsis diagnosis was defined as either (a) a hospital record in HES with sepsis recorded as the first diagnosis in the first episode^c of the hospitalization stay; OR (b) any Read code for sepsis with ED visit; OR (c) any Read code for sepsis with consultation type = GP plus hospitalization^a

^eIn CPRD, a urinary tract infection diagnosis was defined as either (a) any Read code for urinary tract infection with consultation type = GP or ED visit; OR (b) a hospital record in HES with a urinary tract infection recorded as the first diagnosis in the first episode^c of the hospitalization stay

^fIn the HIRD and Medicare, ICD-10-CM and ICD-10-PCS (Medicare only) codes were used for events on or after 1 October 2015. ICD-10-CM and ICD-10-PCS code lists were generated using CMS (Centers for Medicare and Medicaid Services)-based mapping to the ICD-9-CM codes and clinical review

^gIn the HIRD and Medicare, procedure codes included ICD-9-CM procedure codes, ICD-10-PCS procedure codes (events on or after 1 October 2015), Current Procedural Terminology codes, or HCPCS codes

^hIn Medicare, an ED visit is defined as an outpatient record with a revenue center code value of 0450-0459 or 0981 (revenue center codes used by the CMS are copyrighted by the American Hospital Association [51])

ⁱIn the HIRD and Medicare, the admission date of the hospitalization or ED visit with the eligible sepsis diagnosis was considered the “sepsis date”