Use of High Potency Statins and Rates of Admission for Acute Kidney Injury: Multicenter, Retrospective Observational Analysis of Administrative Databases

The study objective is to determine whether the use of high potency statins, compared with the use of low potency statins, is associated with an increased risk of acute kidney injury (AKI) in routine clinical practice. The investigators will use a common-protocol approach to conduct retrospective cohort studies using health care data from nine jurisdictions (the Canadian provinces of Alberta, British Columbia, Manitoba, Nova Scotia, Ontario, Quebec, and Saskatchewan, as well as the United States (US) MarketScan and the United Kingdom (UK) Clinical Practice Research Datalink [CPRD]). The Canadian provincial databases contain information on physician billing, diagnoses and procedures from hospital discharge abstracts, and dispensations for prescription drugs at a population level. The CPRD is a clinical database that is representative of the UK population and contains the records for patients seen at over 680 general practitioner practices in the UK; these data will be linked to the Hospital Episode Statistics (HES) database, which contains in-hospital diagnosis and procedure data.

Study population

In each jurisdiction, the investigators will assemble a study cohort that includes all patients with a new prescription for a statin, including simvastatin, lovastatin, pravastatin, fluvastatin, atorvastatin, and rosuvastatin, from the earliest availability of data at each site to the last date of available data. The date of study cohort entry is defined by the prescription date of the newly-prescribed statin.

For the purpose of this study, two separate cohorts will be created based on the presence or absence of a history of chronic kidney disease at any time prior to and including the date of study cohort entry. Chronic kidney disease is defined as patients who have 1 hospitalization or 1 physician claim 3 years prior to study cohort entry with any of the following diagnoses and corresponding diagnostic codes: chronic or unspecified renal failure (ICD-9: 585, 586; ICD-10: N18, N19), hypertensive renal disease (ICD-9: 403.x1, 404.x2, 404.x3; ICD-10: I12.0, I13.1), nephritis and nephropathy (ICD-9: 582, 583; ICD-10: N03, N05), renal sclerosis or disorder from impaired renal function (ICD-9: 587, 588; ICD-10: S00-T98). Patients in each cohort will be followed from the date of study cohort entry until an event (defined below) or censoring due to death, departure from the database, 24 months after initiation of statin treatment, a dispensing for cerivastatin, or the end of the study period (31 March 2010 or the last date of data availability at that site), whichever occurs first. Data from Alberta, Ontario, and Nova Scotia will be restricted to patients aged 65 years and older as prescription data are not available for younger patients.

Case-control selection