Identifying geographical regions serviced by hospitals to assess laboratory-based outcomes

Abstract

ObjectiveTo define geographical regions (forward sortation areas; FSAs) in Southwestern Ontario, Canada from which patients would reliably present to a hospital with linked laboratory data if they developed adverse events related to medications dispensed in outpatient pharmacies.DesignDescriptive research.SettingForty-five hospitals in Southwestern Ontario, Canada, from 2003 to 2009.ParticipantsPatients aged 66 years and older who received an outpatient prescription for any drug and presented to the emergency department in the subsequent 120 days.Main outcome measureThe proportion of patients in a given FSA presenting to an emergency department at a hospital with linked laboratory data versus a hospital without linked laboratory data. To be included in the catchment area at least 90% of emergency department visits in an FSA must have occurred at laboratory-linked hospitals in a given year.ResultsOver the study period, there were 649 713 emergency department visits by patients with recent prescription claims from pharmacies in 1 of 118 FSAs. In total, 141 302 of these patients presented to an emergency department at a laboratory-linked hospital. For the year 2003, 12 FSAs met our criteria to be in the catchment area and this number grew to 25 FSAs by the year 2009.ConclusionsThe relevant geographical regions for hospitals with linked laboratory data have been successfully identified. Studies can now be conducted using these well-defined areas to obtain reliable information on the incidence and absolute risk of presenting to hospital with laboratory abnormalities in older adults dispensed commonly prescribed medications in outpatient pharmacies.

Antiepileptic drugs and hyponatremia in older adults: Two population‐based cohort studies

“…First, among a subpopulation residing in a catchment area where linked laboratory data were available, we evaluated the association between antiepileptic use and hospitalization with hyponatremia within 30 days using serum sodium values (defined by a concentration ≤132 mmol/L) …”

“…First, among a subpopulation residing in a catchment area where linked laboratory data were available, we evaluated the association between antiepileptic use and hospitalization with hyponatremia within 30 days using serum sodium values (defined by a concentration ≤132 mmol/L). 33 Second, in another subpopulation for which information on outpatient laboratory data were available, we examined the association between antiepileptic use and outpatient hyponatremia within 30 days using serum sodium values (defined by a concentration ≤132 mmol/L).…”

Detecting chronic kidney disease in population-based administrative databases using an algorithm of hospital encounter and physician claim codes

“…Residents of Ontario have universal access to hospital care and physician services and those 65 years of age or older have universal prescription drug coverage. Due to the availability of laboratory data, this study was restricted to those individuals aged 65 and older in Southwestern Ontario, which consisted of 80,000 individuals in the year 2006 [9]. We gathered serum creatinine values from 12 regional hospitals in Southwestern Ontario as well as outpatient laboratories.…”

Calcium-Channel Blocker–Clarithromycin Drug Interactions and Acute Kidney Injury

“…A subpopulation in southwestern Ontario had outpatient serum creatinine measurements available before a new antibiotic coprescription and was in the catchment area of 12 hospitals in which linked inpatient serum creatinine values were also available. 23…”