Quinine exposure and the risk of acute kidney injury: a population based observational study of older people

Objectives: to establish and quantify any observable association between the exposure to community prescriptions for quinine and acute kidney injury (AKI) events in a population of older adults.

Design: two observational studies using the same dataset, a retrospective longitudinal cohort study and a self-controlled case series (SCCS). SETTING: NHS health board in Scotland.

Participants: older adults (60+ years) who received quinine prescriptions in Tayside, Scotland, between January 2004 and December 2015. The first study included 12,744 individuals. The SCCS cohort included 5,907 people with quinine exposure and more than or equal to one AKI event.

Main outcome measured: in the first study, multivariable logistic regression was used to calculate odds ratios (ORs) for AKI comparing between episodes with and without recent quinine exposure after adjustment for demographics, comorbidities and concomitant medications. The SCCS study divided follow-up for each individual into periods 'on' and 'off' quinine, calculating incidence rate ratios (IRRs) for AKI adjusting for age.

Results: during the study period, 273,596 prescriptions for quinine were dispensed in Tayside. A total of 13,616 AKI events occurred during follow-up (crude incidence 12.5 per 100 person-years). In the first study, exposure to quinine before an episode of care was significantly associated with an increased probability of AKI (adjusted OR = 1.27, 95% confidence interval (CI) 1.21-1.33). In the SCCS study, exposure to quinine was associated with an increased relative incidence of AKI compared to unexposed periods (IRR = 1.20, 95% CI 1.15-1.26), with the greatest risk observed within 30 days following quinine initiation (IRR = 1.48, 95% CI 1.35-1.61).

Conclusion: community prescriptions for quinine in an older adult population are associated with an increased risk of AKI.