Acute kidney injury increases risk of kidney stones-a retrospective propensity score matched cohort study.

BACKGROUND: Acute kidney injury (AKI) is common. An episode of AKI may modify the risk of developing kidney stones by potential long-term effects on urine composition. We aimed to investigate the association between AKI and the risk of kidney stone presentations. METHODS: The retrospective cohort study used patient data (1 January 2008-31 December 2017), from an Australian Local Health District, which included AKI diagnosis, demographics, comorbidities and kidney stone admissions. Time-varying Cox proportional hazards and propensity-matched analysis were used to determine the impact of AKI on the risk of kidney stones. To address possible population inhomogeneity in comparisons between no AKI and hospitalized AKI, sub-group analysis was done comparing inpatient and outpatient AKI versus no AKI, to assess consistency of association with future stones. Sensitivity analysis was undertaken to capture the impact of a known AKI status and AKI severity. RESULTS: Out of 137 635 patients, 23 001 (17%) had an AKI diagnosis and 2295 (2%) had kidney stone presentations. In the unadjusted analysis, AKI was associated with kidney stones, with AKI used as a time-varying exposure, [hazard ratio (HR) 1.32, 95% confidence interval (CI) 1.16-1.50)]. Both inpatient-AKI (HR 1.19, 95% CI 1.01-1.39) and outpatient-AKI (HR 1.59, 95% CI 1.30-1.94) were significantly associated with future stones compared to no AKI subjects. This association persisted in the adjusted analysis (HR 1.45, 95% CI 1.26-1.66), propensity-matched dataset (HR 1.67, 95% CI 1.40-1.99) and sensitivity analysis. There was a dose-response relationship with higher stages of AKI being associated with a greater risk of kidney stones. CONCLUSIONS: In a large cohort of patients, AKI is associated with a greater risk of kidney stones, which increases with higher stages of AKI. This association should be examined in other cohorts and populations for verification.

Peritoneal dialysis-related peritonitis as a risk factor for cardiovascular events.

BACKGROUND: Cardiovascular disease is the leading cause of mortality in peritoneal dialysis (PD) patients. Infection is known to increase the risk of cardiovascular events (CVE); however, no studies have examined the association between PD peritonitis and CVE. AIM: To examine peritonitis as a risk factor for CVE in PD patients. METHODS: This retrospective cohort study included all adults undertaking PD for ≥3 months in one Australian health district from 2001 to 2015. Baseline characteristics and peritonitis event information was obtained from the Australian and New Zealand Dialysis and Transplant registry. The Centre for Health Research Illawarra Shoalhaven Population facilitated data linkage using ICD10 coding to capture CVE information. RESULTS: A total of 211 patients was included, with median age of 66 years (interquartile range 54.49-74.45); 64% were male. Peritonitis occurred in 114 (54%) patients and 65 (30.8%) patients experienced a CVE. Identified risk factors for CVE included: cerebrovascular disease (hazard ratio (HR) 2.72, 95% confidence interval (CI) 1.36-5.47), diabetes (HR 2.41, 95% CI 1.47-3.96), coronary artery disease (HR 1.67, 95% CI 1.01-2.77) and age (HR 1.03, 95% CI 1.01-1.06). There was no significant increase in risk of CVE following peritonitis (HR 1.37, 95% CI 0.81-2.32, P = 0.24), even when accounting for age, cerebrovascular disease, diabetes and existing coronary artery disease (HR 1.32, 95% CI 0.78-2.23, P = 0.30). CONCLUSIONS: We did not find an increase in the risk of CVE following a peritonitis episode in PD patients. This result may be due to small sample size or rapid peritonitis treatment mitigating cardiovascular risk.