Background
Acute kidney injury (AKI) either during pregnancy or postpartum is associated with significant maternal and neonatal morbidity. Past population-based studies (1999-2011) in US and Canada suggest the incidence may be increasing, with contributing factors including increasing rates of hypertensive disorders of pregnancy (HDP) and CKD. We aim to determine recent developments in this apparent trend in a local population.
Methods
All public hospital admissions with pregnancy >20 weeks gestation in Victoria, Australia (2006-2016) were identified by ICD-10 diagnostic codes from a validated administrative database. Analysis included 560,778 antenatal and postpartum admissions, of which 533,876 included delivery. Trends in AKI incidence and associated risk factors were examined, and multivariate logistic regression determined whether changes in risk factors explained observed temporal changes.
Results
The incidence of AKI per 10,000 deliveries rose from 2.37 in 2006 to 11.59 in 2016, p<0.001. Of the 499 AKI cases, 228 (45.6%) also had CKD, 22 (4.4%) required renal replacement therapy, and 3 (0.6%) died. The strongest risks factors associated with AKI (unadjusted OR, 95% CI) were: CKD (473.8, 318.1-578.3), chronic hypertension (49.8, 28.2-88.0), HDP (16.1, 11.3-22.9), pre-existing diabetes (43.4, 29.2-64.4), and critical care admission (153.4, 95.9-245.4). Other risk factors included: year of admission, maternal age, sepsis, postpartum haemorrhage, Caesarian delivery, and premature delivery. After adjustment (adjusted OR, 95% CI), the temporal relationship for AKI risk was maintained (1.11, 1.07-1.14), with strongest risk factors being: CKD (37.5, 23.6-59.6), HDP (12.32, 9.63-15.76), and sepsis (7.32, 5.32-10.08), p<0.005 for all variables.
Conclusion
The incidence of obstetric-related AKI continues to rise. This trend persists after adjusting for factors such as HDP, CKD and maternal age. Other, as yet unidentified or unmeasured factors may be implicated, such as greater awareness and reporting of AKI and increasing complexity of maternal comorbidities. Long-term risks of obstetric-related AKI remain to be determined.