The Coding Impact of Acute Kidney Injury in Pediatric Hospital Documentation.

Background: Acute kidney injury (AKI) increases patient morbidity and mortality. In value-based care, the documented and coded diagnoses during hospitalization influences an encounter's relative weight (RW), including severity of illness (SOI), and risk of mortality, which ultimately determines reimbursement for care. The impact of a secondary diagnosis of AKI on RW in pediatric patients has not been evaluated.

Methods: A single-center, retrospective observational study was conducted over six months. The institutional coding database was queried for secondary diagnoses signifying AKI. The RW for each case was determined with and without an AKI secondary diagnosis. Patients were further stratified by their SOI score to evaluate change in RW and SOI.

Results: Over a six-month period, 372 patients had a secondary AKI diagnosis, with a mean RW 2.14 decreasing to a mean RW 1.83 without an AKI diagnosis (p = 2.2e-16). When stratified by SOI, one patient had SOI 1 with RW change -0.286; six patients had SOI 2 with mean RW change -0.0669; 189 patients had SOI 3 with mean RW change -1.862 (p=2.23E-16); and 176 patients had SOI 4 with mean RW change -0.452 (p=9.46E-14), when the AKI secondary diagnosis was removed.

Conclusions: Significant negative changes in RW were observed when AKI was removed, suggesting diagnostic omission may result in inaccurately lesser representation of patient medical complexity and severity of illness upon hospitalization coding, which may lower reimbursement.