Risk of acute kidney injury after lower urinary tract reconstruction with early NSAID therapy: A propensity matched retrospective analysis

Introduction

The opioid epidemic response led to increased use of postoperative, non-opioid analgesia. Some pediatric urologists do not routinely use non-steroidal anti-inflammatory drugs (NSAIDs) for fear of causing acute kidney injury (AKI). While previous studies have demonstrated the safety and efficacy of NSAIDs in children, safety after lower urinary tract reconstruction has not been well characterized.

Objective

ptUsing the Kidney Disease: Improving Global Outcomes (KDIGO) criteria for AKI (increase in creatinine ≥0.3 mg/dL or increase in creatinine ≥1.5x baseline or urine output <0.5 mL/kg/hr for 6 h), we hypothesized there would be a difference in the incidence of postoperative AKI between patients who did and did not receive NSAIDs following surgery.

Study design

Patients 2–18 years old who underwent lower urinary tract reconstruction (i.e., bladder augmentation and/or creation of a catheterizable channel) from 2009 to 2021 and had documented urine output were retrospectively reviewed. Chronic kidney disease (CKD) stage was calculated from creatinine and cystatin C within 6 months of surgery using the CKiD U25 equations. Patients who received NSAIDs were propensity matched on 11 characteristics with patients undergoing similar surgeries who did not receive NSAIDs. The primary outcome was incidence of AKI within 48 h of surgery.

Results

The unmatched cohorts included 243 patients. Propensity matching identified 166 patients in the NSAID arm and 41 in the no NSAID arm. 26 patients with CKD stage 2–3 were included. There was no significant difference in the incidence of postoperative AKI based on any KDIGO criteria (17.1% no NSAID versus 16.3% NSAID, p = 0.87). Median postoperative opioids fell from 0.88 mg/kg in the no NSAID arm to 0.37 mg/kg morphine equivalents in the NSAID arm, although this was not statistically significant. Log-rank testing by Kaplan–Meier analysis demonstrated no difference in time to incidence of low urine output between the groups (p = 0.32). In the whole population not stratified by NSAID use, no differences were seen in AKI between those with and without CKD (16.7% with versus 17.9% without CKD).

Discussion

There was no difference in the incidence of postoperative AKI among patients who did and did not receive NSAIDs after lower urinary tract reconstruction, excluding those with advanced CKD.

Conclusion

These results support that postoperative NSAIDs were an unlikely source of AKI. However, AKI remained a risk following these surgeries, regardless of NSAID use, likely owing to underlying disease, longer operations, and fluid shifts.

Summary Table. Incidence of postoperative AKI among patients who did and did not receive NSAIDs in the operating room or within 6 h after surgery.

Empty Cell	n	No NSAID	NSAID	P value
41 patients	166 patients
Acute kidney injury (any criteria)	207	7 (17.1%)	27 (16.3%)	0.875
Acute kidney injury (criteria 1)	38	3 (23.1%)	3 (12.0%)	0.895
Acute kidney injury (criteria 2)	41	4 (28.6%)	10 (37.0%)	0.380
Acute kidney injury (criteria 3)	207	2 (4.9%)	17 (10.2%)	0.618
Median length of stay (IQR), days	207	5.3 (4.2–7.1)	4.5 (3.4–6.3)	0.970