National Imaging Trends after Percutaneous Nephrolithotomy

Abstract

Purpose: Followup imaging after percutaneous nephrolithotomy serves to detect postoperative complications, residual fragments and silent hydronephrosis. However, the timing and optimal imaging modality remain poorly defined. We describe imaging use patterns after percutaneous nephrolithotomy.

Materials and methods: In the MarketScan® database we identified patients 17 to 64 years old who underwent percutaneous nephrolithotomy between 2007 and 2014. Imaging modalities were identified by CPT, and ICD-9 and 10 codes, and tracked for 1 year after percutaneous nephrolithotomy. The modalities included computerized tomography, renal ultrasound, abdominal x-ray and intravenous pyelogram. Cumulative longitudinal use patterns were characterized and the association with demographic factors was assessed by the chi-square test.

Results: Of the 6,495 patients included in analysis 29% and 15% had undergone no postoperative imaging by 3 and 12 months, respectively. While abdominal x-ray was the most common modality at 3, 6 and 12 months, performed in 46%, 53% and 62% patients, respectively, nearly 50% underwent computerized tomography by 1 year. Of these patients 34% underwent computerized tomography within 3 months, which was done within the first 3 days in 69%. During the study period renal ultrasound use increased by 13% while computerized tomography and abdominal x-ray use remained relatively stable. Female gender, residence in the Northeast, no health maintenance organization status and treatment in a metropolitan statistical area were independently associated with higher rates of renal ultrasound on multivariate analyses (p <0.05).

Conclusions: Among insured adults national imaging patterns vary following percutaneous nephrolithotomy. Many patients do not receive any followup imaging while approximately half undergo computerized tomography within a year. Imaging patterns may be evolving with the increased use of ultrasound.

Keywords: aftercare; diagnostic imaging; kidney calculi; nephrolithotomy; percutaneous; postoperative period.