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Trends in the Diffusion of Laparoscopic Nephrectomy
To the Editor: Based on equal efficacy and easier convalescence compared with the open procedure, some urologists have advocated laparoscopy to be a standard of care for patients undergoing nephrectomy for benign or malignant disease.1-2 There are indications that the use of renal laparoscopy in both academic and community hospitals has been increasing,3 but precise characterization of the diffusion of laparoscopic nephrectomy since its introduction in 1991 has not been available. We therefore describe temporal trends in the nationwide use of laparoscopic nephrectomy and contrast these with other common laparoscopic procedures.
Methods
Data were analyzed for the years 1989-2003 from the Nationwide Inpatient Sample (NIS), a 20% nationally representative annual sample of all hospital discharges in the United States.4 International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9) procedure codes were used to determine the annual number of cholecystectomies (codes, 51.22, 51.23), fundoplications (44.65, 44.66), hysterectomies (68.3, 68.4, 68.5, 68.51, 68.59, 68.6, 68.7, 68.9,), and nephrectomies (55.3, 55.4, 55.5, 55.54, 55.51). Comparison procedures were selected based on their approximately concurrent introduction relative to laparoscopic nephrectomy (late 1980s to the early 1990s) and their predominant performance by surgical specialties other than urology (general surgery or gynecology).
The ICD-9 diagnosis codes were next used to assign a general indication for each nephrectomy, including kidney donation (v59.4), malignancy (189.x), or benign disease (all remaining ICD-9 diagnosis codes for the nephrectomy sample). The proportions of laparoscopic cases were estimated via specific procedure codes (51.23, 68.51) or by identifying all discharges with a concurrent code for laparoscopic exploration (54.21), laparoscopic lysis of adhesions (54.51), or laparoscopic cholecystectomy (51.23). Sampling weights from the NIS were applied to estimate national figures.4
Generalized linear models were used to assess temporal trends (both among and within procedures) in the use of laparoscopy. A logistic regression model was fit, with use of laparoscopy as the outcome variable, and surgical procedure, time elapsed since the introduction of laparoscopy for each procedure (quadratic effect), and interaction terms as covariates. The SURVEYLOGISTIC procedure in SAS v 9.1 (SAS Institute, Cary, NC) was used to account for NIS sampling methodology. Significance testing was 2-sided and carried out at the 5% significance level.
Results
The number and proportion of laparoscopic cases, stratified by surgical procedure, are shown in the Figure and Table. The annual use of laparoscopy increased significantly for each procedure (P<.001). Although still relatively infrequent in 2003, the prevalence of laparoscopic nephrectomy for malignant and benign disease has increased annually since 1998 and 2000, respectively. The proportion of donor nephrectomies performed laparoscopically increased more than 3-fold between 1999 (9%) and 2000 (28%), peaking at 38% in 2002. During the study interval, the proportion of hospitals performing at least 1 laparoscopic nephrectomy annually increased from 4% to 26%.
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Figure. Comparison of Diffusion Curves for Laparoscopic Procedures
National diffusion curves showing proportion of laparoscopic cases within each year following introduction. Laparoscopy was introduced in 1989 for cholecystectomy and hysterectomy and in 1991 for fundoplication and nephrectomy. The nephrectomy sample is stratified by surgical indication (malignancy, benign disease, or donor).
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Table. Annual Number of Laparoscopic Cases
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In addition to temporal changes within procedures, the diffusion of laparoscopy varied among the 6 procedures in the Figure and Table (P<.001). The initial uptake of laparoscopy was more rapid for cholecystectomy and fundoplication; a majority of both procedures was performed laparoscopically within 4 and 6 years of introduction, respectively. The adoption of laparoscopic hysterectomy was less brisk and, with the exception of donor nephrectomy between 2000 and 2003, the annual proportion of hysterectomies and nephrectomies performed laparoscopically never differed by more than 9%.
Comparing indications within nephrectomy, the early dissemination trends were similar; however, in more recent years (2000-2003) laparoscopy has been significantly more common among patients undergoing donor nephrectomy than among those requiring nephrectomy for malignant or benign indications (P<.001 for each comparison).
Comments
By relying on administrative data from the NIS, our study may be limited by imprecise assessment of eligibility for laparoscopy and some degree of procedural misclassification. However, we believe that it demonstrates a gradual dissemination of laparoscopic nephrectomy that is in contrast to the rapid adoption of laparoscopic cholecystectomy and fundoplication. Despite its established advantages for patient convalescence,5 the diffusion curves for renal laparoscopy have been more analogous to hysterectomy, a procedure for which laparoscopy confers no recovery benefit relative to traditional vaginal surgery and may actually increase the risk of urinary tract complications for transabdominal cases.6
Given that the use of laparoscopic nephrectomy is generally concentrated at select hospitals,7 it appears that, unlike cholecystectomy and fundoplication, there have been barriers to a swifter dissemination among surgeons. While skepticism regarding the efficacy of renal laparoscopy might explain the earliest delays in diffusion, this barrier to adoption has not been supported by empirical data.2 Further research should explore alternative explanations for the observed trend, including the degree to which specialty-specific practice styles, unique technical concerns, or local practice environments have dampened the uptake of laparoscopic nephrectomy.8
Author Contributions: Dr Hollenbeck had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Miller, Dunn, Wei, Hollenbeck.
Acquisition of data: Dunn, Wei, Hollenbeck.
Analysis and interpretation of data: Miller, Dunn, Wei, Hollenbeck.
Drafting of the manuscript: Miller, Dunn, Wei, Hollenbeck.
Critical revision of the manuscript for important intellectual content: Miller, Dunn, Wei, Hollenbeck.
Statistical analysis: Dunn.
Obtained funding: Hollenbeck.
Administrative, technical, or material support: Hollenbeck.
Study supervision: Wei, Hollenbeck.
Financial Disclosures: None reported.
Funding/Support: Dr Miller is supported by grant NIH-1-T-32 DKO7782 (DCM), a clinical research training grant, from the National Institute of Diabetes and Digestive and Kidney Diseases.
Role of the Sponsor: The study sponsor had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; or preparation, review, or approval of the manuscript.
David C. Miller, MD, MPH;
John T. Wei, MD, MS;
Rodney L. Dunn, MS;
Brent K. Hollenbeck, MD, MS
bhollen{at}umich.edu
Department of Urology
Division of Clinical Research and Quality Assurance
University of Michigan Medical School
Ann Arbor
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4. Agency for Healthcare Research and Quality. Healthcare Cost and Utilization Project: Nationwide Inpatient Sample. Rockville, Md: Agency for Healthcare Research and Quality; 2005.5. Rudich SM, Marcovich R, Magee JC, et al. Hand-assisted laparoscopic donor nephrectomy: comparable donor/recipient outcomes, costs, and decreased convalescence as compared to open donor nephrectomy. Transplant Proc. 2001;33:1106-1107.
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6. Johnson N, Barlow D, Lethaby A, Tavender E, Curr L, Garry R. Methods of hysterectomy: systematic review and meta-analysis of randomised controlled trials. BMJ. 2005;330:1478-1485.
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7. Miller DC, Taub DA, Dunn RL, Wei JT, Hollenbeck BK. Laparoscopy for renal cell carcinoma: diffusion versus regionalization? J Urol. In press.8. Escarce JJ. Externalities in hospitals and physician adoption of a new surgical technology: an exploratory analysis. J Health Econ. 1996;15:715-734.
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Letters Section Editor: Robert M. Golub, MD, Senior Editor.
JAMA. 2006;295:2480-2482.
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