Cost of Care for Malignant and Benign Renal Masses
Published Online: August 12, 2013
Aviva G. Asnis-Alibozek, PA-C; Michael J. Fine, MD; Paul Russo, MD; Trent McLaughlin, BSc(Pharm), PhD; Eileen M. Farrelly, MPH; Norman LaFrance, MD; and William Lowrance, MD, MPH
Renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and more than 80% of kidney cancers, causing approximately 13,000 deaths in the United States each year.1-3 It is typically characterized by a lack of early warning signs, diverse clinical manifestations, and tumor resistance to radiation and traditional chemotherapy.
The increasingly prevalent use of cross-sectional imaging for nonspecific abdominal complaints has resulted in the earlier diagnosis of RCC and a preponderance of small asymptomatic lesions. Thus, the continual rise in RCC incidence is attributed largely to enhanced detection, with more than 70% of kidney cancers now being discovered incidentally and at a size less than 7 cm.4-8 Nephron-sparing surgery is gaining acceptance as the treatment of choice for these smaller tumors, while radical nephrectomy remains the standard for larger tumors not amenable to partial nephrectomy.
Differentiating between benign and malignant renal tumors through current radiographic or clinical methods remains a challenge. While renal biopsy for molecular analysis of tissues might provide additional information in this setting, it yields nondiagnostic information in up to 20% of cases and is often available only at academic centers.9
Importantly, previous research suggests that approximately 20% of patients who undergo nephrectomy are found to have benign postoperative tumor histology, implying the possibility of surgical overtreatment.10-15 Based on current estimates of 58,000 patients with new RCC diagnoses in the United States each year, the vast majority of whom will undergo nephrectomy prior to a definitive tissue confirmation of cancer, it is conceivable that the American healthcare system is resourcing upward of 10,000 potentially avoidable nephrectomies each year.16
The objectives of this analysis were to confirm previous estimates of postnephrectomy renal mass diagnosis and to assess the economic impact of nephrectomy, both in terms of surgical costs and resource utilization related to postoperative complications, in a large population of commercially insured Americans.
MATERIALS AND METHODS
Data were obtained from the IMS LifeLink Database, which at the time of the study was composed of medical and pharmaceutical claims for approximately 60 million unique patients from 100 health plans, including health maintenance organizations (HMOs), preferred provider organizations (PPOs), point-of-service (POS) plans, indemnity plans, and other types, located throughout the United States. The database includes both inpatient and outpatient diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] codes) and procedures (Current Procedural Terminology, Version 4 [CPT-4] and Healthcare Common Procedure Coding System codes), as well as both standard and mail order pharmacy records. Data elements include demographic variables (age, sex, geographic region), health plan type (eg, HMO, PPO, POS), payer type (eg, commercial, self-pay), provider specialty, reimbursed amount for service, date of service, and start and stop dates for plan enrollment.
Because all pertinent patient information in the database is encrypted and de-identified, and no patient contact was involved, no informed consent or approval by an institutional review board was required or sought. The data source was fully Health Insurance Portability and Accountability compliant.
Patients were eligible for analysis if they had at least 2 medical claims for RCC (defined as ICD-9-CM codes 189.0, 189.1, 198.0, 236.91) during the July 1, 2000, through March 30, 2008, database extraction period. Patients were further required to have a claim for nephrectomy (CPT-4 codes 50220, 50225, 50230, 50234, 50236, 50240, 50543, 50545, 50546, 50547, 50548) during the study period to be included in the analysis (note that the nephrectomy claim could coincide with 1 of the 2 required RCC diagnoses). A minimum of 2 ICD-9-CM RCC diagnoses were required to ensure all patients included in the study presented with a high preoperative clinical suspicion of presumed renal malignancy.
The date of the nephrectomy claim during that period was assigned as the index date. From that date, 6 months of preindex and up to 12 months of postindex data were collected for all health plan–eligible patients. Patients had to have continuous health plan enrollment for 6 months before and at least 6 months after the index date to ensure complete baseline and follow-up information on all patients in the study.
Two mutually exclusive study groups were identified based on medical claims. Patients were categorized as ultimately having either benign disease or malignant disease following the nephrectomy. Benign disease was defined as any patient having a medical claim with a benign diagnosis (ICD-9-CM codes benign neoplasm, kidney, except pelvis [223.0], renal pelvis [223.1]) subsequent to the index date (nephrectomy).To be conservative regarding the prevalence of benign disease postnephrectomy, all other patients (ie, those with a minimum of 2 medical claims for a diagnosis of RCC, but with no benign diagnosis subsequent to the nephrectomy) were considered to have malignant disease.
The postnephrectomy benign and malignant cohorts were compared with respect to patient demographics (age, sex, region of the United States where surgery was performed), surgery type (nephron sparing vs radical nephrectomy), and comorbid conditions (using Charlson Comorbidity Index score, individual comorbidities contributing to the score).17,18 In addition, rates of nephrectomy-related adverse events were calculated for each cohort: hemorrhage (ICD-9-CM 998.1x), deep vein thrombosis (ICD-9-CM 453.40, 453.41, 453.42), pulmonary embolism (ICD-9-CM 415.11, 415.12, 415.19), myocardial infarction (ICD-9-CM 410.x), surgical woundinfection or disruption (ICD-9-CM 686.9, 998.31, 998.32), renal or perinephric abscess (ICD-9-CM 590.2), sepsis (ICD-9-CM 038.0, 038.1, 038.2, 038.3, 038.4, 038.8), acute renal failure (ICD-9-CM 584.xx, 586.xx), and pneumothorax (ICD-9-CM 512.0, 512.1, 512.8) were all considered to be acute adverse events and were measured during the first 30 days after surgery.
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