Association Between Use of the 21-Gene Recurrence Score Assay and Receipt of Chemotherapy Among Medicare Beneficiaries With Early-Stage Breast Cancer, 2005-2009.

IMPORTANCE: Guidelines recommend consideration of chemotherapy for most patients with early-stage, estrogen receptor-positive, invasive breast cancer in the absence of additional prognostic information. The 21-gene recurrence score (RS) assay has been shown in limited academic settings to reduce physician recommendations for adjuvant chemotherapy. Associations between the adoption of the assay and receipt of chemotherapy in the general population have not been examined. OBJECTIVE: To examine whether adoption of the RS assay in a nationally representative sample of patients with early-stage breast cancer was associated with use of chemotherapy. DESIGN, SETTING, AND PARTICIPANTS: Retrospective cohort study of Medicare beneficiaries who received a diagnosis of incident breast cancer between 2005 and 2009 using Surveillance, Epidemiology, and End Results data set with linked Medicare claims. MAIN OUTCOMES AND MEASURES: Receipt of chemotherapy within 12 months after diagnosis. RESULTS: A total of 44,044 patients had low-risk (24.0%), intermediate-risk (51.3%), or high-risk disease (24.6%, lymph node positive) as defined by National Comprehensive Cancer Network (NCCN) guidelines and met the study criteria. We observed no overall association between receipt of the RS assay and chemotherapy (odds ratio [OR], 1.03 [99% CI, 0.88-1.19]). In multivariable analysis, there was a significant interaction between NCCN risk and use of the RS assay, with assay use associated with lower chemotherapy use in high-risk patients (OR, 0.36 [99% CI, 0.26-0.50]) and greater chemotherapy use in low-risk patients (OR, 3.71 [99% CI, 2.30-5.98]), compared with no receipt of the assay (P=.006 for the overall interaction). Results were similar in prespecified subgroup analyses of patients 70 years and younger, with the exception of a shift toward lower chemotherapy use during 2008 (OR, 0.90 [99% CI, 0.77-.1.05]; P=.09) and 2009 (OR, 0.81 [99% CI, 0.66-0.99]; P=.007). In unadjusted analyses, overall chemotherapy use decreased over time in patients 70 years or younger with high-risk disease and those receiving the assay. CONCLUSIONS AND RELEVANCE: The impact of the adoption of the RS assay on receipt of chemotherapy was strongly population dependent and was associated with relatively lower chemotherapy use in groups with high-risk disease and relatively higher chemotherapy use in patients with low-risk disease. Overall use of chemotherapy decreased during the study period in patients who were most likely to receive chemotherapy.

Initial Trends in the Use of the 21-Gene Recurrence Score Assay for Patients With Breast Cancer in the Medicare Population, 2005-2009.

IMPORTANCE: In 2006, the Centers for Medicare & Medicaid Services approved coverage for the use of the 21-gene recurrence score (RS) assay in women with early-stage, estrogen receptor-positive, node-negative breast cancers to help guide recommendations for adjuvant chemotherapy. Use of the assay in community settings has not been previously examined in a nationally representative sample of patients. OBJECTIVE: To examine trends in the use of the RS assay in routine clinical practice in a nationally representative sample of women with breast cancer. DESIGN, SETTING, AND PARTICIPANTS: Retrospective observational study of Medicare beneficiaries diagnosed with incident breast cancer between 2005 and 2009, as recorded in a Surveillance, Epidemiology, and End Results data set with linked Medicare claims through 2010. MAIN OUTCOMES AND MEASURES: Demographic and clinical variables associated with the use of the assay. RESULTS: A total of 70,802 patients met the study criteria. Use of the RS assay increased from 1.1% in 2005 to 10.1% in 2009 (P < .001). The majority of tests (60.9%) occurred in patients with National Comprehensive Cancer Network-defined intermediate-risk disease (ie, estrogen receptor-positive, node-negative tumors >1 cm). Most patients with other than intermediate-risk disease had borderline indications for testing, including T1b (47.5%) or N1 (26.8%) disease. Testing was associated with younger age, fewer comorbid conditions, higher-grade disease, and being married. Among patients younger than 70 years with intermediate-risk disease, testing rates increased from 7.7% in 2005 to 38.8% in 2009 (P < .001). In multivariable analysis, testing was modestly higher in Northeast than in Western registries (odds ratio, 1.83; 95% CI, 1.49-2.26) but was otherwise not associated with region, local census tract demographic characteristics, black race, location in an urban area, or tumor histologic characteristics. CONCLUSIONS AND RELEVANCE: The RS assay was adopted quickly in clinical practice after the Medicare coverage decision in 2006, and use appears to be consistent with guidelines and equitable across geographic and racial groups. Factors influencing adoption of the assay and its impact on adjuvant chemotherapy use in clinical practice remain important areas of study.

Sensitivity of International Classification of Diseases codes for hyponatremia among commercially insured outpatients in the United States.

BACKGROUND: Administrative claims are a rich source of information for epidemiological and health services research; however, the ability to accurately capture specific diseases or complications using claims data has been debated. In this study, the authors examined the validity of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnosis codes for the identification of hyponatremia in an outpatient managed care population. METHODS: We analyzed outpatient laboratory and professional claims for patients aged 18 years and older in the National Managed Care Benchmark Database from Integrated Healthcare Information Services. We obtained all claims for outpatient serum sodium laboratory tests performed in 2004 and 2005, and all outpatient professional claims with a primary or secondary ICD-9-CM diagnosis code of hyponatremia (276.1). RESULTS: A total of 40,668 outpatient serum sodium laboratory results were identified as hyponatremic (serum sodium < 136 mmol/L). The sensitivity of ICD-9-CM codes for hyponatremia in outpatient professional claims within 15 days before or after the laboratory date was 3.5%. Even for severe cases (serum sodium < or = 125 mmol/L), sensitivity was < 30%. Specificity was > 99% for all cutoff points. CONCLUSION: ICD-9-CM codes in administrative data are insufficient to identify hyponatremia in an outpatient population.

Medical costs of abnormal serum sodium levels.

An abnormal serum sodium level is the most common electrolyte disorder in the United States and can have a significant impact on morbidity and mortality. The direct medical costs of abnormal serum sodium levels are not well understood. The impact of hyponatremia and hypernatremia on 6-mo and 1-yr direct medical costs was examined by analyzing data from the Integrated HealthCare Information Services National Managed Care Benchmark Database. During the period analyzed, there were 1274 patients (0.8%) with hyponatremia (serum sodium <135 mmol/L), 162,829 (97.3%) with normal serum sodium levels, and 3196 (1.9%) with hypernatremia (>145 mmol/L). Controlling for age, sex, region, and comorbidities, hyponatremia was a significant independent predictor of costs at 6 mo (41.2% increase in costs; 95% confidence interval, 30.3% to 53.0%) and at 1 yr (45.7% increase; 95% confidence interval, 34.2% to 58.2%). Costs associated with hypernatremia were not significantly different from those incurred by patients with normal serum sodium. In conclusion, hyponatremia is a significant independent predictor of 6-mo and 1-yr direct medical costs.