Physician characteristics and variability of erythropoiesis-stimulating agent use among Medicare patients with cancer

Medication overuse in oncology: current trends and future implications for patients and society

The high cost of cancer care worldwide is largely attributable to rising drugs prices. Despite their high costs and potential toxic effects, anticancer treatments could be subject to overuse, which is defined as the provision of medical services that are more likely to harm than to benefit a patient. We found 30 studies documenting medication overuse in cancer, which included 16 examples of supportive medication overuse and 17 examples of antineoplastic medication overuse in oncology. Few specific agents have been assessed, and no studies investigated overuse of the most toxic or expensive medications currently used in cancer treatment. Although financial, psychological, or physical harms of medication overuse in cancer could be substantial, there is little published evidence addressing these harms, so their magnitude is unclear. Further research is needed to better quantify medication overuse, understand its implications, and help protect patients and the health-care system from overuse.

Adherence to treatment recommendations and outcomes for women with ovarian cancer at first recurrence

OBJECTIVE

Treatment selection for recurrent ovarian cancer is typically based on the duration of time between the completion of adjuvant, platinum-based therapy and the time of recurrence, the platinum free interval (PFI). We examined the use of, and outcomes associated with platinum-based chemotherapy based on the PFI in women with recurrent ovarian cancer.

METHODS

The Surveillance, Epidemiology, and End Results-Medicare database was used to identify women aged >65years with epithelial ovarian cancer who underwent surgery and platinum-based chemotherapy and who developed a recurrence >3months after the completion of adjuvant therapy. Patients were stratified by PFI into 3 groups: PFI <6months, PFI 7-12months, and PFI >12months. Multivariable models were used to examine predictors of use of platinum-based therapy and survival for each group.

RESULTS

A total of 2369 patients were identified. In women with a PFI of ≤6months, treatment consisted of platinum-based combination therapy in 28.2%, single agent platinum in 5.2% and non-platinum therapy in 66.6%. Corresponding rates of these treatments among women with a PFI of 7-12months were 39.7%, 12.4% and 47.9%, respectively; the rates were 57.6%, 13.2% and 29.3% in those with a PFI of >12months, respectively. Median survival was 13, 18, and 27months for patients with a PFI of ≤6months, 7-12months, and >12months, respectively (P<0.0001). For all three groups, platinum combination therapy was associated with decreased risk of death compared to non‑platinum based therapy.

CONCLUSION

Platinum free interval is a strong predictor of survival in elderly women with recurrent ovarian cancer. There is widespread variation in treatment selection for women with recurrent ovarian cancer with many women receiving non-guideline based regimens.

Effects of the US Food and Drug Administration Boxed Warning of Erythropoietin-Stimulating Agents on Utilization and Adverse Outcome

Purpose In March 2007, a US Food and Drug Administration boxed warning was issued for erythropoietin-stimulating agents (ESAs) regarding serious adverse events, such as venous thromboembolism (VTE). We evaluated the US Food and Drug Administration's boxed warning of ESAs used to treat chemotherapy-induced anemia because evidence on the effectiveness of boxed warnings remains inconclusive. Patients and Methods Using 2004 to 2009 SEER-Medicare data, we exploited a natural experiment to examine the effects of ESA boxed warnings on utilization and risk of VTE. The intervention group included Medicare fee-for-services patients diagnosed with colorectal, breast, or lung cancers targeted by this warning and undergoing chemotherapy; the control group included patients with myelodysplastic syndromes not targeted by this warning. The period from January 2004 to September 2006 was used as the prewarning period; the period from April 2007 to September 2009 was used as the postwarning period. The two binary dependent variables included ESA use and hospitalized VTE. Linear probability models with a difference-in-differences specification were used for estimation. Results Our sample consisted of 45,319 unique patients between 2004 and 2009. The trends in ESA use remained similar between the intervention and control groups before the warning, but started declining sharply in the intervention group only after the warning. The trends in hospitalized VTE were relatively stable. Regressions showed that the ESA boxed warning was associated with a 20.2-percentage-point reduction ( P < .001) in the likelihood of ESAs being used to treat cancers targeted by the warning, but not significantly associated with the likelihood of hospitalized VTE. Conclusion Our study showed that the warning was effective in reducing ESA utilization. Future studies should examine other regulatory drug safety actions, such as the Risk Evaluation and Mitigation Strategy initiative, whose effectiveness remains unknown.

On-label and off-label prescribing patterns of erythropoiesis-stimulating agents in inpatient hospital settings in the US during the period of major regulatory changes

BACKGROUND

A number of policy and labeling interventions aimed at reducing inappropriate prescribing of erythropoiesis-stimulating agents (ESAs) were implemented in the U.S. between 2006 and 2010. These interventions included the addition of an FDA Black Box Warning to ESA labeling, the implementation of a Risk Evaluation and Mitigation Strategy program, and the adoption of payment restrictions by the Centers for Medicare and Medicaid Services (CMS). The impact of these safety interventions on different types of ESA prescribing (on-label, off-label; evidence-based, not evidence-based) has not been investigated in a single study.

OBJECTIVES

The objective of this study was to explore the prescribing patterns of ESAs for on- and off-label indications in the U.S. hospital inpatients during the period of major policy and labeling changes.

METHODS

A retrospective analysis of ESAs utilization patterns was conducted using Cerner Health Facts^® database from January 1, 2005 to June 30, 2011. The study population consisted of adult patients admitted to hospitals during the study period who received at least one ESAs order. Indications for ESA use were assigned based on ICD-9 CM diagnosis codes, procedure codes, and medication records. ESA use was then classified based on FDA-approval and the strength of scientific evidence supporting its use. Indication categories included (1) on-label use (ONS); (2) off-label use, supported (OFS); and (3) off-label use, unsupported (OFU). Descriptive statistics were used to examine ESA use by patient, hospital, and physician characteristics and over time.

RESULTS

ESAs were most frequently prescribed for ONS (48.7%), followed by OFU (42.7%) and OFS indications (8.6%). Of all off-label use, 83.2% were for unsupported indications. Between 2005 and 2010, the percent of inpatient visits with ESA use decreased for supported indications, both on-label (-63.2%) and off-label (-78.2%), but increased for unsupported indications (80%). OFU use surpassed ONS use as the most common type of ESA use in 2009.

CONCLUSIONS

Total and ONS ESA use decreased markedly, while OFU ESA use continued to increase during the period of major policy and labeling changes.

Trends in Periodic Surveillance Testing for Early-Stage Uterine Cancer Survivors

OBJECTIVE

To examine the use of periodic surveillance testing for early-stage endometrial cancer survivors.

METHODS

We performed a population-based analysis using the Surveillance, Epidemiology, and End Results-Medicare database, which was used to identify patients with stage I-II endometrioid endometrial cancer treated from 1992 to 2011. Three surveillance periods (7-18, 19-30, 31-42 months) after hysterectomy were examined. Use of vaginal cytology and imaging were quantified.

RESULTS

We identified 17,638 patients. From 1992 to 2011, the use of chest radiography decreased (46.3-34.2%) during the first surveillance period, whereas imaging with chest computed tomography (CT) (0.9-12.6%), abdominopelvic CT (11.7-24.8%), and positron emission tomography (0-2.9%) increased (P<.001 for all). The use of cytology increased from 68.5% in 1992 to 72.3% in 2007 and then decreased to 66.9% in 2011 (P=.02). The mean number of cytologic samples obtained per patient increased from 1.3 in 1992 to 1.6 in 2008 and then declined to 1.3 in 2011, whereas the mean per patient number of chest CTs (0.02-0.2), abdominopelvic CTs (0.2-0.4), and positron emission tomographies (0-0.03) rose from 1992 to 2011. In 2011, 49.3% underwent radiologic surveillance 7-18 months after diagnosis, whereas 11.9% underwent two or more radiologic assessments in combination with cytology. These findings were similar for surveillance periods 2 and 3.

CONCLUSION

The use of chest radiography has decreased and use of cytology has started to decline. However, the use of more costly imaging modalities is increasing despite a lack of evidence for the efficacy of these tests for early-stage endometrial cancer survivors.

Comparative Effectiveness of Minimally Invasive Hysterectomy for Endometrial Cancer

PURPOSE

Despite the potential benefits of minimally invasive hysterectomy for uterine cancer, population-level data describing the procedure's safety in unselected patients are lacking. We examined the use of minimally invasive surgery and the association between the route of the procedure and long-term survival.

METHODS

We used the SEER-Medicare database to identify women with stage I-III uterine cancer who underwent hysterectomy from 2006 to 2011. Patients who underwent abdominal hysterectomy were compared with those who had minimally invasive hysterectomy (laparoscopic and robot-assisted). Perioperative morbidity, use of adjuvant therapy, and long-term survival were examined after propensity score balancing.

RESULTS

We identified 6,304 patients, including 4,139 (65.7%) who underwent abdominal hysterectomy and 2,165 (34.3%) who underwent minimally invasive hysterectomy; performance of minimally invasive hysterectomy increased from 9.3% in 2006 to 61.7% in 2011. Robot-assisted procedures accounted for 62.3% of the minimally invasive operations. Compared with women who underwent abdominal hysterectomy, minimally invasive hysterectomy was associated with a lower overall complication rate (22.7% v 39.7%; P < .001), and lower perioperative mortality (0.6% v 1.1%), but these women were more likely to receive adjuvant pelvic radiotherapy (34.3% v 31.3%) and brachytherapy (33.6% v 31.0%; P < .05). The complication rate was higher after robot-assisted hysterectomy compared with laparoscopic hysterectomy (23.7% v 19.5%; P = .03). There was no association between the use of minimally invasive hysterectomy and either overall (HR, 0.89; 95% CI, 0.75 to 1.04) or cancer-specific (HR, 0.83; 95% CI, 0.59 to 1.16) mortality.

CONCLUSION

Minimally invasive hysterectomy does not appear to compromise long-term survival for women with endometrial cancer.

Adequacy of the National Quality Forum's Colon Cancer Adjuvant Chemotherapy Quality Metric: Is 4 Months Soon Enough?

OBJECTIVE

To ascertain whether the National Quality Forum-endorsed time interval for adjuvant chemotherapy (AC) initiation optimizes patient outcome.

BACKGROUND

Delayed AC initiation for stage III colon cancer is associated with worse survival and the focus of a National Quality Forum quality metric (<4 months among patients aged <80 years).

METHODS

Observational cohort study of patients with stage III colon cancer younger than 80 years within the National Cancer Data Base (2003-2010). The primary outcome was 5-year overall survival evaluated using multivariate Cox proportional hazards regression. Aggregate survival estimates for historical surgery-only controls from pooled National Surgical Adjuvant Breast and Bowel Project trial data were also used.

RESULTS

Among 51,331 patients (60.8 ± 11.6 years, 50.2% males, and 77.3% white), 76.3% received standard AC (≤ 2 months) and 21.6% delayed (>2 and <4 months) AC. Earlier AC was associated with better 5-year overall survival [standard AC, 69.8%; delayed AC, 62.0%; late AC (4-6 months), 51.4%; log-rank, P < 0.001]. The survival rate after late AC was similar to surgery alone (51.1%; Wilcoxon rank sum, P = 0.10). Compared with late AC, standard AC (hazard ratio, 0.62; 95% confidence interval, 0.54-0.72) and delayed AC (hazard ratio, 0.77; 95% confidence interval, 0.66-0.89) significantly decreased risk of death. Risk of death was also lower for standard AC compared to delayed AC (hazard ratio, 0.81; 95% confidence interval, 0.77-0.86).

CONCLUSIONS

One in 5 patients with stage III colon cancer initiates AC within the National Quality Forum-endorsed interval, but does not derive the full benefit. These data support strengthening current quality improvement initiatives and colon cancer treatment guidelines to encourage AC initiation within 2 months of resection when possible, but not beyond 4 months.

Gonadotropin-releasing hormone agonist overuse: urologists' response to reimbursement and characteristics associated with persistent overuse

BACKGROUND

Medicare reimbursement cuts have been associated with declining gonadotropin-releasing hormone (GnRH) agonist overuse in localized prostate cancer. Medical school affiliation and foreign training have been associated with persistent overuse. However, physician-level prescribing changes and the practice type of persistent overusers have not been examined. We sought to describe physician-level changes in GnRH agonist overuse and test the association of time in practice and solo practice type with GnRH agonist overuse.

METHODS

We matched American Medical Association physician data for 2138 urologists to Surveillance, Epidemiology and End Result-Medicare data for 12,943 men diagnosed with early-stage and lower-grade adenocarcinoma of the prostate between 2000 and 2007. We conducted a population-based, retrospective study using multilevel modeling to control for patient and provider characteristics.

RESULTS

Three distinct patterns of GnRH agonist overuse were observed. Urologists' time in practice was not associated with GnRH agonist overuse (odds ratio (OR) 0.89; 95% confidence interval (CI): 0.75-1.05). However, solo practice type (OR 1.65; 95% CI: 1.34-2.02), medical school affiliation (OR 0.65; 95% CI: 0.55-0.77) and patient race were. Compared with non-Hispanic whites, non-Hispanic blacks (OR 1.76; 95% CI: 1.37-2.27), Hispanics (OR 1.41; 95% CI: 1.12-1.79) and men of 'other' race (OR 1.44; 95% CI: 1.04-1.99) had greater odds of receiving unnecessary GnRH agonists.

CONCLUSIONS

GnRH agonist overuse remains high among some urologists who may be professionally isolated and difficult to reach. These urologists treat more vulnerable populations, which may contribute to health disparities in prostate cancer treatment quality. Nonetheless, these findings provide guidance to develop interventions to address overuse in prostate cancer.

Use and duration of chemotherapy and its impact on survival in early-stage ovarian cancer

OBJECTIVE

Although 5-year survival for early-stage ovarian cancer is favorable, prognosis at recurrence is poor, necessitating appropriate initial management. We examined the patterns of care and the impact of the duration of chemotherapy on survival for women with early-stage ovarian cancer.

METHODS

We used the SEER-Medicare database to identify women ≥ 65 years of age with stage I ovarian cancer diagnosed from 1992 to 2009. Patients were categorized as low-risk (non-clear cell histology, stage IA or IB, grade 1 or 2) or high-risk (clear cell histology, grade 3, or stage IC). We used multivariable logistic regression models to determine predictors of chemotherapy use and duration and Cox proportional hazards models to evaluate the effect of chemotherapy use and duration on survival.

RESULTS

We identified 1394 patients. Among low-risk patients, 32.9% received adjuvant chemotherapy and the use of chemotherapy increased with time. Among high-risk patients, 71.9% received adjuvant chemotherapy; 44.2% had ≤ 3 months of treatment, and 55.8% had > 3 months of treatment. Older patients were less likely to receive chemotherapy, while those with higher stage and grade were more likely to receive chemotherapy (P<0.05 for all). Among high-risk patients, the duration of chemotherapy did not impact overall (HR=0.93, 95% CI, 0.67-1.27) or cancer specific (HR=0.93; 95% CI, 0.61-1.42) survival.

CONCLUSIONS

Among early-stage ovarian cancer patients, practice patterns are widely divergent. Extended duration chemotherapy does not appear to impact survival for women with high-risk disease.

Patterns of care, predictors, and outcomes of chemotherapy in elderly women with early-stage uterine carcinosarcoma: a population-based analysis

OBJECTIVE

To examine the patterns of care, predictors, and impact of chemotherapy on survival in elderly women diagnosed with early-stage uterine carcinosarcoma.

METHODS

The Surveillance, Epidemiology, and End Results (SEER)-Medicare database was used to identify women 65 years or older diagnosed with stage I-II uterine carcinosarcomas from 1991 through 2007. Multivariable logistic regression and Cox-proportional hazards models were used for statistical analysis.

RESULTS

A total of 462 women met the eligibility criteria; 374 had stage I, and 88 had stage II uterine carcinosarcomas. There were no appreciable differences over time in the percentages of women administered chemotherapy for early stage uterine carcinosarcoma (14.7% in 1991-1995, 14.9% in 1996-2000, and 17.9% in 2001-2007, P=0.67). On multivariable analysis, the factors positively associated with receipt of chemotherapy were younger age at diagnosis, higher disease stage, residence in the eastern part of the United States, and lack of administration of external beam radiation (P<0.05). In the adjusted Cox-proportional hazards regression models, administration of three or more cycles of chemotherapy did not reduce the risk of death in stage I patients (HR: 1.45, 95% CI: 0.83-2.39) but was associated with non-significant decreased mortality in stage II patients (HR: 0.83, 95% CI: 0.32-1.95).

CONCLUSIONS

Approximately 15-18% of elderly patients diagnosed with early-stage uterine carcinosarcoma were treated with chemotherapy. This trend remained stable over time, and chemotherapy was not associated with any significant survival benefit in this patient population.

Comparative effectiveness of upfront treatment strategies in elderly women with ovarian cancer

BACKGROUND

Observational studies comparing neoadjuvant chemotherapy to primary surgery for advanced-stage ovarian cancer are limited by strong selection bias. Multiple methods were used to control for confounding and selection bias to estimate the effect of primary treatment on survival for ovarian cancer.

METHODS

The Surveillance, Epidemiology, and End Results (SEER)-Medicare database was used to identify women ≥ 65 years of age with stage II-IV epithelial ovarian cancer who survived > 6 months from the date of diagnosis and received treatment from 1991 through 2007. Traditional regression analysis, propensity score-based analysis, and an instrumental variable analysis (IVA) using geographic location as an instrument were used to compare survival between neoadjuvant chemotherapy and primary surgery.

RESULTS

A total of 9587 patients with stage II-IV ovarian cancer were identified. Use of primary surgery decreased from 63.2% in 1991 to 49.5% by 2007, whereas primary chemotherapy increased from 19.7% in 1991 to 31.8% in 2007 (P < .0001). In the observational cohort survival (hazard ratio [HR] = 1.27; 95% confidence interval [CI] = 1.19-1.35) was inferior for patients treated with neoadjuvant chemotherapy; both median survival (15.8 versus 28.8 months) and 2-year survival (36% versus 56%) were lower in the neoadjuvant chemotherapy group compared to those who underwent surgery. In the IVA, primary treatment had minimal effect on overall survival (HR = 1.04; 95% CI = 0.67-1.60). The median survival for patients with a value of the instrument less than the median (24.0 months, 95% CI = 23.0-25.0) and greater than or equal to median value of the IV (24.0 months, 95% CI = 23.0-26.0) were similar.

CONCLUSIONS

Use of neoadjuvant therapy has increased over time. Survival with neoadjuvant chemotherapy did not differ significantly from primary surgery in elderly women in the United States.

Patterns of use of hemostatic agents in patients undergoing major surgery

BACKGROUND

Although a number of prohemostatic agents that are applied intraoperatively have been introduced to minimize bleeding, little is known about the patterns of use and the factors that influence use. We examined the use of hemostatic agents in patients undergoing major surgery.

METHODS

All patients who underwent major general, gynecologic, urologic, cardiothoracic, or orthopedic surgery from 2000-2010 who were recorded in the Perspective database were analyzed.

RESULTS

Among 3,633,799 patients, hemostatic agents were used in 30.3% (n = 1,102,267). The use of hemostatic agents increased from 28.5% in 2000 to 35.2% in 2010. Over the same period, the rates of transfusion declined for pancreatectomy (-14.4%), liver resection (-15.0%), gastrectomy (-11.7%), prostatectomy (-6.6%), nephrectomy (-4.6%), hip arthroplasty (-10.4%), and knee arthroplasty (-6.6%). Over the same time period, the transfusion rate increased for colectomy (6.0%), hysterectomy (3.7%), coronary artery bypass graft (8.4%), valvuloplasty (4.2%), lung resection (1.9%), and spine surgery (1.6%). Transfusion remained relatively stable for thyroidectomy (0.2%).

CONCLUSIONS

The use of hemostatic agents has increased rapidly even for surgeries associated with a small risk of transfusion and bleeding complications. In addition to patient characteristics, surgeon and hospital factors exerted substantial influence on the allocation of hemostatic agents.

Contraindicated use of bevacizumab and toxicity in elderly patients with cancer

PURPOSE

Drugs are approved on the basis of randomized trials conducted in selected populations. However, once approved, these treatments are usually expanded to patients ineligible for the trial.

PATIENTS AND METHODS

We used the SEER-Medicare database to identify subjects older than 65 years with metastatic breast, lung, and colon cancer, diagnosed between 2004 and 2007 and undergoing follow-up to 2009, who received bevacizumab. We defined a contraindication as having at least two billing claims before bevacizumab for thrombosis, cardiac disease, stroke, hemorrhage, hemoptysis, or GI perforation. We defined toxicity as first development of one of these conditions after therapy.

RESULTS

Among 16,085 metastatic patients identified, 3,039 (18.9%) received bevacizumab. Receipt of bevacizumab was associated with white race, later year of diagnosis, tumor type, and decreased comorbid conditions. Of patients who received bevacizumab, 1,082 (35.5%) had a contraindication. In multivariate analysis, receipt of bevacizumab with a contraindication was associated with black race (odds ratio [OR] = 2.6; 95% CI, 1.4 to 4.9), increased age, comorbidity, later year of diagnosis, and lower socioeconomic status. Patients with lung (OR = 1.7; 95% CI, 1.1 to 2.4) and colon cancer (OR = 1.4; 95% CI, 1.1 to 1.9) were more likely to have a contraindication. In the group with no contraindication, 30% had a complication after bevacizumab; black patients were more likely to have a complication than were white patients (OR = 1.9; 95% CI, 1.21 to 2.93).

CONCLUSION

Our study demonstrates widespread use of bevacizumab among patients who had contraindications. Black patients were less likely to receive the drug, but those who did were more likely to have a contraindication. Efforts to understand toxicity and efficacy in populations excluded from clinical trials are needed.

Deviations from guideline-based therapy for febrile neutropenia in cancer patients and their effect on outcomes

IMPORTANCE

Although febrile neutropenia (FN) is a major source of morbidity and mortality for patients with solid tumors, little is known about the use of guideline-based care.

OBJECTIVES

To examine compliance with guideline-based recommendations for FN treatment, explore the factors that influence adherence to consensus guidelines, and analyze how the use of guideline-based care affects the outcomes.

DESIGN

The Perspective database was used to examine the treatment of cancer patients with FN from January 1, 2000, through March 31, 2010. To capture initial decision making, we examined treatment within 48 hours of hospital admission. We determined use of guideline-based antibiotics and nonguideline-based treatments, vancomycin, and granulocyte colony-stimulating factors (GCSF). Hierarchical models were developed to examine the factors associated with treatment. Patients were stratified into low- and high-risk groups, and the effect of the initial treatment on outcome (nonroutine hospital discharge and death) was examined.

SETTING AND PARTICIPANTS

Twenty-five thousand two hundred thirty-one patients with solid tumors hospitalized for neutropenia.

MAIN OUTCOME MEASURE

Use of guideline-based antibiotics, vancomycin, and GCSF and their affect on outcome.

RESULTS

Among 25 231 patients admitted with FN, guideline-based antibiotics were administered to 79%, vancomycin to 37%, and GCSF to 63%. Patients treated at high FN-volume hospitals (odds ratio [OR], 1.56; 95% CI, 1.34-1.81) by high FN-volume physicians (OR, 1.19; 95% CI, 1.03-1.38) and patients managed by hospitalists (OR, 1.49; 95% CI, 1.18-1.88) were more likely to receive guideline-based antibiotics (P < .05). Vancomycin use increased from 17% in 2000 to 55% in 2010, while GCSF use only decreased from 73% to 55%. Among low-risk patients with FN, prompt initiation of guideline-based antibiotics decreased discharge to a nursing facility (OR, 0.77; 95% CI, 0.65-0.92) and death (OR, 0.63; 95% CI, 0.42-0.95).

CONCLUSIONS AND RELEVANCE

While use of guideline-based antibiotics is high, use of the nonguideline-based treatments, vancomycin, and GCSF is also high. Physician and hospital factors are the strongest predictors of both guideline- and nonguideline-based treatment.

Patterns of erythropoiesis-stimulating agent use among Medicare beneficiaries with myelodysplastic syndromes and consistency with clinical guidelines

Erythropoiesis-stimulating agents (ESA) are used commonly to reduce symptomatic anemia in patients with myelodysplastic syndromes (MDS). We assessed population-based patterns of ESA use relative to treatment guidelines using data from the Surveillance, Epidemiology, and End Results (SEER) registries, with linked Medicare claims providing detailed treatment data from 2001 through 2005. The study found widespread use (62%) of ESA in Medicare beneficiaries with MDS. Similar ESA use rates regardless of risk status, low frequency (45%) of serum erythropoietin determination prior to ESA initiation, and high prevalence (60.4%) of short-duration ESA episodes suggest clinically important discrepancies between actual practice and guideline-recommended therapy.

Comparative effectiveness research in oncology methodology: observational data

The goal of comparative effectiveness research is to inform clinical decisions between alternate treatment strategies using data that reflect real patient populations and real-world clinical scenarios for the purpose of improving patient outcomes. Observational studies using population-based registry data are increasingly relied on to fill the information gaps created by lack of evidence from randomized controlled trials. Administrative data sets have many advantages, including large sample sizes, long-term follow-up, and inclusion of data on physician and systems characteristics as well as cost. In this review, we describe the characteristics of many of the commonly used population-based data sets and discuss the elements included within these data sets. An overview of common research themes that rely on population-based data and illustrative examples are presented. Finally, an overview of the analytic techniques commonly employed by health services researchers to limit the effects of selection bias and confounding is discussed. The analysis of well-designed studies of comparative effectiveness is complex. However, careful framing, appropriate study design, and application of sophisticated analytic techniques can improve the accuracy of nonrandomized studies. There are multiple areas where the unique characteristics of observational studies can inform medical decision making and health policy, and it is critical to appreciate the opportunities, strengths, and limitations of observational research.

Cytokine use and survival in the first-line treatment of ovarian cancer: a Gynecologic Oncology Group Study

BACKGROUND

Granulocyte colony stimulating factor (G-CSF) and erythropoietin stimulating agents (ESA) may be used to support patients during chemotherapy. We assessed whether G-CSF or ESA were associated with progression or death in patients with ovarian cancer.

METHODS

Patients with ovarian cancer following surgery, were on a protocol to evaluate bevacizumab with chemotherapy. Guidelines for administering G-CSF and ESA were specified in the protocol. Overall survival (OS) was analyzed with landmark procedures and multivariate, time-dependent hazard models.

RESULTS

Eighteen-hundred-seventy-three women were enrolled, with no differences in clinical and pathologic variables among treatment group. Performance status, hemoglobin, and white cell counts were associated with G-CSF and/or ESA usage during treatment. Nine patients received no protocol directed therapy, leaving 1864 patients for this review. One-thousand-one-hundred-twenty-five patients received neither ESA nor G-CSF; 311 received G-CSF but no ESA; 241 received ESA but no G-CSF; and 187 received both. Median survival following a five month landmark from the start of treatment was 34 versus 38 months for those who did versus did not receive ESA (multivariate hazard ratio: 0.989; 95% confidence interval: 0.849-1.15) and 40 versus 37 months for those who did versus did not receive G-CSF (multivariate hazard ratio: 0.932; 95% confidence interval: 0.800-1.08).

CONCLUSIONS

Neither ESA nor G-CSF had a negative impact on survival after adjustment of prognostic factors among patients with ovarian cancer receiving chemotherapy. ESA may appear to be associated with shorter survival in univariate analyses because factors prognostic for ESA use are also prognostic for progression-free survival.

Triggers of hospitalization for venous thromboembolism

BACKGROUND

The rate of hospitalization for venous thromboembolism (VTE) is increasing in the United States. Although predictors of hospital-acquired VTE are well-known, triggers of VTE before hospitalization are not as clearly defined. The objective of this study was to evaluate triggers of hospitalization for VTE.

METHODS AND RESULTS

A case-crossover study was conducted. Subjects were participants in the Health and Retirement Study, a nationally representative sample of older Americans. Data were linked to Medicare files for hospital and nursing home stays, emergency department visits, outpatient visits including physician visits, and home health visits from years 1991 to 2007 (n=16 781). The outcome was hospitalization for venous thromboembolism (n=399). Exposures during the 90-day period before hospitalization for VTE were compared with exposures occurring in 4 comparison periods. Infection was the most common trigger of hospitalization for VTE, occurring in 52.4% of the risk periods before hospitalization. The adjusted incidence rate ratios (IRRs; 95% confidence interval) were 2.90 (2.13, 3.94) for all infection, 2.63 (1.90, 3.63) for infection without a previous hospital or skilled nursing facility stay, and 6.92 (4.46, 10.72) for infection with a previous hospital or skilled nursing facility stay. Erythropoiesis-stimulating agents and blood transfusion were also associated with VTE hospitalization (IRR=9.33, 95% confidence interval: 1.19, 73.42; IRR=2.57, 95% confidence interval: 1.17, 5.64; respectively). Other predictors included major surgeries, fractures (IRR=2.81), immobility (IRR=4.23), and chemotherapy (IRR=5.70). These predictors, combined, accounted for a large proportion (69.7%) of exposures before VTE hospitalization as opposed to 35.3% in the comparison periods.

CONCLUSIONS

Risk prediction algorithms for VTE should be reevaluated to include infection, erythropoiesis-stimulating agents, and blood transfusion.