Assessing patients' risk of febrile neutropenia: is there a correlation between physician-assessed risk and model-predicted risk?

This study evaluated the correlation between the risk of febrile neutropenia (FN) estimated by physicians and the risk of severe neutropenia or FN predicted by a validated multivariate model in patients with nonmyeloid malignancies receiving chemotherapy. Before patient enrollment, physician and site characteristics were recorded, and physicians self-reported the FN risk at which they would typically consider granulocyte colony-stimulating factor (G-CSF) primary prophylaxis (FN risk intervention threshold). For each patient, physicians electronically recorded their estimated FN risk, orders for G-CSF primary prophylaxis (yes/no), and patient characteristics for model predictions. Correlations between physician-assessed FN risk and model-predicted risk (primary endpoints) and between physician-assessed FN risk and G-CSF orders were calculated. Overall, 124 community-based oncologists registered; 944 patients initiating chemotherapy with intermediate FN risk enrolled. Median physician-assessed FN risk over all chemotherapy cycles was 20.0%, and median model-predicted risk was 17.9%; the correlation was 0.249 (95% CI, 0.179-0.316). The correlation between physician-assessed FN risk and subsequent orders for G-CSF primary prophylaxis (n = 634) was 0.313 (95% CI, 0.135-0.472). Among patients with a physician-assessed FN risk ≥ 20%, 14% did not receive G-CSF orders. G-CSF was not ordered for 16% of patients at or above their physician's self-reported FN risk intervention threshold (median, 20.0%) and was ordered for 21% below the threshold. Physician-assessed FN risk and model-predicted risk correlated weakly; however, there was moderate correlation between physician-assessed FN risk and orders for G-CSF primary prophylaxis. Further research and education on FN risk factors and appropriate G-CSF use are needed.

Discrete choice experiment to estimate breast cancer patients' preferences and willingness to pay for prophylactic granulocyte colony-stimulating factors.

OBJECTIVES: Rising out-of-pocket costs for cancer patients have increased shared decision making. Clinical guidelines recommend prophylactic granulocyte colony-stimulating factor (G-CSF) for patients receiving chemotherapy with a 20% or greater risk of febrile neutropenia. A discrete choice experiment was conducted to explore breast cancer patients' preferences and willingness to pay (WTP) for prophylactic G-CSF to decrease the risk of chemotherapy-induced febrile neutropenia. METHODS: An online discrete choice experiment questionnaire survey of a national US convenience sample of self-reported breast cancer patients with prior chemotherapy treatment was conducted. Sixteen paired G-CSF treatment scenarios, each with four attributes (risk of disruption to chemotherapy schedule due to low white blood cell counts, risk of developing an infection requiring hospitalization, frequency of administration, and total out-of-pocket cost) were presented with a follow-up "no treatment" option. Participant preferences and WTP out of pocket were estimated by logistic regression. RESULTS: Participants (n = 296) preferred G-CSF regimens with lower out-of-pocket costs, lower risk of chemotherapy disruption, lower risk of infection, and greater convenience (one G-CSF injection per chemotherapy cycle). Participants' WTP was $1076 out of pocket per cycle to reduce the risk (high to low) of disrupting their chemotherapy schedule, $884 per cycle to reduce the risk (24% [high] to 7% [low]) of infection, and $851 per cycle to decrease the number of G-CSF injections (11 to 1) per cycle. CONCLUSIONS: Participants highly valued specific features of prophylactic G-CSF treatment including maintaining their chemotherapy schedule, lowering their risk of infection, and reducing the number of injections. Physicians should consider patient preferences to inform the best treatment choices for individual patients.

Risk and consequences of chemotherapy-induced neutropenic complications in patients receiving daily filgrastim: the importance of duration of prophylaxis.

BACKGROUND: To examine duration of daily filgrastim prophylaxis, and risk and consequences of chemotherapy-induced neutropenic complications (CINC) requiring inpatient care. METHODS: Using a retrospective cohort design and US healthcare claims data (2001-2010), we identified all cancer patients who initiated ≥1 course of myelosuppressive chemotherapy and received daily filgrastim prophylactically in ≥1 cycle. Cycles with daily filgrastim prophylaxis were pooled for analyses. CINC was identified based on hospital admissions with a diagnosis of neutropenia, fever, or infection; consequences were characterized in terms of hospital mortality, hospital length of stay (LOS), and CINC-related healthcare expenditures. RESULTS: Risk of CINC requiring inpatient care-adjusted for patient characteristics-was 2.4 (95% CI: 1.6-3.4) and 1.9 (1.3-2.8) times higher with 1-3 (N = 8371) and 4-6 (N = 3691) days of filgrastim prophylaxis, respectively, versus ≥7 days (N = 2226). Among subjects who developed CINC, consequences with 1-3 and 4-6 (vs. ≥7) days of filgrastim prophylaxis were: mortality (8.4% [n/N = 10/119] and 4.0% [3/75] vs. 0% [0/34]); LOS (means: 7.4 [N = 243] and 7.1 [N = 99] vs. 6.5 [N = 40]); and expenditures (means: $18,912 [N = 225] and $14,907 [N = 94] vs. $13,165 [N = 39]). CONCLUSIONS: In this retrospective evaluation, shorter courses of daily filgrastim prophylaxis were found to be associated with an increased risk of CINC as well as poorer outcomes among those developing this condition. Because of the limitations inherent in healthcare claims databases specifically and retrospective evaluations generally, additional research addressing these limitations is needed to confirm the findings of this study.

Incidence, treatment, and consequences of chemotherapy-induced febrile neutropenia in the inpatient and outpatient settings.

OBJECTIVE: To examine the incidence, treatment, and consequences of febrile neutropenia across inpatient and outpatient care settings. METHODS: Data were obtained from Humedica's National Electronic Health Record-Derived Longitudinal Patient-Level Database (2007-2010). The study population included adult patients who received myelosuppressive chemotherapy for a solid tumor or non-Hodgkin's lymphoma. For each patient, each chemotherapy regimen course and each cycle within each regimen course was characterized. Febrile neutropenia episodes were identified on a cycle-specific basis based on any of the following: (1) absolute neutrophil count <1.0 × 10(9)/L and evidence of infection or fever; (2) inpatient diagnosis of neutropenia, fever, or infection; (3) outpatient diagnosis of neutropenia and non-prophylactic antimicrobial use; or (4) mention of febrile neutropenia in physician notes. Febrile neutropenia episodes were categorized as inpatient or outpatient based on the initial setting of care (i.e. acute-care inpatient facility vs. ambulatory care facility). Febrile neutropenia consequences included hospital length of stay and mortality (inpatient cases only), as well as number of febrile neutropenia-related outpatient encounters. RESULTS: Among the 2131 patients in this study, 401 experienced a total of 458 febrile neutropenia episodes. Risk of febrile neutropenia during the chemotherapy regimen course was 16.8% (95% CI: 15.3, 18.4). In cycle 1 alone, risk of febrile neutropenia was 8.1% (7.1, 9.3). Most febrile neutropenia episodes (83.2%) were initially treated in the inpatient setting; the hospital mortality rate was 8.1% (5.8, 11.1), and mean hospital length of stay was 8.4 days (7.7, 9.1). Among febrile neutropenia episodes initially treated in the outpatient setting (16.8%), the mean number of outpatient management encounters was 2.6 (2.1, 3.1), most of which were in the physician's office (69.2%) or emergency department (26.9%). CONCLUSIONS: Febrile neutropenia remains a common occurrence among patients receiving myelosuppressive chemotherapy and typically results in extended hospitalization and, for many patients, death. A minority of patients are, however, treated exclusively on an outpatient basis.

Staff time and motion assessment for administration of erythropoiesis-stimulating agents: a two-phase pilot study in clinical oncology practices.

BACKGROUND: Erythropoiesis-stimulating agents (ESAs) are used for the management of anaemia in patients with non-myeloid malignancies where anaemia is due to the effect of concomitant myelosuppressive chemotherapy. Assessing the impact of different ESA dosing regimens on office staff time and projected labour costs is an important component of understanding the potential for optimization of oncology practice efficiencies. OBJECTIVES: A two-phase study was conducted to evaluate staff time and labour costs directly associated with ESA administration in real-world oncology practice settings among cancer patients undergoing chemotherapy. The objective of Phase 1 was to determine the mean staff time required for the process of ESA administration in patients with anaemia due to concomitantly administered chemotherapy. The objective of Phase 2 was to quantify and compare the mean staff time and mean labour costs of ESA administered once weekly (qw) with ESA once every 3 weeks (q3w) over an entire course of chemotherapy. METHODS: Phase 1 was a prospective, cross-sectional time and motion study conducted in six private oncology practices in the US based on nine steps associated with ESA administration. Using findings from Phase 1, Phase 2 was conducted as a retrospective chart review to collect data on the number and types of visits in two private oncology practices for patients receiving a complete course of myelosuppressive chemotherapy. RESULTS: In Phase 1, the mean total time that clinic staff spent on ESA administration was 23.2 min for patient visits that included chemotherapy administration (n(chemo) = 37) and 21.5 min when only ESA was administered (n(ESAonly) = 36). In Phase 2, the mean duration of treatment was significantly longer for q3w than qw (53.84 days for qw vs. 113.38 for q3w, p < 0.0001); thus, analyses were adjusted using analysis of covariance (ANCOVA) for episode duration for between-group comparisons. Following adjustment by ANCOVA, qw darbepoetin alfa (DA) patients (n(qw) = 83) required more staff time for ESA + chemotherapy visits and ESA-only visits than q3w patients (n(q3w) = 118) over a course of chemotherapy. Overall, mean total staff time expended per chemotherapy course was greater for patients receiving qw versus q3w DA. Weekly DA dosing was associated with greater projected mean labour costs ($US38.16 vs. $US31.20 [average for 2007-2010]). CONCLUSIONS: The results from this real-world study demonstrate that oncology practices can attain staff time and labour costs savings through the use of q3w ESA. The degree of savings depends on the individual oncology practice's staffing model and ESA administration processes, including those that allow for optimized synchronization of patient visits for ESA and chemotherapy administration. These findings indicate that additional research using standard ESA administration protocols for longer periods of time with a larger number of oncology practices and patients should be conducted to confirm these findings.

A retrospective study of the clinical and economic burden during hospitalizations among cancer patients with febrile neutropenia.

OBJECTIVE: The objective of this study was to provide up-to-date estimates of the clinical and economic burden that occurs during inpatient treatment of cancer patients with febrile neutropenia (FN). METHODS: A retrospective cohort study was conducted using 2007-2010 hospital discharge data from the Premier database. The study population included adult patients with discharge diagnoses of neutropenia (ICD-9 code 288.0x) with fever or infection and receipt of intravenous antibiotics and female breast cancer, lung cancer, colorectal cancer, ovarian cancer, non-Hodgkin lymphoma (NHL), or Hodgkin lymphoma. Primary study outcomes were inpatient mortality, hospital length of stay (LOS), and total hospitalization cost for each patient's first FN-related hospitalization. Logistic regressions (for mortality) and multivariate linear regressions (for LOS and cost) were conducted to assess the effect of comorbidities and infection types on study outcomes, adjusting for other patient and hospital characteristics. RESULTS: Among 16,273 cancer patients hospitalized with FN, the inpatient case fatality rate was 10.6%, mean LOS was 8.6 days, and mean total hospitalization cost was $18,880. Lung cancer patients had the highest inpatient case fatality rate (15.7%), and NHL patients had the longest LOS (10.1 days) and the highest cost ($24,218). Multivariate analyses showed that most comorbidities were associated with a greater risk of mortality, longer LOS, and higher cost. Septicemia/bacteremia and pneumonia were associated with a greater risk of mortality, and most types of infection were associated with a longer LOS and higher cost. LIMITATIONS: The total burden of FN may be under-estimated in this study because outpatient treatment and any patient deaths or costs that occurred outside of Premier hospitals could not be captured. CONCLUSIONS: FN-related hospitalizations among cancer patients are costly and accompanied by considerable mortality risk. Substantial differences in the clinical and economic burden of FN exist depending on cancer types, comorbidities, and infection types.

Technical evaluation of methods for identifying chemotherapy-induced febrile neutropenia in healthcare claims databases.

BACKGROUND: Healthcare claims databases have been used in several studies to characterize the risk and burden of chemotherapy-induced febrile neutropenia (FN) and effectiveness of colony-stimulating factors against FN. The accuracy of methods previously used to identify FN in such databases has not been formally evaluated. METHODS: Data comprised linked electronic medical records from Geisinger Health System and healthcare claims data from Geisinger Health Plan. Subjects were classified into subgroups based on whether or not they were hospitalized for FN per the presumptive "gold standard" (ANC <1.0×10(9)/L, and body temperature ≥38.3°C or receipt of antibiotics) and claims-based definition (diagnosis codes for neutropenia, fever, and/or infection). Accuracy was evaluated principally based on positive predictive value (PPV) and sensitivity. RESULTS: Among 357 study subjects, 82 (23%) met the gold standard for hospitalized FN. For the claims-based definition including diagnosis codes for neutropenia plus fever in any position (n=28), PPV was 100% and sensitivity was 34% (95% CI: 24-45). For the definition including neutropenia in the primary position (n=54), PPV was 87% (78-95) and sensitivity was 57% (46-68). For the definition including neutropenia in any position (n=71), PPV was 77% (68-87) and sensitivity was 67% (56-77). CONCLUSIONS: Patients hospitalized for chemotherapy-induced FN can be identified in healthcare claims databases--with an acceptable level of mis-classification--using diagnosis codes for neutropenia, or neutropenia plus fever.

Hemoglobin decline in cancer patients receiving chemotherapy without an erythropoiesis-stimulating agent.

PURPOSE: The aim of this study was to examine the rate and timing of hemoglobin decline from <10 g/dL to <9 g/dL in cancer patients receiving chemotherapy. METHODS: Pooled data from the placebo arms of six randomized, controlled trials (RCTs) of darbepoetin alfa and data from an aggregated US community oncology clinic electronic medical records (EMR) database were analyzed. Patients had baseline hemoglobin ≥10 g/dL (RCTs) or baseline hemoglobin between ≥10 g/dL and <11 g/dL (EMR episodes) that declined to <10 g/dL at least once during the study period. The proportion of patients/episodes with hemoglobin decline to <9 g/dL by 3, 6, and 9 weeks without erythropoiesis-stimulating agents was estimated from data in each of the data sources, as was the rate of transfusions in the RCTs. RESULTS: Data from 411 patients receiving placebo in the RCTs and 10,523 patients (10,942 episodes) in the EMR database were analyzed. Forty percent and 35 % of RCT patients and EMR episodes, respectively, had a hemoglobin decline from <10 g/dL to <9 g/dL at week 3, 54 % and 43 % at week 6, and 58 % and 46 % at week 9. Of patients in the RCTs, 43 % required an RBC transfusion. CONCLUSIONS: Hemoglobin can rapidly decline in cancer patients receiving chemotherapy with hemoglobin levels around 10 g/dL, particularly in patients ≥65 years of age. The rapid rate of hemoglobin decline in these patients should be considered for optimal anemia management.

Trends in neutropenia-related inpatient events.

PURPOSE: Neutropenic complications (NCs) after myelosuppressive chemotherapy are associated with significant morbidity and mortality. We described NC rates by using US hospital discharge data. MATERIALS AND METHODS: This cross-sectional analysis used data from the US National Inpatient Sample database. Hospital discharges with cancer diagnoses (International Classification of Diseases, Ninth Revision, Clinical Modification [ICD-9-CM] code) from 1989 to 2007 were analyzed for the ICD-9-CM neutropenia code. NC rates per 10,000 discharges were calculated for all adult discharges without radiation therapy (study population, all cancers); lung cancer, breast cancer, and non-Hodgkin's lymphoma (NHL); and all three combined. The use of growth factors and myelosuppressive chemotherapy from 1994 to 2008 was estimated by using the IMS Health Drug Distribution Database. RESULTS: Estimated lung cancer and breast cancer discharges remained relatively steady, whereas NHL discharges increased. NC rates for each study cancer increased two-fold until the late 1990s before stabilizing and/or declining. The average hospital stay for all three cancers decreased from 10.4 days to 7.1 days. The mortality rates for NCs for the three cancers combined decreased at a fairly constant rate from 10% in 1989 to 5.4% in 2007. Estimated discharges for NCs from 1989 to 2007 ranged from 111,000 to 169,000 for the study population, from 57,000 to 103,000 for all cancers, and from 21,000 to 40,000 for the three study cancers. The use of growth factors and myelosuppressive chemotherapy increased from 1994 to 2008. CONCLUSION: Whereas the number of hospitalizations with cancer diagnoses has remained steady since 1989, hospitalizations for NCs increased approximately two-fold from 1989 to 1997 and then stabilized.

Evaluation of bleeding-related episodes in patients with immune thrombocytopenia (ITP) receiving romiplostim or medical standard of care.

Romiplostim increases platelet counts and reduces the risk of bleeding in patients with immune thrombocytopenia (ITP). This post hoc analysis compared the effect of romiplostim versus medical standard of care (SOC) on clinically relevant bleeding-related episodes (BREs) in a 52-week open-label study of patients with ITP. BREs were defined as actual bleeding events and/or use of rescue medication. Nonsplenectomized adult patients with ITP were randomized to receive weekly subcutaneous injections of romiplostim (n = 157) or SOC (n = 77). The rate of all BREs (per 100 patient-weeks) was lower in patients treated with romiplostim (3.1) than in those treated with SOC (9.4); the relative rate (romiplostim/SOC) was 0.33 (95 % CI 0.27-0.40). The rate of BREs associated with immunoglobulin (Ig) rescue medication was also lower for romiplostim (0.2) than SOC (4.8); the relative rate (romiplostim/SOC) was 0.05 (95 % CI 0.03-0.08). BRE rates were lower in patients with platelet counts ≥50 × 10(9)/L, and patients treated with romiplostim spent more time with platelet counts ≥50 × 10(9)/L than did patients treated with SOC. Bleeding-related hospitalizations were rare in both groups. Thus, romiplostim treatment provided greater reductions in all BREs, as well as BREs involving Ig rescue medications, than did SOC.

Granulocyte-colony stimulating factor use and medical costs after initial adjuvant chemotherapy in older patients with early-stage breast cancer.

BACKGROUND: Granulocyte-colony stimulating factor (G-CSF) reduces the risk of severe neutropenia associated with chemotherapy, but its cost implications following chemotherapy are unknown. OBJECTIVE: Our objective was to examine associations between G-CSF use and medical costs after initial adjuvant chemotherapy in early-stage (stage I-III) breast cancer (ESBC). METHODS: Women diagnosed with ESBC from 1999 to 2005, who had an initial course of chemotherapy beginning within 180 days of diagnosis and including ≥1 highly myelosuppressive agent, were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Medicare claims were used to describe the initial chemotherapy regimen according to the classes of agents used: anthracycline ([A]: doxorubicin or epirubicin); cyclophosphamide (C); taxane ([T]: paclitaxel or docetaxel); and fluorouracil (F). Patients were classified into four study groups according to their G-CSF use: (i) primary prophylaxis, if the first G-CSF claim was within 5 days of the start of the first chemotherapy cycle; (ii) secondary prophylaxis, if the first claim was within 5 days of the start of the second or subsequent cycles; (iii) G-CSF treatment, if the first claim occurred outside of prophylactic use; and (iv) no G-CSF. Patients were described by age, race, year of diagnosis, stage, grade, estrogen (ER) and progesterone (PR) receptor status, National Cancer Institute (NCI) Co-morbidity Index, chemotherapy regimen and G-CSF use. Total direct medical costs ($US, year 2009 values) to Medicare were estimated from 4 weeks after the last chemotherapy administration up to 48 months. Medical costs included those for ESBC treatment and all other medical services received after chemotherapy. Least squares regression, using inverse probability weighting (IPW) to account for censoring within the cohort, was used to evaluate adjusted associations between G-CSF use and costs. RESULTS: A total of 7026 patients were identified, with an average age of 72 years, of which 63% had stage II disease, and 59% were ER and/or PR positive. Compared with no G-CSF, those receiving G-CSF primary prophylaxis were more likely to have stage III disease (30% vs. 16%; p < 0.0001), to be diagnosed in 2003-5 (87% vs. 26%; p < 0.0001), and to receive dose-dense AC-T (26% vs. 1%; p < 0.0001), while they were less likely to receive an F-based regimen (12% vs. 42%; p < 0.0001). Overall, the estimated average direct medical cost over 48 months after initial chemotherapy was $US 42,628. In multivariate analysis, stage II or III diagnosis (compared with stage I), NCI Co-morbidity Index score 1 or ≥2 (compared with 0), or FAC or standard AC-T (each compared with AC) were associated with significantly higher IPW 48-month costs. Adjusting for patient demographic and clinical factors, costs in the G-CSF primary prophylaxis group were not significantly different from those not receiving primary prophylaxis (the other three study groups combined). In an analysis that included four separate study groups, G-CSF treatment was associated with significantly greater costs (incremental cost = $US 2938; 95% CI 285, 5590) than no G-CSF. CONCLUSIONS: Direct medical costs after initial chemotherapy were not statistically different between those receiving G-CSF primary prophylaxis and those receiving no G-CSF, after adjusting for potential confounders.

Transfusion risk in cancer patients with chemotherapy-induced anemia when initiating darbepoetin alfa therapy at a baseline hemoglobin level of <9 g/dL versus 9 to <10 g/dL versus ≥ 10 g/dL: an exploratory analysis of a phase 3 trial.

Darbepoetin alfa (DA) is an erythropoiesis-stimulating agent (ESA) approved for treating chemotherapy-induced anemia (CIA). Safety concerns have prompted changes to the ESA-product information, which now recommends initiating ESAs at hemoglobin (Hb) levels < 10 g/dL (US) or ≤ 10 g/dL (EU). The present exploratory analysis of a DA trial examined how baseline-Hb levels at ESA initiation affect transfusion rates, Hb response, and safety outcomes in CIA patients. Data were retrospectively analyzed from a phase 3 trial of CIA patients randomised to 500 mcg DA every 3 weeks (Q3 W) or to 2.25 mcg/kg DA weekly (QW) for 15 weeks. In the current analysis, data were reanalyzed by baseline-Hb categories of <9 g/dL (n = 126), 9 to <10 g/dL (n = 225), and ≥ 10 g/dL (n = 354). The Q3 W and QW groups were combined. Transfusion rates were highest in the <9 g/dL baseline-Hb group in all time periods examined. The Kaplan-Meier percentage (95% CI) of patients achieving Hb ≥ 10 g/dL was 68% (59, 78) and 88% (82, 92) in the <9 g/dL and 9 to <10 g/dL baseline-Hb groups, respectively. With lower baseline-Hb, incidence of a ≥ 1 g/dL-Hb rise in 14 days progressively decreased. Incidence of venous thromboembolic events was similar in all baseline-Hb groups and similar between patients with or without a ≥ 1 g/dL-Hb rise in 14 days. Overall, transfusion risk increased and Hb response decreased at lower baseline-Hb levels in this exploratory analysis. When following ESA-product information to initiate ESAs at Hb ≤ 10 g/dL, the greatest benefit may be achieved when initiating close to 10 g/dL. Prospective studies are needed to further examine this hypothesis.

Use of electronic medical records (EMR) for oncology outcomes research: assessing the comparability of EMR information to patient registry and health claims data.

UNLABELLED: Electronic medical records (EMRs) are used increasingly for research in clinical oncology, epidemiology, and comparative effectiveness research (CER). OBJECTIVE: To assess the utility of using EMR data in population-based cancer research by comparing a database of EMRs from community oncology clinics against Surveillance Epidemiology and End Results (SEER) cancer registry data and two claims databases (Medicare and commercial claims). STUDY DESIGN AND SETTING: DEMOGRAPHIC, CLINICAL, AND TREATMENT PATTERNS IN THE EMR, SEER, MEDICARE, AND COMMERCIAL CLAIMS DATA WERE COMPARED USING SIX TUMOR SITES: breast, lung/bronchus, head/neck, colorectal, prostate, and non-Hodgkin's lymphoma (NHL). We identified various challenges in data standardization and selection of appropriate statistical procedures. We describe the patient and clinic inclusion criteria, treatment definitions, and consideration of the administrative and clinical purposes of the EMR, registry, and claims data to address these challenges. RESULTS: Sex and 10-year age distributions of patient populations for each tumor site were generally similar across the data sets. We observed several differences in racial composition and treatment patterns, and modest differences in distribution of tumor site. CONCLUSION: Our experience with an oncology EMR database identified several factors that must be considered when using EMRs for research purposes or generalizing results to the US cancer population. These factors were related primarily to evaluation of treatment patterns, including evaluation of stage, geographic location, race, and specialization of the medical facilities. While many specialty EMRs may not provide the breadth of data on medical care, as found in comprehensive claims databases and EMR systems, they can provide detailed clinical data not found in claims that are extremely important in conducting epidemiologic and outcomes research.

Use of latent growth curve models for assessing the effects of darbepoetin alfa on hemoglobin and fatigue.

BACKGROUND: The relationship between darbepoetin alfa and fatigue in chemotherapy-induced anemia (CIA) patients is complex because of patients receiving transfusions and the mediating effect of hemoglobin. Latent growth models (LGMs) were used to examine simultaneously relationships among drug exposure, fatigue outcomes, covariates, and mediating factors. METHODS: Data from four CIA studies (AMG 20010145: small cell lung cancer, n=547; AMG 980297: lung cancer, n=288; AMG 20000161: lymphoproliferative malignancies, n=339; AMG 20030232: non-myeloid malignancies, n=320) were analyzed separately. Patients reported fatigue using the FACT-Fatigue. The effect of darbepoetin alfa on FACT-F changes mediated through hemoglobin changes was examined with LGMs controlling for transfusions, age, sex, baseline ECOG performance status, and health status (EQ-5D VAS). Model fit was assessed using multiple indices including the comparative fit index (CFI). RESULTS: Darbepoetin alfa increased hemoglobin levels which were associated with decreases in fatigue. Increases in hemoglobin were statistically significantly (p<0.05) related to decreases in fatigue in the studies (AMG 20030145: beta=0.28; AMG 980297: beta=0.46; AMG 20000161: beta=0.59; and AMG 20030232: beta=0.39). Darbepoetin alfa statistically significantly increased hemoglobin (AMG 20010145:beta=0.50, AMG 980297:beta=0.53, AMG 20000161:beta=0.47, and AMG 20030232:beta=0.30) while controlling for covariates. Model fit was acceptable (CFI> or =0.89) in all studies. CONCLUSIONS: Results indicate LGMs may be a valuable statistical method for modeling complex relationships among clinical and patient reported outcomes. A statistically significant effect of darbepoetin alfa on fatigue change through hemoglobin change occurred across four studies, after modeling the effects of transfusions, age, sex, EQ-5D VAS and ECOG.