Weycker, D., Barron, R., Edelsberg, J., Kartashov, A., Legg, J., & Glass, A.G. (2014). Risk and consequences of chemotherapy-induced neutropenic complications in patients receiving daily filgrastim: The importance of duration of prophylaxis. BMC Health Services Research, 14, 189-6963-14-189. 

To determine if the duration of filgrastim prophylaxis affects the risk of chemotherapy-induced neutropenic complications (CINC), healthcare costs, and mortality

This is a retrospective study of medicals claims from two large healthcare claims databases, the Thomson Reuters MarketScan Commercial Claims and Encounters and Medicare Supplemental and Coordination of Benefits Database (MarketScan Database, 2001–2010) and the Intercontinental Marketing Services LifeLink Database (LifeLink Database, 2001–2008). Claims for chemotherapy, filgrastim, and hospital admissions were analyzed to determine the number of daily filgrastim doses following a chemotherapy cycle and neutropenic complications.

• N = 14,288 daily filgrastim prophylaxis patient cycles  
• AGE = 18 years and older
• MALES: About 20%, FEMALES: About 80%
• KEY DISEASE CHARACTERISTICS: Patients who initiated one or more courses of myelosuppressive chemotherapy for a solid tumor or non-Hodgkin lymphoma and who received daily filgrastim prophylaxis during one or more cycle

• SITE: Multi-site    
• SETTING TYPE: Multiple settings    
• LOCATION: United States

• PHASE OF CARE: Active antitumor treatment
• APPLICATIONS: Elder care  

Retrospective study of medical claims

• Data collection from databases using HCPCS, ICD-9-CM, or UB-92 codes and analyzed with statistical analysis software

If patients were treated with one to three days of filgrastim prophylaxis, the risk of CINC during a cycle of chemotherapy was 2.9%. If they were treated with four to six days of filgrastim prophylaxis, the risk of CINC was 2.7%. If the patient was treated with seven or more days, the risk of CINC was 1.8%. In adjusted analyses, the odds of CINC were 2.4 (95% = CI, 1.6–3.4) higher with one to three days of filgrastim prophylaxis versus seven or more days and 1.9 (1.3–2.8) times higher with four to six days of filgrastim prophylaxis versus seven or more days. In the pivotal trials of filgrastim prophylaxis, 10–11 days of filgrastim prophylaxis were needed for adequate neutrophil recovery, yet this study demonstrated that in actual practice, 95% of patients received fewer than 10 days of filgrastim prophylaxis and 58% received only one to three days. In a subgroup of 358 patients who developed CINC and the healthcare expenditures were available, CINC-related healthcare expenditures were $18,912 (14,570– 23,581) with one to three days of prophylaxis (n = 225), $14,907 (11,155–19,728) with four to six days (n = 94), and $13,165 (9,595–17,144) with seven or more days (n = 39). In a subgroup of 228 patients for whom discharge status was available, in-hospital mortality was 8.4% (4.6–14.8) with one to three days of prophylaxis (n = 119), 4% (1.4–11.1) with four to six days (n = 75), and 0% (0–10.2) with seven or more days (n = 34).

Administration of less than seven days of daily filgrastim was not as effective as seven or more days of daily filgrastim to prevent chemotherapy-induced neutropenic complications. The use of seven or more days of filgrastim as primary prophylaxis to prevent chemotherapy-induced neutropenic complications also decreased healthcare costs and mortality.

• Risk of bias (no blinding)
• Risk of bias (no random assignment)
• Unintended interventions or applicable interventions not described that would influence results
• Key sample group differences that could influence results

In clinical trials evaluating the efficacy of CSF prophylaxis, patients were treated with 10 or more daily doses of filgrastim. However, in actual practice, the majority of patients receive prophylaxis with fewer than 10 doses of daily filgrastim, which increases the risk of chemotherapy-induced neutropenic complications, mortality, and healthcare costs. Clinicians need to be aware of most effective CSF dosing requirements.