Comparison of pegfilgrastim with filgrastim on febrile neutropenia, grade IV neutropenia and bone pain: a meta-analysis of randomized controlled trials

Background and objective: While head-to-head clinical trials demonstrate pegfilgrastim to be as efficacious as filgrastim in reducing chemotherapy-induced neutropenia, these studies lacked the statistical power to demonstrate better outcomes with one therapy compared to the other. Our objective was to obtain a pooled estimate of the effect of pegfilgrastim compared with filgrastim on incidence of febrile neutropenia (FN), and related outcomes among patients with solid tumors and malignant lymphomas receiving myelosuppressive chemotherapy. Research design and methods: We searched PubMed and EMBASE for articles published from January 1, 1990 to August 31, 2006 reporting on randomized controlled trials (RCTs) that compared the efficacy and safety of pegfilgrastim versus filgrastim. We only accepted studies in which filgrastim (5 mu g/ kg/day) and pegfilgrastim (100 mu g/kg or a fixed dose of 6 mg) were administered at approved doses indicated on the package insert. Pooled relative risk (RR) was estimated using the conservative random effects, empirical Bayesian method of Hedges and Olkin. Main outcome measures: Rates of grade IV neutropenia and of FN, time to absolute neutrophil count (ANC) recovery, and bone pain. Results: We identified five RCTs, with a total of 617 patients, evaluating the efficacy of a single dose of pegfilgrastim per cycle versus daily filgrastim injections. Although only one study had a statistically significant difference in FN reductions favoring pegfilgrastim over filgrastim (relative risk reduction of 50%; P = 0.027), the pooled RR showed a statistically significant favorable result for pegfilgrastim (RR = 0.64; 95% Cl, 0.43-0.97). Grade IV neutropenia rates (for cycle 1: RR = 0.99; 95% Cl, 0.91-1.08; cycle 2: RR = 0.88; 95% Cl, 0.70-1.11; cycle 3: RR = 0.80; 95% Cl, 0.47-1.36; cycle 4: RR = 0.90; 95% Cl, 0.71-1.13), time to ANC (SMD = 0.11, 95% Cl, -0.34-0.56), and incidence of bone pain (RR = 0.95; 95% Cl, 0.76-1.19) were similar between the two G-CSFs. The included trials varied in the type of cancer, chemotherapy regimen and type of trial. Conclusion: A single dose of pegfilgrastim performed better than a median of 10-14 days of filgrastim in reducing FN rates for patients undergoing myelosuppressive chemotherapy.