Overuse and underuse of pegfilgrastim for primary prophylaxis of febrile neutropenia.

Introduction: Guidelines recommend pegfilgrastim for primary prophylaxis of febrile neutropenia after highly myelosuppressive chemotherapy. While deviations from guidelines could result in overuse and increased costs, underuse is also a concern and could compromise quality of care. Our objectives were to evaluate guideline adherence and quantify the extent to which physician heterogeneity may influence pegfilgrastim use.

Methods: We randomly sampled 550 patients from a retrospective cohort of those who received infusions at an academic cancer center between 1 September 2013 and 1 September 2014. Electronic medical and drug dispensing records provided information on patient characteristics, chemotherapy characteristics, prescribing physician, and pegfilgrastim administration.

Results: We included 154 patients treated by 25 physicians. About half of patients were male and mean age was 61.3 years. Forty (26.1%) patients had no febrile neutropenia risk factors, 62 (40.5%) had one, and 51 (33.3%) had two or more. Thirty patients (19.5%) received pegfilgrastim, of which 12 (40%) received palliative chemotherapy. Nine (60%) of 15 patients on a regimen with a febrile neutropenia risk  ≥ 20% received pegfilgrastim. Pegfilgrastim use significantly varied by cancer type (p < 0.01), chemotherapy regimen (p < 0.001), and regimen febrile neutropenia risk (p < 0.001). Multivariable analysis reaffirmed the association between chemotherapy regimen febrile neutropenia risk ≥ 20% and pegfilgrastim use (odds ratio (OR) = 10.1, 95% confidence interval (CI): 1.6-62.7) and suggested that 31% (95% CI: 8%-71%) of the variation in use was attributable to physician characteristics.

Conclusion: Pegfilgrastim was potentially overused for palliative chemotherapy and underused for chemotherapy regimens with febrile neutropenia risk ≥ 20%. Successful interventions to modify prescribing practices likely require an understanding of the relationship between specific physician characteristics and pegfilgrastim use.