The use of generic docetaxel instead of branded docetaxel was associated with a significantly higher rate of neutropenia and increased healthcare cost during the 6 months after drug initiation, according to a US Oncology study presented at ASCO 2014.
Patients with breast cancer who received generic docetaxel were approximately 40% more likely to have a medical claim for neutropenia than patients receiving branded docetaxel. This cost the healthcare system an additional $9000 per patient, reported Stephen E. Jones, MD, Medical Director, US Oncology Research, Houston, TX, and colleagues.
Dr Jones and colleagues compared the disease burden and resource utilization of 1955 patients with breast cancer who received the generic or branded docetaxel between 2011 and 2012.
Emerging differences between generic and branded formulations during the 6 months after the initiation of docetaxel were examined with a hierarchical mixed-effects model by the adjustment of patient characteristics during the 6 months before starting the drug.
The final analysis included 360 patients whose baseline characteristics were similar, including the use of anthracyclines, cyclophosphamide, and growth factors, as well as comorbidities and previous neutropenia.
More Problems with Generics at 6-Month Follow-Up
During the 6-month follow-up, the generic-receiving cohort showed a higher rate of claims for neutropenia (67.3% vs 48.9%; P <.01) and malaise and fatigue (22.4% vs 13.7%; P <.05) versus the branded-receiving cohort. The branded cohort had higher rates of nausea and vomiting (43.5% vs 29.6%; P = .02).
The baseline variables that were adjusted for the estimation of neutropenia included age, baseline neutropenia, inpatient admission, total healthcare costs, adjuvant therapy, comorbidities, the use of granulocyte colony-stimulating factor (G-CSF) and fosaprepitant, and the number of treatment cycles. Fosaprepitant is indicated for the prevention of delayed vomiting and can cause neutropenia (<1% of patients).
After these adjustments, the rate of neutropenia remained higher with generic than with branded docetaxel (73.9% vs 52.8%; P <.01), even after accounting for history of neutropenia and the baseline use of G-CSF or fosaprepitant.
Further investigation showed that the difference in neutropenia between generic and branded docetaxel was observed only in patients without a history of neutropenia (58.4% vs 35.4%; P = .003) and was not present in patients with a diagnosis for neutropenia at baseline. In the latter group, the risk was approximately 98%, regardless of the drug used.
Generic Costs Were Higher
Excluding the cost of branded docetaxel, the mean outpatient cost after initiating treatment was significantly higher for patients receiving generic docetaxel in the unadjusted model and the model adjusted for age, comorbidities, inpatient admissions, total costs, and adjuvant therapy at baseline.
In the unadjusted model, the mean cost was $50,243 for the branded cohort and $59,177 (P = .009) for the generic cohort, and remained significantly higher after adjustments for baseline healthcare costs, inpatient admissions, and other baseline patient characteristics ($46,698 vs $54,282; P = .03). The mean total healthcare costs in the unadjusted model after initiating treatment were $74,832 with branded docetaxel and $83,982 with generic docetaxel (P = .05) versus $70,736 and $76,454, respectively, in the adjusted model (P = .22).
“The cost differential seems more than offsetting the potential difference in acquisition costs relative to the branded docetaxel,” the authors suggested in a poster.
William M. Sikov, MD, Clinical Associate Professor of Medicine, Brown University, Portland, ME, commented that he found the poster’s results interesting and surprising. He mentioned that, in his center, he is not aware of whether his patients receive branded or generic drugs. Dr Sikov said that he has often questioned whether generic agents may, indeed, be equivalent, and has had some concerns.
“At times, I have tried to influence the pharmacy to buy a brand name when the cost differential is minimal but have been told that I am not allowed [to request that],” Dr Sikov said. “I wonder if the pharmacokinetics are really the same? We are given assurances by the FDA, but we don’t know how extensively they are really tested.”