Interrupted time-series analysis of the impact of generic market entry of antineoplastic products in China

OBJECTIVES: The rapid growth of pharmaceutical costs is a major healthcare issue all over the world. The high prices of new drugs, especially those for cancer, are also a concern for stakeholders. Generic drugs are a major price-reducing opportunity and provide more societal value. The aim of this research is to analyse the impact of generic entry on the volume and cost of antineoplastic agents in China. METHODS: An interrupted time-series design examined monthly sales of three antineoplastic drugs (capecitabine, decitabine, imatinib) from 699 public hospitals during January 2011 to June 2016. The first generic entry times (December 2013, December 2012, August 2013, respectively) were regarded as the intervention time points. We estimated changes in volume and cost following the generic entry. RESULTS: We found that generic entry was associated with increases in the volume of three antineoplastic agents and decreases in their costs. In terms of volume, generic entry was associated with increases in use of capecitabine, decitabine and imatinib by 815.0 (95% CI −66.5 to 1696.5, p>0.05), 11.0 (95% CI 3.7 to 18.3, p=0.004) and 2145.5 (95% CI 1784.1 to 2506.9, p<0.001) units. The entry of generic antineoplastic drugs reduced the monthly cost trend of three agents by ¥3.1 (95% CI −¥3.6 to −¥2.6, p<0.001), ¥84.7 (95% CI −¥104.7 to −¥64.6, p<0.001) and ¥21.3 (95% CI −¥24.2 to −¥18.4, p<0.001), respectively. The entry of generic drugs attenuated the upward trend in volume of three brand-name drugs and even triggered reductions in the volume of brand-name capecitabine. The entry of generics was accompanied by significant increase of ¥2.6 in monthly brand-name decitabine cost (95% CI ¥0.2 to ¥5.1, p=0.04). CONCLUSION: Our findings suggested that entry of generic drugs impacted use and cost of antineoplastic medicines in China. Generic drugs may improve the availability and the affordability of antineoplastic agents, which would benefit more patients.