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Medication adherence and persistence among patients with non-small cell lung cancer receiving tyrosine kinase inhibitors and estimation of the economic burden associated with the unused medicines.

BACKGROUND
Non-small cell lung cancer (NSCLC) is a leading cause of cancer deaths. Its treatment includes specific oral tyrosine kinases inhibitors (TKIs).


OBJECTIVES
To estimate adherence and persistence among patients receiving TKIs and to assess the economic burden of the unused medicines in Alsace (France).


METHOD
This retrospective study was carried out using the Insurance Healthcare database.


MAIN OUTCOME MEASURES
Adherence was calculated using medication possession ratio (MPR), persistence using estimated level of persistence with therapy (ELPT) and economic impact using prescription refill data.


RESULTS
242 patients were receiving TKIs. The most common TKIs prescribed were erlotinib (75.6%, n = 183) and crizotinib (12.8%, n = 31). Total of 149 patients were included in the adherence analysis. Overall MPR was 0.98. 180 patients were included in the persistence analysis. Almost half of patients had stopped treatment at 60 days and only 38.3% (n = 69) were still persistent with the therapy at 120 days. The expenses related to unused TKIs amounted to €356,392 and were related majorly to treatment discontinuation followed by overlapping refills, patient deaths and dose- or drug-switching, respectively.


CONCLUSIONS
Our data indicated overall adherence medicines above the acceptable limit of 0.80 but also pointed out a significant decline in persistence over time. The resulting economic losses justify the need for physicians and pharmacists to closely monitor their patients to ensure continuity of treatment. To limit the cost associated with unused medicines, interventions such as app-based monitoring, dispensing TKIs per unit over shorter periods and not only on monthly intervals could be implemented.