gms | German Medical Science

Background: A number of valsartan products were taken off the German market in the summer of 2018 after it had become public that one source of the substance had provided batches contaminated with NDMA and also NDEA, both of which are known to be carcinogenic. It has been surmised that other sartans might also be affected.

Patients were advised not to stop taking valsartan on their own, because the risk of developing a tumor was estimated to be lower than the risks of cardiovascular events due to interrupted sartan therapy.

Short-term overall risk of cancer has apparently not increased through use of contaminated valsartan [1], while the effects of long-term exposition are still unclear.

Materials and methods: Prescription claims data from the largest German statutory health care funds group were analysed both for valsartan known to be contaminated and assumed not to be contaminated. The main focus was to identify affected patients in the period immediately before the discovery of contaminations, i.e., during the first half of 2018. This was compared to historical data. In a separate step, the speed of changing to products assumed not to be contaminated was assessed.

Results: The share of affected patients in the study period was 17%, with large regional variations due to the influence of drug discount tenders. Dosage of valsartan was overall higher than would be expected from DDD (on average, 2.9 DDD per patient and day).

Calculation of the rate of switching is work in progress, since at the time of writing the necessary data are not yet available. Further results will be presented orally.

Conclusion: A substantial part of the potential target population has been affected by contaminated valsartan. Given that no previous knowledge of the problem existed, it was a random event whether a specific patient was affected or not. Drug discount tenders led to clustering effects, but also permitted rapid communication of the risks and implementation of switching to alternatives.

Identification of affected patients is problematic, because at least for some brands, contamination depended on the specific batch from which the individual pack came. Information about the batch is, however, not routinely available in Germany. Thus, individual exposition of patients cannot be assessed with a sufficient degree of certainty.

Extended coding, which will come into effect in February 2019 in order to fight falsified drugs (securPharm), would offer the possibility to track affected patients, thus enabling focussed risk communication strategies.

However, for this to be effective, pharmacists’ organisations and health care funds would need to agree to include the extended coding into routinely collected health claims data sets.