Choice of and adherence to prophylactic antimalarials.

Background: There were 1,370 cases of imported malaria and six fatalities in the UK in 2008, the majority of which were due to chloroquine-resistant Plasmodium falciparum. Poor adherence to prescribed regimens is known to be an important factor in these cases.

Method: An observational study utilizing questionnaires both pre- and post-travel was conducted to assess the adherence behavior of UK travelers undertaking trips of less than 28 days duration, who were prescribed one of three antimalarials recommended to prevent P falciparum malaria (atovaquone plus proguanil, doxycycline, or mefloquine) in travel clinics in England and Scotland. The primary objectives of the study were to assess travelers' perceptions of, and self-reported adherence to antimalarial medication. A secondary objective was to examine the reasons for the choice of antimalarial therapy from the perspective of prescriber and traveler.

Results: For the primary end point of self-reported adherence specified as the proportion of antimalarial tablets prescribed that were actually taken, statistically significantly higher adherence overall and post-travel was seen with atovaquone plus proguanil compared with doxycycline. It was not possible to calculate the statistical significance of comparisons with mefloquine, but adherence to mefloquine appeared similar to or better than doxycycline and similar to atovaquone plus proguanil for categorical adherence. Effectiveness, side effects, previous experience of antimalarials, and dosing convenience were the main determinants of both travelers and practitioner's choice of antimalarial. The practitioner's recommendation was highly important for 63% of travelers.

Conclusion: A shorter post-travel regimen has a significant impact on adherence to antimalarial prophylaxis. A reassessment of the risk by travelers on returning home may be a major contributor to this poor adherence.