Cognitive predictors of adherence to malaria prophylaxis regimens on return from a malarious region: a prospective study

Cases of 'imported malaria' into countries where malaria is not endemic are increasing and evidence suggests that non-use of malaria prophylaxis and lack of adherence are contributing to this increase. Non-adherence may be especially likely because chemoprophylaxis regimens require travellers to continue to take medication for 4 weeks after their return from a malarious region. This study investigated the extent to which cognition measures specified by the theory of planned behaviour and the health belief model could distinguish between those who reported greater or lesser adherence after their return. Cognitions were measured using a brief questionnaire on the day of departure from the malarious region and reports of adherence were collected between 5 and 7 weeks later. Data from two longitudinal samples of UK tourists returning from The Gambia were analysed; 106 mefloquine users and 61 chloroquine and proguanil users. Results suggested that malaria prophylaxis adherence could be improved. 22.5% of mefloquine users and 31% of chloroquine and proguanil users reported adherence for 3 weeks or less. A model based on the theory of planned behaviour explained approximately 50% of the variance in reported adherence amongst mefloquine users and 40% amongst chloroquine and proguanil users, comparing favorably with other published applications of the theory. Findings suggest that targeting key cognitions could enhance adherence on return from malarious regions. Enhancing perceived control over adherence may be important as well as emphasising susceptibility to malaria infection. Reassuring mefloquine users concerning potential side effects of the drug may also encourage adherence on return. Implications for future research are discussed.