Hoebe 1997.

Methods	Design: retrospective cohort study Study dates: January to June 1995 Malaria transmission pattern and local antimalarial drug resistance: various, not specified Adverse event monitoring: one‐off telephone interview between 4 and 20 weeks post‐travell
Participants	Number enrolled: 454 eligible travellers, 300 successfully contacted and agreed to participate Inclusion criteria: subjects who visited the travel vaccination service of the regional public health institute in Maastricht if they had returned from their journey to tropical countries between 4 and 20 weeks previously. The group of non‐users was formed by people who travelled either to tropical countries without malaria risk or to cities in malarious areas, and by travellers who were prescribed an antimalarial drug but did not commence use Exclusion criteria: participants who had a serious adverse reaction to mefloquine in the first week Country of recruitment: Netherlands Region of malaria exposure: various; Asia, Africa, South America Duration of exposure to malaria: mean ˜3 weeks (range 1 to 9 weeks) Type of participants: travellers
Interventions	Included in the review: 1. Mefloquine (1 x 250 mg tablet) weekly, taken 1 week prior to leaving, during travel and 4 weeks after departure 2. Non‐users of antimalarials Not included in the review: 3. Proguanil (1 x 100 mg tablet) twice daily, taken during travel and 4 weeks after departure
Outcomes	1. Adverse events; any, nausea, vomiting, abdominal pain, diarrhoea, headache, dizziness, abnormal dreams, insomnia, anxiety, depression, pruritis 2. Adverse events; other (palpitations, severity of symptoms, time point of symptoms in relation to drug taking) 3. Discontinuations of study drug due to adverse effects 4. Measure of adherence to the drug regimen
Notes	Funding sources: Not mentioned
Risk of bias
Bias	Authors' judgement	Support for judgement
Other bias	Unclear risk	1. Confounding: moderate Travel destination varies significantly between users of mefloquine and non‐users of prophylaxis (6.7% America mefloquine versus 29.0% non‐users) 2. Selection of participants into the study: low 13/454 (2.8%) of travellers successfully contacted refused to participate 3. Measurement of interventions: low Prescription was provided by a travel clinic which also performed the study, and discontinuations were reported 4. Departures from intended interventions: moderate No information regarding switches been interventions of interest was reported 5. Missing data: moderate "If somebody discontinued drug use within a certain period, symptoms that occurred in the following period were not counted" Comment: Mefloquine has a half life of 17 to 21 days 6. Measurement of outcomes: moderate "The participants were specifically asked about symptoms instead of adverse effects...To hide our focus on symptoms as adverse effects of the drugs, participants were informed that the aim of the study was to investigate symptoms during travelling. We structured the questionnaire so that the interviewers asked about symptoms first and drug use last, in order to blind them to the drug used when addressing symptoms" 7. Selection of the reported results: low All prespecified outcomes were reported. 8. Other: no information Funding source was not mentioned