Table 3 Challenges encountered and changes made to the implementation of the intervention

Call participant up to 3 times if no answer during recruitment call (on different days and times)

34% of participants selected for this study were uncontactable

A text message was sent after the third attempt to explain that this number belongs to SEACO and the purpose of the call. If people were interested to participate in this study, we encouraged them to let us know a time that suits them or to give us a call back.

Outcome: None of the participants replied to the text message and this did not make a different to the study

iFOBT home screening test

Female participant completed test during menstruation

(Solution for participant: Resent the screening pack and asked participant to complete a second test)

Female participants were informed to complete the test when not menstruating during the recruitment call.

Taking photo of the test result and send it to SEACO through What’s App

Some participants required help with taking and/or sending the photo through What’s App

During the reminder call, data collectors asked participants whether they require help/ more information to take/ send the photo and were talked through the steps if needed.

Informing participants of their test result within 7 days

It was not always feasible to provide feedback within 7 days for the medical team members who were asked to review the results.

Extended from 7 to 10 working days and revised in the acknowledgement text message script as well.

Informing participants of their positive result

Some people with a positive iFOBT result did not answer the phone when we called them to inform participant of the result

Participants were called up to three times (different day/time). A voice message was sent to those that didn’t answer and a referral letter with the positive result and referral to doctor.

Invalid results

Some participants sent iFOBTs that showed invalid test results.

Participants who sent the invalid result were called and sent another screening pack (1x) if they agreed to complete the test a second time. The data collectors clarified the procedure again over the phone and answered any questions. If the second iFOBT test was still invalid, then the result was noted as invalid and the participant was referred to the nearest health clinic if they were interested to redo the iFOBT.

Interpreting the result

Some pictures showed very faint lines on the test result

The research staff interpreting results contacted laboratory staff for a third opinion.