Digital Nudges to Improve Heart Health Actions After Community Screening in Malaysia (NADI-MyHeartRisk)

This is a pragmatic, risk-stratified, individually randomized controlled trial testing whether personalised WhatsApp-based digital behavioural nudges can improve completion of cardiovascular preventive actions after community risk screening at NADI centres in Malaysia. Adults attending participating NADI centres will be screened using the MyHeartRisk web-based cardiovascular risk assessment tool. All screened participants will receive their risk result, standard risk explanation and general heart-health education. Participants classified as high cardiovascular risk will also receive a referral letter advising healthcare provider review. Participants classified as moderate or high cardiovascular risk will be randomized 1:1 to either a personalised digital nudge arm or a no-nudge control arm. The nudge arm will receive scheduled WhatsApp messages over 90 days, including action prompts, reminders, engagement check-ins and barrier-solving messages. The control arm will receive standard risk feedback and referral-letter generation where indicated, but no scheduled behavioural nudges. The primary outcome is completion of a risk-appropriate cardiovascular preventive action within 90 days. For moderate-risk participants, this may include completion of blood pressure, glucose or lipid checks, medication review, or healthcare provider review. For high-risk participants, this is attendance at a healthcare provider after receiving the MyHeartRisk referral letter. Low-risk participants will receive standard feedback and may be followed descriptively, but they will not be randomized or included in the primary randomized analysis.