JMIR Publications

ABSTRACT

Background:

Overweight and obesity are major risk factors for numerous chronic diseases, requiring effective prevention and intervention strategies. Community-based BMI screening may enhance awareness of weight status, but its effectiveness remains uncertain.

Objective:

Not available

Methods:

Using data from two waves (2013 and 2018) of a Malaysian population-based cohort study (N=6561), we applied a sharp regression discontinuity design to estimate the causal effects of community-based BMI screening on health outcomes for individuals near the BMI threshold. Participants were aged 35 years or older and completed both follow-ups. The exposure was BMI screening with a light-touch intervention, including height and weight measurement, feedback on results, and referral card distribution. Main outcomes were BMI, blood pressure, and random blood glucose five years post-intervention, along with health behaviors, healthcare utilization, and mental health status.

Results:

BMI screening and intervention showed no significant impact on BMI after five years (0.4 kg/m², 95% CI -0.2 to 0.9, P=0.16). Results remained robust after adjusting for covariates (e.g., 0.4 kg/m², 95% CI -0.1 to 0.9 with age and sex; 0.5 kg/m², 95% CI -0.1 to 1.0 with demographic covariates), altering functional forms (0.4 kg/m², 95% CI -0.2 to 1.1 with quadratic specification), and across different bandwidths or when treating age as either a continuous or categorical variable. Interaction analysis revealed almost no substantial heterogeneity effects. Mechanism analysis and secondary outcomes indicated no significant effects on health behaviors (including smoking, physical activity, diet, and sedentary behavior), healthcare utilization (screening, diagnosis, and medication treatment for hypertension and diabetes), mental health outcomes (anxiety, depression, and stress levels), or cardiovascular risk factors (systolic blood pressure, diastolic blood pressure, random blood glucose; for example, systolic blood pressure showed a non-significant change of 0.2 mmHg, 95% CI -3.5 to 4.0). These findings should be interpreted cautiously, as the study was sufficiently powered to detect larger, clinically meaningful changes but may have lacked power to identify more modest effects.

Conclusions:

This study is the first to assess the causal effects of population-based BMI screening on long-term health outcomes in a Southeast Asian population. The findings suggest that merely informing individuals of their overweight or obese status and implementing light-touch interventions are insufficient to significantly reduce BMI or drive sustained behavior change. Nonetheless, the results do not exclude the possibility of short-term effects, and more frequent or sustained light-touch interventions may still be effective. Future studies should design more intensive interventions and include larger sample sizes. Clinical Trial: Not available