Effect of Health Promotion Intervention on the Prevalence of Non-Communicable Disease among In-School and Out-of-School Adolescents in Rivers State, Nigeria: A Comparative Quasi-Experimental Study

Background: Non-communicable diseases (NCDs) are increasingly recognized among adolescents, but evidence comparing in-school and out-of-school adolescents in South-South Nigeria remains limited. This study assessed and compared the prevalence of NCDs among in-school and out-of-school adolescents in an intervention and control baseline survey. Methods: This comparative cross-sectional and quasi experimental study involved 372 adolescents selected through multi-stage sampling in South-South Nigeria. Prevalence of NCDs was determined using anthropometric measurements, blood pressure assessment, and a validated questionnaire at baseline. NCD indicators assessed included body mass index (BMI), blood pressure, blood glucose, and cholesterol. Group differences were examined using significance testing at baseline. Results: In the intervention group, BMI categories differed significantly between in-school and out-of-school adolescents, with overweight more common among out-of-school respondents and obesity slightly higher among in-school respondents, although overall overweight/obesity did not differ significantly. Mean BMI was significantly higher among out-of-school adolescents. No significant differences were observed in hypertension or blood pressure. Elevated blood glucose was significantly higher among in-school adolescents, while elevated cholesterol occurred only among out-of-school adolescents. In the control group, BMI categories again differed significantly, with obesity more prevalent among out-of-school adolescents, but overall overweight/obesity and mean BMI were broadly similar. Blood pressure did not differ significantly. Elevated blood glucose remained higher among out-of-school adolescents, while cholesterol was absent in both groups. Conclusion: The findings show an important early burden of metabolic risk among adolescents, with distinct patterns by schooling status. Out-of-school adolescents appear more vulnerable to excess body weight and dyslipidemia, while in-school adolescents showed higher glucose burden in the intervention group. These patterns support the need for targeted, setting-specific adolescent NCD prevention strategies in South-South Nigeria.