Comparative effects of SMS, phone call and combined mHealth interventions on tuberculosis knowledge among DOTS patients in Lagos, Nigeria

Abstract Background Tuberculosis (TB) remains a major public health challenge in Nigeria, where poor treatment adherence and inadequate patient knowledge continue to contribute to adverse treatment outcomes and multidrug-resistant TB. Patient knowledge is a key upstream determinant of treatment outcomes, yet scalable strategies for improving TB knowledge in low-resource settings remain limited. This study evaluated the comparative and combined effectiveness of SMS and phone-call mHealth interventions on TB knowledge among patients undergoing Directly Observed Treatment, Short-course (DOTS) therapy in Lagos State, Nigeria. Methods A quasi-experimental longitudinal study was conducted across 12 DOTS centres in four local government areas. A total of 128 adults with laboratory-confirmed TB were allocated to four arms: SMS only, phone-call only, combined SMS and phone-call, and standard care (control), with 32 participants per arm. TB knowledge was assessed at baseline, 6th week, and 12th week. Data were analysed using Generalized Estimating Equations (GEE) with a binomial distribution and logit link, adjusting for age category and education level. A secondary analysis examined the association between TB knowledge and medication adherence using Spearman rank correlations and a separate GEE model. Results Zero attrition was recorded. Phone-call interventions produced the largest knowledge gains (OR = 9.24, 95% CI: 4.07–20.99, p < 0.001), followed by SMS (OR = 3.67, 95% CI: 1.63–8.27, p = 0.002). The combined SMS-plus-phone-call intervention showed no significant benefit over standard care (OR = 0.61, 95% CI: 0.29–1.29, p = 0.197), with estimated marginal means below those of the control group. Significant knowledge gains emerged only at 12-week follow-up (OR = 2.38, p = 0.001), not at midline. The knowledge - adherence correlation attenuated from significant at baseline (rs = 0.326, p < 0.001) and midline (rs = 0.267, p = 0.002) to non-significant at follow-up (rs = 0.066, p = 0.457). Conclusion Phone-call and SMS interventions significantly improved TB knowledge, with phone-calls demonstrating superior effectiveness. Contrary to expectations, combining both modalities conferred no benefit over standard care, suggesting that communication quality and channel appropriateness outweigh message volume. TB programmes should prioritize interactive voice-based follow-up and use SMS as a scalable alternative, while avoiding the uncritical combination of multiple communication channels.