IntroductionPaediatric tuberculosis (TB) underdiagnosis is a critical concern. The INPUT stepped-wedge cluster-randomised trial assessed the impact of integrating child TB services into child healthcare on TB case detection among children under age 5 years.MethodsWe compared the standard of care, providing TB care in specific TB clinics (control phase), with the Catalysing Paediatric TB Innovations (CaP-TB) intervention, integrating TB services across all child health services (intervention phase). 12 clusters in Cameroon and Kenya transitioned from the standard of care to the intervention at randomly assigned times. Children with presumptive TB were enrolled after obtaining their parents’ consent and were followed throughout TB diagnostic procedures and treatment. Study outcomes included the rate of children with presumptive TB receiving TB investigations and that of children diagnosed with TB (the primary outcome was case detection), per thousand children under 5 years attending facilities. Generalised linear mixed Poisson models estimated the intervention’s effect as adjusted rate ratios (aRR) and associated 95% CIs. Ad hoc country-stratified analyses were conducted.ResultsDuring control and intervention phases, respectively, 121 909 and 109 614 children under 5 years attended paediatric entry points, 133 (1.1 per thousand) and 610 (5.6 per thousand) children with presumptive TB received TB investigations, and 79 and 74 were diagnosed with TB, corresponding to a case detection rate of 0.64 and 0.68 per thousand, respectively. CaP-TB significantly increased TB investigations in both countries overall (aRR=3.9, 95% CI 2.4 to 5.4), and in each. Overall, TB case detection was not statistically different between intervention and control (aRR 1.32, 95% CI 0.66 to 2.61, p=0.43). Country-stratified analysis revealed a 10-fold increase (aRR 9.75, 95% CI 1.04 to 91.84, p=0.046) in case detection with CaP-TB in Cameroon and no significant effect in Kenya (aRR 0.94, 95% CI 0.44 to 2.01, p=0.88).ConclusionCaP-TB increased TB investigations in both study countries and markedly enhanced TB case detection in one, underlining integrated TB services' potential to address paediatric TB underdiagnosis.