Effects of the Informed Health Choices secondary school intervention on the ability of lower secondary students in Kenya to think critically about health choices: 1-year follow-up of a cluster-randomized trial

Table 3 Main results

	Control schools	Intervention schools	Difference (95% CI)	Odds ratio (95% CI)	p	ICC
	40 schools	40 schools
Students	1077	1369
Primary outcome^a
Passing score (≥ 9/18)^b	347 (32.2%)	728 (53.2%)	21.2% (14.1 to 28.3%)	2.6 (1.9 to 3.7)	< 0.0001	0.10
Secondary outcomes^a
Mastery score (≥ 14/18)^b	19 (1.8%)	170 (12.4%)	10.2% (6.9 to 13.5%)	7.9 (4.2 to 15.1)	< 0.0001	0.17
Mean score^c	40.4% (15.8)	49.6% (19.3)	9.1% (6.1 to 12.2%)		< 0.0001	0.11
Teachers^d	34	33
Passing score (≥ 9/18)^b	24 (80.0%)	31 (96.9%)	16.8% (1.4 to 32.2%)	7.8 (0.9 to 69.2)	.0663
Mastery score (≥ 14/18)^b	7 (20.6%)	30 (90.9%)	71.9% (55.9 to 87.8%)	51.9 (10.9 to 246.7)	< 0.0001
Mean score^c	64.5% (17.8)	85.0% (11.7)	21.5% (14.6 to 28.5%)		< 0.0001

Note: Data are % (SD), % (95% CI), or n (%). ICC intraclass correlation coefficient. Inverse probability weights were estimated using elastic net logistic regression
^aThe cluster design was accounted for using random intercepts at the level of school
^bLogistic regression was used to estimate an adjusted odds ratio, which is re-expressed as an adjusted risk difference
^cTeachers were treated as equivalent to the units of randomization (schools), so these models did not include random intercepts. The stratification variables were modelled as fixed effects in all analyses. Wald-type confidence intervals and two-sided normal p-values were computed in all analyses

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