Association of risk behaviours, socio-economic characteristics and academic progress in adolescents: an analysis of the 1993 birth cohort in Pelotas, Brazil

Figures & data

Table 1. Descriptive statistics of the sample of the 1993 birth cohort in Pelotas, RS, Brazil.

Variable	N	%	95% IC	% age-grade gap at age 18
Total	3,852ª	100		61.0
Gender
Female	1,952	50.67	49.1–52.2	53.38
Male	1,900	49.33	47.7–50.9	68.89
Skin color
White	2,351	63.68	62.1–65.2	53.93
Non-white	1,341	36.32	34.8–37.9	73.68
Maternal educational level (years)
≥12	257	6.68	5.9–7.5	16.34
9–11	1,052	27.34	25.9–28.7	54.66
5–8	1,886	49.01	47.4–50.6	64.63
0–4	653	16.97	15.8–18.2	78.56
Paternal educational level (years)
≥ 12	215	6.0	5.2–6.8	15.35
9–11	996	27.77	26.3–29.2	52.31
5–8	1,817	50.67	49.0–52.3	64.72
0–4	558	15.56	14.4–16.7	74.37
Family size (people)
2–3	774	20.83	19.5–22.1	53.36
4–5	2,056	55.33	53.7–56.9	57.59
≥6	886	23.84	22.5–25.2	76.86
Socioeconomic level (quintiles)
5º highest	675	18.68	17.4–20.0	24.44
4º	760	21.04	19.7–22.4	51.71
3º	744	20.59	19.3–22.0	63.84
2º	733	20.29	19.0–21.6	75.85
1º lowest	701	19.40	18.1–20.7	85.59
Working at age 11
No	3,563	95.75	95.0–96.3	60.60
Yes	158	4.25	3.6–4.9	75.95
Working at age 15
No	3,012	81.54	80.2–82.7	56.71
Yes	682	18.46	17.2–19.7	80.65
Working at age 18
No	552	18.29	16.9–19.7	64.13
Yes	2,466	81.71	80.3–83.0	66.18
Alcohol mobility (11–15)
No	3,258	94.85	94.0–95.5	59.58
Yes	177	5.15	4.4–5.9	73.45
Alcohol mobility (15–18)
No	1,837	53.48	51.8–55.1	59.55
Yes	1,598	46.52	44.8–48.2	61.14
Started smoking (age)
Never	2,974	77.21	75.8–78.5	54.61
≤12 years old	121	3.14	2.6–3.7	90.08
13–15 years old	433	11.24	10.3–12.3	82.68
>15 years old	324	8.41	7.6–9.3	80.25

ª Of the 4,104 cohort members in 2011, we registered the schooling of 3,852 participants.

Table 2. Series of full and partial F-Tests for different hypotheses (adapted from Mishra et al. (2008)).

	Alcohol			Tobacco			Work
Hypothesis	df	F-statistic	p-value	df	F-statistic	p-value	df	F-statistic	p-value
Accumulation
Strict	6, 3435	13.99	0.0297	6, 3480	6.96	0.3249	6, 2836	34.94	<0.0001
Relaxed	4, 3435	9.77	0.0445	4, 3480	2.85	0.5832	4, 2836	4.82	0.3066
Critical period
11 years	6, 3435	16.60	0.0109	6, 3480	171.29	<0.0001	6, 2836	76.26	<0.0001
15 years	6, 3435	13.57	0.0349	6, 3480	144.52	<0.0001	6, 2836	10.59	0.1019
18 years	6, 3435	17.52	0.0076	6, 3480	14.36	0.0259	6, 2836	84.77	<0.0001
Mobility
11–15 years	5, 3435	9.16	0.1028	5, 3480	145.54	<0.0001	5, 2836	20.08	0.0012
15–18 years	5, 3435	6.26	0.2818	5, 3480	50.95	<0.0001	5, 2836	54.78	<0.0001
11–18 years	5, 3435	16.38	0.0058	5, 3480	14.79	0.0113	5, 2836	86.51	<0.0001
Relaxed	5, 3435	4.35	0.4996	5, 3480	171.10	<0.0001	5, 2836	72.20	<0.0001
No Effect	7, 3435	19.78	0.0061	7, 3480	177.79	<0.0001	7, 2836	86.56	<0.0001

Table 3. The odds ratio of age-grade gap according to demographic, socio-economic and behavioural variables.

	Crude Analysis			Adjusted Analysis
Variables	OR	95% IC	p	OR	95% IC	p
Gender			<0.001			<0.001
Female	1			1
Male	1.93	(1.69–2.20)		2.54	(2.07–3.10)
Skin Color			<0.001			<0.001
White	1			1
Non-white	2.39	(2.06–2.76)		1.47	(1.19–1.82)
Maternal educational level (years)			<0.001			<0.001
≥12	1			1
9–11	6.17	(4.34–8.77)		2.60	(1.47–4.61)
5–8	9.35	(6.63–13.19)		3.02	(1.71–5.32)
0–4	18.75	(12.83–27.42)		3.55	(1.91–6.56)
Paternal educational level (years)			<0.001			<0.001
≥12	1			1
9–11	6.05	(4.09–8.94)		2.32	(1.27–4.25)
5–8	10.12	(6.90–12.84)		2.93	(1.62–5.32)
0–4	16.00	(10.55–24.28)		3.34	(1.77–6.32)
Family size (people)			<0.001			<0.001
2–3	1			1
4–5	1.18	(1.00–1.40)		1.44	(1.13–1.84)
≥6	2.90	(2.35–3.58)		2.49	(1.84–3.38)
Socioeconomic level (quintiles)			<0.001			<0.001
5º highest	1			1
4º	3.31	(2.64–4.15)		2.36	(1.70–3.27)
3º	5.45	(4.33–6.87)		3.27	(2.34–4.56)
2º	9.71	(7.61–12.39)		5.11	(3.60–7.25)
1º lowest	18.36	(13.95–24.15)		9.05	(6.13–13.37)
Working at age 11			<0.001			0.062
No	1			1
Yes	2.05	(1.41–2.97)		1.64	(0.97–2.77)
Working at age 15			<0.001			<0.001
No	1			1
Yes	3.18	(2.59–3.89)		1.66	(1.28–2.16)
Working at age 18			<0.001			0.181
No	1			1
Yes	1.09	(0.90–1.32)		0.84	(0.66–1.08)
Alcohol mobility (11–15)			<0.001			0.006
No	1			1
Yes	1.87	(1.33–2.64)		1.99	(1.10–3.20)
Alcohol mobility (15–18)			0.344			0.022
No	1			1
Yes	1.07	(0.93–1.22)		1.26	(1.03–1.55)
Started smoking (age)			<0.001			<0.001
Never	1			1
≤12 years old	7.55	(4.14–13.76)		4.11	(1.95–8.69)
13–15 years old	3.96	(3.06–5.14)		3.89	(2.72–5.57)
>15 years old	3.37	(2.54–4.48)		2.77	(1.88–4.56)

Mishra, G., Nitsch, D., Black, S., De Stavola, B., Kuh, D., & Hardy, R. (2008). A structured approach to modelling the effects of binary exposure variables over the life course. International Journal of Epidemiology, 38(2), 528–537.

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