Table 1.

Descriptive statistics of those classified as CFS and those classified as non-CFS in ALSPAC at age 16 years

	Non-CFS ALSPAC 13 years	CFS ALSPAC 13 years	Difference (CFS–non-CFS) (95% CI)
Sex (male)	51.57% (50.72% to 52.42%)	56.50% (45.14% to 67.85%)	4.92% (−6.63% to 16.48%)
Total authorised absences*	20.68 (20.21 to 21.15)	31.86 (23.67 to 40.06)	11.19 (4.01 to 18.36)
Total unauthorised absences*	10.42 (9.89 to 10.96)	15.97 (5.68 to 26.26)	5.55 (−4.35 to 15.45)
Family Adversity Index (0–18)	1.85 (−2.33 to 6.03)	2.94 (−25.79 to 31.67)	1.09 (−30.96 to 33.1)
Strength and Difficulties Score (0–40)	7.39 (7.21 to 7.56)	13.69 (10.71 to 16.68)	6.30 (3.61 to 8.90)
Maternal age at delivery (years)	27.98 (27.89 to 28.06)	29.01 (27.76 to 30.26)	1.02 (−0.23 to 2.29)
Maternal education (% with degree)	12.32% (11.75% to 12.88%)	15.88% (9.39% to 22.37%)	3.57 (−2.64 to 9.77)
	Non-CFS ALSPAC 16 years	CFS ALSPAC 16 years	Difference (CFS–non-CFS) (95% CI)
Sex (male)	51.81% (50.91% to 52.69%)	44.59% (32.11% to 57.07%)	−7.22% (−19.99% to 5.54%)
Total authorised absences*	20.37 (19.89 to 20.85)	42.20 (35.09 to 49.31)	21.83 (14.72 to 28.94)
Total unauthorised absences*	10.36 (9.80 to 10.96)	17.19 (6.49 to 27.89)	6.83 (−3.87 to 17.53)
Family Adversity Index (0–18)	1.87 (−2.35 to 6.08)	1.95 (−18.35 to 22.25)	0.08 (−20.22 to 20.3)
Strength and Difficulties Score (0–40)	7.42 (7.24 to 7.60)	10.34 (8.52 to 12.16)	2.92 (1.10 to 4.74)
Maternal age at delivery (years)	27.99 (27.90 to 28.07)	28.38 (27.09 to 29.67)	0.39 (−0.90 to 1.68)
Maternal education (% with degree)	12.27 (11.70 to 12.84)	16.81 (10.63 to 23.00)	4.54% (−1.40% to 10.48%)

Proportions (95% CI) for categorical variables, means (95% CI) for continuous variables. Family Adversity Index collected when the child was 8–10 years.

*Half-day sessions from a typical total of 390 sessions during year 11.

ALSPAC, Avon Longitudinal Study of Parents and Children; CFS, chronic fatigue syndrome.