did and did not participate in the 16–18-year data collection assessmentsEnrolled in ALSPACaRecently participatedOdds ratioCharacteristicCategoryn/n (%)n/n (%)OR (95% CI)P > chi2‡Child sexFemale5470/11 008 (49.69)3181/5535 (57.47)1.88 (1.74–2.03)<0.001Child ethnicityWhite10 505/10 933 (96.09)5322/5508 (96.62)1.34 (1.10–1.62)0.004Low household incomeFSMb682/10 959 (6.22)240/5519 (4.35)0.51 (0.44–0.60)<0.001aAll pupils, from English GMEs, who are from families that have enrolled in ALSPAC by completing an ALSPAC questionnaire or clinical assessment.bEligible for ‘free school meals’ (FSM), indicating a joint parental income of ≤£16 000.7 ‡Chi-squared test for homogeneity (equal odds). Table 5A comparison of socio-demographic characteristics between those children lost to attrition and those who remain eligible for future follow-upEnrolled in ALSPACaIneligible for future follow-up due to study attritionOdds ratioCharacteristicCategoryn/n (%)n/n (%)OR (95% CI)P > chi2‡Child sexFemale5 470/11 008 (49.69)726/1556 (46.66)0.86 (0.77–0.96)0.010Child ethnicityWhite10 505/10 933 (96.09)1473/1545 (95.34)0.81 (0.62–1.05)0.103Low household incomeFSMb682/10 959 (6.22)177/1544 (11.46)2.28 (1.91–2.74)<0.001aAll pupils, from English GMEs, who are from families that have enrolled in ALSPAC by completing an ALSPAC questionnaire or clinical assessment.bEligible for ‘free school meals’ (FSM), indicating a joint parental income of ≤£16 000.7 ‡Chi-squared test for homogeneity (equal odds).
