Table 6. Longitudinal analyses and meta-analyses for APOE and radiographic joint damage for 3 cohorts.

	Estimate (95% CI)	p
Norway APOE	−0.36 (−0.64 to −0.08)	0.01
Leiden APOE	0.03 (−0.08 to 0.13)	0.59
Lund APOE	−0.12 (−0.33 to 0. 09)	0.30
Meta-analysis		0.41

For APOE, the three genotype groups, ε2 carrier, ε3/ε3, and ε4 carrier are coded 0, 1 and 2 respectively. The coefficient estimates and 95% confidence interval (95% CI) from the longitudinal analyses give a measure of the difference in radiographic joint damage score of adjacent APOE genotype groups within each cohort. E.g. in the Norwegian cohort individuals with ε3/ε3 genotype had 0.36 lower radiographic joint damage score than individuals carrying ε2. The coefficient estimates are given on the natural log (ln) scale for radiographic joint damage score. Longitudinal analyses were adjusted for time, age, gender and treatment. Additional adjustments including presence of anti citrullinated protein antibodies and disease duration at baseline were included in the analyses of the Norwegian cohort. A fixed effect meta-analysis was carried out and the p-value is shown.