Table 2 Occurrence of multiple sclerosis with different time intervals after injury*.

Time from injury to MS	Observed number of MS in injury cohort	Expected number of MS in injury cohort	Adjusted rate ratio	95% CI
<6 months	8	8.4	1.0	0.40 to 1.99
6–11 months	2	3.0	0.7	0.08 to 2.60
12–23 months	9	7.5	1.2	0.53 to 2.58
24–35 months	2	3.5	0.6	0.07 to 2.69
36–47 months	9	7.3	1.2	0.54 to 2.82
48–59 months	5	4.7	1.1	0.32 to 2.97
5–9 years	21	19.5	1.1	0.65 to 1.77
10+ years	49	44.4	1.1	0.82 to 1.47
Total	105	97.9	1.1	0.88 to 1.35

*Number of people in the head injury cohort with MS (“observed number”), expected number, ratio of rates in the injury cohort to that in the reference cohort, and 95% confidence intervals for the rate ratio.

CI, confidence interval; MS, multiple sclerosis.