Impact of methodological choices in comparative effectiveness studies: application in natalizumab versus fingolimod comparison among patients with multiple sclerosis

Table 3 Follow-up duration according to the outcomes of interest (in years)

Outcome	Intention-to-treat analysis	Per-protocol analysis
Counts of relapses^a	3.17 (2.01–4.59)	2.09 (1.24–3.41)
Time to first relapse^b	3.11 [3.05; 3.18]	2.27 [2.21; 2.31]
Time to first EDSS worsening^b	3.16 [3.10; 3.23]	2.11 [2.07; 2.16]
Time to first EDSS improvement^b	3.20 [3,13; 3.27]	2.08 [2.02; 2.12]

^a Median (Quartiles) length of follow-up
^b Median [95% confidence interval] survival time of the reverse Kaplan–Meier, taking into account the length and the completeness of follow-up

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