FIGURE 1.

Patient inclusion diagram. Secondary–progressive multiple sclerosis (SP‐MS) patients treated with autologous haematopoietic stem cell transplantation (AHSCT; n = 31) were matched with control patients selected from a cohort of 108 SP‐MS patients treated with cyclophosphamide (Cy) using six covariates as confounders. After estimating propensity score (PS) for all patients, the sample of Cy patients was trimmed by removing 43 patients with values of the estimated PS lower than the smallest estimated PS for the AHSCT cases. The remaining 65 control patients were used as a donor pool, from which a subsample of 31 matched controls was selected with cardinality matching (“best” matched controls). These controls were then removed from the donor pool, and cardinality matching was reapplied to the residual donor pool to select another subsample of 31 matched controls, by slightly relaxing the constraints on the standardized mean differences (“second best” matched controls). All the 62 matched controls were included in the primary analysis; a sensitivity analysis was then performed including the 31 “best” matched controls only