Criteria Affected by PPS Pa Unadjusted OR (CI) Adjusted OR (CI) P Both Sexes Male Female 110 48 62 0.02 1.00 (reference) 2.37 (1.07-3.84) 1.00 (reference) 1.57 (0.72-2.88) 0.2 Age at Onset of Poliob ≤ 12 months > 12 months 64 46 0.01 1.00 (reference) 0.32 (0.16-0.82) 1.00 (reference) 0.23 (0.12-0.89) 0.02 Number of affected musclesc ≤ 3 > 3 38 27 0.7 1.00 (reference) 1.12 (0.43-2.34) __ 0.4 Number of affected functionsc ≤ 2 > 2 28 24 0.3 1.00 (reference) 1.58 (0.71-3.32) __ 0.9 Eductaion (years of school)d 0-5 6-8 >9 43 27 40 0.002 1.00 (reference) 0.30 (0.13-1.04) 0.23 (0.07-0.57) 1.00 (reference) 0.36 (0.15-1.23) 0.21 (0.07-0.69) 0.003 aDifferences between subgroup frequencies are tested by chi2 analysis. Variables are dichotomised according to the median of the distribution in the whole cohort. bAge at onset of poliomyelitis was unknown in one patient affected by PPS. cNumber of affected muscles and number of affected functions were unknown in four patients not affected by PPS. dEducation was unknown in two patients not affected by PPS

Table 1: Frequencies and risk estimates of clinical and demographic characteristics of patients with previous poliomyelitis, affected or not by PPS.