Table 1

Summary table of studies included in meta-analysis

First author, yearNo MSMean age patientsNo controlsMean age controlsQuality (NOS)
Selection (4*)Comparability (3*)Exposure (2*)
Piehl, 20173939.62735.2*****
Trentini, 20143149.61539*****
Novakova, 2017a593739 (dup)33.6*******
Novakova, 2017b4339.73933.6********
Hakansson, 201722unknown2232**********
Bergman, 201611037.711340.2*****
Lam, 20155945.74440.4****
Stilund, 20155941.23940.7*****
Villar, 201512733.63734.6******
Aeinehband, 20154841.21830.4*****
Burman, 20146343.81540.2*****
Axelsson, 201435481442********
Fialová, 201318382433****
Gunnarsson, 20119237.32843*****
  • Each study is scored using a star system based on three domains: (1) selection of study groups (cases and controls)—maximum 4*; (2) comparability of the groups—maximum 2*; (3) ascertainment of outcome—maximum 3*.

  • MS, multiple sclerosis; NOS, Newcastle-Ottawa Scale.