“…Thirty articles examined 14 risk factors for recurrence of BPPV and they included 12,585 participants ( Table 2 ). Twenty-three were retrospective studies [ 1 , 2 , 3 , 4 , 6 , 7 , 8 , 10 , 11 , 12 , 13 , 16 , 18 , 19 , 20 , 21 , 23 , 24 , 25 , 26 , 29 , 30 , 31 ] and seven were prospective cohort studies [ 5 , 14 , 15 , 17 , 22 , 27 , 28 ]. In all studies, the diagnosis of BPPV was established by positive positional tests (Dix-Hallpike, roll tests).…”