“…All studies assessed patients of all age groups, with the mean onset age of PPGL being 28.8 years (as reported in 21 studies ( 21 , 26 , 35 , 40 , 44 , 47 , 55 , 59 , 60 , 61 , 65 , 67 , 71 , 72 , 74 , 77 , 79 , 85 , 86 , 87 , 88 )). Six studies reported a consecutive sample ( 16 , 17 , 29 , 66 , 77 , 78 ), whereas in 39 studies a convenience sample was assessed ( 21 , 25 , 35 , 45 , 47 , 53 , 56 , 59 , 60 , 61 , 62 , 63 , 64 , 65 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 , 90 , 91 , 92 , 93 ).…”