Unless there is an exception, parenthetical citations should not be used. Instead, a superscript number will be used to cite within the text. The end references should be numbered consecutively with arabic numerals in the order in which they are cited in the text.
From AMA Manual, 11th ed., 3.5 Numbering. & Ch. 3.6 Citation.
In-Text Citations
As reported previously,1
Corresponding End Reference