Addenda may be material added to an article late in the publication process or may be material that is considered supplementary to the article. (Note: This is distinct from supplementary Web-only material, although addenda may sometimes be presented as supplementary Web-only material. For that, see 2.12, Online-Only [Supplementary] Material.) The use of addenda is discouraged in JAMA and the Archives Journals. If material is added late in the publication process, well after a manuscript has been accepted for publication (eg, the addition of another case report, extended follow-up, data or information on recent legislation or other relevant event, or additional studies that bear on the present article), this is best handled by incorporating the information into the text. If there is a compelling reason to set this material apart as an addendum, this may be done by adding a final paragraph to the existing manuscript:
After the manuscript was accepted for publication,…
If desired, this paragraph may be set off by extra space and/or a half-column-wide centered hairline rule. Any references cited for the first time in this final paragraph or addendum should follow the numbering of the existing reference list.
Note: If substantial material (eg, new figures, new tables, several additional cases) is added after acceptance of the manuscript or if the conclusions change after acceptance, the editor must approve all such changes; additional peer review may be required.