Inappropriate Indexing of Case Reports to the "Papilledema" Subject Heading: A Systematic Review.

BACKGROUND: Papilledema must be managed distinctly from other causes of optic disc edema (ODE) due to its basis in raised intracranial pressure (ICP). However, evidence indicates that the term "papilledema" is widely misused across specialties to describe ODE without raised ICP. Sources of this misconception remain undiscerned. Because all physicians consult medical databases, our objective was to evaluate whether nonspecific "papilledema" subject heading definitions misleadingly associate articles on other conditions with papilledema proper. METHODS: Systematic review of case reports, prospectively registered on PROSPERO (CRD42022363651). MEDLINE and Embase were searched to July 2022 for any full-length case report indexed to the "papilledema" subject heading. Studies were graded for incorrect indexing, defined as cases lacking evidence for raised ICP. Nonpapilledema diagnoses were assigned to a predefined set of diseases and pathophysiological mechanisms for subsequent comparison. RESULTS: Incorrect indexing occurred in 40.67% of 949 included reports. Embase-derived studies were misindexed significantly less than MEDLINE-derived studies ( P < 0.01). There was also significant heterogeneity in incorrect indexing among specific diseases ( P = 0.0015) and mechanisms ( P = 0.0003). The most commonly misindexed diseases were uveitis (21.24% of errors), optic neuritis (13.47%), and instances with no mention of ODE (13.99%). The most commonly misindexed mechanisms were inflammation (34.97%), other mechanism (e.g., genetic; 25.91%), and ischemia (20.47%). CONCLUSIONS: Database subject headings, especially from MEDLINE, do not adequately distinguish between true papilledema and other causes of ODE. Inflammatory diseases were most often incorrectly indexed among other diseases and mechanisms. Current "papilledema" subject headings should be revised to reduce the probability of misinformation.