Misspelling of Delirium as “Delerium” in the Academic Literature

Delirium derives from the Latin “de lira,” or “off the tracks.” We have noted a tendency for students and healthcare professionals to misspell delirium as “delerium.” We examined if this error also occurs in the academic literature. Using Google Scholar, which indexes the full text of up to 400 million documents, including most peer-reviewed journals and books,1, 2 we examined (on November 10, 2019) the annual relative frequency of the exact words “delirium” and “delerium” in the English-language academic literature since 1900. (Quotation marks were included in the search terms to evade automatic spelling corrections.) Citations (where the misspelling arose in the reference list) and references to the band Delerium (a “new-age ambient electronic musical duo” from Canada3) were excluded. We also examined whether misspellings were more likely in the context of references to delirium tremens. The correct and incorrect spellings coexist in some texts and, using the advanced search option in Google Scholar, the number of texts where “delerium” and “delirium” both occurred was also noted. We used PubMed to find articles containing “delerium” from 1946 (when records begin) to 2019 with sufficient data recorded to allow the country of origin to be examined. We examined the main specialty of journals including “delerium” and the proportion of uses from countries with English as an official language.4 Overall, Google Scholar searches for “delerium” and “delirium” yielded 3024 and 344 842 results, respectively, and “delerium” accounted for 0.9% of the total results. The relative frequency of “delerium” was greatest between 1970 and 1989, with a peak misspelling rate of 4.9% in 1975 (Figure 1). In contrast, the misspelling rate was less than 0.5% from 1900 to 1929 and since 2014. Of 3024 texts containing “delerium,” 1010 (33.4%) also contained the correct spelling. Overall, the misspelling rate for “delerium tremens” vs “delirium tremens” (2.9%) was significantly higher than for “delerium” vs “delirium” without “tremens” (1.2%) (χ2 = 21.2; P < .0001). (The Belgian beer Delirium Tremens was spelled correctly in all four search results.) “Delerium” occurred in the title of 12 articles. Other egregious examples included the use of “delerium” once in a British guideline document on delirium,5 twice in a primer on the spelling of medical terms,6 and four times in a seminal article on cognitive assessment.7 Of 1488 PubMed articles from 1946 to 2019 containing “delerium” and with sufficient data for analysis, 1189 (79.9%) came from countries with English as an official language; 219 (14.7%) were from psychiatry journals, 162 (10.9%) were from general medical journals, 126 (8.5%) were from anesthetic journals, 42 (2.8%) were from neurology journals, and 33 (2.2%) were from geriatric medical journals. To put these findings in context, a review of a random selection of 500 articles from the same time span where delirium was spelled correctly indicted that 73.2% of articles came from countries with English as an official language, 23.0% were in psychiatry journals, 16.5% were in geriatric medicine journals, 9.4% were in general medical journals, 3.7% were in neurology journals, and 2.2% were in anesthetic journals. Misspelling of delirium was relatively common in the 1970s and 1980s, reaching almost 5% in 1975. While now much less common, it is nevertheless surprising to find “delerium” surviving, not only peer review, editing, and proofreading, but also modern word processor software to make it into publication. One criticism of Google Scholar is that it does not screen out low-quality journals where the quality of peer review and editing may be poor. However, many of the examples we found came from widely respected journals. Although few misspellings were found in geriatric medical journals, the frequency in psychiatric journals was surprisingly high and misspellings seem disproportionately high in anesthetic journals. Phonetic spelling due to the pronunciation of delirium as del-EE-rium may explain some errors. Often with nonspecialist colleagues, one is so pleased to find, given its previous neglect, a diagnosis of delirium being made that it seems churlish to complain about the spelling. For writers, though, misspelling a common term will not impress reviewers or, if published, readers. The most widely studied, and potentially misleading, misspelling of a medical term is use of “pruritis” instead of “pruritus.”8-10 Pruritus is misspelled in almost 5% of articles on the topic in PubMed, even in recent years, with a real risk that significant articles might be missed in literature searches or that “pruritis” might “overrun the correct form.”10 “Delerium” is not as significant a problem as “pruritis.” Nevertheless, our results suggest that, in addition to being sometimes misdiagnosed and mismanaged, delirium is also prone to being misspelled. The authors report no conflicts of interest. All authors contributed to study design, data collection, and writing of the article. None.

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