Mohsen Rezaeian

Correspondence:
Professor Mohsen Rezaeian
PhD, Epidemiologist
Social Medicine Department
Occupational Environmental Research Center
Rafsanjan Medical School
Rafsanjan University of Medical Sciences
Rafsanjan-Iran
Tel:03915234003
Fax:03915225209
Email: moeygmr2@yahoo.co.uk

Editorials
Editorials are often very useful and informative non-research papers written by editors or solicited by them. They usually cover important topics of general interests of the readers, authors and reviewers of a journal. They might also convey the policy of the journal in reviewing and publishing the submitted articles.

Letters to the editor
A letter to the editor seems to be the most common type of non-research paper. Letters are usually written by scientists in response and/or reaction to one of the research papers i.e. cross-sectional, ecological, case-control, cohort and trial studies, which a journal has just recently published. The fundamentals of letters are to inform the authors of a research paper, about a shortcoming and/or an overlooked issue in their paper.

Letters are written to the chief editor of the journal and if she/he finds the letter informative, they refer it to the authors of the original paper and ask for a reply. As soon as receiving the proper reply, the chief editor might choose to publish the letter and its reply in the next available issue. Such communications between scientists are vital and may help to correct any possible mistakes in a published research paper.

Book reviews/film reviews
Book reviews and film reviews are two other essential non-research papers. Such papers are usually written by experts in the field (critics) on review of a recently published book or a film production in a specific domain.

By focusing on the pros and cons of a book or a film, these types of reviews would provide authors of a book or producers of a film with valuable feedback. Such feedback could establish a firm ground for a new edition of the book and a new version of the film.

Case reports/case series
Case reports deal with the reporting of a rare clinical disease or a case with rare and unique characteristics. Similarly case series deal with the reporting of a series on rare clinical diseases or syndromes.

In both situations such a report could establish a ground for better understanding of a rare but unique case and might even help to determine a new emerging disease or syndrome. For example , reporting of a young homosexual man with Kaposi's sarcoma could eventually help scientists to determine AIDS as an emerging disease.

Commentaries
Commentaries are those non-research papers which reflect the viewpoints of their authors regarding a specific and usually a hot topic issue. Commentaries could be very informative and might be either unsolicited or solicited i.e. invited commentaries. Invited commentaries are usually commissioned by editors to accompany a research paper in the same issue.

Narrative reviews
Narrative or traditional reviews are other important types of non-research paper through which usually an expert in a given subject, retrieves and summarizes the findings of different research papers. The most important limitation of narrative reviews is that the reviewers usually have not specified their search strategy and this might open such reviews into bias.

Although this shortcoming is referred to as the Achilles' heel of the narrative reviews, such reviews might still provide readers with a rich background on a specific issue. Furthermore, in order to curb this inadequacy of narrative reviews, scientists have developed some other robust types of reviews such as systematic reviews and meta-analyses.