Levels of evidence of published articles in major Nigerian medical journals: a critical appraisal.

In modern day medical practice, "rules of evidence" have been established to grade clinical and research findings according to strength. The aim of this study is to describe the current pattern of publications in 5 major Nigerian medical journals in terms of levels of evidence. Five major peer-review medical journals (Nigerian Q J Hosp Med, Nigerian Post grad Med J, West African J Med, African J Med Med Sci, and Nigerian J Clin Pract) published in Nigeria were included in the study. All articles published in 2005 and 2006 were accessed, classified into four levels of evidence, and pattern of publications was described. All eligible 580 published articles were analysed. None (0%) achieved level I evidence, 15 (3%) were level II, 47 (8%) level III, and 258 (44%) level IV; and the majority (n = 260, 45%) of the published were classified as non-evidence. There were more evidence articles in indexed journals than in non-indexed one (P = 0.000). Among the 260 non-evidence articles there were 97 (37.3%) case reports, 28 (10.8%) non-systematic review articles, 30 (11.5%) animal studies, 6 (2.3%) laboratory studies, 3 (1.1%) technical notes and 94 (36.1%) were classified as others (KAP studies, reports, guidelines, questionnaire-based studies). The general level of evidence of articles published in the five major medical journals in the 2-year period 2005-2006 was low as only 11% of articles were levels II and III. There is a need to improve on the quality and funding of medical research in Nigeria in order to promote better patient care.