Relation between randomized controlled trials published in leading general medical journals and the global burden of disease

BACKGROUND: More than two-thirds of the world's population live in low-income countries, where health priorities are different from those of people living in more affluent parts of the world. We evaluated the relation between the global burden of disease and conditions or diseases studied in randomized controlled trials (RCTs) published in general medical journals. METHODS: A MEDLINE search identified 373 RCTs that had been published in 6 international peer-reviewed general medical journals in 1999. Manual review excluded non-RCTs, brief reports and trials in which the unit of randomization was not the patient; 286 RCTs remained eligible for analysis. We identified the RCTs that studied any of the 40 leading causes of the global burden of disease. Five of these conditions were considered unsuitable for study with an RCT design and were excluded from subsequent analysis. To provide a practical perspective, we asked 12 experts working with international health organizations to rate the relevance to global health of the articles that studied any of the top 10 causes of the global burden of disease, as measured by disability-adjusted life years (DALYs) and mortality, using a 5-point Likert scale. RESULTS: Among the 286 RCTs in our sample, 124 (43.4%) addressed 1 of the 35 leading causes of the global burden of disease. Of these, ischemic heart disease, HIV/AIDS and cerebrovascular disease were the most commonly studied conditions. Ninety articles (31.5%) studied 1 of the top 10 causes of the global burden of disease. The mean rating (and standard deviation) for international health relevance assigned by experts was 2.6 (1.5) out of 5. Only 14 (16%) of the 90 trials received a rating of 4 or greater, indicating high relevance to international health. Almost half of the 40 leading causes of the global burden of disease were not studied by any trial. INTERPRETATION: Many conditions or diseases common internationally are underrepresented in RCTs published in leading general medical journals. Trials published in these journals that studied one of these high-priority conditions were generally rated as being of little relevance to international health.