title: Worldwide inequality in production of systematic reviews.
abstract: BACKGROUND
  Investment in science is vital for the development and well-being of societies. This study aims to assess the scientific productivity of countries by quantifying their publication of systematic reviews taking the gross national income per capita (GNIPC) into account.
  
  
  METHODS
  Medline and ISI Web of Science were searched for systematic reviews published between 1st January 2006 and 31st December 2010. The productivity of each country was quantified by exploring the authors' affiliation. The GNIPC was used according to the World Bank Report. Concentration index (CI) was calculated as the index of inequality.
  
  
  RESULTS
  CI of percentage of systematic reviews as a function of percentage of countries ranked by GNIPC was 0.82 which indicates inequality in production of systematic reviews in pro rich countries. Countries with high income produced 206.23 times more systematic reviews than low income countries, while this ratio for lower middle and upper middle countries was 9.67 and 12.97, respectively. The highest concentration index was observed in clinical sciences (0.76) and the lowest in public health (0.61).
  
  
  CONCLUSIONS
  This study demonstrates a significant gap between industrialized and nonindustrialized countries in the production of systematic reviews. Addressing this gap needs tremendous national and international efforts.
authors.affiliation: MD, MPH, Students' Scientific Research center, Tehran University of Medical Sciences, & Exceptional Talents Development Center, Tehran University of Medical Sciences, Tehran, Iran. ajamali@student.tums.ac.ir.
authors.forename: Arsia
authors.initials: A
authors.lastname: Jamali
authors.affiliation: MD, PhD, Professor in Epidemiology, Epidemiology and Biostatistics Department, School of Public Health, Tehran University of Medical Sciences, & Knowledge Utilization Research Center, Tehran University of Medical Sciences, Tehran, Iran. nejatsan@tums.ac.ir.
authors.forename: Saharnaz
authors.initials: S
authors.lastname: Nedjat
authors.affiliation: MD, PhD, PhD candidate in Epidemiology, Epidemiology and Biostatistics Department, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran. k_heydari1515@yahoo.com.
authors.forename: Kazem
authors.initials: K
authors.lastname: Heidari
authors.affiliation: MD, Students' Scientific Research center, Tehran University of Medical Sciences, Tehran, Iran. jamalira@tums.ac.ir.
authors.forename: Raika
authors.initials: R
authors.lastname: Jamali
authors.affiliation: MD, MPH, Students' Scientific Research center, Tehran University of Medical Sciences, & Exceptional Talents Development Center, Tehran University of Medical Sciences, Tehran, Iran. kiana_h87@yahoo.com.
authors.forename: Kiana
authors.initials: K
authors.lastname: Hassanpour
authors.affiliation: MD, PhD Candidate in Gerontology, Knowledge Utilization Research Center, Tehran University of Medical Sciences, & University of Social Welfare and Rehabilitation, Tehran, Iran. nejat_s@farabi.tums.ac.ir.
authors.forename: Sima
authors.initials: S
authors.lastname: Nedjat
authors.affiliation: MD, MPH, Students' Scientific Research center, Tehran University of Medical Sciences, & Exceptional Talents Development Center, Tehran University of Medical Sciences, Tehran, Iran. panvari@student.tums.ac.ir.
authors.forename: Pasha
authors.initials: P
authors.lastname: Anvari
authors.affiliation: VMD, PhD, Professor in Epidemiology, Epidemiology and Biostatistics Department, School of Public Health, Tehran University of Medical Sciences, & Knowledge Utilization Research Center, Tehran University of Medical Sciences, Tehran, Iran. rezamajd@tums.ac.ir.
authors.forename: Reza
authors.initials: R
authors.lastname: Majdzadeh
keywords: Gross national income; Inequality; Scientific productivity; Systematic review