1. Université de Genève; Institut de Médecine Sociale et Préventive; 1, rue Michel-Servet CH-1211 Genève 4 Geneva Switzerland
2. London School of Hygiene & Tropical Medicine; Cochrane Injuries Group; North Courtyard Keppel Street London UK WC1E 7HT
3. University of Hertfordshire; Centre for Research in Primary and Community Care; College Lane Hatfield Hertfordshire UK AL10 9AB