A few major risk factors are responsible for a large portion of the global disease burden and eliminating them could result in important health gains, A 1993 study reported in The Lancet was the first to estimate the disease burden of multiple risk factors on a global scale, Disease burden and injury attributable to 20 major risk factors in 14 regions around the world was evaluated. Forty-seven percent of premature deaths and 39% of the total disease burden in 2000 were due to the joint effects of the 20 risk factors. The risk factor that contributed the most to the disease burden was childhood and maternal underweight, followed by unsafe sex, high blood pressure and tobacco use. Together, the risk factors accounted for more than 90% of diarrhoea cases, 83% to 89% of ischaemic heart disease cases, 70% to 76% of stroke cases, 72% of lung cancer cases, 55% to 62% of lower respiratory infection cases and 60% of COPD cases. Simultaneous elimination of all risk factors would increase global life expectancy by 9.3 years. However, the benefit would vary greatly by region. The study indicated that the gain in some parts of sub-Saharan Africa would be 16.1 years, while the increase was only 4.4 years in developed regions of the western Pacific.