Input (grade 5): A study by Knutsson et al. in 1986 found that shift workers who had worked in that method for 15 years or more were 300% more likely to develop ischemic heart disease.
Output (grade 10): A study by Knutsson et al in 1986 showed that people who work shift work for more than 15 years, are 3 times more likely to develop ischaemic heart diseases.