October 10, 2011
The paper refers to an analysis of a study – The Framlingham Heart Study – started in 1948 and following 5036 participants every 2 years for 48 years. The age range of participants was 28 to 62 years. The analysis was carried out by Australian, Indonesian and Copenhagen.
The analysis excluded 75% of participants as not being obese at all during the study. This meant 1244 were studied and the average age of obesity onset was 50 and the average number of years lived with obesity was 13 years (range 2-46 years). A very complicated way of calculating person-years eventually led to a finding that 39% died from CVD, 25% form cancer and 36% from non-CVD and non-cancer causes. Smoking behaviour, blood pressure measurements and blood cholesterol levels were considered important and were measured.
The analysis concludes that the length of obesity is significantly associated with a greater risk of mortality. This study was different from others in that it took into account the present BMI of the participants and weight changes over the period of the study. They found that for every 10 years a participant lived with obesity then the risks of all-cause mortality and CVD and cancer mortality was more than doubled. They do however state that in1948 when the study started, then obesity was relatively rare (less than 10%) whereas in the USA in 2008 it was about 30%. The diet would also be substantially different in 1948 with the effects of the Second World War still being present – though as this is a US based study this will be less so than in countries like the UK where rationing affected diets greatly.