Obesity, overweight and liver disease in the Midspan prospective cohort studies

Objectives: To analyse the relationship between body mass index (BMI) and liver disease in men and women. Design: The Midspan prospective cohort studies. Participants: The three studies were: Main study, screened in 1965–1968, workplaces across Scotland, the general population of the island of Tiree and mainland relatives; Collaborative study, conducted from 1970 to 1973, 27 workplaces in Glasgow, Clydebank and Grangemouth; Renfrew/Paisley general population study, screened in 1972–1976. After exclusions there were 16 522 men and 10 216 women, grouped by BMI into under/normal weight (<25 kg m–2), overweight (25 to <30 kg m–2) and obese (greater than or equal to30 kg m–2). Measurements: Relative rates (RRs) of liver disease mortality, subdivided into liver cancer and all other liver disease, by BMI category and per s.d. increase in BMI, followed-up to end 2007. RRs of liver disease from any diagnosis on the death certificate, hospital discharge records or cancer registrations (Collaborative and Renfrew/Paisley studies only 13 027 men and 9328 women). Analyses adjusted for age and study, then other confounders. Results: In total, 146 men (0.9%) and 61 women (0.6%) died of liver disease as main cause. There were strong associations of BMI with liver disease mortality in men (RR per s.d. increase in BMI=1.41 (95% confidence interval 1.21–1.65)). Obese men had more than three times the rate of liver disease mortality than under/normal weight men. Adjustment for other risk factors had very little effect. No substantial or robust associations were observed in women. In all, 325 men (2.5%) and 155 women (1.7%) had liver disease established from any source. Similar positive associations were observed for men, and there was evidence of a relationship in women. Conclusions: BMI is related to liver disease, although not to liver disease mortality in women. The current rise in overweight and obesity may lead to a continuing epidemic of liver disease.