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

OBJECTIVES: To investigate the relationship between BMI and liver disease in men and women. DESIGN: The Midspan prospective cohort studies. PARTICIPANTS: The three studies were: Main, screened 1965-8, workplaces across Scotland, the general population of the island of Tiree and mainland relatives; Collaborative, conducted from 1970-3, 27 workplaces in Glasgow, Clydebank and Grangemouth; Renfrew/Paisley general population study, screened in 1972-6. After exclusions there were 16 522 men and 10 216 women, grouped by body mass index (BMI) into under/normal weight (< 25 kg/m(2)), overweight (25 to < 30 kg/m(2)) and obese (≥ 30 kg/m(2)). MEASUREMENTS: Relative rates (RR) of liver disease mortality, subdivided into liver cancer and all other liver disease, by BMI category and per standard deviation (SD) 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 9 328 women). Analyses adjusted for age and study, then other confounders. RESULTS: 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 SD increase in BMI=1.41 (95% confidence interval (CI) 1.21 to 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 impact. No substantial or robust associations were seen in women. 325 men (2.5%) and 155 women (1.7%) had liver disease established from any source. Similar positive associations were seen 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.