Background: Overweight and obesity have been considered to be the causes of serious health consequences. So far, there have been no studies in Poland to analyse the relationship between Body Mass Index (BMI) and mortality.
Aim: To determine the relationship between BMI and the mortality risk due to all causes and due to cardiovascular diseases (CVD) in the middle-aged population of Poland.
Methods: The study group consisted of men and women aged 35-64, residents of two districts of Warsaw (Praga Północ and Praga Południe) and the former Tarnobrzeg Voivodship who were selected at random for POL-MONICA Project cross-sectional studies in 1983-1994. Risk assessment of death due to all causes and due to CVD was performed using the Cox proportional hazards method. Persons with BMI of 22-23.9 were adopted as reference group.
Results: Sample size consisted of 5,281 men and 5,691 women. Prospective observation was carried out from 5 to 15 years, mean duration 10.7 years. Overall, the observation comprised 117,839 person-years. During the study, 914 men died (including 448 due to CVD) as well as 430 women (including 160 due to CVD). After adjusting for age, place of residence (Warsaw vs. the Tarnobrzeg Voivodship), risk factors (hypercholesterolemia, arterial hypertension and smoking) and self-assessment of health, increased risk of all cause death was found in men with BMI lower than 20 kg/m(2) (relative risk 2.27), with BMI of 32-34.9 kg/m(2) (relative risk 1.41), with BMI > or =35 kg/m(2) (relative risk 1.73), and in women whose BMI was lower than 20 kg/m(2) (relative risk 1.66). Increased risk of CVD death was found in men with BMI lower than 20 kg/m(2) (relative risk 1.97), with BMI of 32-34.9 kg/m(2) (relative risk 1.66), with BMI > or =35 kg/m(2) (relative risk 2.06), and in women with BMI > or =35.0 kg/m(2) (relative risk 2.02).
Conclusions: The POL-MONICA study carried out in the middle-aged Polish population did not confirm a relationship between overweight (BMI from 25 to 29.9 kg/m(2)) and risk of death due to all causes or due to CVD.