Lifestyle factors and hip arthrosis - A case referent study of body mass index, smoking and hormone therapy in 503 Swedish women

We investigated in a case-referent study the relationship between arthrosis of the hip in women and lifestyle factors such as body mass index (BMI), smoking and hormone therapy. The study comprised all women of ages 50-70 years, living in 5 counties and 5 towns in Sweden 1991-1994. The cases (n 230) were women with total hip replacements (THR) because of primary arthrosis, and the referents (n 273) were randomly selected women from the study base, without hip problems. All women were interviewed about height, weight, smoking habits, hormone therapy, sports activities, occupational history, home work, etc, to the age of 50. The relative risk of developing hip arthrosis leading to a THR after the age of 50 was associated with an increased BMI, The highest value, 2.9 (CI 1.3-6.5), was reported in those with BMI greater than or equal to 25 at the age of 40. The preventive value of weight loss seems substantial. There was a greater risk of 1.5 (CI 1.0-2.2) for smokers than for non-smokers, Use of contraceptive pills meant an increase in the relative risk for THR, unlike estrogen substitution which was associated with a lower risk than in unexposed persons.