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Byline: K. MichaA< Keywords: Key words: Cervical -- Estrogen -- Height -- Hip fracture -- Trochanteric Abstract: The two types of hip fracture -- cervical and trochanteric femoral fractures -- are generally considered together in etiologic studies. However, women with a trochanteric fracture may be more osteoporotic than those with cervical hip fractures, and have higher post-fracture mortality. To explore differences in risk factor patterns between the two types of hip fracture we used data from a large population-based case--control study in Swedish women, 50--81 years of age. Data were collected by questionnaire, to which more than 80% of subjects responded. Of the cases included, 811 had had a cervical fracture and 483 a trochanteric fracture during the study period these cases were compared with 3312 randomly selected controls. Height and hormonal factors appeared to affect the risk of the two types of hip fracture differently. For every 5 cm of current height, women with a cervical fracture had an adjusted odds ratio (OR) of 1.23 (95% CI 1.15--1.32) compared with an OR of 1.06 (95% CI 0.97--1.15) for women with trochanteric fractures. Later menopausal age was protective for trochanteric fractures (OR 0.95, 95% CI 0.91--0.99 per 2 years) but no such association was found for cervical fractures. Compared with never smokers, current smokers had an OR of 1.48 (95% CI 1.12--1.95) for trochanteric fractures and 1.22 (95% CI 0.98--1.52) for cervical fractures. Current hormone replacement therapy was similarly protective for both fracture types, but former use substantially reduced risk only for trochanteric fractures: OR 0.55 (95% CI 0.33--0.92) compared with 1.00 (95% CI 0.71--1.39) for cervical fractures. These risk factor patterns suggest etiologic differences between the fracture types which have to be considered when planning preventive interventions. Author Affiliation: (1) Department of Surgery, University Hospital, Uppsala, Sweden, SE (2) Department of Medical Epidemiology, Karolinska Institute, Stockholm, Sweden, SE (3) Division of Epidemiology, Karolinska Hospital, Stockholm, Sweden, SE (4) Departments of Medicine and Community &amp Family Medicine, Dartmouth Medical School, Hanover, New Hampshire, USA, US (5) Vasa Hospital, Gothenburg, Sweden, SE (6) Department of Orthopedics, Halmstad, Sweden , SE (7) Department of Medical Sciences, University Hospital, Uppsala, Sweden, SE Article note: Received: 22 March 1999 / Accepted: 28 May 1999

Byline: K. MichaA< Keywords: Key words:Estrogen -- Hip fracture -- Hormone replacement therapy -- Interaction -- Physical activity -- Weight Abstract: Use of postmenopausal hormone replacement therapy (HRT) has been associated with a reduced risk of osteoporotic fractures. However, it is uncertain whether this risk reduction is modified by other risk factors for hip fracture. In a population-based case--control study in Sweden, we investigated the association between HRT and hip fracture risk within categories of age, body measures and lifestyle factors in postmenopausal women, 50--81 years of age. Mailed questionnaires and telephone interviews were used to collect data. Of those eligible, 1328 incident cases with hip fracture (82.5%) and 3312 randomly selected controls (81.6%) answered the questionnaire. Ever use of HRT in women less than 75 years old was associated with an odds ratio (OR) of 0.66 (95% confidence interval: 95% CI 0.50--0.87) for hip fracture compared with OR 0.40 (95% CI 0.21--0.77) in women 75 years or older. We found a significant interaction between HRT and both weight and physical activity (p&lt 0.05). The protective effect of HRT was particularly pronounced in lean women: compared with never HRT users, ever users weighing under 60 kg had an OR of 0.44 (95% CI 0.30--0.66) whereas women weighing more than 70 kg had an OR of 0.91 (95% CI 0.53-1.-56). Women with low recent leisure physical activity (less than 1 h/week) similarly benefited more from HRT for hip fracture prevention than women with a higher degree of recreational physical activity. The observed interactions with weight and physical activity suggest that HRT has the best protective effect against hip fracture among high-risk women. Author Affiliation: (1) Department of Orthopaedics, University Hospital, Uppsala, Sweden, SE (2) Departments of Medicine and Community &amp Family Medicine, Dartmouth Medical School, Hanover, New Hampshire, USA, US (3) Department of Medical Epidemiology, Karolinska Institute, Stockholm, Sweden, SE (4) Department of Orthopaedics, MalmA<< General Hospital, MalmA< (5) Department of Internal Medicine, University Hospital, Uppsala, Sweden, SE Article note: Received: 7 October 1997 / Revised: 21 January 1998