Osteoporosis in women : Epidemiological and diagnostic perspectives

• An epidemiological study of 15.462 hip fractures in Östergötland 1940-86 showed a large incidence increase mainly due to an increase in age-specific incidence of trochanteric fractures. A trendforecast assuming the same increase in incidence as over the study period and a population forecast according to the official prognosis, predicted 70% more hip fractures in the year 2000 compared to 1985. The different forecasts models were validated for the year 1995 and showed a good correlation between estimated and observed number of fractures, but varied dependent on which fracture and prognosis model that were evaluated.A follow-up investigation of 11.517 hip fractures 1982-96 showed a downturn in incidence of female fractures and a continous increase for males, particularly of trochanteric fractures. A trend brake was thus seen and this continues up to 2010 according to our trendforecasts but may be counteracted by the increasing number of elderly after 2020. Gender ratio changed over time with increasing number of male fractures, more trochanteric fractures relative to cervical (c/t-ratio) and an increasing mean age of the fracture patient.Age specific reference values were established for bone mineral density (BMD) in forearm, lumbar spine and hip after investigation of 429 women 20-80 years, randomly sampled from the general population. Bone density was assessed from cross-sectional data for the various skeletal sites over an almost complete adult life period and these were then compared to values obtained from other studies, densitometry technologies and reference materials. Large discordances were found between the different technologies and reference materials.The outcome of using the T-score proposed by a WHO study group 1994 as a diagnostic cutoff principle for the diagnosis of osteoporosis (T<-2.5) and osteopenia (T<-1 - -2.5) was evaluated by calculating the resulting prevalence in a cohort of 210 women, 70 years of age. The use of different approaches in calculation of T -score and different reference samples, yielded unacceptable disparities in disease prevalence of between 9 and 72%. The differences were also heavely dependent of which and how many sites that were included in the diagnostic decision.We studied biochemical markers of bone turnover (alkaline phosphatase, osteocalcin, hydroxyproline and calcium excretion in the urine) in relation to age, menopause and BMD, and their ability to predict bone loss in a 5-year follow-up perspective. Markers varied inversely to BMD, increased markedly at menopause and predicted bone loss over the next 5 years up to 75% at individual level, (AUC of an ROC analysis).A case. finding strategy using low-energy index fractures in forearm, spine, hip or humerus was performed to detect subjects with osteoporosis. 303 consecutive women 55-75 years with a recent fracture were examined with densitometry and a risk profile questionnaire. The lowest BMD was found in spine and hip fracture patients. Odds ratio for osteoporosis was at least 8 for a patient with a prior hip fracture. The number of previous fractures correlated inversely with bone density (Z-score). Despite 92% of the fracture patients (many with a multiple fracture history) had a low bone mass (t-score<1), only 15% had been treated for osteoporosis before the index fracture.

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