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| 3. |
- Jönsson, Bengt, et al.
(författare)
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Cost-effectiveness of preventing hip fracture in the general female population
- 2001
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Ingår i: Osteoporosis international. - : Springer. - 1433-2965 .- 0937-941X. ; 12:5, s. 356-361
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Tidskriftsartikel (refereegranskat)abstract
- The aims of this study were to determine whether treatments that reduce the incidence of hip fracture might be used in the general female population rather than screening or case-finding strategies. Cost-effectiveness, measured as cost per quality-adjusted life-year (QALY) gained using threshold values for cost-effectiveness of $20.000 or $30.000/QALY gained, was assessed during and after treatment using a computer simulation model applied to the female population of Sweden. The base case assumed a 5-year intervention that reduced the risk of hip fracture by 35% during the treatment period, and an effect that reversed to the pretreatment risk during the next 5 years. Sensitivity analyses included the effects of age, different treatment costs and effectiveness. Cost-effectiveness was critically dependent upon the age and costs of intervention. Reasonable cost-effectiveness was shown even with relatively high intervention costs for women at average risk at the age of 84 years or more. For the cheapest interventions ($63/year) cost-effectiveness could be found from the age of 53 years. Variations in effectiveness (15–50% risk reduction) had marked effects on the age that treatment was worthwhile. We conclude that segments of the apparently healthy population could be advantaged by treatment if efficacy were supported by randomized controlled studies.
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| 4. |
- Kanis, J A, et al.
(författare)
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Long-term risk of osteoporotic fracture in Malmo
- 2000
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 11:8, s. 669-674
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of the present study were to estimate long-term risks of osteoporotic fractures. The incidence of hip, distal forearm, proximal humerus and vertebral fracture were obtained from patient records in Malmo, Sweden. Vertebral fractures were confined to those coming to clinical attention, either as an inpatient or an outpatient case. Patient records were examined to exclude individuals with prior fractures at the same site. Future mortality rates were computed for each year of age from Poisson models using the Swedish Patient Register and the Statistical Year Book. The incidence and lifetime risk of any fracture were determined from the proportion of individuals fracture-free from the age of 45 years. Lifetime risk of shoulder, forearm, hip and spine fracture were 13.3%, 21.5%, 23.3% and 15.4% respectively in women at the age of 45 years. Corresponding values for men at the age of 45 years were 4.4%, 5.2%, 11.2% and 8.6%. The risk of any of these fractures was 47.3% and 23.8% in women and men respectively. Remaining lifetime risk was stable with age for hip fracture, but decreased by 20-30% by the age of 70 years in the case of other fractures. Ten and 15 year risks for all types of fractures increased with age until the age of 80 years, when they approached lifetime risks because of the competing probabilities of fracture and death. We conclude that fractures of the hip and spine carry higher risks than fractures at other sites, and that lifetime risks of fracture of the hip in particular have been underestimated.
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| 5. |
- Kanis, J.A., et al.
(författare)
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Prediction of fracture from low bone mineral density measurements overestimates risk
- 2000
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Ingår i: Bone (New York, N.Y.). - : Elsevier Inc. - 1873-2763 .- 8756-3282. ; 26:4, s. 387-391
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Tidskriftsartikel (refereegranskat)abstract
- There is a well-established relationship between bone mineral density (BMD) and fracture risk. Estimates of the relative risk of fracture from BMD have been derived mainly from short-term studies in which the correlation between BMD at assessment and BMD in later life ranged from 0.8 to 0.9. Because individuals lose bone mineral at different rates throughout later life, the long-term predictive value of low BMD is likely to decrease progressively with time. This article examines and formalizes the relationship between current BMD, correlation coefficients, and long-term risk. The loss of predictive value has important implications for early assessment and supports the view that measurements should be optimally targeted at the time interventions are contemplated and, when necessary, repeated in later life.
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| 6. |
- Kanis, J.A, et al.
(författare)
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Risk of hip fracture according to the World Health Organization criteria for osteopenia and osteoporosis
- 2000
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Ingår i: Bone. - : Elsevier Inc. - 1873-2763 .- 8756-3282. ; 27:5, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- The risk of hip fracture is commonly expressed as a relative risk. The aim of this study was to examine the utility of relative risks of hip fracture in men and women using World Health Organization (WHO) diagnostic criteria for low bone mass and osteoporosis. Reference data for bone mineral density (BMD) at the femoral neck, from the third National Health and Nutrition Examination Survey (NHANES III), were applied to the population of Sweden. Relative risks (RRs) were calculated from the known relationship between BMD at the femoral neck and hip fracture risk. The apparent prevalence of low bone mass and osteoporosis depended on the segment of the young population chosen for reference ranges. Using a reference derived from women aged 20–29 years, the prevalence of osteoporosis was 21.2% in women between the ages of 50 and 84 years and 6.3% in men. The RRs associated with osteoporosis depended markedly on the risk comparison. For example, in men or women aged 50 years, the RR of hip fracture in those with osteoporosis compared to those without osteoporosis was 7.4 and 6.1, respectively. The RR of those at the threshold value for osteoporosis compared to those with an average value for BMD at that age was 6.6 and 4.6 in men and women, respectively. RRs were lower comparing those at the threshold value compared to the risk of the general population at that age (4.2 and 2.9, respectively). When RR was expressed in relation to the population risk rather than to the risk at the average value for BMD, RR decreased at all ages by 37%. Such adjustments are required for risk assessment in individuals and for the combined use of different risk factors. Because the average T score at each age decreased with age, the RR of hip fracture at any age decreased with advancing age in the presence of osteoporosis. The decrease in relative risk with age is, however, associated with an increase in absolute risk. Thus, for clinical use, the expression of absolute risks may be preferred to relative risks.
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| 7. |
- Kanis, J A, et al.
(författare)
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Risk of hip fracture derived from relative risks: an analysis applied to the population of Sweden
- 2000
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Ingår i: Osteoporosis international. - 1433-2965 .- 0937-941X. ; 11:2, s. 120-127
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Tidskriftsartikel (refereegranskat)abstract
- Bone mineral density measurements are widely used to estimate the relative risk of hip fracture. In addition, many other risk factors have been identified, some of which are known to add to the risk independently of other risk factors, including bone mineral density measurements. In this paper we develop an algorithm that converts relative risks for hip fracture to absolute (15 years and lifetime) risks, modeled on the population of Sweden. Lifetime risks increased as expected with increments in relative risk. Average lifetime risk in women at the age of 50 years was 22.7%, which increased to 64.9% when the relative risk was 6.0. In men the risk increased from 11.1% to 41.3%. The identification of high-risk groups had little effect on the specificity of assessments but increased the sensitivity over a wide range of assumptions. The increment in lifetime risk was relatively stable across all ages, reducing the complexity of computing lifetime risks from relative risk. The derivation of absolute risk from relative risk permits the optimization of selection of individuals or populations either for further risk assessment or for treatment.
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| 8. |
- Kanis, J A, et al.
(författare)
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Ten year probabilities of osteoporotic fractures according to BMD and diagnostic thresholds
- 2001
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Ingår i: Osteoporosis international. - : Springer Science and Business Media LLC. - 1433-2965 .- 0937-941X. ; 12:12, s. 989-995
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of the present study were to estimate 10 year probabilities of osteoporotic fractures in men and women according to age and bone mineral density (BMD) at the femoral neck. Risks were computed from the incidence of a first hip, distal forearm, proximal humerus and symptomatic vertebral fracture from patient records in Malmö, Sweden and future mortality rates for each year of age from Poisson models using the Swedish patient register and statistical year book. Fracture probability was computed using the Swedish population and cut-off values for T-scores based on the NHANES III female population. We assumed that the risk of fracture increased with decreasing BMD as assessed by meta-analysis in independent studies. The 10-year probability of any fracture was determined from the proportion of individuals fracture-free from the age of 45 years. With the exception of forearm fractures in men, 10 year probabilities increased with age and T-score. In the case of hip and spine fractures, fracture probabilities for any age with low BMD were similar between men and women. The effect of age on risk independently of BMD suggests that intervention thresholds should not be at a fixed T-score but vary according to absolute probabilities. Intervention thresholds based on hip BMD T-scores are similar between sexes.
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| 9. |
- Lettevall, Erland, et al.
(författare)
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Social structure and residency in aggregations of male sperm whales
- 2002
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Ingår i: Canadian Journal of Zoology-Revue Canadienne De Zoologie. - 0008-4301. ; 80:7, s. 1189-1196
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Tidskriftsartikel (refereegranskat)abstract
- Sperm whales (Physeter macrocephalus) are sexually dimorphic in several respects, including size, latitudinal distribution, and social structure. Females are known to have complex social structures, including long-term bonds, but the social structures of sexually mature or maturing males have received much less attention. Using data from aggregations of males off Norway, Nova Scotia, New Zealand, and the Galapagos Islands, we examined aggregation size, residence times within aggregations, clustering at the surface, and long-term bonds. Results were generally consistent among study areas. The aggregations found in each area contained around 10-30 males at any time, and were usually a few tens of kilometres across. Mean residence times within aggregations ranged from a few days to a few weeks. Close clustering at the surface was rare, but present at each site. There was no evidence for preferred companionship between individuals at any temporal scale in any of the study areas. The rarity of clustering and the apparent lack of long-term relationships amongst male sperm whales contrast strongly with results of studies on females, suggesting that both close spatial proximity at the surface and permanent bonds between individuals may be a consequence of the need for care of the young.
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| 10. |
- Oden, A, et al.
(författare)
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The burden of osteoporotic fractures : A method for setting intervention thresholds
- 2001
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Ingår i: Osteoporosis international. - : Springer. - 1433-2965 .- 0937-941X. ; 12:5, s. 417-427
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess the relationship between morbidity from hip fracture and that from other osteoporotic fractures by age and sex based on the population of Sweden. Osteoporotic fractures were designated as those associated with low bone mineral density (BMD) and those that increased in incidence with age after the age of 50 years. Severity of fractures was weighted according to their morbidity using utility values based on those derived by the National Osteoporosis Foundation. Morbidity from fractures other than hip fracture was converted to hip fracture equivalents according to their disutility weights. Excess morbidity was 3.34 and 4.75 in men and women at the age of 50 years, i.e. the morbidity associated with osteoporotic fractures was 3-5 times that accounted for by hip fracture. Excess morbidity decreased with age to approximately 1.25 between the ages of 85 and 89 years. On the assumption that the age- and sex-specific pattern of fractures due to osteoporosis is similar in different communities, the computation of excess morbidity can be utilized to determine the total morbidity from osteoporotic fractures from knowledge of hip fracture rates alone. Such data can be used to weight probabilities of hip fracture in different countries in order to take into account the morbidity from fractures other than hip fracture, and to modify intervention thresholds based on hip fracture risk alone. If, for example, a 10-year probability of hip fracture of 10% was considered an intervention threshold, this would be exceeded in women with osteoporosis aged 65 years and more, but when weighted for other osteoporotic fractures would be exceeded in all women (and men) with osteoporosis.
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