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Papers by Chris Laet

Journal of Bone and Mineral Research, 2009

Abstract—Limited information exists about the consequences,of hypertension during adulthood on re... more Abstract—Limited information exists about the consequences,of hypertension during adulthood on residual life expectancy with cardiovascular disease. We aimed to analyze the life course of people with high blood pressure levels at age 50 in terms of total life expectancy,and life expectancy,with and without,cardiovascular disease compared,with normotensives. We constructed multistate life tables for cardiovascular disease, myocardial infarction, and stroke using data

International Journal of Technology Assessment in Health Care, 2009

The cost-effectiveness of adding a human papillomavirus (HPV) vaccination program in 12-year-old ... more The cost-effectiveness of adding a human papillomavirus (HPV) vaccination program in 12-year-old females to the recommended cervical cancer screening in Belgium is examined. Moreover, the health and economic consequences of a potential decline in screening uptake after initiation of a HPV vaccination program are investigated. A static Markov model is developed to estimate the direct effect of vaccination on precancerous lesions and cervical cancers. Vaccination is estimated to avoid 20 percent of the cervical cancers occurring in a 12-year-old girls' cohort and to cost 32,665 euro per quality-adjusted life-year (QALY) gained (95 percent credibility interval [CrI]: 17,447 euro to 68,078 euro), assuming a booster injection after 10 years, a limited duration of protection and discounting costs and effects at 3 percent and 1.5 percent, respectively. Assuming lifelong protection, HPV vaccination is estimated to cost 14,382 euro (95 percent CrI: 9,238 euro to 25,644 euro) per QALY gained, while avoiding 50 percent of the cervical cancer cases. In the base-case, a 10 percent reduction in screening compliance after vaccination obliterates the effect of vaccination on cervical cancer cases avoided, whereas further declines in the level of screening compliance even turned out to be detrimental for the cohort's health, inducing a mean loss in QALYs and life-year gained compared with the situation prevaccination. An HPV vaccination program should only be considered if the level of screening after vaccination can be maintained.

Osteoporosis International, 2005

The value of bone mineral density (BMD) measurements to stratify fracture probability can be enha... more The value of bone mineral density (BMD) measurements to stratify fracture probability can be enhanced in a case-finding strategy that combines BMD measurement with independent clinical risk indicators. Putative risk indicators include age and gender, BMI or weight, prior fracture, the use of corticosteroids, and possibly others. The aim of the present study was to develop a mathematical framework to

Osteoporosis International, 2005

The aim of this study was to determine the threshold of fracture probability at which interventio... more The aim of this study was to determine the threshold of fracture probability at which interventions became cost-effective in men and women, based on data from Sweden. We modeled the effects of a treatment costing $500 per year given for 5 years that decreased the risk of all osteoporotic fractures by 35% followed by a waning of effect for a further

Osteoporosis International, 2004

The aim of this study was to determine the risk and burden of vertebral fractures judged as those... more The aim of this study was to determine the risk and burden of vertebral fractures judged as those coming to clinical attention and as morphometric fractures. Incidence and utility loss were computed from data from Malmo, Sweden. Clinical fractures accounted for 23% of all vertebral deformities in women and for 42% in men. The average 10-year fracture probability for morphometric

Bone, 2000

The risk of hip fracture is commonly expressed as a relative risk. The aim of this study was to e... more 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

Osteoporosis International, 2004

The aim of this study was to examine the pattern of mortality following osteoporotic fractures at... more The aim of this study was to examine the pattern of mortality following osteoporotic fractures at the spine, shoulder, hip, and forearm. We studied 2,847 patients with fractures at these sites identified from the radiology department in Malmö, Sweden. Poisson regression was used to compute mortality immediately after the fracture and with time. Mortality immediately after fracture was significantly higher

Osteoporosis International, 2001

Osteoporosis International, 2005

The diagnosis of osteoporosis is based on the measurement of bone mineral density (BMD). There ar... more The diagnosis of osteoporosis is based on the measurement of bone mineral density (BMD). There are a number of clinical risk factors that provide information on fracture risk over and above that given by BMD. The assessment of fracture risk thus needs to be distinguished from diagnosis to take account of the independent value of the clinical risk factors. These

PharmacoEconomics, 2009

There has been a steep increase in the number of percutaneous coronary intervention procedures pe... more There has been a steep increase in the number of percutaneous coronary intervention procedures performed for coronary heart disease since their introduction about 30 years ago. Recently, the use of drug-eluting stents (DES) compared with the original bare metal stents (BMS) has increased in many countries. To assess the cost effectiveness of DES versus BMS in a real-world setting from the Belgian healthcare payer perspective. We developed a decision analysis model to estimate incremental costs (year 2004 or 2007 values [depending on the underlying variable]) and effectiveness. Incremental effectiveness was calculated by combining relative benefits from published meta-analyses with real-world observations from a Belgian registry. Probabilistic modelling and sensitivity analyses were performed. The model had a 1-year time horizon. Sixteen sub groups were created based on the following characteristics: initial stent type, diabetic status, complex lesion and multi-vessel disease. Scenario analyses were performed for the influence on reinterventions and the duration of clopidogrel use. In each analysis, 1000 Monte Carlo simulations were performed. The incremental costs for switching from BMS to DES are substantial (approximately euro1000), while the benefits, expressed as QALYs, are extremely small (on average <0.001 QALYs gained). This led to very high incremental cost-effectiveness ratios: over euro860 000 per QALY gained in all subgroups and scenario analyses. Comparing DES with BMS, no life-years are gained and small quality-of-life improvements are achieved for short periods, resulting in a high likelihood that DES are not cost effective. When there is competition for scarce resources this should be considered when deciding on the reimbursement of this technology.

Osteoporosis International, 2000

Osteoporosis International, 2004

The aim of this study was to examine the pattern of fracture risk following a prior fracture at t... more The aim of this study was to examine the pattern of fracture risk following a prior fracture at the spine, shoulder or hip. We studied 1918 patients with fractures at these sites identified from the Department of Radiology in Malmo who were followed for 5 years. Poisson regression was used to compute fracture rates immediately after the initial fracture and at 5 years thereafter in men and women aged 60 or 80 years. Immediate fracture risk was higher than that of the general population, more markedly so at the age of 60 than at 80 years. At the age of 60 years, the risk of hip, forearm and spine fractures were significantly increased following a prior spine, hip or shoulder fracture in men. A similar pattern was seen in women, except that the increase in risk of forearm fracture following a spine or hip fracture was not statistically significant. The incidence of further fractures at the shoulder, spine or hip fell with time after the first fracture, a fall that was significant for all fractures after a shoulder fracture, hip fracture after a spine fracture, and hip and spine fractures after a hip fracture. We conclude that the risk of a subsequent fracture immediately after an osteoporotic fracture is highest immediately after the event. This provides a rationale for very early intervention immediately after fractures to avoid recurrent fractures.

Osteoporosis International, 2001

Osteoporosis International, 2005

Osteoporosis International, 2004

An excess mortality is well described after vertebral fracture. Deaths are in part related to co-... more An excess mortality is well described after vertebral fracture. Deaths are in part related to co-morbidity, but could also be due to the fracture event itself, either directly or indirectly. The aim of this study was to examine the quantum and pattern of mortality following vertebral fracture. We identified 16,051 men and women aged 50 years or more with a vertebral fracture that required hospitalization in 28.8 million person years from the patient register of Sweden. Mortality after vertebral fracture was examined using Poisson models applied to fracture patients and compared to that of the general population. At all ages, the risk of death was markedly increased immediately after the event. After a short period of declining risk, the risk increased with age at a rate that was higher than that of the general population and comparable to that 1 year after hip fracture. The latter function was assumed to be due to deaths related to co-morbidity and the residuum assumed to be due to the vertebral fracture. Causally related deaths comprised 28% of all deaths associated with vertebral fracture (depending on age). We conclude that a minority of deaths following hospitalization for vertebral fracture are attributable to the fracture itself under the assumptions we used.

Osteoporosis International, 2005

Osteoporosis International, 2005

Osteoporosis International, 2005

Smoking is widely considered a risk factor for future fracture. The aim of this study was to quan... more Smoking is widely considered a risk factor for future fracture. The aim of this study was to quantify this risk on an international basis and to explore the relationship of this risk with age, sex and bone mineral density (BMD). We studied 59,232 men and women (74% female) from ten prospective cohorts comprising EVOS/EPOS, DOES, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, Hiroshima and two cohorts from Gothenburg. Cohorts were followed for a total of 250,000 person-years. The effect of current or past smoking, on the risk of any fracture, any osteoporotic fracture and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined were age, sex and BMD. The results of the different studies were merged using the weighted beta-coefficients. Current smoking was associated with a significantly increased risk of any fracture compared to non-smokers (RR=1.25; 95% Confidence Interval (CI)=1.15-1.36). Risk ratio (RR) was adjusted marginally downward when account was taken of BMD, but it remained significantly increased (RR=1.13). For an osteoporotic fracture, the risk was marginally higher (RR=1.29; 95% CI=1.13-1.28). The highest risk was observed for hip fracture (RR=1.84; 95% CI=1.52-2.22), but this was also somewhat lower after adjustment for BMD (RR=1.60; 95% CI=1.27-2.02). Risk ratios were significantly higher in men than in women for all fractures and for osteoporotic fractures, but not for hip fracture. Low BMD accounted for only 23% of the smoking-related risk of hip fracture. Adjustment for body mass index had a small downward effect on risk for all fracture outcomes. For osteoporotic fracture, the risk ratio increased with age, but decreased with age for hip fracture. A smoking history was associated with a significantly increased risk of fracture compared with individuals with no smoking history, but the risk ratios were lower than for current smoking. We conclude that a history of smoking results in fracture risk that is substantially greater than that explained by measurement of BMD. Its validation on an international basis permits the use of this risk factor in case finding strategies.

Osteoporosis International, 2002

Journal of Bone and Mineral Research, 2009

Abstract—Limited information exists about the consequences,of hypertension during adulthood on re... more Abstract—Limited information exists about the consequences,of hypertension during adulthood on residual life expectancy with cardiovascular disease. We aimed to analyze the life course of people with high blood pressure levels at age 50 in terms of total life expectancy,and life expectancy,with and without,cardiovascular disease compared,with normotensives. We constructed multistate life tables for cardiovascular disease, myocardial infarction, and stroke using data

International Journal of Technology Assessment in Health Care, 2009

The cost-effectiveness of adding a human papillomavirus (HPV) vaccination program in 12-year-old ... more The cost-effectiveness of adding a human papillomavirus (HPV) vaccination program in 12-year-old females to the recommended cervical cancer screening in Belgium is examined. Moreover, the health and economic consequences of a potential decline in screening uptake after initiation of a HPV vaccination program are investigated. A static Markov model is developed to estimate the direct effect of vaccination on precancerous lesions and cervical cancers. Vaccination is estimated to avoid 20 percent of the cervical cancers occurring in a 12-year-old girls' cohort and to cost 32,665 euro per quality-adjusted life-year (QALY) gained (95 percent credibility interval [CrI]: 17,447 euro to 68,078 euro), assuming a booster injection after 10 years, a limited duration of protection and discounting costs and effects at 3 percent and 1.5 percent, respectively. Assuming lifelong protection, HPV vaccination is estimated to cost 14,382 euro (95 percent CrI: 9,238 euro to 25,644 euro) per QALY gained, while avoiding 50 percent of the cervical cancer cases. In the base-case, a 10 percent reduction in screening compliance after vaccination obliterates the effect of vaccination on cervical cancer cases avoided, whereas further declines in the level of screening compliance even turned out to be detrimental for the cohort's health, inducing a mean loss in QALYs and life-year gained compared with the situation prevaccination. An HPV vaccination program should only be considered if the level of screening after vaccination can be maintained.

Osteoporosis International, 2005

The value of bone mineral density (BMD) measurements to stratify fracture probability can be enha... more The value of bone mineral density (BMD) measurements to stratify fracture probability can be enhanced in a case-finding strategy that combines BMD measurement with independent clinical risk indicators. Putative risk indicators include age and gender, BMI or weight, prior fracture, the use of corticosteroids, and possibly others. The aim of the present study was to develop a mathematical framework to

Osteoporosis International, 2005

The aim of this study was to determine the threshold of fracture probability at which interventio... more The aim of this study was to determine the threshold of fracture probability at which interventions became cost-effective in men and women, based on data from Sweden. We modeled the effects of a treatment costing $500 per year given for 5 years that decreased the risk of all osteoporotic fractures by 35% followed by a waning of effect for a further

Osteoporosis International, 2004

The aim of this study was to determine the risk and burden of vertebral fractures judged as those... more The aim of this study was to determine the risk and burden of vertebral fractures judged as those coming to clinical attention and as morphometric fractures. Incidence and utility loss were computed from data from Malmo, Sweden. Clinical fractures accounted for 23% of all vertebral deformities in women and for 42% in men. The average 10-year fracture probability for morphometric

Bone, 2000

The risk of hip fracture is commonly expressed as a relative risk. The aim of this study was to e... more 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

Osteoporosis International, 2004

The aim of this study was to examine the pattern of mortality following osteoporotic fractures at... more The aim of this study was to examine the pattern of mortality following osteoporotic fractures at the spine, shoulder, hip, and forearm. We studied 2,847 patients with fractures at these sites identified from the radiology department in Malmö, Sweden. Poisson regression was used to compute mortality immediately after the fracture and with time. Mortality immediately after fracture was significantly higher

Osteoporosis International, 2001

Osteoporosis International, 2005

The diagnosis of osteoporosis is based on the measurement of bone mineral density (BMD). There ar... more The diagnosis of osteoporosis is based on the measurement of bone mineral density (BMD). There are a number of clinical risk factors that provide information on fracture risk over and above that given by BMD. The assessment of fracture risk thus needs to be distinguished from diagnosis to take account of the independent value of the clinical risk factors. These

PharmacoEconomics, 2009

There has been a steep increase in the number of percutaneous coronary intervention procedures pe... more There has been a steep increase in the number of percutaneous coronary intervention procedures performed for coronary heart disease since their introduction about 30 years ago. Recently, the use of drug-eluting stents (DES) compared with the original bare metal stents (BMS) has increased in many countries. To assess the cost effectiveness of DES versus BMS in a real-world setting from the Belgian healthcare payer perspective. We developed a decision analysis model to estimate incremental costs (year 2004 or 2007 values [depending on the underlying variable]) and effectiveness. Incremental effectiveness was calculated by combining relative benefits from published meta-analyses with real-world observations from a Belgian registry. Probabilistic modelling and sensitivity analyses were performed. The model had a 1-year time horizon. Sixteen sub groups were created based on the following characteristics: initial stent type, diabetic status, complex lesion and multi-vessel disease. Scenario analyses were performed for the influence on reinterventions and the duration of clopidogrel use. In each analysis, 1000 Monte Carlo simulations were performed. The incremental costs for switching from BMS to DES are substantial (approximately euro1000), while the benefits, expressed as QALYs, are extremely small (on average <0.001 QALYs gained). This led to very high incremental cost-effectiveness ratios: over euro860 000 per QALY gained in all subgroups and scenario analyses. Comparing DES with BMS, no life-years are gained and small quality-of-life improvements are achieved for short periods, resulting in a high likelihood that DES are not cost effective. When there is competition for scarce resources this should be considered when deciding on the reimbursement of this technology.

Osteoporosis International, 2000

Osteoporosis International, 2004

The aim of this study was to examine the pattern of fracture risk following a prior fracture at t... more The aim of this study was to examine the pattern of fracture risk following a prior fracture at the spine, shoulder or hip. We studied 1918 patients with fractures at these sites identified from the Department of Radiology in Malmo who were followed for 5 years. Poisson regression was used to compute fracture rates immediately after the initial fracture and at 5 years thereafter in men and women aged 60 or 80 years. Immediate fracture risk was higher than that of the general population, more markedly so at the age of 60 than at 80 years. At the age of 60 years, the risk of hip, forearm and spine fractures were significantly increased following a prior spine, hip or shoulder fracture in men. A similar pattern was seen in women, except that the increase in risk of forearm fracture following a spine or hip fracture was not statistically significant. The incidence of further fractures at the shoulder, spine or hip fell with time after the first fracture, a fall that was significant for all fractures after a shoulder fracture, hip fracture after a spine fracture, and hip and spine fractures after a hip fracture. We conclude that the risk of a subsequent fracture immediately after an osteoporotic fracture is highest immediately after the event. This provides a rationale for very early intervention immediately after fractures to avoid recurrent fractures.

Osteoporosis International, 2001

Osteoporosis International, 2005

Osteoporosis International, 2004

An excess mortality is well described after vertebral fracture. Deaths are in part related to co-... more An excess mortality is well described after vertebral fracture. Deaths are in part related to co-morbidity, but could also be due to the fracture event itself, either directly or indirectly. The aim of this study was to examine the quantum and pattern of mortality following vertebral fracture. We identified 16,051 men and women aged 50 years or more with a vertebral fracture that required hospitalization in 28.8 million person years from the patient register of Sweden. Mortality after vertebral fracture was examined using Poisson models applied to fracture patients and compared to that of the general population. At all ages, the risk of death was markedly increased immediately after the event. After a short period of declining risk, the risk increased with age at a rate that was higher than that of the general population and comparable to that 1 year after hip fracture. The latter function was assumed to be due to deaths related to co-morbidity and the residuum assumed to be due to the vertebral fracture. Causally related deaths comprised 28% of all deaths associated with vertebral fracture (depending on age). We conclude that a minority of deaths following hospitalization for vertebral fracture are attributable to the fracture itself under the assumptions we used.

Osteoporosis International, 2005

Osteoporosis International, 2005

Osteoporosis International, 2005

Smoking is widely considered a risk factor for future fracture. The aim of this study was to quan... more Smoking is widely considered a risk factor for future fracture. The aim of this study was to quantify this risk on an international basis and to explore the relationship of this risk with age, sex and bone mineral density (BMD). We studied 59,232 men and women (74% female) from ten prospective cohorts comprising EVOS/EPOS, DOES, CaMos, Rochester, Sheffield, Rotterdam, Kuopio, Hiroshima and two cohorts from Gothenburg. Cohorts were followed for a total of 250,000 person-years. The effect of current or past smoking, on the risk of any fracture, any osteoporotic fracture and hip fracture alone was examined using a Poisson model for each sex from each cohort. Covariates examined were age, sex and BMD. The results of the different studies were merged using the weighted beta-coefficients. Current smoking was associated with a significantly increased risk of any fracture compared to non-smokers (RR=1.25; 95% Confidence Interval (CI)=1.15-1.36). Risk ratio (RR) was adjusted marginally downward when account was taken of BMD, but it remained significantly increased (RR=1.13). For an osteoporotic fracture, the risk was marginally higher (RR=1.29; 95% CI=1.13-1.28). The highest risk was observed for hip fracture (RR=1.84; 95% CI=1.52-2.22), but this was also somewhat lower after adjustment for BMD (RR=1.60; 95% CI=1.27-2.02). Risk ratios were significantly higher in men than in women for all fractures and for osteoporotic fractures, but not for hip fracture. Low BMD accounted for only 23% of the smoking-related risk of hip fracture. Adjustment for body mass index had a small downward effect on risk for all fracture outcomes. For osteoporotic fracture, the risk ratio increased with age, but decreased with age for hip fracture. A smoking history was associated with a significantly increased risk of fracture compared with individuals with no smoking history, but the risk ratios were lower than for current smoking. We conclude that a history of smoking results in fracture risk that is substantially greater than that explained by measurement of BMD. Its validation on an international basis permits the use of this risk factor in case finding strategies.

Osteoporosis International, 2002