Abdelouahid Tajar | University of Oxford (original) (raw)
Papers by Abdelouahid Tajar
The Journal of Clinical Endocrinology and Metabolism, Apr 1, 2010
European Journal of Endocrinology, 2013
ObjectiveHealth and lifestyle factors are associated with variations in serum testosterone levels... more ObjectiveHealth and lifestyle factors are associated with variations in serum testosterone levels in ageing men. However, it remains unclear how age-related changes in testosterone may be attenuated by lifestyle modifications. The objective was to investigate the longitudinal relationships between changes in health and lifestyle factors with changes in hormones of the reproductive endocrine axis in ageing men.DesignA longitudinal survey of 2736 community-dwelling men aged 40–79 years at baseline recruited from eight centres across Europe. Follow-up assessment occurred mean (±s.d.) 4.4±0.3 years later.ResultsPaired testosterone results were available for 2395 men. Mean (±s.d.) annualised hormone changes were as follows: testosterone −0.1±0.95 nmol/l; free testosterone (FT) −3.83±16.8 pmol/l; sex hormone-binding globulin (SHBG) 0.56±2.5 nmol/l and LH 0.08±0.57 U/l. Weight loss was associated with a proportional increase, and weight gain a proportional decrease, in testosterone and SHB...
Circulation, 2013
Background— HIV infection continues to be endemic worldwide. Although treatments are successful, ... more Background— HIV infection continues to be endemic worldwide. Although treatments are successful, it remains controversial whether patients receiving optimal therapy have structural, functional, or biochemical cardiac abnormalities that may underlie their increased cardiac morbidity and mortality. The purpose of this study was to characterize myocardial abnormalities in a contemporary group of HIV-infected individuals undergoing combination antiretroviral therapy. Methods and Results— Volunteers with HIV who were undergoing combination antiretroviral therapy and age-matched control subjects without a history of cardiovascular disease underwent cardiac magnetic resonance imaging and spectroscopy for the determination of cardiac function, myocardial fibrosis, and myocardial lipid content. A total of 129 participants were included in this analysis. Compared with age-matched control subjects (n=39; 30.23%), HIV-infected subjects undergoing combination antiretroviral therapy (n=90; 69.77%...
BMC Medical Research Methodology, 2014
The Endocrine Society's 92nd Annual Meeting, June 19–22, 2010 - San Diego, 2010
Pain, 2010
Evidence from clinic-based studies suggests that the fibromyalgia syndrome (FMS) is associated wi... more Evidence from clinic-based studies suggests that the fibromyalgia syndrome (FMS) is associated with impairment in cognitive function though the mechanism is unclear. The aim of this analysis was to determine whether there is a similar association between chronic widespread pain (CWP), a cardinal feature of FMS, and impaired cognition in a community setting. Men (n=3369, 40-79 years) were recruited from population registers in eight centres for participation in the European Male Ageing Study (EMAS). The subjects completed a pain questionnaire and pain manikin, with the presence of CWP defined using the American College of Rheumatology criteria. The cognitive functions measured were visuospatial-constructional ability and visual memory (Rey-Osterrieth Complex Figure [ROCF]); visual recognition (Camden Topographical Recognition Memory test [CTRM]); and psychomotor processing speed (Digit-Symbol Substitution test [DSST]). We restricted our analysis to those subjects reporting pain that satisfied the criteria for CWP and those who were pain free. Of these 1539 men [mean (SD) age 60 (11) years], 266 had CWP. All cognitive test scores declined cross-sectionally with age (P<0.05). In age-adjusted linear regressions men with CWP had a lower DSST score (β=-2.4, P<0.001) compared to pain-free subjects. After adjustment for lifestyle and health factors the association between pain status and the DSST score was attenuated but remained significant (β=-1.02, P=0.04). There was no association between CWP and the ROCF-copy, ROCF-recall or CTRM scores. CWP is associated with slower psychomotor processing speed among community-dwelling European men. Prospective studies are required to confirm this observation and explore possible mechanisms for the association.
The Journals of Gerontology: Series A, 2012
Journal of Bone and Mineral Research, 2009
Genes involved in sex hormone pathways are candidates for influencing bone strength. Polymorphism... more Genes involved in sex hormone pathways are candidates for influencing bone strength. Polymorphisms in these genes were tested for association with heel quantitative ultrasound (QUS) parameters in middle-aged and elderly European men. Men 40-79 yr of age were recruited from population registers in eight European centers for the European Male Aging Study (EMAS). Polymorphisms were genotyped in AR, ESR1, ESR2, CYP19A1, CYP17A1, SHBG, SRD5A2, LHB, and LHCGR. QUS parameters broadband ultrasound attenuation (BUA) and speed of sound (SOS) were measured in the heel and used to derive BMD. The relationships between QUS parameters and polymorphisms were assessed using linear regression adjusting for age and center. A total of 2693 men, with a mean age of 60.1 +/- 11.1 (SD) yr were included in the analysis. Their mean BUA was 80.0 +/- 18.9 dB/Mhz, SOS was 1550.2 +/- 34.1 m/s, and BMD was 0.542 +/- 0.141 g/cm(2). Significant associations were observed between multiple SNPs in a linkage disequilibrium (LD) block within CYP19A1, peaking at the TCT indel with the deletion allele associating with reduced ultrasound BMD in heterozygotes (beta =-0.016, p = -0.005) and homozygotes (beta = -0.029, p = 0.001). The results for BUA and SOS were similar. Significant associations with QUS parameters were also observed for the CAG repeat in AR and SNPs in CYP17A1, LHCGR, and ESR1. Our data confirm evidence of association between bone QUS parameters and polymorphisms in CYP19A1, as well as modest associations with polymorphisms in CYP17A1, ESR1, LHCGR, and AR in a population sample of European men; this supports a role for genetically determined sex hormone actions in influencing male bone health.
Archives of Gerontology and Geriatrics, 2013
Few studies have directly compared the ability of the most commonly used models of frailty to pre... more Few studies have directly compared the ability of the most commonly used models of frailty to predict mortality among community-dwelling individuals. Here, we used a frailty index (FI), frailty phenotype (FP), and FRAIL scale (FS) to predict mortality in the EMAS. Participants were aged 40-79 years (n=2929) at baseline and 6.6% (n=193) died over a median 4.3 years of follow-up. The FI was generated from 39 deficits, including self-reported health, morbidities, functional performance and psychological assessments. The FP and FS consisted of five phenotypic criteria and both categorized individuals as robust when they had 0 criteria, prefrail as 1-2 criteria and frail as 3+ criteria. The mean FI increased linearly with age (r(2)=0.21) and in Cox regression models adjusted for age, center, smoking and partner status the hazard ratio (HR) for death for each unit increase of the FI was 1.49. Men who were prefrail or frail by either the FP or FS definitions, had a significantly increased risk of death compared to their robust counterparts. Compared to robust men, those who were FP frail at baseline had a HR for death of 3.84, while those who were FS frail had a HR of 3.87. All three frailty models significantly predicted future mortality among community-dwelling, middle-aged and older European men after adjusting for potential confounders. Our data suggest that the choice of frailty model may not be of paramount importance when predicting future risk of death, enabling flexibility in the approach used.
The Journal of Clinical Endocrinology & Metabolism, 2012
European Journal of Endocrinology, 2012
ObjectiveIt has been suggested that elevated levels of C-reactive protein (CRP) might interfere w... more ObjectiveIt has been suggested that elevated levels of C-reactive protein (CRP) might interfere with leptin signalling and contribute to leptin resistance. Our aim was to assess whether plasma levels of CRP influence leptin resistance in humans, and our hypothesis was that CRP levels would modify the cross-sectional relationships between leptin and measures of adiposity.Design and methodsWe assessed four measures of adiposity: BMI, waist circumference, fat mass and body fat (%) in 2113 British Regional Heart Study (BRHS) men (mean (s.d.) age 69 (5) years), with replication in 760 (age 69 (6) years) European Male Ageing Study (EMAS) subjects.ResultsIn BRHS subjects, leptin correlated with CRP (Spearman's r=0.22, P<0.0001). Leptin and CRP correlated with all four measures of adiposity (r value range: 0.22–0.57, all P<0.0001). Age-adjusted mean levels for adiposity measures increased in relation to leptin levels, but CRP level did not consistently influence the β-coefficients...
European Journal of Endocrinology, 2011
ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the a... more ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.DesignA cross-sectional population-based survey.MethodsMen aged 40–79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E2), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.ResultsA total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment...
European Journal of Endocrinology, 2011
ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the a... more ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.DesignA cross-sectional population-based survey.MethodsMen aged 40–79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E2), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.ResultsA total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment...
European Journal of Endocrinology, 2011
ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the a... more ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.DesignA cross-sectional population-based survey.MethodsMen aged 40–79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E2), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.ResultsA total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment...
BMC musculoskeletal disorders, Jan 16, 2016
The association between low levels of vitamin D and the occurrence of chronic widespread pain (CW... more The association between low levels of vitamin D and the occurrence of chronic widespread pain (CWP) remains unclear. The aim of our analysis was to determine the relationship between low vitamin D levels and the risk of developing CWP in a population sample of middle age and elderly men. Three thousand three hundred sixty nine men aged 40-79 were recruited from 8 European centres for a longitudinal study of male ageing, the European Male Ageing Study. At baseline participants underwent assessment of lifestyle, health factors, physical characteristics and gave a fasting blood sample. The occurrence of pain was assessed at baseline and follow up (a mean of 4.3 years later) by shading painful sites on a body manikin. The presence of CWP was determined using the ACR criteria for fibromyalgia. Serum 25-hydroxyvitamin D (25-(OH) D) was assessed by radioimmunoassay. Logistic regression was used to determine the relationship between baseline vitamin D levels and the new occurrence of CWP. T...
The Journal of Clinical Endocrinology and Metabolism, Apr 1, 2010
European Journal of Endocrinology, 2013
ObjectiveHealth and lifestyle factors are associated with variations in serum testosterone levels... more ObjectiveHealth and lifestyle factors are associated with variations in serum testosterone levels in ageing men. However, it remains unclear how age-related changes in testosterone may be attenuated by lifestyle modifications. The objective was to investigate the longitudinal relationships between changes in health and lifestyle factors with changes in hormones of the reproductive endocrine axis in ageing men.DesignA longitudinal survey of 2736 community-dwelling men aged 40–79 years at baseline recruited from eight centres across Europe. Follow-up assessment occurred mean (±s.d.) 4.4±0.3 years later.ResultsPaired testosterone results were available for 2395 men. Mean (±s.d.) annualised hormone changes were as follows: testosterone −0.1±0.95 nmol/l; free testosterone (FT) −3.83±16.8 pmol/l; sex hormone-binding globulin (SHBG) 0.56±2.5 nmol/l and LH 0.08±0.57 U/l. Weight loss was associated with a proportional increase, and weight gain a proportional decrease, in testosterone and SHB...
Circulation, 2013
Background— HIV infection continues to be endemic worldwide. Although treatments are successful, ... more Background— HIV infection continues to be endemic worldwide. Although treatments are successful, it remains controversial whether patients receiving optimal therapy have structural, functional, or biochemical cardiac abnormalities that may underlie their increased cardiac morbidity and mortality. The purpose of this study was to characterize myocardial abnormalities in a contemporary group of HIV-infected individuals undergoing combination antiretroviral therapy. Methods and Results— Volunteers with HIV who were undergoing combination antiretroviral therapy and age-matched control subjects without a history of cardiovascular disease underwent cardiac magnetic resonance imaging and spectroscopy for the determination of cardiac function, myocardial fibrosis, and myocardial lipid content. A total of 129 participants were included in this analysis. Compared with age-matched control subjects (n=39; 30.23%), HIV-infected subjects undergoing combination antiretroviral therapy (n=90; 69.77%...
BMC Medical Research Methodology, 2014
The Endocrine Society's 92nd Annual Meeting, June 19–22, 2010 - San Diego, 2010
Pain, 2010
Evidence from clinic-based studies suggests that the fibromyalgia syndrome (FMS) is associated wi... more Evidence from clinic-based studies suggests that the fibromyalgia syndrome (FMS) is associated with impairment in cognitive function though the mechanism is unclear. The aim of this analysis was to determine whether there is a similar association between chronic widespread pain (CWP), a cardinal feature of FMS, and impaired cognition in a community setting. Men (n=3369, 40-79 years) were recruited from population registers in eight centres for participation in the European Male Ageing Study (EMAS). The subjects completed a pain questionnaire and pain manikin, with the presence of CWP defined using the American College of Rheumatology criteria. The cognitive functions measured were visuospatial-constructional ability and visual memory (Rey-Osterrieth Complex Figure [ROCF]); visual recognition (Camden Topographical Recognition Memory test [CTRM]); and psychomotor processing speed (Digit-Symbol Substitution test [DSST]). We restricted our analysis to those subjects reporting pain that satisfied the criteria for CWP and those who were pain free. Of these 1539 men [mean (SD) age 60 (11) years], 266 had CWP. All cognitive test scores declined cross-sectionally with age (P&amp;amp;amp;amp;amp;amp;amp;lt;0.05). In age-adjusted linear regressions men with CWP had a lower DSST score (β=-2.4, P&amp;amp;amp;amp;amp;amp;amp;lt;0.001) compared to pain-free subjects. After adjustment for lifestyle and health factors the association between pain status and the DSST score was attenuated but remained significant (β=-1.02, P=0.04). There was no association between CWP and the ROCF-copy, ROCF-recall or CTRM scores. CWP is associated with slower psychomotor processing speed among community-dwelling European men. Prospective studies are required to confirm this observation and explore possible mechanisms for the association.
The Journals of Gerontology: Series A, 2012
Journal of Bone and Mineral Research, 2009
Genes involved in sex hormone pathways are candidates for influencing bone strength. Polymorphism... more Genes involved in sex hormone pathways are candidates for influencing bone strength. Polymorphisms in these genes were tested for association with heel quantitative ultrasound (QUS) parameters in middle-aged and elderly European men. Men 40-79 yr of age were recruited from population registers in eight European centers for the European Male Aging Study (EMAS). Polymorphisms were genotyped in AR, ESR1, ESR2, CYP19A1, CYP17A1, SHBG, SRD5A2, LHB, and LHCGR. QUS parameters broadband ultrasound attenuation (BUA) and speed of sound (SOS) were measured in the heel and used to derive BMD. The relationships between QUS parameters and polymorphisms were assessed using linear regression adjusting for age and center. A total of 2693 men, with a mean age of 60.1 +/- 11.1 (SD) yr were included in the analysis. Their mean BUA was 80.0 +/- 18.9 dB/Mhz, SOS was 1550.2 +/- 34.1 m/s, and BMD was 0.542 +/- 0.141 g/cm(2). Significant associations were observed between multiple SNPs in a linkage disequilibrium (LD) block within CYP19A1, peaking at the TCT indel with the deletion allele associating with reduced ultrasound BMD in heterozygotes (beta =-0.016, p = -0.005) and homozygotes (beta = -0.029, p = 0.001). The results for BUA and SOS were similar. Significant associations with QUS parameters were also observed for the CAG repeat in AR and SNPs in CYP17A1, LHCGR, and ESR1. Our data confirm evidence of association between bone QUS parameters and polymorphisms in CYP19A1, as well as modest associations with polymorphisms in CYP17A1, ESR1, LHCGR, and AR in a population sample of European men; this supports a role for genetically determined sex hormone actions in influencing male bone health.
Archives of Gerontology and Geriatrics, 2013
Few studies have directly compared the ability of the most commonly used models of frailty to pre... more Few studies have directly compared the ability of the most commonly used models of frailty to predict mortality among community-dwelling individuals. Here, we used a frailty index (FI), frailty phenotype (FP), and FRAIL scale (FS) to predict mortality in the EMAS. Participants were aged 40-79 years (n=2929) at baseline and 6.6% (n=193) died over a median 4.3 years of follow-up. The FI was generated from 39 deficits, including self-reported health, morbidities, functional performance and psychological assessments. The FP and FS consisted of five phenotypic criteria and both categorized individuals as robust when they had 0 criteria, prefrail as 1-2 criteria and frail as 3+ criteria. The mean FI increased linearly with age (r(2)=0.21) and in Cox regression models adjusted for age, center, smoking and partner status the hazard ratio (HR) for death for each unit increase of the FI was 1.49. Men who were prefrail or frail by either the FP or FS definitions, had a significantly increased risk of death compared to their robust counterparts. Compared to robust men, those who were FP frail at baseline had a HR for death of 3.84, while those who were FS frail had a HR of 3.87. All three frailty models significantly predicted future mortality among community-dwelling, middle-aged and older European men after adjusting for potential confounders. Our data suggest that the choice of frailty model may not be of paramount importance when predicting future risk of death, enabling flexibility in the approach used.
The Journal of Clinical Endocrinology & Metabolism, 2012
European Journal of Endocrinology, 2012
ObjectiveIt has been suggested that elevated levels of C-reactive protein (CRP) might interfere w... more ObjectiveIt has been suggested that elevated levels of C-reactive protein (CRP) might interfere with leptin signalling and contribute to leptin resistance. Our aim was to assess whether plasma levels of CRP influence leptin resistance in humans, and our hypothesis was that CRP levels would modify the cross-sectional relationships between leptin and measures of adiposity.Design and methodsWe assessed four measures of adiposity: BMI, waist circumference, fat mass and body fat (%) in 2113 British Regional Heart Study (BRHS) men (mean (s.d.) age 69 (5) years), with replication in 760 (age 69 (6) years) European Male Ageing Study (EMAS) subjects.ResultsIn BRHS subjects, leptin correlated with CRP (Spearman's r=0.22, P<0.0001). Leptin and CRP correlated with all four measures of adiposity (r value range: 0.22–0.57, all P<0.0001). Age-adjusted mean levels for adiposity measures increased in relation to leptin levels, but CRP level did not consistently influence the β-coefficients...
European Journal of Endocrinology, 2011
ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the a... more ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.DesignA cross-sectional population-based survey.MethodsMen aged 40–79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E2), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.ResultsA total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment...
European Journal of Endocrinology, 2011
ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the a... more ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.DesignA cross-sectional population-based survey.MethodsMen aged 40–79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E2), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.ResultsA total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment...
European Journal of Endocrinology, 2011
ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the a... more ObjectiveTo assess the influence of sex hormones on markers of bone turnover and to explore the association between these markers and bone health in middle-aged and elderly European men.DesignA cross-sectional population-based survey.MethodsMen aged 40–79 years were recruited from population registers in eight European centres. Subjects completed a postal questionnaire which included questions concerning lifestyle and were invited to undergo quantitative ultrasound (QUS) of the calcaneus and to provide a fasting blood sample from which the bone markers serum N-terminal propeptide of type 1 procollagen (P1NP) and crosslinks (β C-terminal cross-linked telopeptide (β-cTX)), total testosterone, total oestradiol (E2), sex hormone-binding globulin (SHBG) and insulin-like growth factor 1 (IGF1) were measured. Dual-energy X-ray absorptiometry (DXA) of the hip and lumbar spine was performed in two centres.ResultsA total of 3120, mean age 59.9 years (s.d.=11.0) were included. After adjustment...
BMC musculoskeletal disorders, Jan 16, 2016
The association between low levels of vitamin D and the occurrence of chronic widespread pain (CW... more The association between low levels of vitamin D and the occurrence of chronic widespread pain (CWP) remains unclear. The aim of our analysis was to determine the relationship between low vitamin D levels and the risk of developing CWP in a population sample of middle age and elderly men. Three thousand three hundred sixty nine men aged 40-79 were recruited from 8 European centres for a longitudinal study of male ageing, the European Male Ageing Study. At baseline participants underwent assessment of lifestyle, health factors, physical characteristics and gave a fasting blood sample. The occurrence of pain was assessed at baseline and follow up (a mean of 4.3 years later) by shading painful sites on a body manikin. The presence of CWP was determined using the ACR criteria for fibromyalgia. Serum 25-hydroxyvitamin D (25-(OH) D) was assessed by radioimmunoassay. Logistic regression was used to determine the relationship between baseline vitamin D levels and the new occurrence of CWP. T...