Automatic registration of falls and other accidents among community dwelling older people: feasibility and reliability of the telephone inquiry system.
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Biomedical subjects
Publications and source records attributed to D L Knook.
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We tested the hypothesis that an additional effort to increase the response rate would diminish selection bias in a community-based cohort study. In the Leiden 85-plus Study, all subjects of the town of Leiden who had reached their 85th birthday were informed of the study by mail and then asked to participate by telephone. In an additional recruitment stage, those subjects who did not participate directly were visited and personally asked to participate. When these subjects refused, some nonresponse questions were asked. In this way we collected data on the whole source population. Of 691 eligible elderly subjects, 511 subjects (74%) participated directly. Of those who did not participate directly, 88 subjects participated after the additional effort. The response rate increased from 74% to 87%. Compared to the 511 subjects who directly participated, the 88 subjects who entered the study after the additional effort had poorer health and lower survival. The subjects who refused were more healthy and had poorer mood. The direct sample did not differ from the source population with respect to socio-demographics, health, and mortality. In conclusion, we showed that given a moderately high direct response the additional effort was effective in increasing the response rate, but was also selective and was not necessary to prevent selection bias.
Ample evidence supports a role for tumour necrosis factor alpha (TNFalpha) in the development of type 2 diabetes and cardiovascular disease. TNFalpha expression was found to be influenced by a -308G/A polymorphism in the promoter of the gene encoding TNFalpha (TNF). We investigated the contribution of this polymorphism to diabetes and cardiovascular mortality in a population-based cohort of 664 subjects aged 85 years and over (Leiden 85-plus Study). The -308G/A TNF promoter polymorphism was associated with the prevalence of diabetes in old age (P = 0.006). The risk of diabetes among subjects homozygous for the A-allele was estimated to be 4.6-fold (95% CI, 1.6-13.3) higher than among subjects homozygous for the common G-allele. The promoter polymorphism did not, however, predict mortality from all causes, cardiovascular diseases, cancer or infectious diseases during a 10-year follow-up period. In addition to the promoter polymorphism, TNFa and TNFc microsatellite genotypes were determined but these polymorphisms were not associated with morbidity or mortality. In conclusion, the -308G/A polymorphism in the TNF promoter is strongly associated with the risk of diabetes but not cardiovascular mortality in old age.
Responses to influenza vaccination are poor in frail elderly subjects who suffer the greatest morbidity and mortality due to infection. Therefore, a randomized clinical trial was performed to determine the effect of a double dose and booster vaccination on antibody responses after influenza vaccination. A total of 815 patients (median age 83 years, median disability score 8, median disease categories 2 and median number of medications 4) residing in 14 nursing homes in the Netherlands were vaccinated during the influenza season 1997-98. The first vaccine dose (15 or 30 microg) was given on Day 0 followed by a booster dose (placebo or 15 microg) on Day 84. Blood samples were taken before and 25 days after vaccination. There were four treatment groups: (i) 15 microg and placebo, (ii) 15 microg and 15 microg booster, (iii) 30 microg and placebo and (iv) 30 microg and 15 microg booster. Geometric mean antibody titers of those receiving the double vaccine dose was 15% (95% CI, 6% to 24%, P = 0.001) higher as compared to the standard 15 microg dose. A booster dose, given 84 days after the first vaccination, yielded postvaccination titters that were 14% (95% CI, 9% to 19%, P = 0.001) higher as compared to placebo. Subgroup analysis did not reveal patient groups that had a proportionally greater benefit from adapted vaccination strategies. It is concluded that higher antibody responses can be achieved in frail elderly people by a double vaccine dose or a booster vaccination.
After an introduction on the development of biological ageing research in the Netherlands during the past decades, 606 papers on aging published by Dutch institutes in the period 1991-2000, collected from PubMed, were analysed for their relevance to research into biological ageing. For the period 1996-2000, the total number of research papers on biological ageing amounted to 142, which accounts for 23% of all publications on ageing in that period. The number of publications per year did not change. On the basis of these papers and additional information provided by research groups a comprehensive overview of biological ageing research in the Netherlands is presented, together with an extensive literature list. Ageing of the central nervous system (CNS), of the endocrinological system and of the cardiovascular system are the topics most studied. It is concluded that general biological ageing research has not increased in the Netherlands over the last ten years, and that the infrastructure for basic biological ageing research in the Netherlands is weak.
OBJECTIVE: To investigate the discrepancies between outcomes for competence (can do) and actual performance (do do) in activities of daily living (ADLs). DESIGN: Baseline measurements of a population-based follow-up study. SETTING: Leiden 85-Plus Study, the Netherlands. PARTICIPANTS: Five hundred and ninety-nine persons, age 85. The response rate was 86%. MEASUREMENTS: Face-to-face interviews. Measurements of competence and actual performance were based on the Groningen Activity Restriction Scale. Help received was assessed for several domains. Prevalence rates for disability were assessed according to the concepts of both competence and actual performance. Analysis was performed separately for basic activities of daily living (BADLs) and instrumental activities of daily living (IADLs). RESULTS: Seventy-seven percent of the oldest old were competent to perform all the BADLs and performed them regularly. Fifteen percent were not competent to perform certain BADLs independently but performed them regularly with help from others. The prevalence of disability defined as inability in one or more BADLs was 22% for women and 10% for men. The prevalence of disability defined as inactivity in one or more BADLs was 16% for women and 17% for men. Only 5% of the oldest old were competent to perform all IADLs and performed them regularly. In spite of being competent, 70% did not perform certain IADLs regularly. The prevalence of disability defined as inability in one or more IADLs was 64% for women and 55% for men. The prevalence of disability defined as inactivity in one or more IADLs was 92% for women and 98% for men. CONCLUSION: The structural discrepancies between the outcomes of competence and actual performance have important consequences when estimating disability in old people. Promoting actual performance in IADLs may reduce disability.
OBJECTIVE: Limited formal education is associated with poor cognitive function. This could explain sex differences in cognitive function in the oldest old. Whether limited formal education explains differences in cognitive function between elderly women and men was explored. METHODS: The Leiden 85-plus Study is a population based study investigating all 85 year old inhabitants of Leiden with an overall response rate of 87%. A sample of 599 participants were visited at their place of residence. The mini mental state examination was completed by all participants. Cognitive speed and memory were determined with four neuropsychological tests in participants with a mini mental state examination score higher than 18 points. RESULTS: The proportion of women with limited formal education was significantly higher than that of men (70% v 53%, p=0.001), but women had better scores for cognitive speed and memory than men (p<0.05). After adjustment for differences in limited formal education and the presence of depressive symptoms, the odds ratio for women to have a higher cognitive speed than men was 1.7 (95% CI; 1.0 to 2.6), and for them to have a better memory the odds ratio was 1.8 (95%CI; 1.2 to 2.7). CONCLUSION: Women have a better cognitive function than men, despite their lower level of formal education. Limited formal education alone, therefore, cannot explain the differences in cognitive function in women and men. These findings support the alternative hypothesis that biological differences, such as atherosclerosis, between women and men account for the sex differences in cognitive decline.
Recent studies indicate that the enzyme paraoxonase may be an important modulator of cardiovascular disease risk because of its ability to protect LDL from oxidation. We tested for association between two functional variants of the paraoxonase gene (Met-55/Leu and Gln-192/Arg) and both all-cause mortality and fatal cardiovascular disease. This was done within a population-based study among subjects aged 85 years and over in a cross-sectional and a prospective design. In the cross-sectional analysis, the distribution of both paraoxonase genotypes was found to be similar in the subset of 364 elderly subjects who were born in Leiden, The Netherlands, as compared with 250 young subjects whose families originated from the same geographical region. The polymorphisms were in strong linkage disequilibrium (P<0.00001) and the frequency of the haplotype carrying both risk alleles was not lower in the elderly than in the young (0.313 vs. 0.284). The complete cohort of 666 elderly subjects was followed over 10 years. The risk of all-cause and cardiovascular mortality was not increased in elderly subjects with the paraoxonase Leu/Leu (RR, 1.1 [95% CI, 0.9-1.5] and 1.3 [95% CI, 0.8-2.0], respectively) or the Arg/Arg genotype (RR, 0. 9 [95% CI, 0.7-1.2] and 0.7 [95% CI, 0.4-1.3], respectively). In a subset of patients with diabetes, the all-cause mortality risk was elevated in Arg/Arg carriers (RR, 2.1 [95% CI, 0.8-5.8]) but this did not reach statistical significance. Analysis of genotype combinations did not yield significant associations with mortality. The paraoxonase gene variants, previously associated with coronary artery disease, are thus not likely to have a major effect on the risk of fatal cardiovascular disease in the population at large. Adverse effects of the gene variants might be observed in subjects exposed to factors that enhance oxidative stress such as diabetes.
CONTEXT: Whether hemoglobin concentrations defined as anemia by the World Health Organization (WHO) are associated with increased mortality in older persons is not known. OBJECTIVE: To investigate the association between hemoglobin concentration and cause-specific mortality in older persons. DESIGN: Community-based study conducted from 1986 to 1996 (follow-up period, 10 years). SETTING: Leiden, the Netherlands. PARTICIPANTS: A total of 1016 community residents aged 85 years and older were eligible and 872 agreed to have a blood sample taken. Hemoglobin concentration was measured in 755 persons (74%). MAIN OUTCOME MEASURES: Hemoglobin concentration, 10-year survival, and primary cause of death. According to the WHO criteria, anemia was defined as a hemoglobin concentration below 7.5 mmol/L (120 g/L) in women and below 8.1 mmol/L (130 g/L) in men. RESULTS: Compared with persons with a normal hemoglobin concentration, the mortality risk was 1.60 (95% confidence interval [CI], 1.24-2.06; P<.001) in women with anemia, and 2.29 (95% CI, 1.60-3.26; P<.001) in men with anemia. In both sexes, the mortality risk increased with lower hemoglobin concentrations. In persons without self-reported clinical disease at baseline, the mortality risk of anemia was 2.21 (95% CI, 1.37-3.57; P=.002). Mortality from malignant and infectious diseases was higher in persons with anemia. CONCLUSIONS: Anemia defined by the WHO criteria was associated with an increased mortality risk in persons aged 85 years and older. The criteria are thus appropriate for older persons. A low hemoglobin concentration at old age signifies disease.
This paper studies a non-response problem in survival analysis where the occurrence of missing data in the risk factor is related to mortality. In a study to determine the influence of blood pressure on survival in the very old (85+ years), blood pressure measurements are missing in about 12.5 per cent of the sample. The available data suggest that the process that created the missing data depends jointly on survival and the unknown blood pressure, thereby distorting the relation of interest. Multiple imputation is used to impute missing blood pressure and then analyse the data under a variety of non-response models. One special modelling problem is treated in detail; the construction of a predictive model for drawing imputations if the number of variables is large. Risk estimates for these data appear robust to even large departures from the simplest non-response model, and are similar to those derived under deletion of the incomplete records.
OBJECTIVES: We studied the contribution of putative risk genotypes at the angiotensin I-converting enzyme inhibitor (ACE D/D) and plasminogen activator inhibitor-1 (PAI-1 4G/4G) loci to all-cause and cardiovascular mortality in a population-based cohort. BACKGROUND: The ACE D/D and PAI-1 4G/4G genotypes have been consistently associated with elevated plasma activities of the gene products. Their role in cardiovascular disease, although explored intensively, is still equivocal. METHODS: The ACE and PAI-1 genotypes were determined in 648 subjects > or =85 years old. In a cross-sectional analysis, the genotype distributions in a subset of 356 elderly subjects who were born in Leiden, The Netherlands, were compared with those in 250 young subjects whose families originated from the same geographic region. In addition, the complete cohort of elderly subjects was followed over 10 years for all-cause and cardiovascular mortality and was stratified according to genotype. RESULTS: In the cross-sectional analysis, the ACE and PAI-1 genotype distributions were similar in elderly and young subjects. In the prospective follow-up study, however, the age-adjusted risk of fatal ischemic heart disease was increased threefold (95% confidence interval [CI] 1.2 to 7.6) in elderly men carrying the PAI-1 4G/4G genotype. The risk of all-cause mortality was not increased among elderly subjects carrying the PAI-1 4G/4G (relative risk [RR] 0.9, 95% CI 0.7 to 1.1) or the ACE D/D genotype (RR 0.9, 95% CI 0.7 to 1.1), nor did we observe elevated risks of death from all cardiovascular diseases combined. There was no interaction between the genotypes. CONCLUSIONS: The PAI 4G/4G genotype may be a risk factor for fatal ischemic heart disease in elderly men. The impact of moderately increased ACE and PAI-1 activities associated with the ACE D/D and PAI-1 4G/4G genotypes is too small to affect mortality in the general population.
Doubt about the serologic efficacy of annually repeated influenza vaccination prompted investigations into the course of hemagglutination-inhibiting (HI), IgG, and IgA antibody titers and the IgG and IgA avidity index to influenza A/Taiwan/1/86 and A/Beijing/353/89 after annual vaccination. Fifty-four healthy elderly persons >70 years of age and 24 healthy young adults <30 years of age received standard influenza vaccine during 3 consecutive years. On average, prevaccination HI, IgG, and IgA titers to both influenza virus strains increased >=4 fold between the first and the third vaccination (analysis of variance, P<.001). The postvaccination HI and IgG titers remained unchanged after annual vaccination. The avidity index of IgG and IgA antibodies increased somewhat after annual vaccination, although the increase was statistically significant only in the young subjects. These data indicate that annual influenza vaccination of healthy elderly and young subjects results in an overall increase in protective antibodies.
OBJECTIVES: Previous reports have shown raised plasma concentrations of homocysteine in older persons with cognitive impairment. This may be caused by environmental and genetic factors. The relation between cognitive function and a common ala/val mutation in the methylenetetrahydrofolate reductase (MTHFR) gene was studied in those over 85. Homozygous carriers of this mutation are characterised by a lifelong exposure to moderately raised plasma concentrations of homocysteine. METHODS: In the Leiden 85-plus Study, a population based study of persons aged 85 years and over, the score on the mini mental state examination (MMSE) and the presence of dementia dependent on the MTHFR genotypes were compared in 641 participants (456 women, 185 men) at baseline. In addition, the association between the MTHFR genotype and cognitive decline was studied by re-examining cognitive function of 172 participants without dementia at baseline after a median follow up of 4.0 years. RESULTS: At baseline, carriers of the ala/ala genotype had a median MMSE score of 27 points (interquartile range (IQR) 21.5-29), for the ala/val genotype it was 26 points (IQR 20-29), and for the val/val genotype it was 27 points (IQR 20-28.3) (p=0.3). The prevalence of dementia was also not significantly different for the various genotypes (ala/ala 22%, ala/val 28%, val/val 27%; p=0.4). None of the carriers of the val/val genotype without cognitive impairment at baseline developed dementia during the follow up. CONCLUSIONS: Although previous studies have shown that older persons with cognitive impairment have raised plasma concentrations of homocysteine, homozygosity for the ala to val mutation in the MTHFR gene is not a genetic risk factor for cognitive impairment in persons aged 85 years and over.
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The factor V Leiden mutation (conferring resistance to activated protein C) has been implicated in the risk of arterial thrombosis and is a well-established risk factor for venous thrombosis especially in the elderly. We studied whether the disease association of the factor V mutation is reflected in an increased all-cause and cause-specific mortality. First, the prevalence of the factor V Leiden mutation was determined in a population-based study among subjects aged 85 years and over (4.7%, n = 660) and was found to correspond to the prevalence in young subjects aged 18 to 40 years (5.0%, n = 321). Secondly, we studied the association of factor V Leiden with the risk of all-cause mortality and specific causes of death in the elderly cohort during a 10-year follow-up period. Neither the all-cause mortality risk (RR 1.0; 95% CI, 0.7-1.5), nor the risk of death due to cardiovascular disease (RR 0.9; 95% CI, 0.5-1.7) were increased in elderly subjects heterozygous for factor V Leiden. Our study thus indicates that heterozygosity for factor V Leiden does not affect population mortality.
OBJECTIVE: Description of the activities of daily living and the use of care in relation to several determinants in persons aged 85 years and over. DESIGN: Cross-sectional survey. SETTING: General population from the city of Leiden, the Netherlands. METHOD: A representative sample from the inhabitants aged 85 years and over of the city of Leiden was enrolled. A physician visited 239 'oldest old' (response rate 83%) at their places of residence, in 1991/'92. Data were obtained on health (joint disorder, cardiovascular disease, diabetes mellitus, Parkinson's disease; disorders in cognition, eyesight, hearing; limitation of mobility), self care and household activities in daily living and the use of care (informal care by neighbours or family, (geriatric) home help, district nurse, private help). Statistical analysis was performed by non-parametric tests and logistic regression. RESULTS: Of the 'oldest old' 111 (46%) lived independently, and 67 of them (28% of the total group) had no professional help. Almost all 'oldest old' had at least one health disorder. In all, 129 women (77%) and 43 men (61%) had restrictions in basic and (or) instrumental activities of daily living. These restrictions were strongly related to disorders in cognition, vision and mobility, less related to chronic disease and not related to hearing disorders. Restrictions in the activities of daily living were also related to the living condition. This relation was particularly strong for women. Men living without a partner were more likely to be institutionalised. Among the 'oldest old' who lived independently, restrictions in the activities of daily living were related to the use of care, with the exception of privately organised care. CONCLUSION: One out of four persons aged 85 years and over lived without professional help. Marked differences between the sexes were found for the interrelation between activities in daily living and the use of care.
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BACKGROUND: The impact of total serum cholesterol as a risk factor for cardiovascular disease decreases with age, which casts doubt on the necessity for cholesterol-lowering therapy in the elderly. We assessed the influence of total cholesterol concentrations on specific and all-cause mortality in people aged 85 years and over. METHODS: In 724 participants (median age 89 years), total cholesterol concentrations were measured and mortality risks calculated over 10 years of follow-up. Three categories of total cholesterol concentrations were defined: < 5.0 mmol/L, 5.0-6.4 mmol/L, and > or = 6.5 mmol/L. In a subgroup of 137 participants, total cholesterol was measured again after 5 years of follow-up. Mortality risks for the three categories of total cholesterol concentrations were estimated with a Cox proportional-hazards model, adjusted for age, sex, and cardiovascular risk factors. The primary causes of death were coded according to the International Classification of Diseases (ICD-9). FINDINGS: During 10 years of follow-up from Dec 1, 1986, to Oct 1, 1996, a total of 642 participants died. Each 1 mmol/L increase in total cholesterol corresponded to a 15% decrease in mortality (risk ratio 0.85 [95% CI 0.79-0.91]). This risk estimate was similar in the subgroup of participants who had stable cholesterol concentrations over a 5-year period. The main cause of death was cardiovascular disease with a similar mortality risk in the three total cholesterol categories. Mortality from cancer and infection was significantly lower among the participants in the highest total cholesterol category than in the other categories, which largely explained the lower all-cause mortality in this category. INTERPRETATION: In people older than 85 years, high total cholesterol concentrations are associated with longevity owing to lower mortality from cancer and infection. The effects of cholesterol-lowering therapy have yet to be assessed.