Search PubMed⌕ Search

Biomedical subjects

J C Seidell

Publications and source records attributed to J C Seidell.

At least 55 records · Page 3Linked to original sources
PubMed2000

Influence of question structure on the recall of self-reported drug use.

Epidemiological studies often rely on self-reported information as a source of drug exposure. Several studies have evaluated the accuracy of self-reported information on drug use. The influence of question structure on the accuracy of recall, however, has not been studied extensively in these studies. In this study we examined the recall accuracy of questionnaire information on drug use in a ongoing public health survey with special attention to the influence of question structure on sensitivity of recall. A sample of 372 hypertensive subjects for whom questionnaire information and pharmacy records were available was examined. Self-reported information on drug use was obtained through questions about medications used for a specific condition and one final open-ended question. This information was compared with the pharmacy medication history. About 71% of all drugs that were currently in use according to the pharmacy records were recalled through the self-administered questionnaire, and 94% of all drugs mentioned in the questionnaire could be traced in the pharmacy records. Recall sensitivity was higher for questions about medications used for a specific indication (88%) than for the open-ended question (41%). The type of drug that was used might have caused part of this difference in recall. We conclude that questionnaire structure might be of influence on the accuracy of recall of self-reported drug use, and more attention should be paid to the structure of questions on drug use.

Adult↗
PubMed2000

Estimating the prevalence of hypertension corrected for the effect of within-person variability in blood pressure.

The objective of our study was to assess the applicability of using estimates of within-person variance (WPV) from reproducibility studies for a correction of blood pressure values in another study to improve the accuracy of the prevalence estimation of hypertension. Data were collected from two cross-sectional population-based studies on cardiovascular disease risk factors conducted from 1987 to 1995 among 55,026 subjects aged 20-59 years. Correction factors were calculated from a reproducibility study among 924 subjects who were examined in 1989 and 1990. All other studies with repeated measurements of blood pressure were searched in MEDLINE from 1966 onward. Six studies satisfied the inclusion criteria. The prevalence of hypertension, uncorrected and corrected with factors from other studies, were compared with the prevalence of hypertension corrected with the factor from our study. The uncorrected prevalence of hypertension was 17.3% [95%CI:17.0-17.7]. The prevalence of hypertension after correction for WPV with the factor from our study was 13.5% [95%CI:13.2-13.8]. Correction for WPV with factors from the appropriate studies (depending on factors such as number of measurements taken per visit, and time interval between visits) resulted in prevalences ranging from 13.9% to 14.7%. The bias that occurs when no correction for WPV is performed is much larger (29% overestimation) than the bias that occurs when correction factors are derived from other studies (3.1-8.4% overestimation). When repeated measurements of blood pressure are not available in a population study for a sample of that same study, it is advisable to use data from another study to correct for WPV.

Adult↗
PubMed2000

Influence of correction for within-person variability in blood pressure on the prevalence, awareness, treatment, and control of hypertension.

We assessed the influence of correction for within-person variability (WPV) on the prevalence, awareness, treatment, and control of hypertension. Data were collected from two cross-sectional population-based studies on cardiovascular disease risk factors from 1987 to 1995 among 56,026 subjects aged 20 to 59 years. Correction factors were calculated from an internal reproducibility study among 924 subjects who were examined in 1989 and 1990. The prevalence of hypertension without a correction of blood pressure values for WPV was substantially overestimated (38%), whereas the prevalence of awareness and treatment of hypertension were substantially underestimated (-13% and -28%). The prevalence of control of hypertension did not change much after this correction. It may be advisable to perform a correction for within-person variability to obtain valid prevalence estimates in surveys that only take one or two measurements of blood pressure.

Adult↗
PubMed2000

Obesity, insulin resistance and diabetes--a worldwide epidemic.

Obesity is now commonly defined in adults as a BMI > 30 kg/m2. The prevalence of obesity in established market economies (Europe, USA, Canada, Australia, etc.) varies greatly, but a weighed estimate suggests an average prevalence in the order of 15-20%. The prevalence in these countries generally shows increasing trends over time. Obesity is also relatively common in Latin America, but much less so in sub-Saharan Africa and Asia where the majority of the world population lives. Nevertheless obesity rates are increasing there as well and, more importantly, rates of diabetes are increasing even more quickly, particularly in Asian countries. The risks of type 2 diabetes mellitus in these countries tend to increase sharply at levels of BMI generally classified as acceptable in European and North American white people. There have been suggestions to adopt specific classifications of obesity in Asians (e.g. BMI 23 for overweight and 25 or 27 kg/m2 for obesity) and this will greatly affect the prevalence estimates of obesity worldwide (currently at about 250 million people). Particularly for health promotion purposes BMI may be replaced by a classification based on waist circumference, but also specific classifications for different ethnic groups may be necessary. The number of diabetics has been projected to increase from 135 million in 1995 to 300 million in 2025. Much of this increase will be seen in Asia. In summary, both obesity and type 2 diabetes are common consequences of changing lifestyles (increased sedentary lifestyles and increased energy density of diets). Both are potentially preventable through lifestyle modification on a population level, but this requires a coherent and multifaceted strategy. Such strategies are not developed or implemented. These developments point toward the great urgency to develop global and national plans for adequate prevention and management of obesity and type 2 diabetes mellitus.

Adult↗
PubMed2000

Sex differences in the medication choice for hypertension in general practice. A study with written case simulations.

The objective of this study was to explore explanations for the preference of physicians to prescribe beta-blockers to hypertensive men and diuretics to hypertensive women. A qualitative study among 12 family physicians was conducted with a combination of written case simulations, semi-structured interviews and statements on attitudes of physicians towards antihypertensive drug choice. Among the male hypertensive cases the most frequently prescribed drugs were beta-blockers, whereas among the female hypertensive cases diuretics were more often prescribed. Physician characteristics associated with a preferred prescribing of beta-blockers to hypertensive men and diuretics to hypertensive women were: older age (no residency in family medicine), the believe that beta-blockers are more effective in men with regard to lowering blood pressure and that diuretics are more effective in women, a non-evidence based attitude and a sex-related attitude towards the choice of beta-blockers and diuretics in general, and in particular towards the prescribing of beta-blockers to hypertensive men because men have a higher absolute risk of coronary heart disease than women. An additional explanation for these findings may be the higher prevalence of ankle oedema among women. Patient characteristics associated with more prescribing of beta-blockers to hypertensive men and diuretics to hypertensive women were: current employment and a "high-risk" profile in terms of blood pressure level and additional cardiovascular risk factors. Although, most considerations underlying a preferred prescribing of beta-blockers to hypertensive men and diuretics to hypertensive women were not evidence-based, the actual choice of antihypertensive drug (diuretic or beta-blocker) was evidence-based. These considerations may also play a role in the sex difference in the choice of calcium antagonists and angiotensin converting enzyme inhibitors and require further investigation.

Adrenergic beta-Antagonists↗
PubMed2000

Body weight and weight change and their health implications for the elderly.

After the age of 60 y, body weight on average tends to decrease. The contribution of fat mass to this weight loss is relatively small, but fat tends to be redistributed with advancing age toward more abdominal (particularly visceral) fat. Anthropometric data are relatively poor indicators of these aging processes. This may be one of the explanations why the relationship between high body mass index and mortality is less pronounced in older than in younger people. Reduced lipolysis in the visceral fat depot with aging is among potential explanations why increased visceral fat seems to be less harmful in elderly subjects compared to young adults. Even though the relative contribution of increased fat mass to mortality may be less pronounced in elderly people, the impact on disability and functional limitations is found to be important from both a clinical and a public health point of view. At the other end of the scale studies have shown that low body mass index and weight loss in the elderly are both strong predictors of subsequent mortality. This cannot be explained by effects of smoking and early mortality after baseline. There are only few systematic studies comparing the predictive validity of different anthropometric data for mortality. One recent prospective study showed that a high waist circumference (in nonsmoking men) may be a better predictor of all-cause mortality than high body mass index and waist/hip ratio. Low BMI was a better predictor of mortality than low waist circumference. In conclusion changes in body composition and fat distribution with aging are poorly captured by standard anthropometric data. Low lean body mass is probably better reflected by low BMI, whereas increased (abdominal) fatness is better reflected by increased waist circumference.

Adipose Tissue↗
PubMed2000

Misclassification of high-risk older subjects using waist action levels established for young and middle-aged adults--results from the Rotterdam Study.

OBJECTIVES: In the literature, cutoff points based on waist circumference (waist action levels) have been suggested to replace cutoff points based on body mass index (BMI) and waist-hip ratio (WHR) in identifying subjects who are overweight or obese and/or with central fat distribution. These cutoff points have been based on analysis in mainly middle-aged and younger adults. In this article, we examine the applicability of the suggested waist action levels in an older population. PARTICIPANTS: A total of 6,423 men and women aged 55 or over participating in the Rotterdam Study, a population-based cohort study. MEASUREMENTS: Sensitivities and specificities of the proposed waist action levels in relation to the cutoff points for BMI and WHR were calculated. Also, cardiovascular risk factor levels at baseline examination in the different categories defined by high/low waist circumference, BMI and WHR were investigated. RESULTS: At waist action level 1 (waist circumference > or =94 cm in men, > or =80 cm in women), sensitivity was 71% in men and 86% in women for detecting those with high BMI (> or =25 kg/m2) and/or WHR (> or =0.95 in men, > or =0.80 in women). At waist action level 2 (waist circumference > or =102 cm in men, > or =88 cm in women in comparison with BMI > or =30 kg/m2 and/or WHR > or =0.95 in men, > or =0.80 in women), sensitivity was considerably lower: 35% in men and 59% in women. This was mainly due to a large proportion of subjects with low waist and BMI but high WHR. Specificity was high (>90%) at both action levels. Cardiovascular disease risk factors, except smoking, tended to increase with increasing waist circumference, WHR, and BMI. CONCLUSIONS: The suggested cutoff points for waist circumference are only to a limited degree useful in identifying subjects with overweight and obesity and/or central fat distribution in an older population. This concerns especially the upper cutoff point (waist action level 2) and is mainly due to the increased central distribution of fat with advancing age.

Age Factors↗
PubMed2000

Educational level, relative body weight, and changes in their association over 10 years: an international perspective from the WHO MONICA Project.

OBJECTIVES: This study assessed the consistency and magnitude of the association between educational level and relative body weight in populations with widely different prevalences of over-weight and investigated possible changes in the association over 10 years. METHODS: Differences in age-adjusted mean body mass index (BMI) between the highest and the lowest tertiles of years of schooling were calculated for 26 populations in the initial and final surveys of the World Health Organization (WHO) MONICA (Monitoring Trends and Determinants in Cardiovascular Disease) Project. The data are derived from random population samples, including more than 42,000 men and women aged 35 to 64 years in the initial survey (1979-1989) and almost 35,000 in the final survey (1989-1996). RESULTS: For women, almost all populations showed a statistically significant inverse association between educational level and BMI; the difference between the highest and the lowest educational tertiles ranged from -3.3 to 0.4 kg/m2. For men, the difference ranged from -1.5 to 2.2 kg/m2. In about two thirds of the populations, the differences in BMI between the educational levels increased over the 10-year period. CONCLUSION: Lower education was associated with higher BMI in about half of the male and in almost all of the female populations, and the differences in relative body weight between educational levels increased over the study period. Thus, socioeconomic inequality in health consequences of obesity may increase in many countries.

Adult↗
PubMed2000

[Undertreatment of hypertension and the risk of stroke in the oldest old].

The benefit of pharmacological treatment of hypertension in the prevention of cardiovascular diseases has been established mainly in subjects younger than 80 years of age. The consequences of undertreatment of hypertension with regard to the occurrence of stroke was studied in the Netherlands. About 33% of the hypertensives younger than 80 years and 55% of the hypertensives older than 80 years were not pharmacologically treated, although they were 'candidates' for pharmacological treatment of hypertension. About 19% (n = 1350) of all strokes that occurred in the Netherlands in 1994 among hypertensives younger than 80 years may be attributable to untreated hypertension. Among hypertensives older than 80 years this percentage was 32% (n = 1345). Although the benefit of pharmacological treatment of hypertension in persons older than 80 years has not been established experimentally, the results suggest that a considerable proportion of the strokes among this group of hypertensives may be prevented.

Aged↗
PubMed1999

[Physical activity in relation to sociodemographic variables and health status of adult men and women in Amsterdam, Doetinchen and Maastricht].

OBJECTIVE: To gain insight into the physical activity level of a sample of the Dutch population, to identify groups with an increased prevalence of physical inactivity and to investigate if increased moderate activity is associated with a more favourable cardiovascular risk profile and a higher self-rated health. DESIGN: Descriptive. METHOD: In 1993-1997 a monitoring project on risk factors and health has been carried out in a random sample of inhabitants of Doetinchem, Amsterdam and Maastricht. Using a questionnaire, information was obtained from the participants about physical activity, demographic characteristics, smoking behaviour and self-rated health. Also, height, weight and blood pressure were measured and a blood sample was taken. In this sample, the serum concentrations of total and high density lipoproteins were determined. This article concerns the activity in 1997 and the trend in activity in the period 1994-1997. In 1997, 4,029 persons, aged 20-64 years, took part. RESULTS: In 1997 46% (n = 1864) of the study population were, on average, active in moderate activities for less than half an hour per day, and 21% (n = 831) for less than half an hour per week ('inactives'). Inactivity was most common in subjects aged 50-59 years (28%), subjects with a low educational level (38%), widowed subjects (34%) and unemployed (36%) or disabled (42%) subjects. Since 1994, the proportion of inactive subjects increased among individuals with a low level of education. Regular physical activity, whether moderate or strenuous, was associated with a more favourable risk profile and a better self-rated health. CONCLUSION: Almost half of the persons examined were little active, which was associated with a less favourable cardiovascular risk profile and a less good self-rated health.

Adult↗
PubMed1999

Impairment of health and quality of life using new US federal guidelines for the identification of obesity.

BACKGROUND: Estimating total burdens of disease associated with overweight and obesity has been hampered by a lack of consistent published data using standardized body mass index (BMI or Quetelet index [calculated as weight in kilograms divided by the square of the height in meters: weight (kg)/[height x (m)2]]) diagnostic criteria, and by poorly standardized reference populations. SUBJECTS AND METHODS: Symptoms of respiratory insufficiency, low back pain, non-insulin-dependent diabetes mellitus, cardiovascular risk factors, and physical functioning using SF-36 questionnaire were determined in a cross-sectional representative survey of 5887 men and 7018 women aged 20 to 59 years from the Netherlands and analyzed using BMI criteria of the National Institutes of Health and the World Health Organization guidelines. RESULTS: The prevalences of cardiovascular risks were higher in men than women, but the other health outcomes were more frequent in women. Virtually all health outcomes considered were significantly influenced by BMI. A BMI of 25 to 30 kg/m2 had a generally greater impact on odds ratios for health outcomes in women than in men. People with BMI below 25 kg/m2 were considered the reference group, with low prevalence of symptoms of obesity-related diseases and good quality of life. Between 25 to 30 kg/m2, the prevalences of these were all increased, and above 30 kg/m2 greatly increased. After adjustments for age and lifestyle factors, odds ratios (95% confidence intervals [95% CI]) in those with a BMI of 30 kg/m2 or higher were 3.5 (95% CI, 2.8-4.4) in men and 3.3 (95% CI, 2.8-3.9) in women for shortness of breath when walking upstairs, 4.6 (95% CI, 2.4-8.8) in men and 5.4 (95% CI, 2.8-10.5) in women for non-insulin-dependent diabetes mellitus, 5.5 (95% CI, 4.5-6.6) in men and 2.9 (95% CI, 2.4-3.4) in women for having at least 1 major cardiovascular risk factor. Both men and women with BMI of 30 kg/m2 or higher were twice as likely to have difficulties in performing a range of basic daily physical activities. Compared with women with BMI lower than 25 kg/m2, those with BMI of 30 kg/m2 or higher were 1.5 times more likely to have symptoms of intervertebral disk herniation. Significantly more overweight women had problems associated with low back pain, including hindrance to their daily business, absence from work, and medical consultation. CONCLUSIONS: Health risks for a range of problems are presented using the standard BMI cutoff points. Overweight and obesity are associated with increased risks of chronic diseases, secondary symptoms, and impairment of quality of life.

Adult↗
PubMed1999

Changes in fat cell size and in vitro lipolytic activity of abdominal and gluteal adipocytes after a one-year cross-sex hormone administration in transsexuals.

We prospectively studied the effects of cross-sex hormone administration on fat cell size and in vitro lipolytic activity in subcutaneous abdominal and gluteal fat biopsies obtained from 19 male-to-female (M-F) transsexuals and 17 female-to-male (F-M) transsexuals. The amount of subcutaneous fat at the abdominal and gluteal levels was quantified with the use of magnetic resonance imaging (MRI). Before cross-sex hormone administration, M-F transsexuals had less subcutaneous fat with smaller fat cells compared with F-M transsexuals, with a higher baseline in vitro lipolytic activity expressed as glycerol release per milligram of triglyceride (TG) in the abdominal region (P < .05). Before cross-sex hormone treatment, no differences in lipolytic activity stimulated with arterenol (ART), isoproterenol (ISO), or ISO + insulin (INS) were observed between groups or regions. After a 1-year treatment with estrogens and antiandrogens in M-F transsexuals, subcutaneous fat areas on MRI and fat cell size were increased (P < .001) and reductions were observed in the basal lipolytic activity of gluteal and abdominal fat biopsies (P < .05). Following administration of testosterone to F-M transsexuals, subcutaneous fat and fat cell size at the gluteal and abdominal depots were decreased (P < .01) and basal lipolysis was increased significantly at the abdominal level (P < .05) but not at the gluteal level. In both M-F and F-M transsexuals, no effect of sex hormone administration was observed on stimulated lipolytic activities. In conclusion, regional sex differences in the amount of subcutaneous fat, adipocyte size, and in vitro basal lipolytic activity were demonstrated that could be largely reversed by cross-sex hormone treatment in adult subjects, providing evidence for their dependence on the sex steroid milieu.

Abdomen↗
PubMed1999

Cardiovascular diseases and risk factors in a population-based study in The Netherlands: agreement between questionnaire information and medical records.

BACKGROUND: Since 1987 the Monitoring Project on Cardiovascular Risk Factors has been carried out in The Netherlands. The purpose of the present study was to assess the agreement between the self-reported questionnaire information that was collected in this survey on cardiovascular diseases and risk factors and information from medical records. METHODS: From 1987 to 1991, over 36,000 men and women aged 20-59 years have participated in the Monitoring Project on Cardiovascular Disease Risk Factors, a cross-sectional population-based study. We compared self-reported information on cardiovascular diseases and risk factors with the general practitioners medical records from a sample of 899 hypertensive subjects. RESULTS: The highest proportion of positive self-reports could be confirmed by the medical records for diabetes conditional on self-report of medication use for this condition (100%), and a history of hypertension conditional on the presence of blood pressure recordings in the medical records (91%). The lowest percentage of positive self-reports confirmed by medical records was a family history of myocardial infarction (3-5%). More than 80% of the negative self-reports were confirmed by the medical records for most conditions, except for history of hypertension, conditional on the presence of blood pressure recordings in the medical records (40%). The overall agreement above chance was substantial for cerebrovascular disease (kappa = 0.78) and diabetes (kappa = 0.75), moderate for myocardial infarction (kappa = 0.55), poor for myocardial infarction of the respondents' father (kappa = 0.07) and mother (kappa = 0.05), and fair to moderate for all other self-reported conditions. CONCLUSION: Agreement between self-reported information and medical records was variable. For further studies, self-reports of cardiovascular diseases and risk factors should preferably be complemented with information from other sources such as medical records.

Adult↗
PubMed1999

Varying sensitivity of waist action levels to identify subjects with overweight or obesity in 19 populations of the WHO MONICA Project.

It has been suggested in the literature that cut-off points based on waist circumference (waist action levels) should replace cut-off points based on body mass index (BMI) and waist-to-hip ratio in identifying subjects with overweight or obesity. In this article, we examine the sensitivity and specificity of the cut-off points when applied to 19 populations with widely different prevalences of overweight. Our design was a cross-sectional study based on random population samples. A total of 32,978 subjects aged 25-64 years from 19 male and 18 female populations participating in the second MONICA survey from 1987 to 1992 were included in this study. We found that at waist action level 1 (waist circumference > or =94 cm in men and > or =80 cm in women), sensitivity varied between 40% and 80% in men and between 51% and 86% in women between populations when compared with the cut-off points based on BMI (> or =25 kg/m2) and waist-to-hip ratio (> or =0.95 for men, > or =0.80 for women). Specificity was high (> or =90%) in all populations. At waist action level 2 (waist circumference > or =102 cm and > or =88 cm in men and women, respectively, BMI > or =30 kg/m2), sensitivity varied from 22% to 64% in men and from 26% to 67% in women, whereas specificity was >95% in all populations. Sensitivity was in general lowest in populations in which overweight was relatively uncommon, whereas it was highest in populations with relatively high prevalence of overweight. We propose that cut-off points based on waist circumference as a replacement for cut-off points based on BMI and waist-to-hip ratio should be viewed with caution. Based on the proposed waist action levels, very few people would unnecessarily be advised to have weight management, but a varying proportion of those who would need it might be missed. The optimal screening cut-off points for waist circumference may be population specific.

Abdomen↗
PubMed1999

Agreement between self-reported antihypertensive drug use and pharmacy records in a population-based study in The Netherlands.

From 1987 to 1991, over 36,000 men and women aged 20-59 years have been examined in the Monitoring Project on Cardiovascular Disease Risk Factors in The Netherlands. Classification of the treatment status of hypertensives in this population-based study was based on self-administered questionnaires. In order to assess the accuracy of self-reported antihypertensive drug use we compared the questionnaire information with computerized pharmacy records from a sample of 372 hypertensive subjects. Most antihypertensive drugs that were mentioned in the questionnaire were present in the pharmacy medication history (93%). However, this percentage was less (76%) when a comparison was made with the calculated duration of use based on the number of units prescribed and the directions for use in the pharmacy records. About 94% of the hypertensive subjects who were using an antihypertensive drug according to the pharmacy records, also mentioned at least one antihypertensive drug in the questionnaire. Agreement between self-reported antihypertensive drug use and pharmacy records was consistently high for all classes of antihypertensive drugs. Among 321 (86%) subjects, the number and types of self-reported antihypertensive drugs were exactly the same as in the pharmacy records. In conclusion, the agreement between self-reported antihypertensive drug use and pharmacy records was high, and the self-reported questionnaire information on antihypertensive drug use can be reliably used for the classification of treatment status of hypertensive subjects in this population-based study.

Adult↗
PubMed1999

Physical activity modulates the effect of a lipoprotein lipase mutation (D9N) on plasma lipids and lipoproteins.

We investigated interactions between a mutation (D9N) in the lipoprotein lipase (LPL) gene and physical activity, as well as other lifestyle factors, on lipid traits in a population-based sample of Dutch men and women (n = 379). We used questionnaire information to classify physical activity, alcohol consumption, and smoking habits, while overweight was defined as a body mass index (BMI) > 25 kg/m2. Non-fasting blood samples were used for the determination of lipid traits and the D9N genotype. Fifteen subjects (4%) carried the mutation. They presented with higher levels of total cholesterol, apolipoprotein (apo) B and triglycerides compared to non-carriers. While no interactions with overweight, alcohol consumption, and smoking were found, a strong interaction between the D9N mutation and physical activity became apparent. Physically inactive D9N carriers (n = 5) had considerably higher total cholesterol (+2 mmol/l, p < or = 0.0001) and apo B levels (+63 mg/dl, p < or = 0.0001) compared to non-carriers of this mutation, whereas their high-density lipoprotein (HDL)-cholesterol concentrations were lower (-0.22 mmol/l, p < 0.05). This was not the case for physically active D9N carriers (n = 10). In conclusion, a common variant of the LPL gene (D9N) adversely affects plasma lipid and lipoprotein profiles. However, the unfavorable consequences may be counteracted by physical activity.

Adult↗