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Dive into the research topics where W.P.J. den Elzen is active.

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Featured researches published by W.P.J. den Elzen.


Alimentary Pharmacology & Therapeutics | 2008

Long-term use of proton pump inhibitors and vitamin B12 status in elderly individuals

W.P.J. den Elzen; Y. Groeneveld; W. de Ruijter; J. H. M. Souverijn; S. le Cessie; Willem J. J. Assendelft; Jacobijn Gussekloo

Background  Some studies have shown that short‐term use of proton pump inhibitors decreases the absorption of vitamin B12, but the results of studies into long‐term proton pump inhibitor use and vitamin B12 deficiency are inconsistent.


Haematologica | 2013

Plasma hepcidin levels and anemia in old age. The Leiden 85-plus Study

W.P.J. den Elzen; A.J.M. de Craen; Erwin T. Wiegerinck; R.G.J. Westendorp; Dorine W. Swinkels; Jacobijn Gussekloo

Hepcidin, an important regulator of iron homeostasis, is suggested to be causally related to anemia of inflammation. The aim of this study was to explore the role of plasma hepcidin in anemia among older persons from the general population. The Leiden 85-Plus Study is a population-based study of 85-year olds in Leiden, the Netherlands. Eighty-five-year old inhabitants of Leiden were enrolled between September 1997 and September 1999. At the age of 86, plasma hepcidin was determined with time of flight mass spectrometry in 490 participants [160 (32.7%) male, 114 (23.3%) with anemia]. Anemia was defined according to criteria of the World Health Organization (hemoglobin level <13 g/dL for men and hemoglobin <12 g/dL for women). The median plasma hepcidin level was 3.0 nM [interquartile range (IQR) 1.8–4.9]. We found strong correlations between plasma hepcidin and body iron status, C-reactive protein and erythropoietin levels. Significantly higher hepcidin levels were found in participants with anemia of inflammation (P<0.01), in participants with anemia of kidney disease (P=0.01), and in participants with unexplained anemia (P=0.01) than in participants without anemia. Participants with iron-deficiency anemia had significantly lower plasma hepcidin levels than participants without anemia (P<0.01). In conclusion, older persons with anemia of inflammation have higher hepcidin levels than their counterparts without anemia. The potential clinical value of hepcidin in future diagnostic algorithms for anemia has to be explored.


Thorax | 2008

Incidence and predictive factors of lower respiratory tract infections among the very elderly in the general population. The Leiden 85-plus Study.

A Sliedrecht; W.P.J. den Elzen; T J M Verheij; R.G.J. Westendorp; Jacobijn Gussekloo

Objectives: To target preventive strategies in old age, which of the very elderly are predisposed to developing lower respiratory tract infections was investigated. Design: Prospective observational follow-up study. Setting: General population. Participants: Unselected cohort of 587 participants aged 85 years in Leiden, The Netherlands. Measurements: As reported in the literature, predictive factors were selected and assessed at baseline. During a 5 year follow-up period, information on the development of lower respiratory tract infections was obtained from general practitioners or nursing home physicians. Associations between predictive factors were analysed with Cox regression, and population attributable risks were calculated. Results: The incidence of lower respiratory tract infections among persons aged 85–90 years was 94 (95% CI 80–108) per 1000 person years. After multivariate analysis, history of chronic obstructive pulmonary disease (COPD), smoking, oral glucocorticosteroid use, severe cognitive impairment, history of stroke and declined functional status remained independently associated with the occurrence of lower respiratory tract infections. Smoking was the greatest contributor with a population attributable risk of 32%. Conclusion: In the very old, smoking, COPD, stroke and declined functional status were associated with the occurrence of lower respiratory tract infections and provide a means of targeting patients at risk of severe health complications.


Quality of Life Research | 2015

Validation of the Care-Related Quality of Life Instrument in different study settings: findings from The Older Persons and Informal Caregivers Survey Minimum DataSet (TOPICS-MDS)

Jennifer E. Lutomski; N.J.A. van Exel; Gertrudis I. J. M. Kempen; E P Moll van Charante; W.P.J. den Elzen; Aaltje P. D. Jansen; Paul F. M. Krabbe; Bas Steunenberg; Ewout W. Steyerberg; M.G.M. Olde Rikkert; R.J.F. Melis

PurposeValidity is a contextual aspect of a scale which may differ across sample populations and study protocols. The objective of our study was to validate the Care-Related Quality of Life Instrument (CarerQol) across two different study design features, sampling framework (general population vs. different care settings) and survey mode (interview vs. written questionnaire).MethodsData were extracted from The Older Persons and Informal Caregivers Minimum DataSet (TOPICS-MDS, www.topics-mds.eu), a pooled public-access data set with information on >3,000 informal caregivers throughout the Netherlands. Meta-correlations and linear mixed models between the CarerQol’s seven dimensions (CarerQol-7D) and caregiver’s level of happiness (CarerQol-VAS) and self-rated burden (SRB) were performed.ResultsThe CarerQol-7D dimensions were correlated to the CarerQol-VAS and SRB in the pooled data set and the subgroups. The strength of correlations between CarerQol-7D dimensions and SRB was weaker among caregivers who were interviewed versus those who completed a written questionnaire. The directionality of associations between the CarerQol-VAS, SRB and the CarerQol-7D dimensions in the multivariate model supported the construct validity of the CarerQol in the pooled population. Significant interaction terms were observed in several dimensions of the CarerQol-7D across sampling frame and survey mode, suggesting meaningful differences in reporting levels.ConclusionsAlthough good scientific practice emphasises the importance of re-evaluating instrument properties in individual research studies, our findings support the validity and applicability of the CarerQol instrument in a variety of settings. Due to minor differential reporting, pooling CarerQol data collected using mixed administration modes should be interpreted with caution; for TOPICS-MDS, meta-analytic techniques may be warranted.


British Journal of General Practice | 2015

International variation in GP treatment strategies for subclinical hypothyroidism in older adults: a case-based survey

W.P.J. den Elzen; A. A. Lefebre-van de Fliert; Vanessa Virgini; Simon P. Mooijaart; Peter Frey; Patricia M. Kearney; Ngaire Kerse; Christian D. Mallen; Vera J. C. McCarthy; Christiane Muth; Thomas Rosemann; Audrey Russell; Henk Schers; David J. Stott; M.W.M. de Waal; A. Warner; R.G.J. Westendorp; Nicolas Rodondi; Jacobijn Gussekloo

BACKGROUND There is limited evidence about the impact of treatment for subclinical hypothyroidism, especially among older people. AIM To investigate the variation in GP treatment strategies for older patients with subclinical hypothyroidism depending on country and patient characteristics. DESIGN AND SETTING Case-based survey of GPs in the Netherlands, Germany, England, Ireland, Switzerland, and New Zealand. METHOD The treatment strategy of GPs (treatment yes/no, starting-dose thyroxine) was assessed for eight cases presenting a woman with subclinical hypothyroidism. The cases differed in the patient characteristics of age (70 versus 85 years), vitality status (vital versus vulnerable), and thyroid-stimulating hormone (TSH) concentration (6 versus 15 mU/L). RESULTS A total of 526 GPs participated (the Netherlands n = 129, Germany n = 61, England n = 22, Ireland n = 21, Switzerland n = 262, New Zealand n = 31; overall response 19%). Across countries, differences in treatment strategy were observed. GPs from the Netherlands (mean treatment percentage 34%), England (40%), and New Zealand (39%) were less inclined to start treatment than GPs in Germany (73%), Ireland (62%), and Switzerland (52%) (P = 0.05). Overall, GPs were less inclined to start treatment in 85-year-old than in 70-year-old females (pooled odds ratio [OR] 0.74 [95% confidence interval [CI] = 0.63 to 0.87]). Females with a TSH of 15 mU/L were more likely to get treated than those with a TSH of 6 mU/L (pooled OR 9.49 [95% CI = 5.81 to 15.5]). CONCLUSION GP treatment strategies of older people with subclinical hypothyroidism vary largely by country and patient characteristics. This variation underlines the need for a new generation of international guidelines based on the outcomes of randomised clinical trials set within primary care.


Tijdschrift Voor Gerontologie En Geriatrie | 2015

[TOPICS-MDS: a versatile resource for generating scientific and social knowledge for elderly care]

D. van den Brink; Jennifer E. Lutomski; Li Qin; W.P.J. den Elzen; G.I.J.M. (Ruud) Kempen; Paul F. M. Krabbe; Ewout W. Steyerberg; Maaike E. Muntinga; E.P. Moll van Charante; Nienke Bleijenberg; M.G.M. Olde Rikkert; R.J.F. Melis

Developed as part of the National Care for the Elderly Programme (NPO), TOPICS-MDS is a uniform, national database on the health and wellbeing of the older persons and caregivers who participated in NPO-funded projects. TOPICS-MDS Consortium has gained extensive experience in constructing a standardized questionnaire to collect relevant health care data on quality of life, health services utilization, and informal care use. A proactive approach has been undertaken not only to ensure the standardization and validation of instruments but also the infrastructure for external data requests. Efforts have been made to promote scientifically and socially responsible use of TOPICS-MDS; data has been available for secondary use since early 2014. Through this data sharing initiative, researchers can explore health issues in a broader framework which may have not been possible within individual NPO projects; this broader framework is highly relevant for influencing health policy. In this article, we provide an overview of the development and on-going progress of TOPICS-MDS. We further describe how information derived from TOPICS-MDS can be applied to facilitate future scientific innovations and public health initiatives to improve care for frail older persons and their caregivers.


Epidemiology | 2015

Physician's Prescribing Preference as an Instrumental Variable: Exploring Assumptions Using Survey Data.

Boef Ag; S. le Cessie; Olaf M. Dekkers; Peter Frey; Patricia M. Kearney; Ngaire Kerse; Christian D. Mallen; Vera J. C. McCarthy; Simon P. Mooijaart; Christiane Muth; Nicolas Rodondi; Thomas Rosemann; Audrey Russell; Henk Schers; Vanessa Virgini; M.W.M. de Waal; A. Warner; Jacobijn Gussekloo; W.P.J. den Elzen

Background: Physician’s prescribing preference is increasingly used as an instrumental variable in studies of therapeutic effects. However, differences in prescribing patterns among physicians may reflect differences in preferences or in case-mix. Furthermore, there is debate regarding the possible assumptions for point estimation using physician’s preference as an instrument. Methods: A survey was sent to general practitioners (GPs) in The Netherlands, the United Kingdom, New Zealand, Ireland, Switzerland, and Germany, asking whether they would prescribe levothyroxine to eight fictitious patients with subclinical hypothyroidism. We investigated (1) whether variation in physician’s preference was observable and to what extent it was explained by characteristics of GPs and their patient populations and (2) whether the data were compatible with deterministic and stochastic monotonicity assumptions. Results: Levothyroxine prescriptions varied substantially among the 526 responding GPs. Between-GP variance in levothyroxine prescriptions (logit scale) was 9.9 (95% confidence interval: 8.0, 12) in the initial mixed effects logistic model, 8.3 (6.7, 10) after adding a fixed effect for country and 8.2 (6.6, 10) after adding GP characteristics. The occurring prescription patterns falsified the deterministic monotonicity assumption. All cases in all countries were more likely to receive levothyroxine if a different case of the same GP received levothyroxine, which is compatible with the stochastic monotonicity assumption. The data were incompatible with this assumption for a different definition of the instrument. Conclusions: Our study supports the existence of physician’s preference as a determinant in treatment decisions. Deterministic monotonicity will generally not be plausible for physician’s preference as an instrument. Depending on the definition of the instrument, stochastic monotonicity may be plausible.


Age and Ageing | 2018

Effectiveness and cost-effectiveness of proactive and multidisciplinary integrated care for older people with complex problems in general practice: an individual participant data meta-analysis

Jeanet W. Blom; W.B. van den Hout; W.P.J. den Elzen; Yvonne M. Drewes; Nienke Bleijenberg; Isabelle Natalina Fabbricotti; A P D Jansen; Gertrudis I. J. M. Kempen; Raymond T. C. M. Koopmans; Willemijn Looman; R.J.F. Melis; Silke F. Metzelthin; E P Moll van Charante; M E Muntinga; Mattijs E. Numans; Franca G.H. Ruikes; Sophie Spoorenberg; Theo Stijnen; Jacqueline J. Suijker; N.J. de Wit; Klaske Wynia; Annet W. Wind

Abstract Purpose to support older people with several healthcare needs in sustaining adequate functioning and independence, more proactive approaches are needed. This purpose of this study is to summarise the (cost-) effectiveness of proactive, multidisciplinary, integrated care programmes for older people in Dutch primary care. Methods design individual patient data (IPD) meta-analysis of eight clinically controlled trials. Setting primary care sector. Interventions combination of (i) identification of older people with complex problems by means of screening, followed by (ii) a multidisciplinary integrated care programme for those identified. Main outcome activities of daily living, i.e. a change on modified Katz-15 scale between baseline and 1-year follow-up. Secondary outcomes quality of life (visual analogue scale 0–10), psychological (mental well-being scale Short Form Health Survey (SF)-36) and social well-being (single item, SF-36), quality-adjusted life years (Euroqol-5dimensions-3level (EQ-5D-3L)), healthcare utilisation and cost-effectiveness. Analysis intention-to-treat analysis, two-stage IPD and subgroup analysis based on patient and intervention characteristics. Results included were 8,678 participants: median age of 80.5 (interquartile range 75.3; 85.7) years; 5,496 (63.3%) women. On the modified Katz-15 scale, the pooled difference in change between the intervention and control group was −0.01 (95% confidence interval −0.10 to 0.08). No significant differences were found in the other patient outcomes or subgroup analyses. Compared to usual care, the probability of the intervention group to be cost-effective was less than 5%. Conclusion compared to usual care at 1-year follow-up, strategies for identification of frail older people in primary care combined with a proactive integrated care intervention are probably not (cost-) effective.


Archive | 2010

Thyroid Studies Collaboration

Nicolas Rodondi; W.P.J. den Elzen; Douglas C. Bauer; Anne R. Cappola; Salman Razvi; John P. Walsh


Nederlands Tijdschrift voor Geneeskunde | 2014

[Frailty, disability and multi-morbidity: the relationship with quality of life and healthcare costs in elderly people]

Jennifer E. Lutomski; M.A.E. Baars; H. Boter; Bianca M. Buurman; W.P.J. den Elzen; Aaltje P. D. Jansen; G.I.J.M. (Ruud) Kempen; Bas Steunenberg; Ewout W. Steyerberg; M.G.M. Olde Rikkert; R.J.F. Melis

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Jacobijn Gussekloo

Leiden University Medical Center

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R.J.F. Melis

Radboud University Nijmegen

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Ewout W. Steyerberg

Erasmus University Rotterdam

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Aaltje P. D. Jansen

VU University Medical Center

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Simon P. Mooijaart

Leiden University Medical Center

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