BackgroundPrevious studies have proposed different formulas of estimating glomerular filtration rate (eGFR) among clinical patients. The comprehensive comparison of eGFR formulas is not well... Show moreBackgroundPrevious studies have proposed different formulas of estimating glomerular filtration rate (eGFR) among clinical patients. The comprehensive comparison of eGFR formulas is not well established in a Japanese population. We compared eGFR values and chronic kidney disease (CKD) classification of nine different eGFR in a Japanese general population sample.MethodsWe analyzed 469 Japanese community-dwelling adults (184 men) without any self-reported kidney disease. GFR estimated using the 4- and 6-parameter Modification of Diet in Renal Disease (MDRD) formulas (MDRD4 and MDRD6); the CKD-EPI formulas based on creatinine with (CKD-EPI-2009) and without race coefficient (CKD-EPI-2021), on cystatin C (CKD-EPI-Cys), on both (CKD-EPI-CreCys); the Japanese creatinine-based formula (JPN-Cre), cystatin C-based formula (JPN-Cys), and modified CKD-EPI formula (JPN-CKD-EPI). CKD stages were defined by KDIGO guidelines (eGFR < 60 ml/min/1.73 m2).ResultseGFRJPN-Cre (mean = 71.2; SD = 14.3) were much lower than eGFRCKD-EPI-2021 (mean = 94.2; SD = 12.7), while eGFRJPN-Cys (mean = 102.8; SD = 24.2) was comparable to the MDRD and CKD-EPI formulas. The difference between eGFRCKD-EPI-2021 and eGFRJPN-Cre showed a V-shaped distribution across eGFR levels, indicating complex errors between these formulas. We observed very low agreement in CKD classification between eGFRJPN-Cre and the eGFRCKD-EPI-2021 (kappa = 0.13; 95% confidence interval: 0.06, 0.23).ConclusionsJPN-Cre was substantially different from the CKD-EPI formula without race term (CKD-EPI-2021), which means that it is impossible to recalibrate those with a simple coefficient. Although a comparison with measured GFR should be necessary, choice of the estimation method needs caution in clinical decision-making and academic research. Show less
Bergstra, S.A.; Sepriano, A.; Kerschbaumer, A.; Heijde, D. van der; Caporali, R.; Edwards, C.J.; ... ; Landewe, R.B.M. 2022
This systematic literature review (SLR) regarding the efficacy, duration of use and safety of glucocorticoids (GCs), was performed to inform the 2022 update of the EULAR recommendations for the... Show moreThis systematic literature review (SLR) regarding the efficacy, duration of use and safety of glucocorticoids (GCs), was performed to inform the 2022 update of the EULAR recommendations for the management of rheumatoid arthritis (RA). Studies on GC efficacy were identified from a separate search on the efficacy of disease-modifying antirheumatic drugs (DMARDs). A combined search was performed for the duration of use and safety of GCs in RA patients. Dose-defined and time-defined GC treatment of any dose and duration (excluding intra-articular GCs) prescribed in combination with other DMARDs were considered. Results are presented descriptively. Two included studies confirmed the efficacy of GC bridging as initial therapy, with equal efficacy after 2 years of initial doses of 30 mg/day compared with 60 mg/day prednisone. Based on a recently performed SLR, in clinical trials most patients starting initial GC bridging are able to stop GCs within 12 (22% patients continued on GCs) to 24 months (10% patients continued on GCs). The safety search included 12 RCTs and 21 observational studies. Well-known safety risks of GC use were confirmed, including an increased risk of osteoporotic fractures, serious infections, diabetes and mortality. Data on cardiovascular outcomes were Inconsistent. Overall, safety risks increased with increasing dose and/or duration, but evidence on which dose is safe was conflicting. In conclusion, this SLR has confirmed the efficacy of GCs in the treatment of RA. In clinical trials, most patients have shown to be able to stop GCs within 12-24 months. Well-known safety risks of GC use have been confirmed, but with heterogeneity between studies. Show less
Velde, J.H.P.M. van der; Boone, S.C.; Winters-van Eekelen, E.; Hesselink, M.K.C.; Schrauwen-Hinderling, V.B.; Schrauwen, P.; ... ; Mutsert, R. de 2022
Aims/hypothesis We hypothesised that the insulin-sensitising effect of physical activity depends on the timing of the activity. Here, we examined cross-sectional associations of breaks in sedentary... Show moreAims/hypothesis We hypothesised that the insulin-sensitising effect of physical activity depends on the timing of the activity. Here, we examined cross-sectional associations of breaks in sedentary time and timing of physical activity with liver fat content and insulin resistance in a Dutch cohort.Methods In 775 participants of the Netherlands Epidemiology of Obesity (NEO) study, we assessed sedentary time, breaks in sedentary time and different intensities of physical activity using activity sensors, and liver fat content by magnetic resonance spectroscopy (n=256). Participants were categorised as being most active in the morning (06:00-12:00 hours), afternoon (12:0018:00 hours) or evening (18:00-00:00 hours) or as engaging in moderate-to-vigorous-physical activity (MVPA) evenly distributed throughout the day. Most active in a certain time block was defined as spending the majority (%) of total daily MVPA in that block. We examined associations between sedentary time, breaks and timing of MVPA with liver fat content and HOMA-IR using linear regression analyses. adjusted for demographic and lifestyle factors including total body fat. Associations of timing of MVPA were additionally adjusted for total MVPA.Results The participants (42% men) had a mean (SD) age of 56 (4) years and a mean (SD) BMI of 26.2 (4.1) kg/m(2). Total sedentary time was not associated with liver fat content or insulin resistance, whereas the amount of breaks in sedentary time was associated with higher liver fat content. Total MVPA (-5%/h [95% CI -10%/h, 0%/h]) and timing of MVPA were associated with reduced insulin resistance but not with liver fat content. Compared with participants who had an even distribution of MVPA throughout the day. insulin resistance was similar (-3% [95% CI -25%, 16%]) in those most active in morning, whereas it was reduced in participants who were most active in the afternoon (-18% [95% CI -33%, -2%]) or evening (-25% [95% CI -49%, -4%]).Conclusions/interpretation The number of daily breaks in sedentary time was not associated with lower liver fat content or reduced insulin resistance. Moderate-to-vigorous activity in the afternoon or evening was associated with a reduction of up to 25% in insulin resistance. Further studies should assess whether timing of physical activity is also important for the occurrence of type 2 diabetes. Show less
A growing body of scientific literature documents a putative role of commensal and pathogenic bacteria in the initiation and progression of cancers. One such bacterium is nontyphoidal Salmonella ... Show moreA growing body of scientific literature documents a putative role of commensal and pathogenic bacteria in the initiation and progression of cancers. One such bacterium is nontyphoidal Salmonella (NTS), which has been associated with colon cancer in a few studies. Yet, a lot is still unknown about the magnitude and underlying mechanisms, including the necessary conditions or ‘prerequisites’, of the potential colon carcinogenesis promoting effects of Salmonella. In this thesis, we performed several complementary analyses based on both experimental and epidemiological study designs. Significant excess risk of NTS infection was observed among several occupational groups including those involving contact with live animals or animal manure and animal-derived food sale. The risk of colon cancer was not elevated in these groups. Also, no clear association between NTS and colon cancer was found in a Danish cohort. Two-fold infection of mouse embryonic fibroblasts (MEFs) with a low dose of NTS was more successful than a single high-dose infection (i.e. more and larger colonies). Substantial variation between NTS isolates was found in their capacity to infect MEFs and to induce cellular transformation, with a tendency towards higher transformation efficiency in isolates originating from people who were diagnosed with colon cancer later in life. Show less
Jansen, S.J.; Hoeven, A. van der; Akker, T. van den; Veenhof, M.; Asmuth, E.G.J. von; Veldkamp, K.E.; ... ; Lopriore, E. 2022
Nosocomial bloodstream infections (NBSIs), commonly due to central-line associated bloodstream infections (CLABSI), contribute substantially to neonatal morbidity and mortality. We aimed to... Show moreNosocomial bloodstream infections (NBSIs), commonly due to central-line associated bloodstream infections (CLABSI), contribute substantially to neonatal morbidity and mortality. We aimed to identify longitudinal changes in incidence of NBSI, microbiological-spectrum, and antibiotic exposure in a large cohort of preterm neonates admitted to the neonatal intensive care unit. We retrospectively assessed differences in annual rates of NBSI (per 1000 patient-days), CLABSI (per 1000 central-line days), and antibiotic consumption (per 1000 patient-days) among preterm neonates (< 32 weeks' gestation) hospitalized between January 2012 and December 2020. Multi-state Markov models were created to model states of progression of NBSI and infection risk given a central-line on days 0, 3, 7, and 10 of admission. Of 1547 preterm infants, 292 (19%) neonates acquired 310 NBSI episodes, 99 (32%) of which were attributed to a central-line. Over the years, a significant reduction in central-line use was observed (p < 0.001), although median dwell-time increased (p = 0.002). CLABSI incidence varied from 8.83 to 25.3 per 1000 central-line days, with no significant difference between years (p = 0.27). Coagulase-negative staphylococci accounted for 66% of infections. A significant decrease was found in antibiotic consumption (p < 0.001). Probability of NBSI decreased from 16% on day 3 to 6% on day 10. NBSI remains a common problem in preterm neonates. Overall antibiotic consumption decreased over time despite the absence of a significant reduction in infection rates. Further research aimed at reducing NBSI, in particular CLABSI, is warranted, particularly with regard to limiting central-line dwell-time and fine-tuning insertion and maintenance practices. Show less
With the worldwide digitalisation of medical records, electronic health records (EHRs) have become an increasingly important source of real-world data (RWD). RWD can complement traditional study... Show moreWith the worldwide digitalisation of medical records, electronic health records (EHRs) have become an increasingly important source of real-world data (RWD). RWD can complement traditional study designs because it captures almost the complete variety of patients, leading to more generalisable results. For rheumatology, these data are particularly interesting as our diseases are uncommon and often take years to develop. In this review, we discuss the following concepts related to the use of EHR for research and considerations for translation into clinical care: EHR data contain a broad collection of healthcare data covering the multitude of real-life patients and the healthcare processes related to their care. Machine learning (ML) is a powerful method that allows us to leverage a large amount of heterogeneous clinical data for clinical algorithms, but requires extensive training, testing, and validation. Patterns discovered in EHR data using ML are applicable to real life settings, however, are also prone to capturing the local EHR structure and limiting generalisability outside the EHR(s) from which they were developed. Population studies on EHR necessitates knowledge on the factors influencing the data available in the EHR to circumvent biases, for example, access to medical care, insurance status. In summary, EHR data represent a rapidly growing and key resource for real-world studies. However, transforming RWD EHR data for research and for real-world evidence using ML requires knowledge of the EHR system and their differences from existing observational data to ensure that studies incorporate rigorous methods that acknowledge or address factors such as access to care, noise in the data, missingness and indication bias. Show less
Background: During the COVID-19 pandemic, several factors, such as improved hand hygiene, social distancing, and restricted hospital referral, may have had an influence on the epidemiology of... Show moreBackground: During the COVID-19 pandemic, several factors, such as improved hand hygiene, social distancing, and restricted hospital referral, may have had an influence on the epidemiology of Clostridioides difficile infections (CDI). Methods: The annual CDI incidence rate of nine hospitals participating in the Dutch sentinel CI surveillance with complete data was compared between 2020 and the previous five surveillance years. Trends in characteristics of hos-pitalised CDI patients in 21-24 participating hospitals were compared between the first (March 13-May 12, 2020) or second Dutch COVID-19 wave (September 17, 2020-January 1, 2021) and the same calendar periods in 2015 through 2019. All analyses were adjusted for trend changes over time. Findings: The annual CDI incidence rate in 2020 was lower compared to previous years. During the second wave, the percentage of CDI patients with severe CDI was higher compared to earlier (25.8% in 2020 vs 17.9% in 2015-2019 (RR 1.6; 95%CI 1.1-2.3)). After adjustment for delayed C. difficile diagnostics (>= 8 days from start symptoms), the increase disappeared. Delayed C. difficile diagnostics was indeed more common during the second wave (RR 1.7; 95%CI 1.1-2.6), but only for community-onset CDI (CO-CDI). Interpretation: This study shows that a higher percentage of severe CDI cases was observed during the second COVID-19 wave. This may partially be caused by delayed diagnostics, potentially due to decreased visits to a physi-cian or restricted hospital referral for CO-CDI patients. Funding Dutch ministry of Health. Copyright (C) 2022 The Authors. Published by Elsevier Ltd. Show less
This thesis aims to assess the differences and similarities between autoantibody-positive and autoantibody-negative RA from the start of complaints to the end of the disease. The described research... Show moreThis thesis aims to assess the differences and similarities between autoantibody-positive and autoantibody-negative RA from the start of complaints to the end of the disease. The described research was performed with the ultimate goal to clarify whether autoantibody-negative and autoantibody-positive RA are distinct diseases that require different diagnoses and treatment. Show less
Lauper, K.; Ludici, M.; Mongin, D.; Bergstra, S.A.; Choquette, D.; Codreanu, C.; ... ; Finckh, A. 2022
Background: JAK-inhibitors (JAKi), recently approved in rheumatoid arthritis (RA), have changed the landscape of treatment choices. We aimed to compare the effectiveness of four current second-line... Show moreBackground: JAK-inhibitors (JAKi), recently approved in rheumatoid arthritis (RA), have changed the landscape of treatment choices. We aimed to compare the effectiveness of four current second-line therapies of RA with different modes of action, since JAKi approval, in an international collaboration of 19 registers. Methods: In this observational cohort study, patients initiating tumour necrosis factor inhibitors (TNFi), interleukin-6 inhibitors (IL-6i), abatacept (ABA) or JAKi were included. We compared the effectiveness of these treatments in terms of drug discontinuation and Clinical Disease Activity Index (CDAI) response rates at 1 year. Analyses were adjusted for patient, disease and treatment characteristics, including lines of therapy and accounted for competing risk. Results: We included 31 846 treatment courses: 17 522 TNFi, 2775 ABA, 3863 IL-6i and 7686 JAKi. Adjusted analyses of overall discontinuation were similar across all treatments. The main single reason of stopping treatment was ineffectiveness. Compared with TNFi, JAKi were less often discontinued for ineffectiveness (adjusted HR (aHR) 0.75, 95% CI 0.67 to 0.83), as was IL-6i (aHR 0.76, 95% CI 0.67 to 0.85) and more often for adverse events (aHR 1.16, 95% CI 1.03 to 1.33). Adjusted CDAI response rates at 1 year were similar between TNFi, JAKi and IL-6i and slightly lower for ABA. Conclusion: The adjusted overall drug discontinuation and 1 year response rates of JAKi and IL-6i were similar to those observed with TNFi. Compared with TNFi, JAKi were more often discontinued for adverse events and less for ineffectiveness, as were IL-6i. Show less
Aims: To quantify metabolic impairment via a one-factor approach with confirmatory factor analysis (CFA) including MRI-derived visceral and subcutaneous adipose tissues and to associate it with... Show moreAims: To quantify metabolic impairment via a one-factor approach with confirmatory factor analysis (CFA) including MRI-derived visceral and subcutaneous adipose tissues and to associate it with diastolic dysfunction. Methods: In this cross-sectional analysis, 916 participants (53% female, mean age (SD): 56 (6)) underwent abdominal and cardiovascular MRI. With CFA a metabolic-load factor of metabolic-syndrome variables and visceral and subcutaneous adipose tissues was constructed. A piecewise structural equation model approach with adjustment for confounding factors was used to determine associations with left-ventricular diastolic function, cardiac morphology and hemodynamics. Results: Model fitting excluding blood pressure and waist circumference but including visceral and subcutaneous adipose tissues, fasting glucose, HDL-c and triglycerides was used to construct the metabolic-load factor. Evaluating measurement invariance demonstrated sex-specificity. Change in mitral early/late peak filling rate ratio was -0.12 for both males [-0.20; -0.05, p > 0.05] and females [-0.17; -0.07, p > 0.001] per SD of metabolicload factor. Change in deceleration time of mitral early filling was -11.83 ms in females [-17.38; -6.27] per SD of metabolic-load factor. Conclusion: A single latent metabolic-load factor via CFA including MRI-derived adipose tissues increased sensitivity for metabolic impairment obsoleting waist circumference and is associated with a decreased leftventricular diastolic function, more apparent in females than in males. Show less
Over the last decades, increasingly so in the last years, epidemiological methods have been refined, making it challenging to keep abreast of all methodological developments. The choice of the data... Show moreOver the last decades, increasingly so in the last years, epidemiological methods have been refined, making it challenging to keep abreast of all methodological developments. The choice of the data analytical method directly influences the interpretation and clinical meaning of results of an analysis, yet it is undesirable that technical considerations define the subject of the investigation. Having a deeper understanding of the impact that data analytical decisions can have on the interpretation of numerical results of a study would help to apply analytical tools that are both suitable and appropriate to answer clinical questions. The aim of this thesis was to investigate the impact of choices regarding the design and statistical analysis of a study on the meaning of its numerical results in two sets of case studies in research into causal effects (Part I) and prediction research (Part II). The thesis concludes with a discussion on the role and importance of clinical research questions and estimands. Clearly defining a clinically relevant estimand ensures that data analytical decisions yield meaningful results. Making targeted research questions central to quantitative clinical research can reduce fallacious confidence in (complex) methods and can add to intelligibility of findings. Show less
Schuttevaer, R.; Boogers, W.; Brink, A.; Dijk, W. van; Steenwinkel, J. de; Schuit, S.; ... ; Alsma, J. 2022
Objectives To investigate whether the Charlson Comorbidity Index (CCI) predicted short-term and long-term mortality in patients with a bloodstream infection visiting the emergency department (ED)... Show moreObjectives To investigate whether the Charlson Comorbidity Index (CCI) predicted short-term and long-term mortality in patients with a bloodstream infection visiting the emergency department (ED) and compare it to the often-validated National Early Warning Score (NEWS). Design A retrospective cohort study. Setting A tertiary hospital in the Netherlands. Participants Adult patients attending the ED with a blood culture-proven infection between 2012 and 2017 were included. We collected the comorbidities from the CCI and the vital signs from the NEWS. Main outcomes Short-term mortality (30-day) and long-term mortality (1 year). We assessed the predictive performance by discrimination, expressed as the area under the curve (AUC). Results We included 1039 patients with a blood culture-proven infection. Mortality was 10.4% within 30 days and 27.8% within 1 year. On average patients had two comorbidities (ranging from 0 to 6). Highly prevalent comorbidities were malignancy (30.2%) and diabetes mellitus (20.5%). The predictive performance of the CCI was highest for 1-year mortality (AUC 0.696 (95%CI) (0.660 to 0.732)) and better compared with the NEWS (AUC (95% CI) 0.594 (0.555 to 0.632)). For prediction of 30-day mortality, the NEWS was superior (AUC (95% CI) 0.706 (0.656 to 0.756)) to the comorbidities of the CCI (AUC (95% CI) 0.568 (0.507 to 0.628)). Conclusions We found that presenting comorbidity (ie, the CCI) is most useful to prognosticate long-term outcome in patients with bloodstream infection in the ED. Short-term mortality is more accurately predicted by deviating vital signs (ie, the NEWS). Show less
A direct comparison of two methods for estimating the treated incidence of schizophrenia: the first-contact design (current standard) vs. an electronic psychiatric case-register (new method). The... Show moreA direct comparison of two methods for estimating the treated incidence of schizophrenia: the first-contact design (current standard) vs. an electronic psychiatric case-register (new method). The assumptions underlying the first-contact design are tested. The causes of 2 to 4-fold difference in estimates are conceptualized in a 3-dimensional model. The model is tested on the Norther European incidence literature. Show less
Kok, A.A.L.; Pan, K.Y.; Rius-Ottenheim, N.; Jorg, F.; Eikelenboom, M.; Horsfall, M.; ... ; Penninx, B.W.J.H. 2022
Background: Little is known about the longer-term impact of the Covid-19 pandemic beyond the first months of 2020, particularly for people with pre-existing mental health disorders. Studies... Show moreBackground: Little is known about the longer-term impact of the Covid-19 pandemic beyond the first months of 2020, particularly for people with pre-existing mental health disorders. Studies including pre-pandemic data from large psychiatric cohorts are scarce. Methods: Between April 2020 and February 2021, twelve successive online questionnaires were distributed among participants of the Netherlands Study of Depression and Anxiety, Netherlands Study of Depression in Older Persons, and Netherlands Obsessive Compulsive Disorder Association Study (N = 1714, response rate 62%). Outcomes were depressive symptoms, anxiety, worry, loneliness, perceived mental health impact of the pandemic, fear of Covid-19, positive coping, and happiness. Using linear mixed models we compared trajectories between subgroups with different pre-pandemic chronicity of disorders and healthy controls. Results: Depressive, anxiety and worry symptoms were stable since April-May 2020 whereas happiness slightly decreased. Furthermore, positive coping steadily decreased and loneliness increased - exceeding pre-Covid and April-May 2020 levels. Perceived mental health impact and fear of Covid-19 fluctuated in accordance with national Covid-19 mortality rate changes. Absolute levels of all outcomes were poorer with higher chronicity of disorders, yet trajectories did not differ among subgroups. Limitations: The most vulnerable psychiatric groups may have been underrepresented and results may not be generalizable to lower income countries. Conclusions: After a year, levels of depressive and worry symptoms remained higher than before the pandemic in healthy control groups, yet not in psychiatric groups. Nevertheless, persistent high symptoms in psychiatric groups and increasing loneliness in all groups are specific points of concern for mental health care professionals. Show less
Hitzl, W.; Stamm, T.; Kloppenburg, M.; Ritter, M.; Gaisberger, M.; Zee-neuen, A. van der 2022
Background The present study aimed to predict the expected number of patients with osteoarthritis (OA) in Austria up to the year 2080. Methods Demographic data and population projections between... Show moreBackground The present study aimed to predict the expected number of patients with osteoarthritis (OA) in Austria up to the year 2080. Methods Demographic data and population projections between 2019 and 2080 were obtained from European authorities. Information about recent age- and sex-stratified prevalence of patients with self-reported physician-diagnosed OA was obtained from the Austrian Health Interview Survey (n = 15,771). Projections were stratified by age and sex; sensitivity analyses were performed based on aging, main (most likely), and growth scenarios of the population. Results Based on the projection, the overall increase in the total number of patients with OA from 2019 to 2080 will be 38% for men and women. In 2019, the highest number of OA-patients nested in the groups of persons aged 70-79 (n = 238,749) and 60-69 (n = 237,729) years. In 2080, the 80+ age group is predicted to have the highest number of OA with 421,548 individuals (i.e. factor 3.45 and factor 2.48 increase in the male and female group, respectively, compared to 2019), followed by the group aged 70-79 with 314,617 individuals (factor 1.45 and factor 1.28 increase in the male and female group, respectively, compared to 2019). Similar trends were found in the ageing and growing scenarios. Conclusions The projected increase in the occurrence of OA will likely lead to a substantial socioeconomic burden for the Austrian healthcare system in the near and far future. The current findings plead for the development of sustainable concepts for the treatment and prevention of OA by European authorities. Show less
This thesis describes studies on methods for answering questions about causality, specifically so-called what-if questions, in the presence of methodological obstacles such as confounding, missing... Show moreThis thesis describes studies on methods for answering questions about causality, specifically so-called what-if questions, in the presence of methodological obstacles such as confounding, missing data, and measurement error. Show less
In the last decade, through Clinical Outcome Assessment, and especially measurement of patient-reported outcome measures (PROM)s, we, among others, have initiated a shift in focus from meningioma... Show moreIn the last decade, through Clinical Outcome Assessment, and especially measurement of patient-reported outcome measures (PROM)s, we, among others, have initiated a shift in focus from meningioma tumors to meningioma patients. In various studies we describe an improvement in surgical approaches for skull base meningioma. Nevertheless, patient functioning remains impaired in the long-term. We describe that on average nine years after treatment or diagnosis patients still suffer from participation restrictions in social situations with their friends, family, and at work. Often, at the outpatient clinic, we do not pay enough attention to these problems, especially as patient visits become less frequent in the long-term. Importantly, functioning of patients and their informal caregivers (i.e., close relatives/friends) is strongly interdependent. Moreover, patients and healthcare providers find different outcomes and care processes relevant. This underlines the importance of implementation of PROMs in clinical practice. The studies in this thesis suggest that meningioma care trajectories could benefit from the use of 1) case managers guiding patients and their informal caregivers, 2) implementation of PROMs, and 3) prediction models assisting in the identification of individual patients at high risk of long-term lowered functioning. Ideally, these trajectories should follow the value-based healthcare (VBHC) principles. Show less
Bizzarri, D.; Reinders, M.J.T.; Beekman, M.; Slagboom, P.E.; BBMRI-NL; Akker, E.B. van den 2022
Background Missing or incomplete phenotypic information can severely deteriorate the statistical power in epidemiological studies. High-throughput quantification of small-molecules in bio-samples,... Show moreBackground Missing or incomplete phenotypic information can severely deteriorate the statistical power in epidemiological studies. High-throughput quantification of small-molecules in bio-samples, i.e. `metabolomics', is steadily gaining popularity, as it is highly informative for various phenotypical characteristics. Here we aim to leverage metabolomics to impute missing data in clinical variables routinely assessed in large epidemiological and clinical studies.Methods To this end, we have employed similar to 26,000 H-1-NMR metabolomics samples from 28 Dutch cohorts collected within the BBMRI-NL consortium, to create 19 metabolomics-based predictors for clinical variables, including diabetes status (AUC(5-Fold CV) = 0.94) and lipid medication usage (AUC(5-Fold CV) = 0.90).Findings Subsequent application in independent cohorts confirmed that our metabolomics-based predictors can indeed be used to impute a wide array of missing clinical variables from a single metabolomics data resource. In addition, application highlighted the potential use of our predictors to explore the effects of totally unobserved confounders in omics association studies. Finally, we show that our predictors can be used to explore risk factor profiles contributing to mortality in older participants.Interpretation To conclude, we provide H-1-NMR metabolomics-based models to impute clinical variables routinely assessed in epidemiological studies and illustrate their merit in scenarios when phenotypic variables are partially incomplete or totally unobserved. Copyright (C) 2021 The Author(s). Published by Elsevier B.V. Show less
The increasing amount and complexity of data over the past decades have given rise to new sorts of questions, also in the field of infectious disease epidemiology. This thesis proposes methods to... Show moreThe increasing amount and complexity of data over the past decades have given rise to new sorts of questions, also in the field of infectious disease epidemiology. This thesis proposes methods to analyze data available at multiple resolution levels and to combine different data types in infectious disease surveillance. Hereby using techniques central to data science. Show less
Due to the increased incidence of breast cancer and improved survival, more women are at risk of developing contralateral breast cancer (CBC). The aim of this thesis was to explore risk factors... Show moreDue to the increased incidence of breast cancer and improved survival, more women are at risk of developing contralateral breast cancer (CBC). The aim of this thesis was to explore risk factors associated with CBC. We observed significant associations for a polygenic risk score of common germline variants (PRS313) and for different adjuvant systemic therapy regimens with (subtype-specific) CBC risk. These factors may be incorporated in CBC risk prediction models together with other known and available risk factors. For support of clinical decision making more biological information is needed to understand CBC development in women with invasive breast cancer and DCIS. As a first step towards implementation of a risk prediction model, we performed an exploratory interview study, which showed that patients had varying preferences for graphical presentation of probabilities in a CBC prediction model. In future studies, the prediction model should be incorporated in a decision support tool and implemented in clinical practice. This tool can then help to better identify women at high risk of CBC who may benefit from prophylactic surgery, while the estimates can also be used to reassure patients who are at low risk of developing CBC. Show less
