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van Essen TA, van Erp IA, Lingsma HF, Pisică D, Yue JK, Singh RD, van Dijck JT, Volovici V, Younsi A, Kolias A, Peppel LD, Heijenbrok-Kal M, Ribbers GM, Menon DK, Hutchinson PJ, Manley GT, Depreitere B, Steyerberg EW, Maas AI, de Ruiter GC, Peul WC. Comparative effectiveness of decompressive craniectomy versus craniotomy for traumatic acute subdural hematoma (CENTER-TBI): an observational cohort study. EClinicalMedicine 2023; 63:102161. [PMID: 37600483 PMCID: PMC10432786 DOI: 10.1016/j.eclinm.2023.102161] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 07/25/2023] [Accepted: 07/27/2023] [Indexed: 08/22/2023] Open
Abstract
Background Limited evidence existed on the comparative effectiveness of decompressive craniectomy (DC) versus craniotomy for evacuation of traumatic acute subdural hematoma (ASDH) until the recently published randomised clinical trial RESCUE-ASDH. In this study, that ran concurrently, we aimed to determine current practice patterns and compare outcomes of primary DC versus craniotomy. Methods We conducted an analysis of centre treatment preference within the prospective, multicentre, observational Collaborative European NeuroTrauma Effectiveness Research in Traumatic Brain Injury (known as CENTER-TBI) and NeuroTraumatology Quality Registry (known as Net-QuRe) studies, which enrolled patients throughout Europe and Israel (2014-2020). We included patients with an ASDH who underwent acute neurosurgical evacuation. Patients with severe pre-existing neurological disorders were excluded. In an instrumental variable analysis, we compared outcomes between centres according to treatment preference, measured by the case-mix adjusted proportion DC per centre. The primary outcome was functional outcome rated by the 6-months Glasgow Outcome Scale Extended, estimated with ordinal regression as a common odds ratio (OR), adjusted for prespecified confounders. Variation in centre preference was quantified with the median odds ratio (MOR). CENTER-TBI is registered with ClinicalTrials.gov, number NCT02210221, and the Resource Identification Portal (Research Resource Identifier SCR_015582). Findings Between December 19, 2014 and December 17, 2017, 4559 patients with traumatic brain injury were enrolled in CENTER-TBI of whom 336 (7%) underwent acute surgery for ASDH evacuation; 91 (27%) underwent DC and 245 (63%) craniotomy. The proportion primary DC within total acute surgery cases ranged from 6 to 67% with an interquartile range (IQR) of 12-26% among 46 centres; the odds of receiving a DC for prognostically similar patients in one centre versus another randomly selected centre were trebled (adjusted median odds ratio 2.7, p < 0.0001). Higher centre preference for DC over craniotomy was not associated with better functional outcome (adjusted common odds ratio (OR) per 14% [IQR increase] more DC in a centre = 0.9 [95% CI 0.7-1.1], n = 200). Primary DC was associated with more follow-on surgeries and complications [secondary cranial surgery 27% vs. 18%; shunts 11 vs. 5%]; and similar odds of in-hospital mortality (adjusted OR per 14% IQR more primary DC 1.3 [95% CI (1.0-3.4), n = 200]). Interpretation We found substantial practice variation in the employment of DC over craniotomy for ASDH. This variation in treatment strategy did not result in different functional outcome. These findings suggest that primary DC should be restricted to salvageable patients in whom immediate replacement of the bone flap is not possible due to intraoperative brain swelling. Funding Hersenstichting Nederland for the Dutch NeuroTraumatology Quality Registry and the European Union Seventh Framework Program.
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Affiliation(s)
- Thomas A. van Essen
- University Neurosurgical Center Holland, Leiden University Medical Center, Haaglanden Medical Center, HAGA, Leiden and The Hague, the Netherlands
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge and Addenbrooke's Hospital, Cambridge, United Kingdom
- Department of Surgery, Division of Neurosurgery, QEII Health Sciences Centre and Dalhousie University, Halifax, Nova Scotia, Canada
| | - Inge A.M. van Erp
- University Neurosurgical Center Holland, Leiden University Medical Center, Haaglanden Medical Center, HAGA, Leiden and The Hague, the Netherlands
| | - Hester F. Lingsma
- Center for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center, Rotterdam, the Netherlands
| | - Dana Pisică
- Center for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center, Rotterdam, the Netherlands
- Department of Neurosurgery, Erasmus MC – University Medical Center, Rotterdam, the Netherlands
| | - John K. Yue
- Brain and Spinal Injury Center, Department of Neurological Surgery, Zuckerberg San Francisco General Hospital, University of California San Francisco, San Francisco, USA
| | - Ranjit D. Singh
- University Neurosurgical Center Holland, Leiden University Medical Center, Haaglanden Medical Center, HAGA, Leiden and The Hague, the Netherlands
| | - Jeroen T.J.M. van Dijck
- University Neurosurgical Center Holland, Leiden University Medical Center, Haaglanden Medical Center, HAGA, Leiden and The Hague, the Netherlands
| | - Victor Volovici
- Center for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center, Rotterdam, the Netherlands
- Department of Neurosurgery, Erasmus MC – University Medical Center, Rotterdam, the Netherlands
| | - Alexander Younsi
- Department of Neurosurgery, University Hospital Heidelberg, University of Heidelberg, Heidelberg, Germany
| | - Angelos Kolias
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge and Addenbrooke's Hospital, Cambridge, United Kingdom
- NIHR Global Health Research Group on Neurotrauma, University of Cambridge, Cambridge, United Kingdom
| | - Lianne D. Peppel
- Rijndam Rehabilitation and Department of Rehabilitation Medicine, Erasmus MC – University Medical Center, Rotterdam, the Netherlands
| | - Majanka Heijenbrok-Kal
- Rijndam Rehabilitation and Department of Rehabilitation Medicine, Erasmus MC – University Medical Center, Rotterdam, the Netherlands
| | - Gerard M. Ribbers
- Rijndam Rehabilitation and Department of Rehabilitation Medicine, Erasmus MC – University Medical Center, Rotterdam, the Netherlands
| | - David K. Menon
- Division of Anaesthesia, Addenbrooke's Hospital, University of Cambridge, Cambridge, United Kingdom
| | - Peter J.A. Hutchinson
- Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge and Addenbrooke's Hospital, Cambridge, United Kingdom
- NIHR Global Health Research Group on Neurotrauma, University of Cambridge, Cambridge, United Kingdom
| | - Geoffrey T. Manley
- Brain and Spinal Injury Center, Department of Neurological Surgery, Zuckerberg San Francisco General Hospital, University of California San Francisco, San Francisco, USA
| | - Bart Depreitere
- Department of Neurosurgery, University Hospital KU Leuven, Leuven, Belgium
| | - Ewout W. Steyerberg
- Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands
| | - Andrew I.R. Maas
- Department of Neurosurgery, Antwerp University Hospital and University of Antwerp, Edegem, Belgium
| | - Godard C.W. de Ruiter
- University Neurosurgical Center Holland, Leiden University Medical Center, Haaglanden Medical Center, HAGA, Leiden and The Hague, the Netherlands
| | - Wilco C. Peul
- University Neurosurgical Center Holland, Leiden University Medical Center, Haaglanden Medical Center, HAGA, Leiden and The Hague, the Netherlands
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Persson J, Yan J, Angerås O, Venetsanos D, Jeppsson A, Sjögren I, Linder R, Erlinge D, Ivert T, Omerovic E. PCI or CABG for left main coronary artery disease: the SWEDEHEART registry. Eur Heart J 2023; 44:2833-2842. [PMID: 37288564 PMCID: PMC10406339 DOI: 10.1093/eurheartj/ehad369] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 03/21/2023] [Accepted: 04/25/2023] [Indexed: 06/09/2023] Open
Abstract
AIMS An observational nationwide all-comers prospective register study to analyse outcomes after coronary artery bypass grafting (CABG) or percutaneous coronary intervention (PCI) in unprotected left main coronary artery (LMCA) disease. METHODS AND RESULTS All patients undergoing coronary angiography in Sweden are registered in the Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies registry. Between 01/01/2005 and 12/31/2015, 11 137 patients with LMCA disease underwent CABG (n = 9364) or PCI (n = 1773). Patients with previous CABG, ST-elevation myocardial infarction (MI) or cardiac shock were excluded. Death, MI, stroke, and new revascularization during follow-up until 12/31/2015 were identified using national registries. Cox regression with inverse probability weighting (IPW) and an instrumental variable (IV), administrative region, were used. Patients undergoing PCI were older, had higher prevalence of comorbidity but lower prevalence of three-vessel disease. PCI patients had higher mortality than CABG patients after adjustments for known cofounders with IPW analysis (hazard ratio [HR] 2.0 [95% confidence interval (CI) 1.5-2.7]) and known/unknown confounders with IV analysis (HR 1.5 [95% CI 1.1-2.0]). PCI was associated with higher incidence of major adverse cardiovascular and cerebrovascular events (MACCE; death, MI, stroke, or new revascularization) than CABG, with IV analysis (HR 2.8 [95% CI 1.8-4.5]). There was a quantitative interaction for diabetic status regarding mortality (P = 0.014) translating into 3.6 years (95% CI 3.3-4.0) longer median survival time favouring CABG in patients with diabetes. CONCLUSION In this non-randomized study, CABG in patients with LMCA disease was associated with lower mortality and fewer MACCE compared to PCI after multivariable adjustment for known and unknown confounders.
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Affiliation(s)
- Jonas Persson
- Division of Cardiovascular Medicine, Department of Clinical Sciences, Karolinska Institutet, Danderyd University Hospital, Entrevägen 2, 182 88 Stockholm, Sweden
| | - Jacinth Yan
- Division of Biostatistics, Institute of Environmental Medicine, Karolinska Institutet, Nobels väg 13, 17177 Stockholm, Sweden
| | - Oskar Angerås
- Department of Cardiology, Sahlgrenska University Hospital, Blå stråket 5, 413 45 Gothenburg, Sweden
| | - Dimitrios Venetsanos
- Division of Cardiology, Department of Medicine, Karolinska Institutet Solna and Karolinska University Hospital, Eugeniavägen 3, 171 76 Stockholm, Sweden
| | - Anders Jeppsson
- Department of Cardiothoracic Surgery, Sahlgrenska University Hospital, Blå stråket 5, 413 46 Gothenburg, Sweden
- Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Blå stråket 5B, 413 45 Gothenburg, Sweden
| | - Iwar Sjögren
- Department of Cardiology, Falu Hospital, Lasarettsvägen 10, 791 82 Falun, Sweden
| | - Rikard Linder
- Division of Cardiovascular Medicine, Department of Clinical Sciences, Karolinska Institutet, Danderyd University Hospital, Entrevägen 2, 182 88 Stockholm, Sweden
| | - David Erlinge
- Clinical Sciences, Lund University, Sölvegatan 19, BMC I12, 221 84 Lund, Sweden
| | - Torbjörn Ivert
- Department of Cardiothoracic Surgery, Karolinska University Hospital and Department of Molecular Medicine and Surgery, Karolinska Institutet, Eugeniavägen 3, 171 76 Stockholm, Sweden
| | - Elmir Omerovic
- Department of Cardiology, Sahlgrenska University Hospital, Blå stråket 5, 413 45 Gothenburg, Sweden
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Yu B, Zachrisson HD, Cheesman R, Ystrom E, Nes RB. Boys with overweight status lagged behind girls with overweight status in reading: evidence from mendelian randomization. J Clin Epidemiol 2023; 159:199-205. [PMID: 37156340 DOI: 10.1016/j.jclinepi.2023.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 04/05/2023] [Accepted: 05/01/2023] [Indexed: 05/10/2023]
Abstract
OBJECTIVES We investigated the relationship between childhood weight status and academic achievement across sexes and different school subjects in Norway. STUDY DESIGN AND SETTING We used data from the Norwegian Mother, Father and Child Cohort Study (MoBa), which includes genetic data (N = 13,648, 8-year-old children). We employed within-family mendelian randomization, using a body mass index (BMI) polygenic risk score as an instrument to address unobserved heterogeneity. RESULTS Contrary to most previous findings, we observed that overweight status (including obesity) has more detrimental effects on reading achievement in boys than in girls; the test scores of boys with overweight were about a standard deviation lower than those of normal weight boys, and the negative effects on reading achievement became stronger in the later grade. CONCLUSION Previous obesity prevention studies have mainly targeted girls, based on the assumption that the obesity penalty is greater for girls. Our findings highlight that particular attention to boys with overweight may help reduce the existing gender gap in academic achievement.
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Affiliation(s)
- Baeksan Yu
- Department of Education, Gwangju National University of Education, Gwangju, South Korea.
| | | | - Rosa Cheesman
- PROMENTA Research Center, Department of Psychology, University of Oslo, Oslo, Norway
| | - Eivind Ystrom
- PROMENTA Research Center, Department of Psychology, University of Oslo, Oslo, Norway
| | - Ragnhild Bang Nes
- PROMENTA Research Center, Department of Psychology, University of Oslo, Oslo, Norway; Department of Mental Health and Suicide, Norwegian Institute of Public Health, Oslo, Norway; Department of Philosophy, Classics, and History of Arts and Ideas, University of Oslo, Oslo, Norway
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Uddin MJ, Ahammed T, Kabir AH. Evaluation of instrumental variable method using Cox proportional hazard model in epidemiological studies. MethodsX 2023; 10:102211. [PMID: 37234936 PMCID: PMC10205781 DOI: 10.1016/j.mex.2023.102211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 05/07/2023] [Indexed: 05/28/2023] Open
Abstract
The instrumental variable (IV) method with a Cox proportional hazard (PH) model has been used to evaluate treatment effects in epidemiological studies involving survival data. The effectiveness of the IV methods in these circumstances has yet to be fully understood, though. The study aimed to evaluate the performance of IV methods using a Cox model. We evaluated the validity of treatment effects estimated by two-stage IV models using simulated scenarios with varying confounder strengths and baseline hazards. Our simulation demonstrated that when observed confounders were not taken into account in the IV models, and the confounder strength was moderate, the treatment effects based on the two-stage IV models were similar to the true value. However, the effect estimates diverged from the true value when observed confounders were taken into account in the IV models. In the case of a null treatment effect (i.e., hazard ratio=1), the estimates from the unadjusted and adjusted IV models (only two-stage) were close to the true value. The implication of our study findings is that the treatment effects obtained through IV analyses using the Cox PH model remain valid if the estimates are reported from unadjusted IV models with moderate confounding effects or if the treatment does not impact the outcome.•For every simulation, we utilized a sample size of 10,000 and performed 1,000 replications.•The true treatment effects (HR) of 3, 2, and 1 (null effect) were evaluated.•The 95% confidence intervals (CI) were calculated as the range between the 2.5 and 97.5 percentiles of the 1000 estimates.
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Affiliation(s)
- Md. Jamal Uddin
- Department of Statistics, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh
- Department of General Educational Development (GED), Daffodil International University, Dhaka, Bangladesh
| | - Tanvir Ahammed
- Department of Statistics, Shahjalal University of Science and Technology, Sylhet 3114, Bangladesh
| | - A.Z.M. Hasan Kabir
- Department of Mathematics, Comilla Victoria Government College, Cumilla, Bangladesh
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Gaml-Sørensen A, Brix N, Hærvig KK, Lindh C, Tøttenborg SS, Hougaard KS, Høyer BB, Ernst A, Arendt LH, Clemmensen PJ, Bonde JPE, Henriksen TB, Toft G, Arah OA, Ramlau-Hansen CH. Maternal vitamin D levels and male reproductive health: a population-based follow-up study. Eur J Epidemiol 2023; 38:469-484. [PMID: 36952117 PMCID: PMC10976978 DOI: 10.1007/s10654-023-00987-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 03/05/2023] [Indexed: 03/24/2023]
Abstract
Maternal vitamin D levels during pregnancy may be important for reproductive health in male offspring by regulating cell proliferation and differentiation during development. We conducted a follow-up study of 827 young men from the Fetal Programming of Semen Quality (FEPOS) cohort, nested in the Danish National Birth Cohort to investigate if maternal vitamin D levels were associated with measures of reproductive health in adult sons. These included semen characteristics, testes volume, and reproductive hormone levels and were analysed according to maternal vitamin D (25(OH)D3) levels during pregnancy. In addition, an instrumental variable analysis using seasonality in sun exposure as an instrument for maternal vitamin D levels was conducted. We found that sons of mothers with vitamin D levels < 25 nmol/L had 11% (95% CI - 19 to - 2) lower testes volume and a 1.4 (95% CI 1.0 to 1.9) times higher risk of having low testes volume (< 15 mL), in addition to 20% (95% CI - 40 to 9) lower total sperm count and a 1.6 (95% CI 0.9 to 2.9) times higher risk of having a low total sperm count (< 39 million) compared with sons of mothers with vitamin D levels > 75 nmol/L. Continuous models, spline plots and an instrumental variable analysis supported these findings. Low maternal vitamin D levels were associated with lower testes volume and lower total sperm count with indications of dose-dependency. Maternal vitamin D level above 75 nmol/L during pregnancy may be beneficial for testes function in adult sons.
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Affiliation(s)
- Anne Gaml-Sørensen
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark.
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA.
| | - Nis Brix
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
- Department of Clinical Genetics, Aarhus University Hospital, 8200, Aarhus N, Denmark
| | - Katia Keglberg Hærvig
- Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen University Hospital, 2400, Copenhagen NV, Denmark
| | - Christian Lindh
- Division of Occupational and Environmental Medicine, Lund University, 22363, Lund, Sweden
| | - Sandra Søgaard Tøttenborg
- Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen University Hospital, 2400, Copenhagen NV, Denmark
- Department of Public Health, University of Copenhagen, 1014, Copenhagen K, Denmark
| | - Karin Sørig Hougaard
- Department of Public Health, University of Copenhagen, 1014, Copenhagen K, Denmark
- National Research Centre for the Working Environment, 2100, Copenhagen Ø, Denmark
| | - Birgit Bjerre Høyer
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
- Department of Regional Development, Region of Southern Denmark, 7100, Vejle, Denmark
| | - Andreas Ernst
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
- Department of Urology, Aarhus University Hospital, 8200, Aarhus N, Denmark
| | - Linn Håkonsen Arendt
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
- Department of Obstetrics and Gynaecology, Aarhus University Hospital, 8200, Aarhus N, Denmark
| | - Pernille Jul Clemmensen
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
| | - Jens Peter Ellekilde Bonde
- Department of Occupational and Environmental Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen University Hospital, 2400, Copenhagen NV, Denmark
- Department of Public Health, University of Copenhagen, 1014, Copenhagen K, Denmark
| | - Tine Brink Henriksen
- Perinatal Epidemiology Research Unit, Aarhus University, Aarhus C, Denmark
- Department of Paediatrics and Adolescent Medicine, Aarhus University Hospital, 8200, Aarhus N, Denmark
| | - Gunnar Toft
- Steno Diabetes Center Aarhus, Aarhus University Hospital, 8200, Aarhus N, Denmark
| | - Onyebuchi A Arah
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
- Department of Statistics, Division of Physical Sciences, UCLA College, Los Angeles, CA, 90024, USA
| | - Cecilia Høst Ramlau-Hansen
- Department of Public Health, Research Unit for Epidemiology, Aarhus University, Bartholins Allé 2, 8000, Aarhus C, Denmark
- Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles (UCLA), Los Angeles, CA, 90095, USA
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Lin JH, Huang YT, Yu JC, Chan KA, Huang YT. Mediation and instrumental variable analyses for vaccine-induced antibody titer against influenza B. Vaccine 2023:S0264-410X(23)00261-X. [PMID: 36925423 DOI: 10.1016/j.vaccine.2023.03.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 03/03/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023]
Abstract
OBJECTIVE Immune correlate analyses for vaccine trials have been applied to investigate associations of vaccine efficacy and surrogate markers such as vaccine-induced antibodies. However, the role of antibody as a surrogate marker in predicting the outcome can vary by time, and surrogate-outcome confounding may have resulted in bias even in randomized trials. We provide a framework for surrogate marker assessment to address the aforementioned issues. STUDY DESIGN AND SETTING We reanalyzed the vaccine randomized trial for influenza B. We conducted a mediation analysis that enables estimation of vaccine efficacy, mediation effects and proportion of mediation on disease probabilities at various follow-up times. We proposed instrumental variable (IV) analyses with randomized vaccination as an IV accounting for potential unmeasured confounding. RESULTS The mediation effect of vaccine efficacy by hemagglutination inhibition (HAI) titer was significantly protective at 181 days after vaccination: 63.2% [95% confidence interval, (CI) = (39.9%, 82.0%)], and HAI titer explained 61.1% [95% CI = (36.7%, 96.2%)] of the protective effect of vaccination. CONCLUSIONS Most of vaccine efficacy is mediated by HAI titer, particularly in children 10 years and older. Our contribution is to provide causal analytics for the role of surrogate marker with weaker assumptions regarding surrogate-disease causation.
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Beumer BR, Polak WG, de Man RA, Metselaar HJ, van Klaveren D, Labrecque J, IJzermans JN. Impact of waiting time on post-transplant survival for recipients with hepatocellular carcinoma: A natural experiment randomized by blood group. JHEP Rep 2023; 5:100629. [PMID: 36654943 DOI: 10.1016/j.jhepr.2022.100629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 10/27/2022] [Accepted: 10/27/2022] [Indexed: 11/24/2022] Open
Abstract
Background & Aims When listing for liver transplantation, one can transplant as soon as possible or introduce a test-of-time to better select patients, as the tumor's biological behavior is observed. Knowing the degree of harm caused by time itself is essential to advise patients and decide on the maximum duration of the test-of-time. Therefore, we investigated the causal effect of waiting time on post-transplant survival for patients with hepatocellular carcinoma. Methods We analyzed the UNOS-OPTN dataset and exploited a natural experiment created by blood groups. Relations between variables and assumptions were described in a causal graph. Selection bias was addressed by inverse probability weighting. Confounding was avoided using instrumental variable analysis, with an additive hazards model in the second stage. The causal effect was evaluated by estimating the difference in 5-year overall survival if all patients waited 2 months instead of 12 months. Upper bounds of the test-of-time were evaluated for probable scenarios by means of simulation. Results The F-statistic of the first stage was 86.3. The effect of waiting 12 months vs. 2 months corresponded with a drop in overall survival rate of 5.07% (95% CI 0.277-9.69) and 8.33% (95% CI 0.47-15.60) at 5- and 10-years post-transplant, respectively. The median survival dropped by 3.41 years from 16.21 years (95% CI 15.98-16.60) for those waiting 2 months to 12.80 years (95% CI 10.72-15.90) for those waiting 12 months. Conclusions From a patient's perspective, the choice between ablate-and-wait vs. immediate transplantation is in favor of immediate transplantation. From a policy perspective, the extra waiting time can be used to increase the utility of scarce donor livers. However, the duration of the test-of-time is bounded, and it likely should not exceed 8 months. Impact and implications When listing patients with liver cancer for transplantation, it is unclear whether a test-of-time or immediate transplantation offer better outcomes at the population level. In this study, we found that increased liver transplant waiting times are detrimental in patients with liver cancer. Furthermore, our simulation showed that a pre-operative observational period can be useful to ensure good donor liver allocation, but that its duration should not exceed 8 months.
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Schaapherder AF, Kaisar M, Mumford L, Robb M, Johnson R, de Kok MJ, Bemelman FJ, van de Wetering J, van Zuilen AD, Christiaans MH, Baas MC, Nurmohamed AS, Berger SP, Bastiaannet E, de Vries AP, Sharples E, Ploeg RJ, Lindeman JH. Donor characteristics and their impact on kidney transplantation outcomes: Results from two nationwide instrumental variable analyses based on outcomes of donor kidney pairs accepted for transplantation. EClinicalMedicine 2022; 50:101516. [PMID: 35784435 PMCID: PMC9240982 DOI: 10.1016/j.eclinm.2022.101516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2021] [Revised: 05/22/2022] [Accepted: 05/27/2022] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Donor-characteristics and donor characteristics-based decision algorithms are being progressively used in the decision process whether or not to accept an available donor kidney graft for transplantation. While this may improve outcomes, the performance characteristics of the algorithms remains moderate. To estimate the impact of donor factors of grafts accepted for transplantation on transplant outcomes, and to test whether implementation of donor-characteristics-based algorithms in clinical decision-making is justified, we applied an instrumental variable analysis to outcomes for kidney donor pairs transplanted in different individuals. METHODS This analysis used (dis)congruent outcomes of kidney donor pairs as an instrument and was based on national transplantation registry data for all donor kidney pairs transplanted in separate individuals in the Netherlands (1990-2018, 2,845 donor pairs), and the United Kingdom (UK, 2000-2018, 11,450 pairs). Incident early graft loss (EGL) was used as the primary discriminatory factor. It was reasoned that a scenario with a dominant impact of donor variables on transplantation outcomes would result in high concordance of EGL in both recipients, whilst dominance of asymmetrical outcomes could indicate a more complex scenario, involving an interaction of donor, procedural and recipient factors. FINDINGS Incidences of congruent EGL (Netherlands: 1·2%, UK: 0·7%) were slightly lower than the arithmetical (stochastic) incidences, suggesting that once a graft has been accepted for transplantation, donor factors minimally contribute to incident EGL. A long-term impact of donor factors was explored by comparing outcomes for functional grafts from donor pairs with asymmetrical vs. symmetrical outcomes. Recipient survival was similar for both groups, but a slightly compromised graft survival was observed for grafts with asymmetrical outcomes in the UK cohort: (10-years Hazard Ratio for graft loss: 1·18 [1·03-1·35] p<0·018); and 5 years eGFR (48·6 [48·3-49·0] vs. 46·0 [44·5-47·6] ml/min in the symmetrical outcome group, p<0·001). INTERPRETATION Our results suggest that donor factors for kidney grafts deemed acceptable for transplantation impact minimally on transplantation outcomes. A strong reliance on donor factors and/or donor-characteristics-based decision algorithms could result in unjustified rejection of grafts. Future efforts to optimize transplant outcomes should focus on a better understanding of the recipient factors underlying transplant outcomes. FUNDING None.
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Affiliation(s)
- Alexander F. Schaapherder
- Department of Surgery and Leiden Transplant Center, Leiden University Medical Center, Leiden, the Netherlands
| | - Maria Kaisar
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom
- Research and Development, NHS Blood and Transplant, Bristol & Oxford, United Kingdom
| | - Lisa Mumford
- Statistics and Clinical Studies, NHS Blood and Transplant, Bristol, United Kingdom
| | - Matthew Robb
- Statistics and Clinical Studies, NHS Blood and Transplant, Bristol, United Kingdom
| | - Rachel Johnson
- Statistics and Clinical Studies, NHS Blood and Transplant, Bristol, United Kingdom
| | - Michèle J.C. de Kok
- Department of Surgery and Leiden Transplant Center, Leiden University Medical Center, Leiden, the Netherlands
| | - Frederike J. Bemelman
- Department of Internal Medicine (Nephrology), Amsterdam UMC, Academic Medical Center, Amsterdam, the Netherlands
| | - Jacqueline van de Wetering
- Department of Internal Medicine (Nephrology), Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Arjan D. van Zuilen
- Department of Internal Medicine (Nephrology), University Medical Center Utrecht, Utrecht, the Netherlands
| | - Maarten H.L. Christiaans
- Department of Internal Medicine (Nephrology), Maastricht University Medical Center, Maastricht, the Netherlands
| | - Marije C. Baas
- Department of Internal Medicine (Nephrology), Radboud University Medical Center, Nijmegen, the Netherlands
| | - Azam S. Nurmohamed
- Department of Internal Medicine (Nephrology), Amsterdam UMC, VU Medical Center, Amsterdam, the Netherlands
| | - Stefan P. Berger
- Department of Internal Medicine (Nephrology), University Medical Center Groningen, Groningen, the Netherlands
| | - Esther Bastiaannet
- Department of Surgery, Leiden University Medical Center, Leiden, The Netherlands. Current address: Dept. Epidemiology, UZH, Zurich, Switzerland
| | - Aiko P.J. de Vries
- Division of Nephrology, Department of Internal Medicine and Leiden Transplant Center, Leiden University Medical Center, Leiden, the Netherlands
| | - Edward Sharples
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom
| | - Rutger J. Ploeg
- Department of Surgery and Leiden Transplant Center, Leiden University Medical Center, Leiden, the Netherlands
- Nuffield Department of Surgical Sciences, University of Oxford, Oxford, United Kingdom
| | - Jan H.N. Lindeman
- Department of Surgery and Leiden Transplant Center, Leiden University Medical Center, Leiden, the Netherlands
- Corresponding author at: Department of Surgery, Leiden University Medical Center, PObox 9600, 2300 RC Leiden, the Netherlands.
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Ceyisakar IE, van Leeuwen N, Steyerberg EW, Lingsma HF. Instrumental variable analysis to estimate treatment effects: a simulation study showing potential benefits of conditioning on hospital. BMC Med Res Methodol 2022; 22:121. [PMID: 35468748 PMCID: PMC9036707 DOI: 10.1186/s12874-022-01598-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/05/2022] [Indexed: 11/10/2022] Open
Abstract
Background Instrumental variable (IV) analysis holds the potential to estimate treatment effects from observational data. IV analysis potentially circumvents unmeasured confounding but makes a number of assumptions, such as that the IV shares no common cause with the outcome. When using treatment preference as an instrument, a common cause, such as a preference regarding related treatments, may exist. We aimed to explore the validity and precision of a variant of IV analysis where we additionally adjust for the provider: adjusted IV analysis. Methods A treatment effect on an ordinal outcome was simulated (beta − 0.5 in logistic regression) for 15.000 patients, based on a large data set (the IMPACT data, n = 8799) using different scenarios including measured and unmeasured confounders, and a common cause of IV and outcome. We compared estimated treatment effects with patient-level adjustment for confounders, IV with treatment preference as the instrument, and adjusted IV, with hospital added as a fixed effect in the regression models. Results The use of patient-level adjustment resulted in biased estimates for all the analyses that included unmeasured confounders, IV analysis was less confounded, but also less reliable. With correlation between treatment preference and hospital characteristics (a common cause) estimates were skewed for regular IV analysis, but not for adjusted IV analysis. Conclusion When using IV analysis for comparing hospitals, some limitations of regular IV analysis can be overcome by adjusting for a common cause. Trial registration We do not report the results of a health care intervention. Supplementary Information The online version contains supplementary material available at 10.1186/s12874-022-01598-6.
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Affiliation(s)
- I E Ceyisakar
- Centre for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.
| | - N van Leeuwen
- Centre for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
| | - E W Steyerberg
- Centre for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands.,Department of Biomedical Data Sciences, Leiden University Medical Centre, Leiden, the Netherlands
| | - H F Lingsma
- Centre for Medical Decision Making, Department of Public Health, Erasmus MC - University Medical Center Rotterdam, PO Box 2040, 3000 CA, Rotterdam, The Netherlands
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Yao YC, Chen JQ, Yin L, Lin WH, Peng JH, Fan WH. Primary tumor resection with or without metastasectomy for left- and right-sided stage IV colorectal cancer: an instrumental variable analysis. BMC Gastroenterol 2022; 22:114. [PMID: 35264117 PMCID: PMC8908621 DOI: 10.1186/s12876-022-02184-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/21/2022] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Whether primary tumor location (PTL) is predictive of survival benefits following primary tumor resection plus metastasectomy (PMTR) and primary tumor resection (PTR) alone in stage IV colorectal cancer patients is not known. We sought to address this issue by employing instrumental variable analysis to evaluate the efficacy of PMTR and PTR with stratification for primary tumor location in stage IV colorectal cancer patients. PATIENTS AND METHODS Stage IV colorectal cancer patients diagnosed between January 1, 2005 and December 31, 2015 were identified from the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute. To account for both measured and unmeasured confounders, the efficacy of PMTR and PTR in the left- and right-sided subgroups was evaluated using instrumental variable analysis, with the health service area as the instrument variable. Overall survival (OS) was the primary outcome of interest. RESULTS A total of 50,333 eligible patients were analyzed (left-sided, n = 29,402 and right-sided, n = 20,931). OS was significantly better with PMTR than with other treatments (PTR, metastasectomy only, or no surgery) in patients with left-sided tumors (hazard ratio [HR] = 0.37 [95% CI 0.24-0.58], P < 0.001), but not in patients with right-sided tumors (HR = 0.98 [95% CI 0.65-1.47], P = 0.910; interaction test P < 0.001). OS was comparable in patients treated with PTR and those treated with no surgery in both the left-sided (HR = 1.11 [95% CI 0.68-1.81], P = 0.690) and right-sided (HR = 0.85 [95% CI 0.50-1.43], P = 0.530; interaction test P = 0.466) subgroups. CONCLUSIONS PMTR appears to only benefit patients with left-sided stage IV colorectal cancer but not those with right-sided tumors. PTR does not improve OS, regardless of primary tumor location. When selecting patients for PMTR, primary tumor location should be considered. Overuse of PTR should be avoided.
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Affiliation(s)
- Yi-Chen Yao
- Department of Medical Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, People's Republic of China
| | - Jun-Quan Chen
- Department of Medical Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, People's Republic of China
| | - Ling Yin
- Department of Clinical Research, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, People's Republic of China
| | - Wu-Hao Lin
- Department of Medical Oncology, State Key Laboratory of Oncology in South China, Collaborative Innovation Center of Cancer Medicine, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, People's Republic of China
| | - Jian-Hong Peng
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, People's Republic of China.
| | - Wen-Hua Fan
- Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Sun Yat-Sen University Cancer Center, 651 Dong Feng Road East, Guangzhou, 510060, People's Republic of China.
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11
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Lebenbaum M, Laporte A, de Oliveira C. The effect of mental health on social capital: An instrumental variable analysis. Soc Sci Med 2021; 272:113693. [PMID: 33508656 DOI: 10.1016/j.socscimed.2021.113693] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 01/05/2021] [Accepted: 01/07/2021] [Indexed: 10/22/2022]
Abstract
Although a large body of literature has examined the effect of social capital on health and theoretical models suggest a reciprocal relationship between the two variables, there are relatively few studies that have investigated the effect of mental health on social capital. This paper evaluates the impact of mental health on the stock of social capital using data from the cross-sectional 2012 (N = 21,844) and 2002 (N = 31,089) Canadian Community Health Survey - Mental Health editions. Mental health was measured retrospectively as self-rated mental health, past year mental health conditions, and past 30-day psychological distress. Given the reciprocal relationship, we used an instrumental variable approach with family history of mental health problems as the instrument and examined forms of social capital - sense of belonging and workplace social support - that are largely measures of social capital provided by non-family members in the community and workplace. The analysis suggests there are large and significant associations between measures of mental health and both outcomes, which persist in the instrumental variable analyses. These findings highlight the urgent need for policy makers to implement greater prevention and treatment of poor mental health, and provide greater support for individuals with poor mental health so they can build and maintain their social capital.
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Affiliation(s)
- Michael Lebenbaum
- Institute for Health Policy, Management and Evaluation (IHPME), University of Toronto, Canadian Centre for Health Economics (CCHE), Canada.
| | - Audrey Laporte
- IHPME, University of Toronto, Canadian Centre for Health Economics (CCHE), Canada.
| | - Claire de Oliveira
- IHPME, University of Toronto, Centre for Health Economics and Hull York Medical School, University of York, UK.
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Liu JX, Au Yeung SL, Kwok MK, Leung JYY, Lin SL, Hui LL, Leung GM, Schooling CM. Birth weight, gestational age and late adolescent liver function using twin status as instrumental variable in a Hong Kong Chinese birth cohort: "Children of 1997". Prev Med 2018; 111:190-197. [PMID: 29545162 DOI: 10.1016/j.ypmed.2018.03.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/25/2018] [Accepted: 03/09/2018] [Indexed: 02/04/2023]
Abstract
Birth weight (BW) is inversely associated with diabetes and liver function in Mendelian Randomization studies. Observationally, lower BW is usually also associated with poorer liver function. However, these studies could be confounded by socioeconomic position. Here we assessed if BW is associated with liver function in a unique population with little socio-economic patterning of BW, using both instrumental variable and an observational analysis. We used instrumental variable analysis (IVA) to assess the association of BW with liver function (alanine transaminase (ALT), alkaline phosphatase (ALP), bilirubin, and albumin) at ~17 years with twin status as an instrumental variable in the prospective population-representative "Children of 1997" birth cohort (n = 8327). We also conducted an observational analysis adjusted for sex, maternal age, maternal migrant status, smoking and parental socio-economic position. A generalized linear model with gamma family was used for ALT, ALP, and bilirubin because they are not normally distributed. Using IVA, BW was not associated with ALT, ALP or bilirubin, but was possibly negatively associated with albumin (-1.12 g/L, 95% confidence interval (CI) -2.08 to -0.16). Observationally, BW was negatively associated with ALT (-1.23 IU/L, 95% CI -2.16 to -0.30), ALP (-1.72 IU/L, 95% CI -3.43 to -0.01) and higher albumin (-0.23 g/L, 95% CI -0.40 to -0.06). Poor liver function may be a pathway by which the risks of lower BW are actuated. This insight might help identify post-natal targets of intervention to mitigate the adverse health effects of lower birth weight.
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Affiliation(s)
- Jun Xi Liu
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Shiu Lun Au Yeung
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Man Ki Kwok
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - June Yue Yan Leung
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Shi Lin Lin
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Lai Ling Hui
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; Department of Paediatrics, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Gabriel Matthew Leung
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - C Mary Schooling
- School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, China; City University of New York Graduate School of Public Health and Health Policy, New York, NY, USA.
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Cejvanovic V, Kjær LK, Bergholdt HKM, Torp-Pedersen A, Henriksen T, Weimann A, Ellervik C, Poulsen HE. Iron induced RNA-oxidation in the general population and in mouse tissue. Free Radic Biol Med 2018; 115:127-135. [PMID: 29157668 DOI: 10.1016/j.freeradbiomed.2017.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 11/10/2017] [Accepted: 11/14/2017] [Indexed: 12/19/2022]
Abstract
Iron promotes formation of hydroxyl radicals by the Fenton reaction, subsequently leading to potential oxidatively generated damage of nucleic acids. Oxidatively generated damage to RNA, measured as 8-oxo-7,8-dihydroguanosine (8-oxoGuo) in urine, is increased in patients with genetic iron overload, which have led us to test the hypothesis that high iron status, assessed by iron biomarkers and genetic disposition, increases urinary excretion of 8-oxoGuo. In a general Danish population study we used a Mendelian randomization design with HFE genotypes as a proxy for iron status and supplemented with ex vivo experiments in mice muscle tissue exposed to iron(II) sulfate to attempt to clarify this hypothesis. The biomarkers ferritin, transferrin, and transferrin saturation (TS) were associated with 8-oxoGuo (in linear univariable and multivariable regression analyses: P < 0.001). Mendelian randomization indicated a causal pathway between genetically elevated iron biomarkers (assessed by ferritin and TS) and high levels of 8-oxoGuo. The ex vivo experiments showed a monotonically increase in 8-oxoGuo with increased iron concentration (ANOVA: P = 0.0008) that was prevented with iron chelation (P = 0.01). Our results indicate a causal relationship between iron biomarkers and 8-oxoGuo. Furthermore, the ex vivo experiment shows a mechanistic link between iron and 8-oxoGuo formation. Both iron overload and the biomarker 8-oxoGuo have been linked to e.g. diabetes, which merits future studies to investigate if iron induced 8-oxoGuo is involved in disease development.
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Affiliation(s)
- Vanja Cejvanovic
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
| | - Laura Kofoed Kjær
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Arendse Torp-Pedersen
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
| | - Trine Henriksen
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
| | - Allan Weimann
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark
| | - Christina Ellervik
- Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Laboratory Medicine, Boston Children's Hospital, Boston, MA, USA; Department of Production, Research and Innovation, Region Zealand, Denmark
| | - Henrik Enghusen Poulsen
- Department of Clinical Pharmacology, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark; Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Rockers PC, Røttingen JA, Shemilt I, Tugwell P, Bärnighausen T. Inclusion of quasi-experimental studies in systematic reviews of health systems research. Health Policy 2015; 119:511-21. [PMID: 25776033 DOI: 10.1016/j.healthpol.2014.10.006] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 09/29/2014] [Accepted: 10/11/2014] [Indexed: 12/30/2022]
Abstract
Systematic reviews of health systems research commonly limit studies for evidence synthesis to randomized controlled trials. However, well-conducted quasi-experimental studies can provide strong evidence for causal inference. With this article, we aim to stimulate and inform discussions on including quasi-experiments in systematic reviews of health systems research. We define quasi-experimental studies as those that estimate causal effect sizes using exogenous variation in the exposure of interest that is not directly controlled by the researcher. We incorporate this definition into a non-hierarchical three-class taxonomy of study designs - experiments, quasi-experiments, and non-experiments. Based on a review of practice in three disciplines related to health systems research (epidemiology, economics, and political science), we discuss five commonly used study designs that fit our definition of quasi-experiments: natural experiments, instrumental variable analyses, regression discontinuity analyses, interrupted times series studies, and difference studies including controlled before-and-after designs, difference-in-difference designs and fixed effects analyses of panel data. We further review current practices regarding quasi-experimental studies in three non-health fields that utilize systematic reviews (education, development, and environment studies) to inform the design of approaches for synthesizing quasi-experimental evidence in health systems research. Ultimately, the aim of any review is practical: to provide useful information for policymakers, practitioners, and researchers. Future work should focus on building a consensus among users and producers of systematic reviews regarding the inclusion of quasi-experiments.
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