Jan Serroyen
Maastricht University
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Publication
Featured researches published by Jan Serroyen.
International Urogynecology Journal | 2012
Mirjam Weemhoff; Tineke F. M. Vergeldt; Kim Notten; Jan Serroyen; Paul H. N. M. Kampschöer; Frans J. M. E. Roumen
Introduction and hypothesisThis study aimed to determine the relationship of recurrent cystocele with avulsion of puborectalis muscle and other risk factors.MethodsIn this prospective observational cohort study, 245 women undergoing anterior colporrhaphy were invited for a 2-year follow-up visit consisting of a questionnaire, physical examination, and translabial 3D ultrasonography. Women with and without recurrent cystocele were compared to identify recurrence risk factors.ResultsOf the 245 women, 156 agreed to the follow-up visit (63.7%). Objective recurrence rate was 80 of 156 (51.3%). Seventeen of the 156 (10.9%) reported subjective recurrence. Risk factors for anatomical recurrence were complete avulsion of puborectalis muscle (OR, 2.4; 95% CI, 1.3, 4.7), advanced preoperative stage (OR, 2.0; 95% CI, 1.0, 4.1), family history of prolapse (OR, 2.4; 95% CI, 1.2, 4.9), and sacrospinous fixation (OR, 6.5; 95% CI, 2.0, 21.2).ConclusionsRisk factors for anatomical cystocele recurrence after anterior colporrhaphy were complete avulsion of puborectalis muscle, advanced preoperative stage, family history of prolapse, and sacrospinous fixation.
Circulation-arrhythmia and Electrophysiology | 2013
Sander Verheule; Els Tuyls; Ali Gharaviri; Sarah Hulsmans; Arne van Hunnik; Marion Kuiper; Jan Serroyen; Stef Zeemering; Nico H.L. Kuijpers; Ulrich Schotten
Background—The transition from persistent to permanent atrial fibrillation (AF) is associated with increased complexity of fibrillatory conduction. We have investigated the spatial distribution of fibrillation waves and structural alterations in the atrial free walls in a goat model of AF. Methods and Results—AF was maintained for 3 weeks (short term [ST], persistent AF) or 6 months (long term [LT], permanent AF). Fibrillation patterns were assessed with epicardial mapping. The origin of fibrillation waves and sites of conduction abnormalities were more homogeneously distributed in LT than in ST goats. Histologically, the total area fraction occupied by fibrous tissue and the degree of perimysial fibrosis (separation between myocyte bundles) were not significantly different between groups. However, endomysial fibrosis (distance between myocytes within bundles) was significantly larger in LT goats, particularly in the outer millimeter of the atria. By contrast, myocyte diameters were larger in LT goats throughout the atrial walls. High-resolution optical mapping showed that epicardial wavefront expansion was slower and more anisotropic in LT than in ST goats. Finally, a mathematical model of a simplified atrial architecture confirmed the potential impact of epicardial endomysial fibrosis on AF complexity. Conclusions—Altered propagation after 6 months of AF is consistent with homogeneous structural remodeling in the outer millimeter of the atria. Loss of continuity of the epicardial layer because of endomysial fibrosis may reduce its synchronizing effect, thereby increasing the complexity of fibrillatory conduction pathways. The exact distribution of fibrosis may be more important for the occurrence of conduction disturbances than the overall quantity.
Circulation-arrhythmia and Electrophysiology | 2013
Sander Verheule; Els Tuyls; Ali Gharaviri; Sarah Hulsmans; Arne van Hunnik; Marion Kuiper; Jan Serroyen; Stef Zeemering; Nico H.L. Kuijpers; Ulrich Schotten
Background—The transition from persistent to permanent atrial fibrillation (AF) is associated with increased complexity of fibrillatory conduction. We have investigated the spatial distribution of fibrillation waves and structural alterations in the atrial free walls in a goat model of AF. Methods and Results—AF was maintained for 3 weeks (short term [ST], persistent AF) or 6 months (long term [LT], permanent AF). Fibrillation patterns were assessed with epicardial mapping. The origin of fibrillation waves and sites of conduction abnormalities were more homogeneously distributed in LT than in ST goats. Histologically, the total area fraction occupied by fibrous tissue and the degree of perimysial fibrosis (separation between myocyte bundles) were not significantly different between groups. However, endomysial fibrosis (distance between myocytes within bundles) was significantly larger in LT goats, particularly in the outer millimeter of the atria. By contrast, myocyte diameters were larger in LT goats throughout the atrial walls. High-resolution optical mapping showed that epicardial wavefront expansion was slower and more anisotropic in LT than in ST goats. Finally, a mathematical model of a simplified atrial architecture confirmed the potential impact of epicardial endomysial fibrosis on AF complexity. Conclusions—Altered propagation after 6 months of AF is consistent with homogeneous structural remodeling in the outer millimeter of the atria. Loss of continuity of the epicardial layer because of endomysial fibrosis may reduce its synchronizing effect, thereby increasing the complexity of fibrillatory conduction pathways. The exact distribution of fibrosis may be more important for the occurrence of conduction disturbances than the overall quantity.
Journal of Clinical Epidemiology | 2015
Wolfgang Viechtbauer; Luc Smits; Daniel Kotz; Luc Budé; Mark Spigt; Jan Serroyen; Rik Crutzen
One of the goals of a pilot study is to identify unforeseen problems, such as ambiguous inclusion or exclusion criteria or misinterpretations of questionnaire items. Although sample size calculation methods for pilot studies have been proposed, none of them are directed at the goal of problem detection. In this article, we present a simple formula to calculate the sample size needed to be able to identify, with a chosen level of confidence, problems that may arise with a given probability. If a problem exists with 5% probability in a potential study participant, the problem will almost certainly be identified (with 95% confidence) in a pilot study including 59 participants.
Pain | 2011
Ivan P.J. Huijnen; Hanne P.J. Kindermans; Henk A. M. Seelen; Madelon L. Peters; Rob Smeets; Jan Serroyen; Jeffrey Roelofs; M. Goossens; Jeanine A. Verbunt
Summary The self‐discrepancy model is applied to chronic low back pain to explain persistence and avoidance behaviour. Whether both styles are related to disability and quality of life is evaluated. ABSTRACT In chronic low back pain (CLBP) research, the self‐discrepancy model has been applied to explain dysfunctional avoidance and persistence behaviour. The main aim of this study was to evaluate whether specific self‐discrepancies in patients with CLBP are associated with the abovementioned types of activity‐related behaviour and whether changes in self‐discrepancies over time are associated with changes in activity‐related behaviour. Furthermore, the aim was to evaluate whether avoidance and persistence behaviour are associated with a higher level of disability and a diminished quality of life and whether changes over time in avoidance and persistence behaviour result in changes in disability and quality of life. A longitudinal cohort study in a sample of patients with CLBP (N = 116), in which self‐discrepancies, disability, quality of life, and objectively registered characteristics of activity‐related behaviour were measured, was performed to evaluate the pathways in the aforementioned self‐discrepancy model. Results indicate that patients with CLBP who feel closer to their ideal‐other show more characteristics of persistence behaviour. Patients who move further away from their ideal‐own also show more characteristics of persistence behaviour. Furthermore, in patients characterized as avoider, a decrease in a patient’s daily uptime was associated with a decrease of mental health‐related quality of life.
The American Statistician | 2009
Jan Serroyen; Geert Molenberghs; Geert Verbeke; Marie Davidian
Whereas marginal models, random-effects models, and conditional models are routinely considered to be the three main modeling families for continuous and discrete repeated measures with linear and generalized linear mean structures, respectively, it is less common to consider nonlinear models, let alone frame them within the above taxonomy. In the latter situation, indeed, when considered at all, the focus is often exclusively on random-effects models. In this article, we consider all three families, exemplify their great flexibility and relative ease of use, and apply them to a simple but illustrative set of data on tree circumference growth of orange trees. This article has supplementary material online.
Journal of Psychosomatic Research | 2013
Rob J.C.G. Verdonschot; Laura W. J. Baijens; Jan Serroyen; Carsten Leue; Bernd Kremer
OBJECTIVE The aim of the present study is to determine the presence and severity of symptoms of anxiety and depression in patients with oropharyngeal dysphagia who visit the outpatient clinic for dysphagia. METHODS Symptoms of anxiety and depression (affective symptoms) were prospectively assessed in 96 patients using the validated Hospital Anxiety and Depression Scale. In addition, all patients underwent a standardized examination protocol used for regular healthcare in the outpatient setting for dysphagia. The protocol included the following: otorhinolaryngological examination, logopedic observation of oral intake, fiber optic endoscopic evaluation of swallowing, videofluoroscopy of swallowing, the Functional Oral Intake Scale, a dysphagia severity scale, and the M.D. Anderson Dysphagia Inventory. Depending on the presence/absence of symptoms of anxiety and depression, several groups were distinguished. Descriptive statistics and the Mann-Whitney U test were used to test for group differences. Logistic regression models were used to identify factors associated with symptoms of anxiety and/or depression (cut-off score >8). RESULTS Clinically relevant symptoms of anxiety were observed in 37% (N=34) and clinically relevant symptoms of depression in 32.6% (N=31) of the present patient population, with 21.3% having symptoms of both anxiety and depression. In total, 47.3% (N=43) of this population showed affective symptoms. CONCLUSION Given that psychological burden can enhance somatic complaints, the high number of patients suffering from affective symptoms is a relevant clinical outcome in dysphagic patients. The contribution of anxiety or depression to the development or worsening of oropharyngeal dysphagia and their role in interdisciplinary treatment strategy is warranting further research.
Hand | 2012
Joline F. Mermans; Bas Franssen; Jan Serroyen; René R. W. J. van der Hulst
BackgroundOptimal surgical management of digital nerve lesions remains uncertain despite the publication of numerous studies. The purposes of this review were primarily to analyze whether there is a superior surgical technique for digital nerve repair and secondarily to statistically verify the variables to be predictors of sensory recovery.MethodsA literature search was performed using PubMed including citation from MEDLINE. Studies were included if they involved patients with digital nerve lacerations in whom end-to-end neurorrhaphy, nerve grafts, conduits, or end-to-side neurorrhaphy were performed. Further, the sensory outcome had to be assessed according to the modified American Society for Surgery of the Hand guidelines to stratify for two-point discrimination in millimeters. The variables age, follow-up, delay in repair, type of trauma, and gap length were extracted. The association between each predictor and response was assessed using a linear mixed model and corrected for heterogeneity between studies. Significance was considered present at p ≤ 0.05.ResultsOf the 34 articles found, 14 articles were included giving appropriate individual data for 191 nerves. There was no statistically significant difference in outcome between operation techniques. Age and follow-up were verified predictors of sensory recovery.ConclusionIn this review, the type of operation for digital nerve repair does not influence sensory outcome. However, we verified outcome to be influenced by the patient’s age and the follow-up period. To add more scientific evidence to our results, larger cohort prospective studies need to be done with better detailed description of data.
Communications in Statistics - Simulation and Computation | 2014
Haftom T. Abebe; Frans E. S. Tan; Gerard van Breukelen; Jan Serroyen; Martijn P. F. Berger
The Bayesian design approach accounts for uncertainty of the parameter values on which optimal design depends, but Bayesian designs themselves depend on the choice of a prior distribution for the parameter values. This article investigates Bayesian D-optimal designs for two-parameter logistic models, using numerical search. We show three things: (1) a prior with large variance leads to a design that remains highly efficient under other priors, (2) uniform and normal priors lead to equally efficient designs, and (3) designs with four or five equidistant equally weighted design points are highly efficient relative to the Bayesian D-optimal designs.
British Journal of Nutrition | 2014
Karianna F. M. Teunissen-Beekman; J. Dopheide; Johanna M. Geleijnse; Stephan J. L. Bakker; Elizabeth J. Brink; Peter W. de Leeuw; Jan Serroyen; Marleen A. van Baak
Diet composition may affect blood pressure (BP), but the mechanisms are unclear. The aim of the present study was to compare postprandial BP-related responses to the ingestion of pea protein, milk protein and egg-white protein. In addition, postprandial BP-related responses to the ingestion of maltodextrin were compared with those to the ingestion of sucrose and a protein mix. We hypothesised that lower postprandial total peripheral resistance (TPR) and BP levels would be accompanied by higher plasma concentrations of nitric oxide, insulin, glucagon-like peptide 1 (GLP-1) and glucagon. On separate occasions, six meals were tested in a randomised order in forty-eight overweight or obese adults with untreated elevated BP. Postprandial responses of TPR, BP and plasma concentrations of insulin, glucagon, GLP-1 and nitrite, nitroso compounds (RXNO) and S-nitrosothiols (NO(x)) were measured for 4 h. No differences were observed in TPR responses. Postprandial BP levels were higher after the ingestion of the egg-white-protein meal than after that of meals containing the other two proteins (P≤ 0·01). The ingestion of the pea-protein meal induced the highest NO(x) response (P≤ 0·006). Insulin and glucagon concentrations were lowest after the ingestion of the egg-white-protein meal (P≤ 0·009). Postprandial BP levels were lower after the ingestion of the maltodextrin meal than after that of the protein mix and sucrose meals (P≤ 0·004), while postprandial insulin concentrations were higher after the ingestion of the maltodextrin meal than after that of the sucrose and protein mix meals after 1-2 h (P≤ 0·0001). Postprandial NO(x), GLP-1 and glucagon concentrations were lower after the ingestion of the maltodextrin meal than after that of the protein mix meal (P≤ 0·008). In conclusion, different protein and carbohydrate sources induce different postprandial BP-related responses, which may be important for BP management. Lower postprandial BP levels are not necessarily accompanied by higher NO(x), insulin, glucagon or GLP-1 responses.