Background Up to 88% of infants with haemolytic disease of the fetus and newborn who are treated with intrauterine transfusions require erythrocyte transfusions after birth. We aimed to investigate... Show moreBackground Up to 88% of infants with haemolytic disease of the fetus and newborn who are treated with intrauterine transfusions require erythrocyte transfusions after birth. We aimed to investigate the effect of darbepoetin alfa on the prevention of postnatal anaemia in infants with haemolytic disease of the fetus and newborn. Methods We conducted an open-label, single-centre, phase 2 randomised controlled trial to evaluate the effect of darbepoetin alfa on the number of erythrocyte transfusions in infants with haemolytic disease of the fetus and newborn. All infants who were treated with intrauterine transfusion and born at 35 weeks of gestation or later at the Leiden University Medical Center, Leiden, Netherlands, were eligible for inclusion. Included infants were randomised by computer at birth to treatment with 10 mu g/kg darbepoetin alfa subcutaneously once a week for 8 weeks or standard care (1:1 allocation, in varying blocks of four and six, with no stratification). Treating physicians and parents were not masked to treatment allocation, but the research team, data manager, and statistician were masked to treatment allocation during the process of data collection. The primary outcome was the number of erythrocyte transfusion episodes per infant from birth up to 3 months of life in the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT03104426) and has been completed.Findings Between Oct 31, 2017, and April 31, 2022, we recruited 76 infants, of whom 44 (58%) were randomly assigned to a treatment group (20 [45%] were allocated to receive darbepoetin alfa and 24 [55%] were allocated to receive standard care). Follow-up lasted 3 months and one infant dropped out of the trial before commencement of treatment. A significant reduction in erythrocyte transfusion episodes was identified with darbepoetin alfa treatment compared with standard care (median 1 center dot 0 [IQR 1 center dot 0-2 center dot 0] transfusion episodes vs 2 center dot 0 [1 center dot 3-3 center dot 0] transfusion episodes; p=0 center dot 0082). No adverse events were reported and no infants died during the study. Interpretation Darbepoetin alfa reduced the transfusion episodes after intrauterine transfusion treatment for haemolytic disease of the fetus and newborn. Treatment with darbepoetin alfa or other types of erythropoietin should be considered as part of the postnatal treatment of severe haemolytic disease of the fetus and newborn. Show less
Vermeulen, C.; Burg, L.L.J. van der; Geloven, N. van; Eggink, C.A.; Cheng, Y.Y.Y.; Nuijts, R.M.M.A.; ... ; Klei, T.R.L. 2023
IntroductionAllogeneic serum from blood donors is starting to be used to treat patients with dry eye disease (DED). However, the optimal dose is not known. We therefore aimed to evaluate the... Show moreIntroductionAllogeneic serum from blood donors is starting to be used to treat patients with dry eye disease (DED). However, the optimal dose is not known. We therefore aimed to evaluate the clinical efficaciousness and user-friendliness of micro-sized versus conventional-sized allogeneic serum eye drops (SEDs).MethodsIn a randomized trial, patients with DED first receive micro-sized SEDs (7 mu l/unit) for 1 month, followed by a 1-month washout, before receiving conventional-sized SEDs (50 mu l/unit) for 1 month; or vice versa. The primary endpoint was the Ocular Surface Disease Index (OSDI) score. Secondary endpoints were tear break-up time (TBT), tear production (TP), and presence of corneal punctate lesions (CP). The user-friendliness of both application systems was also compared. A linear mixed model for cross-over design was applied to compare both treatments.ResultsForty-nine patients completed the trial. The mean OSDI score significantly improved from 52 +/- 3 to 41 +/- 3 for micro-sized SEDs, and from 54 +/- 3 to 45 +/- 3 for conventional-sized SEDs. Non-inferiority (margin = 6) of micro-sized SEDs was established. We demonstrate a significant improvement for TBT in case of conventional-sized SEDs and for CP in both treatment groups. TP trended towards an improvement in both treatment groups. The user-friendliness of the conventional drop system was significantly higher.ConclusionsFor the first time, non-inferiority of micro-sized allogeneic SEDs was established. The beneficial effect of both SED volumes was similar as measured by the OSDI score. Although user-friendliness of the micro drop system was significantly lower, it is an attractive alternative as it saves valuable donor serum.Trial RegistrationClinicalTrials.gov (NCT03539159). Show less
Introduction: In early-stage vulvar squamous cell carcinoma (VSCC) a sentinel lymph node (SLN) procedure is regarded successful if at least one SLN is removed with minimal residual radioactivity.... Show moreIntroduction: In early-stage vulvar squamous cell carcinoma (VSCC) a sentinel lymph node (SLN) procedure is regarded successful if at least one SLN is removed with minimal residual radioactivity. An inguinofemoral lymphadenectomy is considered if not all SLNs visualized on lymphoscintigraphy can be found, with subsequent increased morbidity. We correlated lymphoscintigraphy findings with surgical outcome and groin recurrence with focus on number of SLNs found. Methods: This study concerns a retrospective cohort of 171 women treated for early-stage VSCC who underwent a SLN procedure between 2000 and 2020. The risk of groin recurrence was compared after either a successful or complete SLN procedure, i.e. removal of all SLNs that were visualized on lymphoscintigraphy. Results: In 13 (7.6%) groins of 171 patients SLN visualization on lymphoscintigraphy failed. In 230 of the 246 (93.5%) groins in which a SLN was visualized, at least one SLN was found during surgery. In 224 of the 246 (91.1%) groins the SLN procedure was regarded either successful (n = 14) or complete (n = 210). An isolated groin recurrence was documented in 5 out of 192 (2.6%, 95%-CI; 0.34 to 4.9) SLN-negative groins after a median follow-up of 47.0 months. All recurrences were noted in the complete SLN group (5/180 groins). The difference with the successful SLN group (0/12 groins) was not significant. Conclusion: Risk of groin recurrence was 2.6% after SLN negative biopsy in early-stage VSCC. The risk appeared not increased if at least one SLN was found with minimal residual radioactivity, in case more SLNs were visualized on lymphoscintigraphy. Show less
Luijken, K.; Eekelen, R. van; Gardarsdottir, H.; Groenwold, R.H.H.; Geloven, N. van 2023
Purpose: Ideally, the objectives of a pharmacoepidemiologic comparative effectiveness or safety study should dictate its design and data analysis. This paper discusses how defining an estimand is... Show morePurpose: Ideally, the objectives of a pharmacoepidemiologic comparative effectiveness or safety study should dictate its design and data analysis. This paper discusses how defining an estimand is instrumental to this process.Methods: We applied the ICH-E9 (Statistical Principles for Clinical Trials) R1 addendum on estimands - which originally focused on randomized trials - to three examples of observational pharmacoepidemiologic comparative effectiveness and safety studies. Five key elements specify the estimand: the population, contrasted treatments, endpoint, intercurrent events, and population-level summary measure.Results: Different estimands were defined for case studies representing three types of pharmacological treatments: (1) single-dose treatments using a case study about the effect of influenza vaccination versus no vaccination on mortality risk in an adult population of =60 years of age; (2) sustained-treatments using a case study about the effect of dipeptidyl peptidase 4 inhibitor versus glucagon-like peptide-1 agonist on hypoglycemia risk in treatment of uncontrolled diabetes; and (3) as needed treatments using a case study on the effect of nitroglycerin spray as-needed versus no nitroglycerin on syncope risk in treatment of stabile angina pectoris.Conclusions: The case studies illustrated that a seemingly clear research question can still be open to multiple interpretations. Defining an estimand ensures that the study targets a treatment effect that aligns with the treatment decision the study aims to inform. Estimand definitions further help to inform choices regarding study design and data-analysis and clarify how to interpret study findings. Show less
Aliasi, M.; Mastenbroek, M.; Papakosta, S.; Geloven, N. van; Haak, M.C. 2023
ObjectiveCongenital heart disease (CHD) is associated with decreased birthweight (BW) compared to population-based references. The aim of this study was to compare the BW of isolated CHD cases to... Show moreObjectiveCongenital heart disease (CHD) is associated with decreased birthweight (BW) compared to population-based references. The aim of this study was to compare the BW of isolated CHD cases to their siblings, thus controlling for unknown and unmeasured confounders within the family. MethodsAll isolated CHD cases in the Leiden University Medical Center were included (2002-2019). Generalized estimated equation models were constructed to compare BW z scores of CHD neonates with their siblings. Cases were clustered to minor or severe CHD and stratified according to the aortic flow and oxygenation to the brain. ResultsThe overall BW z score of siblings was 0.032 (n = 471). The BW z score was significantly lower in CHD cases (n = 291) compared to their siblings (-0.20, p = 0.005). The results were consistent in the subgroup analysis of severe and minor CHD (BW z score difference -0.20 and -0.10), but did not differ significantly (p = 0.63). Stratified analysis regarding flow and oxygenation showed no BW difference between the groups (p = 0.1). ConclusionIsolated CHD cases display a significantly lower BW z score compared to their siblings. As the siblings of these CHD cases show a BW distribution similar to the general population, this suggests that shared environmental and maternal influences between siblings do not explain the difference in BW. Show less
Gharbharan, A.; Jordans, C.; Zwaginga, L.; Papageorgiou, G.; Geloven, N. van; Wijngaarden, P. van; ... ; CoV-Early study grp 2023
Objectives: The potential benefit of convalescent plasma (CP) therapy for coronavirus disease 2019 (COVID-19) is highest when administered early after symptom onset. Our objective was to determine... Show moreObjectives: The potential benefit of convalescent plasma (CP) therapy for coronavirus disease 2019 (COVID-19) is highest when administered early after symptom onset. Our objective was to determine the effectiveness of CP therapy in improving the disease course of COVID-19 among high-risk outpatients. Methods: A multicentre, double-blind randomized trial was conducted comparing 300 mL of CP with non-CP. Patients were >= 50 years, were symptomatic for <8 days, had confirmed RT-PCR or antigen test result for COVID-19 and had at least one risk factor for severe COVID-19. The primary endpoint was the highest score on a 5-point ordinal scale ranging from fully recovered (score = 1) or not (score = 2) on day 7, over hospital admission (score = 3), intensive care unit admission (score = 4) and death (score = 5) in the 28 days following randomization. Secondary endpoints were hospital admission, symptom duration and viral RNA excretion. Results: After the enrolment of 421 patients and the transfusion in 416 patients, recruitment was dis-continued when the countrywide vaccination uptake in those aged >50 years was 80%. Patients had a median age of 60 years, symptoms for 5 days, and 207 of 416 patients received CP therapy. During the 28 day follow-up, 28 patients were hospitalized and two died. The OR for an improved disease severity score with CP was 0.86 (95% credible interval, 0.59-1.22). The OR was 0.58 (95% CI, 0.33-1.02) for patients with <5 days of symptoms. The hazard ratio for hospital admission was 0.61 (95% CI, 0.28-1.34). No difference was found in viral RNA excretion or in the duration of symptoms. Conclusions: In patients with early COVID-19, CP therapy did not improve the 5-point disease severity score. Arvind Gharbharan, Clin Microbiol Infect 2023;29:208 (c) 2022 The Authors. Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/). Show less
McLernon, D.J.; Giardiello, D.; Calster, B. van; Wynants, L.; Geloven, N. van; Smeden, M. van; ... ; STRATOS Initiative 2022
Risk prediction models need thorough validation to assess their performance. Validation of models for survival outcomes poses challenges due to the censoring of observations and the varying time... Show moreRisk prediction models need thorough validation to assess their performance. Validation of models for survival outcomes poses challenges due to the censoring of observations and the varying time horizon at which predictions can be made. This article describes measures to evaluate predictions and the potential improvement in decision making from survival models based on Cox proportional hazards regression.As a motivating case study, the authors consider the prediction of the composite outcome of recurrence or death (the "event ") in patients with breast cancer after surgery. They developed a simple Cox regression model with 3 predictors, as in the Nottingham Prognostic Index, in 2982 women (1275 events over 5 years of follow-up) and externally validated this model in 686 women (285 events over 5 years). Improvement in performance was assessed after the addition of progesterone receptor as a prognostic biomarker.The model predictions can be evaluated across the full range of observed follow-up times or for the event occurring by the end of a fixed time horizon of interest. The authors first discuss recommended statistical measures that evaluate model performance in terms of discrimination, calibration, or overall performance. Further, they evaluate the potential clinical utility of the model to support clinical decision making according to a net benefit measure. They provide SAS and R code to illustrate internal and external validation.The authors recommend the proposed set of performance measures for transparent reporting of the validity of predictions from survival models. Show less
Introduction: Recurrent pregnancy loss (RPL) is defined as the loss of two or more conceptions before 24 weeks gestation. Despite extensive diagnostic workup, in only 25%-40% an underlying cause is... Show moreIntroduction: Recurrent pregnancy loss (RPL) is defined as the loss of two or more conceptions before 24 weeks gestation. Despite extensive diagnostic workup, in only 25%-40% an underlying cause is identified. Several factors may increase the risk for miscarriage, but the chance of a successful pregnancy is still high. Prognostic counselling plays a significant role in supportive care. The main limitation in current prediction models is the lack of a sufficiently large cohort, adjustment for relevant risk factors, and separation between cumulative live birth rate and the success chance in the next conception. In this project, we aim to make an individualised prognosis for the future chance of pregnancy success, which could lead to improved well-being and the ability managing reproductive choices. Methods and analysis: In this multicentre study, we will include both a prospective and a retrospective cohort of at least 931 and 1000 couples with RPL, respectively. Couples who have visited one of the three participating university hospitals in the Netherlands for intake are eligible for the study participation, with a follow-up duration of 5 years. General medical and obstetric history and reports of pregnancies after the initial consultation will be collected. Multiple imputation will be performed to cope for missing data. A Cox proportional hazards model for time to pregnancy will be developed to estimate the cumulative chance of a live birth within 3 years after intake. To dynamically estimate the chance of an ongoing pregnancy, given the outcome of earlier pregnancies after intake, a logistic regression model will be developed. Ethics and dissemination: The Medical Ethical Research Committee of the Leiden University Medical Center approved this study protocol (N22.025). There are no risks or burden associated with this study. Participant written informed consent is required for both cohorts. Findings will be published in peer-reviewed journals and presentations at international conferences. Show less
Ratna, M.B.; Bhattacharya, S.; Geloven, N. van; McLernon, D.J. 2022
STUDY QUESTION Can we develop an IVF prediction model to estimate individualized chances of a live birth over multiple complete cycles of IVF in couples embarking on their second complete cycle of... Show moreSTUDY QUESTION Can we develop an IVF prediction model to estimate individualized chances of a live birth over multiple complete cycles of IVF in couples embarking on their second complete cycle of treatment? SUMMARY ANSWER Yes, our prediction model can estimate individualized chances of cumulative live birth over three additional complete cycles of IVF. WHAT IS KNOWN ALREADY After the completion of a first complete cycle of IVF, couples who are unsuccessful may choose to undergo further treatment to have their first child, while those who have had a live birth may decide to have more children. Existing prediction models can estimate the overall chances of success in couples before commencing IVF but are unable to revise these chances on the basis of the couple's response to a first treatment cycle in terms of the number of eggs retrieved and pregnancy outcome. This makes it difficult for couples to plan and prepare emotionally and financially for the next step in their treatment. STUDY DESIGN, SIZE, DURATION For model development, a population-based cohort was used of 49 314 women who started their second cycle of IVF including ICSI in the UK from 1999 to 2008 using their own oocytes and their partners' sperm. External validation was performed on data from 39 442 women who underwent their second cycle from 2010 to 2016. PARTICIPANTS/MATERIALS, SETTING, METHODS Data about all UK IVF treatments were obtained from the Human Fertilisation and Embryology Authority (HFEA) database. Using a discrete time logistic regression model, we predicted the cumulative probability of live birth from the second up to and including the fourth complete cycles of IVF. Inverse probability weighting was used to account for treatment discontinuation. Discrimination was assessed using c-statistic and calibration was assessed using calibration-in-the-large and calibration slope. MAIN RESULTS AND THE ROLE OF CHANCE Following exclusions, 49 314 women with 73 053 complete cycles were included. 12 408 (25.2%) had a live birth resulting from their second complete cycle. Cumulatively, 17 394 (35.3%) had a live birth over complete cycles two to four. The model showed moderate discriminative ability (c-statistic: 0.65, 95% CI: 0.64 to 0.65) and evidence of overprediction (calibration-in-the-large = -0.08) and overfitting (calibration slope 0.85, 95% CI: 0.81 to 0.88) in the validation cohort. However, after recalibration the fit was much improved. The recalibrated model identified the following key predictors of live birth: female age (38 versus 32 years-adjusted odds ratio: 0.59, 95% CI: 0.57 to 0.62), number of eggs retrieved in the first complete cycle (12 versus 4 eggs; 1.34, 1.30 to 1.37) and outcome of the first complete cycle (live birth versus no pregnancy; 1.78, 1.66 to 1.91; live birth versus pregnancy loss; 1.29, 1.23 to 1.36). As an example, a 32-year-old with 2 years of non-tubal infertility who had 12 eggs retrieved from her first stimulation and had a live birth during her first complete cycle has a 46% chance of having a further live birth from the second complete cycle of IVF and an 81% chance over a further three cycles. LIMITATIONS, REASONS FOR CAUTION The developed model was updated using validation data that was 6 to 12 years old. IVF practice continues to evolve over time, which may affect the accuracy of predictions from the model. We were unable to adjust for some potentially important predictors, e.g. BMI, smoking and alcohol intake in women, as well as measures of ovarian reserve such as antral follicle count.These were not available in the linked HFEA dataset. WIDER IMPLICATIONS OF THE FINDINGS By appropriately adjusting for couples who discontinue treatment, our novel prediction model will provide more realistic chances of live birth in couples starting a second complete cycle of IVF. Clinicians can use these predictions to inform discussion with couples who wish to plan ahead. This prediction tool will enable couples to prepare emotionally, financially and logistically for IVF treatment. STUDY FUNDING/COMPETING INTEREST(S) This study was supported by an Elphinstone scholarship scheme at the University of Aberdeen and Aberdeen Fertility Centre, University of Aberdeen. The authors have no conflict of interest. Show less
Geloven, N. van; Giardiello, D.; Bonneville, E.F.; Teece, L.; Ramspek, C.L.; Smeden, M. van; ... ; STRATOS Initiative 2022
Data on convalescent plasma (CP) treatment in COVID-19 outpatients are scarce. We aimed to assess whether CP administered during the first week of symptoms reduced the disease progression or risk... Show moreData on convalescent plasma (CP) treatment in COVID-19 outpatients are scarce. We aimed to assess whether CP administered during the first week of symptoms reduced the disease progression or risk of hospitalization of outpatients. Two multicenter, double-blind randomized trials (NCT04621123, NCT04589949) were merged with data pooling starting when <20% of recruitment target was achieved. A Bayesian-adaptive individual patient data metaanalysis was implemented. Outpatients aged >= 50 years and symptomatic for <= 7days were included. The intervention consisted of 200-300mL of CP with a predefined minimum level of antibodies. Primary endpoints were a 5-point disease severity scale and a composite of hospitalization or death by 28 days. Amongst the 797 patients included, 390 received CP and 392 placebo; they had a median age of 58 years, 1 comorbidity, 5 days symptoms and 93% had negative IgG antibody-test. Seventy-four patients were hospitalized, 6 required mechanical ventilation and 3 died. The odds ratio (OR) of CP for improved disease severity scale was 0.936 (credible interval (CI) 0.667-1.311); OR for hospitalization or death was 0.919 (CI 0.592-1.416). CP effect on hospital admission or death was largest in patients with <= 5 days of symptoms (OR 0.658, 95%CI 0.394-1.085). CP did not decrease the time to full symptom resolution. Show less
Musta, E.; Geloven, N. van; Anninga, J.; Gelderblom, H.; Fiocco, M. 2022
Objectives Cure rate models accounting for cured and uncured patients, provide additional insights into long and short-term survival. We aim to evaluate the prognostic value of histological... Show moreObjectives Cure rate models accounting for cured and uncured patients, provide additional insights into long and short-term survival. We aim to evaluate the prognostic value of histological response and chemotherapy intensification on the cure fraction and progression-free survival (PFS) for the uncured patients.Design Retrospective analysis of a randomised controlled trial, MRC BO06 (EORTC 80931).Setting Population-based study but proposed methodology can be applied to other trial designs.Participants A total of 497 patients with resectable highgrade osteosarcoma, of which 118 were excluded because chemotherapy was not started, histological response was not reported, abnormal dose was reported or had disease progression during treatment.Intervention(s) Two regimens with the same anticipated cumulative dose (doxorubicin 6x75 mg/m(2)/week; cisplatin 6x100 mg/m(2)/week) over different time schedules: every 3 weeks in regimen-C and every 2 weeks in regimen-DI. Primary and secondary outcome measures The primary outcome is PFS computed from end of treatment because cure, if it occurs, may happen at any time during treatment. A mixture cure model is used to study the effect of histological response and intensified chemotherapy on the cure status and PFS for the uncured patients.Results Histological response is a strong prognostic factor for the cure status (OR 3.00, 95% CI 1.75 to 5.17), but it has no clear effect on PFS for the uncured patients (HR 0.78, -95% CI 0.53 to 1.16). The cure fractions are 55% (46%-63%) and 29% (22%-35%), respectively, among patients with good and poor histological response (GR, PR). The intensified regimen was associated with a higher cure fraction among PR (OR 1.90, 95% CI 0.93 to 3.89), with no evidence of effect for GR (OR 0.78, 95% CI 0.38 to 1.59).Conclusions Accounting for cured patients is valuable in distinguishing the covariate effects on cure and PFS. Estimating cure chances based on these prognostic factors is relevant for counselling patients and can have an impact on treatment decisions. Show less
Musta, E.; Geloven, N. van; Anninga, J.; Gelderblom, H.; Fiocco, M. 2022
Objectives Cure rate models accounting for cured and uncured patients, provide additional insights into long and short-term survival. We aim to evaluate the prognostic value of histological... Show moreObjectives Cure rate models accounting for cured and uncured patients, provide additional insights into long and short-term survival. We aim to evaluate the prognostic value of histological response and chemotherapy intensification on the cure fraction and progression-free survival (PFS) for the uncured patients.Design Retrospective analysis of a randomised controlled trial, MRC BO06 (EORTC 80931).Setting Population-based study but proposed methodology can be applied to other trial designs.Participants A total of 497 patients with resectable highgrade osteosarcoma, of which 118 were excluded because chemotherapy was not started, histological response was not reported, abnormal dose was reported or had disease progression during treatment.Intervention(s) Two regimens with the same anticipated cumulative dose (doxorubicin 6x75 mg/m(2)/week; cisplatin 6x100 mg/m(2)/week) over different time schedules: every 3 weeks in regimen-C and every 2 weeks in regimen-DI. Primary and secondary outcome measures The primary outcome is PFS computed from end of treatment because cure, if it occurs, may happen at any time during treatment. A mixture cure model is used to study the effect of histological response and intensified chemotherapy on the cure status and PFS for the uncured patients.Results Histological response is a strong prognostic factor for the cure status (OR 3.00, 95% CI 1.75 to 5.17), but it has no clear effect on PFS for the uncured patients (HR 0.78, -95% CI 0.53 to 1.16). The cure fractions are 55% (46%-63%) and 29% (22%-35%), respectively, among patients with good and poor histological response (GR, PR). The intensified regimen was associated with a higher cure fraction among PR (OR 1.90, 95% CI 0.93 to 3.89), with no evidence of effect for GR (OR 0.78, 95% CI 0.38 to 1.59).Conclusions Accounting for cured patients is valuable in distinguishing the covariate effects on cure and PFS. Estimating cure chances based on these prognostic factors is relevant for counselling patients and can have an impact on treatment decisions. Show less
Aliasi, M.; Snoep, M.C.; Geloven, N. van; Haak, M.C. 2022
Background Birthweight (BW) is an important prognostic factor in newborns with congenital heart defects (CHD). Objectives To give an overview of the literature on BW z-score in children with... Show moreBackground Birthweight (BW) is an important prognostic factor in newborns with congenital heart defects (CHD). Objectives To give an overview of the literature on BW z-score in children with isolated CHD. Search strategy A systematic search was performed on isolated CHD and BW in PubMed, Embase, Web of Science, COCHRANE Library and Emcare. Selection criteria Neonates with isolated CHD were included if a BW percentile, BW z-score or % small-or-gestational age (SGA) was reported. Data collection and analysis BW z-score and percentage SGA were pooled with random-effect meta-analysis. Quality and risk of bias were assessed using the modified Newcastle Ottawa Scale. Main results Twenty-three articles (27 893 cases) were included. BW z-scores were retrieved from 11 articles, resulting in a pooled z-score of -0.20 (95% CI -0.50 to 0.11). The overall pooled prevalence of SGA <10th percentile was 16.0% (95% CI 11.4-20.5; 14 studies). Subgroup analysis of major CHD showed similar results (BW z-score -0.23 and percentage SGA 16.2%). Conclusions Overall BW in isolated CHD is within range of normality but impaired, with a 1.6-fold higher risk of SGA, irrespective of the type of CHD (major CHD vs all CHD combined). Our findings underline the association between CHD and BW. The use of BW z-scores provides insight into growth of all fetuses with CHD. Show less
Geloven, N. van; Giardiello, D.; Bonneville, E.F.; Teece, L.; Ramspek, C.L.; Smeden, M. van; ... ; Steyerberg, E. 2022
Thorough validation is pivotal for any prediction model before it can be advocated for use in medical practice. For time-to-event outcomes such as breast cancer recurrence, death from other causes... Show moreThorough validation is pivotal for any prediction model before it can be advocated for use in medical practice. For time-to-event outcomes such as breast cancer recurrence, death from other causes is a competing risk. Model performance measures must account for such competing events. In this article, we present a comprehensive yet accessible overview of performance measures for this competing eventsetting, including the calculation and interpretation of statistical measures for calibration, discrimination, overall prediction error, and clinical usefulness by decision curve analysis. All methods are illustrated for patients with breast cancer, with publicly available data and R code. Show less
Ramspek, C.L.; Teece, L.; Snell, K.I.E.; Evans, M.; Riley, R.D.; Smeden, M. van; ... ; Diepen, M. van 2021
Background: External validation of prognostic models is necessary to assess the accuracy and generalizability of the model to new patients. If models are validated in a setting in which competing... Show moreBackground: External validation of prognostic models is necessary to assess the accuracy and generalizability of the model to new patients. If models are validated in a setting in which competing events occur, these competing risks should be accounted for when comparing predicted risks to observed outcomes. Methods: We discuss existing measures of calibration and discrimination that incorporate competing events for time-to-event models. These methods are illustrated using a clinical-data example concerning the prediction of kidney failure in a population with advanced chronic kidney disease (CKD), using the guideline-recommended Kidney Failure Risk Equation (KFRE). The KFRE was developed using Cox regression in a diverse population of CKD patients and has been proposed for use in patients with advanced CKD in whom death is a frequent competing event. Results: When validating the 5-year KFRE with methods that account for competing events, it becomes apparent that the 5-year KFRE considerably overestimates the real-world risk of kidney failure. The absolute overestimation was 10%age points on average and 29%age points in older high-risk patients. Conclusions: It is crucial that competing events are accounted for during external validation to provide a more reliable assessment the performance of a model in clinical settings in which competing risks occur. Show less
Youssef, A.; Hoorn, M.L.P. van der; Dongen, M.; Visser, J.; Bloemenkamp, K.; Lith, J. van; ... ; Lashley, E.E.L.O. 2021
Study question: What is the predictive performance of a currently recommended prediction model in an external Dutch cohort of couples with unexplained recurrent pregnancy loss (RPL)?Summary answer: .. Show moreStudy question: What is the predictive performance of a currently recommended prediction model in an external Dutch cohort of couples with unexplained recurrent pregnancy loss (RPL)?Summary answer: The model shows poor predictive performance on a new population; it overestimates, predicts too extremely and has a poor discriminative ability.What is known already: In 50-75% of couples with RPL, no risk factor or cause can be determined and RPL remains unexplained. Clinical management in RPL is primarily focused on providing supportive care, in which counselling on prognosis is a main pillar. A frequently used prediction model for unexplained RPL, developed by Brigham et al. in 1999, estimates the chance of a successful pregnancy based on number of previous pregnancy losses and maternal age. This prediction model has never been externally validated.Study design, size, duration: This retrospective cohort study consisted of 739 couples with unexplained RPL who visited the RPL clinic of the Leiden University Medical Centre between 2004 and 2019.Participants/materials, setting, methods: Unexplained RPL was defined as the loss of two or more pregnancies before 24 weeks, without the presence of an identifiable cause for the pregnancy losses, according to the ESHRE guideline. Obstetrical history and maternal age were noted at intake at the RPL clinic. The outcome of the first pregnancy after intake was documented. The performance of Brigham's model was evaluated through calibration and discrimination, in which the predicted pregnancy rates were compared to the observed pregnancy rates.Main results and the role of chance: The cohort included 739 women with a mean age of 33.1 years (±4.7 years) and with a median of three pregnancy losses at intake (range 2-10). The mean predicted pregnancy success rate was 9.8 percentage points higher in the Brigham model than the observed pregnancy success rate in the dataset (73.9% vs 64.0% (95% CI for the 9.8% difference 6.3-13.3%)). Calibration showed overestimation of the model and too extreme predictions, with a negative calibration intercept of -0.46 (95% CI -0.62 to -0.31) and a calibration slope of 0.42 (95% CI 0.11-0.73). The discriminative ability of the model was very low with a concordance statistic of 0.55 (95% CI 0.51-0.59). Recalibration of the Brigham model hardly improved the c-statistic (0.57; 95% CI 0.53-0.62).Limitations, reasons for caution: This is a retrospective study in which only the first pregnancy after intake was registered. There was no time frame as inclusion criterium, which is of importance in the counselling of couples with unexplained RPL. Only cases with a known pregnancy outcome were included.Wider implications of the findings: This is the first study externally validating the Brigham prognostic model that estimates the chance of a successful pregnancy in couples with unexplained RPL. The results show that the frequently used model overestimates the chances of a successful pregnancy, that predictions are too extreme on both the high and low ends and that they are not much more discriminative than random luck. There is a need for revising the prediction model to estimate the chance of a successful pregnancy in couples with unexplained RPL more accurately.Study funding/competing interest(s): No external funding was used and no competing interests were declared.Trial registration number: N/A.Keywords: external validation; miscarriage; prediction model; pregnancy success rate; recurrent pregnancy loss. Show less
Baart, S.J.; Palen, R.L.F. van der; Putter, H.; Tsonaka, R.; Blom, N.A.; Rizopoulos, D.; Geloven, N. van 2021
BACKGROUND: Most patients with congenital heart disease survive into adulthood; however, residual abnormalities remain and management of the patients is life-long and personalized. Patients with... Show moreBACKGROUND: Most patients with congenital heart disease survive into adulthood; however, residual abnormalities remain and management of the patients is life-long and personalized. Patients with surgical repair of transposition of the great arteries, for example, face the risk to develop neoaortic valve regurgitation. Cardiologists update the prognosis of the patient intuitively with updated information of the cardiovascular status of the patient, for instance from echocardiographic imaging.METHODS: Usually a time-dependent version of the Cox model is used to analyze repeated measurements with a time-to-event outcome. New statistical methods have been developed with multiple advantages, of which the most prominent one being the joint model for longitudinal and time-to-event outcome. In this tutorial, the joint modeling framework is introduced and applied to patients with transposition of the great arteries after surgery with a long-term follow-up, where repeated echocardiographic values of the neoaortic root are evaluated against the risk of neoaortic valve regurgitation.RESULTS: The data are analyzed with the time-dependent Cox model as benchmark method, and the results are compared with a joint model, leading to different conclusions. The flexibility of the joint model is shown by adding the growth rate of the neoaortic root to the model and adding repeated values of body surface area to obtain a multimarker model. Lastly, it is demonstrated how the joint model can be used to obtain personalized dynamic predictions of the event.CONCLUSIONS: The joint model for longitudinal and time-to-event data is an attractive method to analyze data in follow-up studies with repeated measurements. Benefits of the method include using the estimated natural trajectory of the longitudinal outcome, great flexibility through multiple extensions, and dynamic individualized predictions. Show less