Estimation from cross-sectional data under a semiparametric truncation model

Biometrika ◽  
2020 ◽  
Vol 107 (2) ◽  
pp. 449-465
Author(s):  
C Heuchenne ◽  
J De Uña-Álvarez ◽  
G Laurent
Keyword(s):  
Mean Squared Error ◽  
Disease Onset ◽  
Lifetime Distribution ◽  
Parametric Models ◽  
Parametric Family ◽  
Cross Sectional ◽  
Right Censored Data ◽  
Lifetime Distributions ◽  
Likelihood Approach ◽  
Event Times

Summary Cross-sectional sampling is often used when investigating inter-event times, resulting in left-truncated and right-censored data. In this paper, we consider a semiparametric truncation model in which the truncating variable is assumed to belong to a certain parametric family. We examine two methods of estimating both the truncation and the lifetime distributions. We obtain asymptotic representations of the estimators for the lifetime distribution and establish their weak convergence. Both of the proposed estimators perform better than Wang’s (1991) nonparametric maximum likelihood estimator in terms of the integrated mean squared error, when the parametric family for the truncation is sufficiently close to its true distribution. The full likelihood approach is preferable to the conditional likelihood approach in estimating the lifetime distribution, though not necessarily the truncation distribution. In an application to Alzheimer’s disease data, hypothesis tests reject the uniform truncation distribution, but several other parametric models lead to similar behaviour of the truncation and lifetime distributions after disease onset.

Celiac Disease in Kosovar Albanian Children: Evaluation of Clinical Features and Diagnosis

2020 ◽  
Vol 16 (3) ◽  
pp. 241-247
Author(s):  
Atifete Ramosaj-Morina ◽  
Alije Keka-Sylaj ◽  
Arbana Baloku Zejnullahu ◽  
Lidvana Spahiu ◽  
Virgjina Hasbahta ◽  
...  
Keyword(s):  
Celiac Disease ◽  
Disease Onset ◽  
Clinical Manifestations ◽  
Gastrointestinal Symptoms ◽  
Dominant Mode ◽  
Primary School Children ◽  
Cross Sectional ◽  
Classical Form ◽  
Wide Range ◽  
The Mean

Background: Celiac disease is an immune-mediated disorder characterized by variable clinical manifestations, specific antibodies, HLA-DQ2/DQ8 haplotypes, and enteropathy. Objectives: The aim of this study was to present the clinical spectrum and patterns of celiac disease in Kosovar Albanian children. Methods: A cross-sectional retrospective study was performed with Albanian children aged 0-18 years, treated for celiac disease in the Pediatric Clinic, University Clinical Center of Kosovo from 2005 to 2016. Results: During the study period, 63 children were treated for celiac disease. The mean age at diagnosis was 5.5 years (SD ± 3.31). The mean age at celiac disease onset was 3.3 years (SD ± 2.02), while the mean delay from the first symptoms indicative of celiac disease to diagnosis was 2.2 years (SD ± 2.09). More than 70% of the patients were diagnosed in the first 7 years of life, mainly presented with gastrointestinal symptoms, while primary school children and adolescents mostly showed atypical symptoms (p<0.001). The classical form of celiac disease occurred in 78% of the cases. Sixty (95%) patients carried HLA-DQ2.5, DQ2.2 and/or HLA-DQ8 heterodimers, and only three of them tested negative. Conclusions: Kosovo, as the majority of developing countries, is still facing the classical form of celiac disease as the dominant mode of presentation; as a result, most children with other forms of the celiac disease remain undiagnosed. : Physicians should be aware of the wide range of clinical presentations and utilize low testing thresholds in order to prevent potential long-term problems associated with untreated celiac disease.

Adult systemic lupus erythematosus in Egypt: The nation-wide spectrum of 3661 patients and world-wide standpoint

Lupus ◽  
2021 ◽  
pp. 096120332110142
Author(s):  
Tamer A Gheita ◽  
Rasha Abdel Noor ◽  
Esam Abualfadl ◽  
Osama S Abousehly ◽  
Iman I El-Gazzar ◽  
...  
Keyword(s):  
Systemic Lupus Erythematosus ◽  
Lupus Erythematosus ◽  
Age Of Onset ◽  
Wide Spectrum ◽  
Age At Onset ◽  
Disease Onset ◽  
Clinical Manifestations ◽  
Population Based ◽  
Systemic Lupus ◽  
Cross Sectional

Objective The aim of this study was to present the epidemiology, clinical manifestations and treatment pattern of systemic lupus erythematosus (SLE) in Egyptian patients over the country and compare the findings to large cohorts worldwide. Objectives were extended to focus on the age at onset and gender driven influence on the disease characteristics. Patients and method This population-based, multicenter, cross-sectional study included 3661 adult SLE patients from Egyptian rheumatology departments across the nation. Demographic, clinical, and therapeutic data were assessed for all patients. Results The study included 3661 patients; 3296 females and 365 males (9.03:1) and the median age was 30 years (17–79 years), disease duration 4 years (0–75 years) while the median age at disease onset was 25 years (4–75 years). The overall estimated prevalence of adult SLE in Egypt was 6.1/100,000 population (1.2/100,000 males and 11.3/100,000 females).There were 316 (8.6%) juvenile-onset (Jo-SLE) and 3345 adult-onset (Ao-SLE). Age at onset was highest in South and lowest in Cairo (p < 0.0001). Conclusion SLE in Egypt had a wide variety of clinical and immunological manifestations, with some similarities with that in other nations and differences within the same country. The clinical characteristics, autoantibodies and comorbidities are comparable between Ao-SLE and Jo-SLE. The frequency of various clinical and immunological manifestations varied between gender. Additional studies are needed to determine the underlying factors contributing to gender and age of onset differences.

scholarly journals Differential Diagnosis of Chorea—HIV Infection Delays Diagnosis of Huntington’s Disease by Years

2021 ◽  
Vol 11 (6) ◽  
pp. 710
Author(s):  
Jannis Achenbach ◽  
Simon Faissner ◽  
Carsten Saft
Keyword(s):  
Hiv Infection ◽  
Huntington's Disease ◽  
Huntington’S Disease ◽  
Disease Onset ◽  
Diagnostic Delay ◽  
Depression Scale ◽  
Cag Repeat ◽  
Psychiatric Disease ◽  
Disease Manifestation ◽  
Cross Sectional

Background: There is a broad range of potential differential diagnoses for chorea. Besides rare, inherited neurodegenerative diseases such as Huntington’s disease (HD) chorea can accompany basal ganglia disorders due to vasculitis or infections, e.g., with the human immunodeficiency virus (HIV). The clinical picture is complicated by the rare occurrence of HIV infection and HD. Methods: First, we present a case suffering simultaneously from HIV and HD (HIV/HD) focusing on clinical manifestation and disease onset. We investigated cross-sectional data regarding molecular genetic, motoric, cognitive, functional, and psychiatric disease manifestation of HIV/HD in comparison to motor-manifest HD patients without HIV infection (nonHIV/HD) in the largest cohort of HD patients worldwide using the registry study ENROLL-HD. Data were analyzed using ANCOVA analyses controlling for covariates of age and CAG repeat length between groups in IBM SPSS Statistics V.25. Results: The HD diagnosis in our case report was delayed by approximately nine years due to the false assumption that the HIV infection might have been the cause of chorea. Out of n = 21,116 participants in ENROLL-HD, we identified n = 10,125 motor-manifest HD patients. n = 23 male participants were classified as suffering from HIV infection as a comorbidity, compared to n = 4898 male non-HIV/HD patients. Except for age, with HIV/HD being significantly younger (p < 0.050), we observed no group differences regarding sociodemographic, genetic, educational, motoric, functional, and cognitive parameters. Male HIV/HD patients reported about a 5.3-year-earlier onset of HD symptoms noticed by themselves compared to non-HIV/HD (p < 0.050). Moreover, patients in the HIV/HD group had a longer diagnostic delay of 1.8 years between onset of symptoms and HD diagnosis and a longer time regarding assessment of first symptoms by the rater and judgement of the patient (all p < 0.050). Unexpectedly, HIV/HD patients showed less irritability in the Hospital Anxiety and Depression Scale (all p < 0.05). Conclusions: The HD diagnosis in HIV-infected male patients is secured with a diagnostic delay between first symptoms noticed by the patient and final diagnosis. Treating physicians therefore should be sensitized to think of potential alternative diagnoses in HIV-infected patients also afflicted by movement disorders, especially if there is evidence of subcortical atrophy and a history of hyperkinesia, even without a clear HD-family history. Those patients should be transferred for early genetic testing to avoid further unnecessary diagnostics and improve sociomedical care.

Effect of Design Parameters on Drop Test Performance of Wafer Level Chip Scale Packages (WLCSP)

2011 ◽  
Author(s):  
Pushkraj Tumne ◽  
Vikram Venkatadri ◽  
Santosh Kudtarkar ◽  
Michael Delaus ◽  
Daryl Santos ◽  
...  
Keyword(s):  
Flip Chip ◽  
Bulk Solder ◽  
Consumer Electronics ◽  
Drop Test ◽  
Design Parameters ◽  
Mechanical Shock ◽  
Wafer Level ◽  
Cross Sectional ◽  
Right Censored Data ◽  
Solder Balls

Today’s consumer market demands electronics that are smaller, faster and cheaper. To cater to these demands, novel materials, new designs, and new packaging technologies are introduced frequently. Wafer Level Chip Scale Package (WLCSP) is one of the emerging package technologies that have the key advantages of reduced cost and smaller footprint. The portable consumer electronics are frequently dropped; hence the emphasis of reliability is shifting towards study of effects of mechanical shock loading increasingly. Mechanical loading typically induces brittle fractures (also known as intermetallic failures) between the solder bumps and bond pads at the silicon die side. This type of failure mechanism is typically characterized by the board level drop test. WLCSP is a variant of the flip-chip interconnection technique. In WLCSPs, the active side of the die is inverted and connected to the PCB by solder balls. The size of these solder balls is typically large enough (300μm pre-reflow for 0.5mm pitch and 250μm pre-reflow for 0.4mm pitch) to avoid use of underfill that is required for the flip-chip interconnects. Several variations are incorporated in the package design parameters to meet the performance, reliability, and footprint requirements of the package assembly. The design parameters investigated in this effort are solder ball compositions with different Silver (Ag) content, backside lamination with different thickness, WLCSP type –Direct and Re-Distribution Layer (RDL), bond pad thickness, and sputtered versus electroplated Under Bump Metallurgy (UBM) deposition methods for 8×8, 9×9, and 10×10 array sizes. The test vehicles built using these design parameters were drop tested using JEDEC recommended test boards and conditions as per JESD22-B11. Cross sectional analysis was used to identify, confirm, and classify the intermetallic, and bulk solder failures. The objective of this research was to quantify the effects and interactions of WLCSP design parameters through drop test. The drop test data was collected and treated as a right censored data. Further, it was analyzed by fitting empirical distributions using the grouped and un-grouped data approach. Data analysis showed that design parameters had a significant effect on the drop performance and played a vital role in influencing the package reliability.

scholarly journals A cross-sectional survey of multi-generation inflammatory bowel disease consanguinity and its relationship with disease onset

2017 ◽  
Vol 23 (6) ◽  
pp. 337 ◽  
Author(s):  
Mahmoud Mosli ◽  
Abdulelah Alzahrani ◽  
Showlag Showlag ◽  
Abdullah Alshehri ◽  
Ahmed Hejazi ◽  
...  
Keyword(s):  
Inflammatory Bowel Disease ◽  
Bowel Disease ◽  
Disease Onset ◽  
Cross Sectional Survey ◽  
Cross Sectional ◽  
Inflammatory Bowel

The Association Between Disease Activity and Duration in Systemic Sclerosis

2010 ◽  
Vol 37 (11) ◽  
pp. 2299-2306 ◽  
Author(s):  
JENNIFER G. WALKER ◽  
RUSSELL J. STEELE ◽  
MIREILLE SCHNITZER ◽  
SUZANNE TAILLEFER ◽  
MURRAY BARON ◽  
...  
Keyword(s):  
Systemic Sclerosis ◽  
Disease Activity ◽  
Disease Duration ◽  
Activity Index ◽  
Disease Onset ◽  
Depression Scale ◽  
Disease Activity Index ◽  
Cross Sectional ◽  
Diffuse Disease ◽  
Patient Reported

Objective.The absence of a standardized disease activity index has been an important barrier in systemic sclerosis (SSc) research. We applied the newly derived Valentini Scleroderma Disease Activity Index (SDAI) among our cohort of patients with SSc to document changes in disease activity over time and to assess possible differences in activity between limited and diffuse disease.Methods.Cross-sectional study of a national cohort of patients enrolled in the Canadian Scleroderma Research Group Registry. Disease activity was measured using the SDAI. Depression scores were measured using the Centre for Epidemiologic Studies Depression Scale (CES-D).Results.A total of 326 out of 639 patients had complete datasets at the time of this analysis; 87% were female, of mean age 55.6 years, with mean disease duration 14.1 years. SDAI declined steeply in the first 5 years after disease onset and patients with diffuse disease had 42% higher SDAI scores than patients with limited disease with the same disease duration and depression scores (standardized relative risk 1.42, 95% CI 1.21, 1.65). Patients with higher CES-D scores had higher SDAI scores relative to patients with the same disease duration and disease subset (standardized RR 1.22, 95% CI 1.14, 1.31). Among the 10 components that make up the SDAI, only skin score (standardized OR 0.59, 95% CI 0.43, 0.82) and patient-reported change in skin (standardized OR 0.64, 95% CI 0.45, 0.92) decreased with increasing disease duration. High skin scores (standardized OR 32.2, 95% CI 15.8, 72.0) were more likely and scleredema (standardized OR 0.58, 95% CI 0.37, 0.92) was less likely to be present in patients with diffuse disease. High depression scores were associated with positive responses for patient-reported changes in skin and cardiopulmonary function.Conclusion.Disease activity declined with time and patients with diffuse disease had consistently higher SDAI scores. Depression was found to be associated with higher patient activity scores and strongly associated with patient self-response questions. The role of depression should be carefully considered in future applications of the SDAI, particularly as several components of the score rely upon patient recall.

Identifying Transition Rates of Ion Channels with One Loop

2011 ◽  
Vol 282-283 ◽  
pp. 395-398
Author(s):  
Xu Yan Xiang ◽  
Li Fang Liu ◽  
Ye Chen
Keyword(s):  
Markov Chain ◽  
Ion Channels ◽  
Lifetime Distribution ◽  
Transition Rates ◽  
Lifetime Distributions ◽  
Constrained Equations ◽  
Gating Scheme

The constrained equations between transition rates and the derivative of open lifetime and shut lifetime distribution for a given state set of Markov Chain are provided. For gating scheme of ion channels with one loop, it is derived by those underlying information that all transition rates can be identified by their open and shut lifetime distributions at state 0 and any other two adjacent states.

P019 Adulthood of juvenile idiopathic arthritis patients: professional outcome

Rheumatology ◽  
2021 ◽  
Vol 60 (Supplement_5) ◽  
Author(s):  
S Miladi ◽  
S Bouzid ◽  
A Fazaa ◽  
L Souabni ◽  
M Sellami ◽  
...  
Keyword(s):  
Juvenile Idiopathic Arthritis ◽  
College Graduates ◽  
Disease Onset ◽  
Cross Sectional Study ◽  
Full Time ◽  
Family Status ◽  
Cross Sectional ◽  
Telephone Interviews ◽  
The Mean ◽  
Professional Outcome

Abstract Background Juvenile idiopathic arthritis (JIA) is a heterogeneous group of rheumatic diseases characterized by onset before the age of 16. Since the disease starts at an early age, it may lead to socio-professional difficulties in adulthood for JIA patients. This study aimed to describe the professional outcome of a series of 20 JIA patients. Methods A cross-sectional study including patients aged 20 years and more and fulfilling the ILAR criteria for the diagnosis of JIA was carried out. Telephone interviews were conducted. The responders answered questions about family status, current occupation, working h, eventual workplace adjustments, and sick leave frequency. Results Twenty patients answered the questionary; 14 males and 6 females. The mean age of the disease onset was 8 years. The mean age of patients at the time of the study was 24.27 years [20–36]. Polyarticular form was the most frequent (10 cases). Other subtypes diagnosed were systemic (4 cases), enthesitis-related arthritis (5 cases), oligoarticular (one case). Hip arthritis was observed in 8 patients and surgical intervention was needed in three. Eight patients were treated with csDMARDSs and 12 with bDMARDs. Three of our patients were married (aged 24, 34, and 36). Five were still studying: 4 had good grades without absenteeism. However, one patient needed special aid to go to school and had a higher absence rate. Five other patients were full-time college students without absenteeism. Four patients were college graduates. Among them, two were searching for a job for &gt;6 months. The other two were full-time administrative workers with no absenteeism. One patient did need workplace adjustments. Six patients could not work because of their physical disabilities. Conclusion According to our results, a quarter of our patients could not access professional life. Disease activity and hip destruction are the two main factors causing JIA patients to miss out on important personal and professional opportunities.

Predictors of persistent inflammation in familial Mediterranean fever and association with damage

Rheumatology ◽  
2020 ◽  
Vol 60 (1) ◽  
pp. 333-339
Author(s):  
Hakan Babaoglu ◽  
Berkan Armagan ◽  
Erdal Bodakci ◽  
Hasan Satis ◽  
Nuh Atas ◽  
...  
Keyword(s):  
Disease Onset ◽  
Damage Index ◽  
Treatment Strategies ◽  
Leg Pain ◽  
Cross Sectional ◽  
Persistent Inflammation ◽  
Increased Risk ◽  
Education Levels ◽  
History Of ◽  
Mediterranean Fever

Abstract Objective Persistent inflammation is an insidious and less studied feature of FMF. We investigated clinical determinants of persistent inflammation and its associations with individual damage items. Methods This is a cross-sectional analysis of 917 FMF patients, who fulfilled the Tel Hashomer criteria and had at least 6 months’ follow-up. Patients were stratified based on whether they had persistent inflammation. We used logistic regression analysis to investigate independent predictors of persistent inflammation and the associated individual damage items. Results One hundred and forty-two (15%) patients had persistent inflammation. Active FMF (54%) was the most prominent reason for the persistent inflammation. Spondylarthritis (16%), other inflammatory arthritis (8%) and IBD (2%) were other frequent reasons. Male gender, history of exertional leg pain, inflammatory comorbidities, M694V homozygosity, colchicine resistance, lower education levels and musculoskeletal attack dominance were found to be the independent predictors of persistent inflammation. Earlier disease onset led to a tendency towards persistent inflammation. Patients with persistent inflammation were more likely to suffer damage. There is an increased risk of developing proteinuria, amyloidosis and renal insufficiency. Conclusion We identified, for the first time, the predictors of persistent inflammation in adult FMF patients and related individual damage items of the Autoinflammatory Disease Damage Index. Persistent inflammation is insidious and one of the chief causes of damage; therefore, especially patients with these predictors should be followed up more closely. If detected, underlying inflammatory comorbidities should be assessed meticulously as early detection and proper treatment strategies may favourably impact the natural history of the disease.

scholarly journals Estimation of incubation period distribution of COVID-19 using disease onset forward time: A novel cross-sectional and forward follow-up study

2020 ◽  
Vol 6 (33) ◽  
pp. eabc1202 ◽  
Author(s):  
Jing Qin ◽  
Chong You ◽  
Qiushi Lin ◽  
Taojun Hu ◽  
Shicheng Yu ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Incubation Period ◽  
Renewal Process ◽  
Low Cost ◽  
Disease Onset ◽  
Recall Bias ◽  
Cross Sectional ◽  
Follow Up Study ◽  
Period Distribution

We have proposed a novel, accurate low-cost method to estimate the incubation-period distribution of COVID-19 by conducting a cross-sectional and forward follow-up study. We identified those presymptomatic individuals at their time of departure from Wuhan and followed them until the development of symptoms. The renewal process was adopted by considering the incubation period as a renewal and the duration between departure and symptoms onset as a forward time. Such a method enhances the accuracy of estimation by reducing recall bias and using the readily available data. The estimated median incubation period was 7.76 days [95% confidence interval (CI): 7.02 to 8.53], and the 90th percentile was 14.28 days (95% CI: 13.64 to 14.90). By including the possibility that a small portion of patients may contract the disease on their way out of Wuhan, the estimated probability that the incubation period is longer than 14 days was between 5 and 10%.

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