scholarly journals Selection bias introduced by informative censoring in studies examining effects of vaccination in infancy

2019 ◽  
Vol 48 (6) ◽  
pp. 2001-2009 ◽  
Author(s):  
José A López-López ◽  
Jonathan A C Sterne ◽  
Julian P T Higgins
Keyword(s):  
Health Status ◽  
Detrimental Effect ◽  
Informative Censoring ◽  
Right Censoring ◽  
Simulation Studies ◽  
Specific Effects ◽  
Hazard Ratios ◽  
Measles Vaccination ◽  
Dtp Vaccine

Abstract Background Many studies have examined ‘non-specific’ vaccine effects on infant mortality: attention has been particularly drawn to diphtheria-tetanus-pertussis (DTP) vaccine, which has been proposed to be associated with an increased mortality risk. Both right and left censoring are common in such studies. Methods We conducted simulation studies examining right censoring (at measles vaccination) and left censoring (by excluding early follow-up) in a variety of scenarios in which confounding was and was not present. We estimated both unadjusted and adjusted hazard ratios (HRs), averaged across simulations. Results We identified scenarios in which right-censoring at measles vaccination was informative and so introduced bias in the direction of a detrimental effect of DTP vaccine. In some, but not all, situations, adjusting for confounding by health status removed the bias caused by censoring. However, such adjustment will not always remove bias due to informative censoring: inverse probability weighting was required in one scenario. Bias due to left censoring arose when both health status and DTP vaccination were associated with mortality during the censored early follow-up and was in the direction of attenuating a beneficial effect of DTP on mortality. Such bias was more severe when the effect of DTP changed over time. Conclusions Estimates of non-specific effects of vaccines may be biased by informative right or left censoring. Authors of studies estimating such effects should consider the potential for such bias and use appropriate statistical approaches to control for it. Such approaches require measurement of prognostic factors that predict censoring.

scholarly journals Association Between Pre-diagnostic Dietary Supplements Intake and Ovarian Cancer Survival: Findings From a Prospective Cohort Study in Chinese Women

2021 ◽  
Vol 8 ◽  
Author(s):  
Jia-Hui Gu ◽  
Ting-Ting Gong ◽  
Qi-Jun Wu ◽  
Fang-Hua Liu ◽  
Zhao-Yan Wen ◽  
...  
Keyword(s):  
Ovarian Cancer ◽  
Dietary Supplements ◽  
Detrimental Effect ◽  
Cancer Survival ◽  
Proportional Hazards ◽  
Chinese Women ◽  
Cox Proportional Hazards ◽  
Hazard Ratios ◽  
Ovarian Cancer Survival

Background: As a result of a limited number of studies and inconsistent findings, there remains uncertainty in whether pre-diagnostic dietary supplements intake affects survival after ovarian cancer (OC) diagnosis.Methods: The association between pre-diagnostic dietary supplements intake and all-cause OC mortality was examined in the OC follow-up study, which included a hospital-based cohort (n = 703) of Chinese women diagnosed with OC between 2015 and 2020. Pre-diagnostic dietary supplements information was collected using self-administered questionnaires. Deaths were ascertained up to March 31, 2021, via death registry linkage. Cox proportional hazards were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for the aforementioned association.Results: A total of 130 women died during the median follow-up of 37.2 months (interquartile: 24.7–50.2 months). We found no evidence that any pre-diagnostic dietary supplements intake compared with never is associated with OC survival (HR = 0.75, 95%CI: 0.47–1.18). Furthermore, our study suggested no association for ever supplements intakes of vitamin A (HR = 0.48, 95%CI: 0.07–3.46), vitamin C (HR = 0.64, 95%CI: 0.27–1.54), vitamin D (HR = 1.19, 95%CI: 0.28–5.03), vitamin E (HR = 0.47, 95%CI: 0.06–3.87), multivitamin (HR = 0.49, 95%CI: 0.14–1.67), calcium (HR = 0.96, 95%CI: 0.53–1.72), and fish oil/DHA (HR = 0.31, 95%CI: 0.04–2.37) with OC survival. Interestingly, we only found a detrimental effect of vitamin B supplementation intake (HR = 3.78, 95%CI: 1.33–0.69) on OC survival.Conclusions: We found no evidence that any pre-diagnostic dietary supplements intake is associated with OC survival. Considering lower exposure of dietary supplements before OC diagnosis in the present study, further studies are warranted to confirm these findings.

scholarly journals Metabolic Obesity Phenotypes and Risk of Cellulitis: A Cohort Study

2019 ◽  
Vol 8 (7) ◽  
pp. 953
Author(s):  
Cheong ◽  
Chang ◽  
Cho ◽  
Ryu
Keyword(s):  
Cohort Study ◽  
Health Status ◽  
Metabolic Health ◽  
Metabolic Phenotype ◽  
Model Assessment ◽  
Metabolic Syndrome Component ◽  
Hazard Ratios ◽  
Increased Risk ◽  
Metabolically Healthy

No cohort studies have evaluated the effect of obesity on the risk of cellulitis according to metabolic health status. We investigated an association of BMI and metabolic health status with the development of cellulitis. We conducted a cohort study of 171,322 Korean adults who underwent a health checkup examination and were followed from 2011 to 2016 for cellulitis and hospital admission related to cellulitis, which were ascertained through the linkage to the Health Insurance and Review Agency database. Being metabolically healthy was defined as not having any metabolic syndrome component and having a homeostasis model assessment of insulin resistance <2.5. During 638,240.4 person-years of follow-up, 14,672 cases of incident cellulitis were identified with 225 cases of cellulitis-related admission. After adjustment for possible confounders, the multivariable-adjusted hazard ratios (95% CI) for incident cellulitis comparing BMIs 23–24.9, 25–29.9, and ≥30 with a BMI of 18.5–22.9 kg/m2 as the reference were 1.07 (1.02–1.11), 1.09 (1.04-1.13), and 1.19 (1.08-1.31), respectively, whereas the corresponding multivariable-adjusted hazard ratios (95% CI) for cellulitis-related admission were 1.55 (1.05–2.3), 2.47 (1.73–3.53), and 4.8 (2.86–8.05), respectively. These associations were consistently observed in both metabolically healthy and unhealthy individuals with no significant interaction. In a large cohort of apparently healthy adults, increased BMI was associated with an increased risk of cellulitis and hospitalization for cellulitis in both metabolically healthy and unhealthy individuals. Obesity appears to be an independent risk factor for cellulitis regardless of metabolic phenotype.

Serum Thyroid Peroxidase Antibody Level and Incident Hypertension in Iranian Men: A Suggestion for the Role of Thyroid Autoimmunity

2020 ◽  
Vol 20 (10) ◽  
pp. 1711-1718
Author(s):  
Maryam Tohidi ◽  
Aidin Baghbani-Oskouei ◽  
Atieh Amouzegar ◽  
Ladan Mehran ◽  
Fereidoun Azizi ◽  
...  
Keyword(s):  
Total Population ◽  
Thyroid Autoimmunity ◽  
Elevated Serum ◽  
Thyroid Peroxidase ◽  
Incident Hypertension ◽  
Natural Logarithm ◽  
Hazard Ratios ◽  
Thyroid Peroxidase Antibody ◽  
Unit Increase

Background: Dysfunction of the thyroid gland has profound effects on the cardiovascular system. Objective: We aimed to explore the relation of serum thyroid peroxidase antibody (TPO-Ab), as a marker of thyroid autoimmunity with incident hypertension among a euthyroid population. Methods: A total of 3681 participants (1647 men) entered the study. Multivariate Cox proportional hazard models were conducted to estimate the association between TPO-Ab and incident hypertension. Results: The mean age (standard deviation) of the participants was 37.5 (12.8) years. During a median follow-up of 12.2 years, 511 men and 519 women developed hypertension. The multivariable hazard ratios (HRs) and related 95% confidence intervals (CIs) of 1-unit increase in natural logarithm (ln) of TPO-Ab for incident hypertension were 1.09 (1.00-1.19), 1.03 (0.97-1.10), and 1.05 (1.00-1.11) for men, women, and total population, respectively. Moreover, considering the TPO-Ab status as a categorical variable (i.e. TPO-Ab positive or TPO-Ab negative), the multivariate-adjusted HRs (95% CIs) of TPO-Ab positivity for incident hypertension, were 1.33 (0.95-1.85), 1.12 (0.86-1.45) and 1.19 (0.97- 1.46) for men, women, and total population, respectively. Conclusion: Elevated serum TPO-Ab level can contribute to the development of hypertension among euthyroid men during a long follow-up; suggesting a role for thyroid autoimmunity.

scholarly journals High risk groups for severe COVID-19 in a whole of population cohort in Australia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Bette Liu ◽  
Paula Spokes ◽  
Wenqiang He ◽  
John Kaldor
Keyword(s):  
Socioeconomic Status ◽  
New South ◽  
Severe Disease ◽  
Risk Groups ◽  
Prevention Strategies ◽  
Complete Case ◽  
Relative Risks ◽  
South Wales ◽  
Hazard Ratios

Abstract Background Increasing age is the strongest known risk factor for severe COVID-19 disease but information on other factors is more limited. Methods All cases of COVID-19 diagnosed from January–October 2020 in New South Wales Australia were followed for COVID-19-related hospitalisations, intensive care unit (ICU) admissions and deaths through record linkage. Adjusted hazard ratios (aHR) for severe COVID-19 disease, measured by hospitalisation or death, or very severe COVID-19, measured by ICU admission or death according to age, sex, socioeconomic status and co-morbidities were estimated. Results Of 4054 confirmed cases, 468 (11.5%) were classified as having severe COVID-19 and 190 (4.7%) as having very severe disease. After adjusting for sex, socioeconomic status and comorbidities, increasing age led to the greatest risk of very severe disease. Compared to those 30–39 years, the aHR for ICU or death from COVID-19 was 4.45 in those 70–79 years; 8.43 in those 80–89 years; 16.19 in those 90+ years. After age, relative risks for very severe disease associated with other factors were more moderate: males vs females aHR 1.40 (95%CI 1.04–1.88); immunosuppressive conditions vs none aHR 2.20 (1.35–3.57); diabetes vs none aHR 1.88 (1.33–2.67); chronic lung disease vs none aHR 1.68 (1.18–2.38); obesity vs not obese aHR 1.52 (1.05–2.21). More comorbidities was associated with significantly greater risk; comparing those with 3+ comorbidities to those with none, aHR 5.34 (3.15–9.04). Conclusions In a setting with high COVID-19 case ascertainment and almost complete case follow-up, we found the risk of very severe disease varies by age, sex and presence of comorbidities. This variation should be considered in targeting prevention strategies.

scholarly journals A comparison of zero-inflated and hurdle models for modeling zero-inflated count data

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Cindy Xin Feng
Keyword(s):  
Health Services ◽  
Count Data ◽  
Goodness Of Fit ◽  
Negative Binomial ◽  
Simulation Studies ◽  
Final Choice ◽  
Hurdle Models ◽  
Count Distribution ◽  
Careful Assessment

AbstractCounts data with excessive zeros are frequently encountered in practice. For example, the number of health services visits often includes many zeros representing the patients with no utilization during a follow-up time. A common feature of this type of data is that the count measure tends to have excessive zero beyond a common count distribution can accommodate, such as Poisson or negative binomial. Zero-inflated or hurdle models are often used to fit such data. Despite the increasing popularity of ZI and hurdle models, there is still a lack of investigation of the fundamental differences between these two types of models. In this article, we reviewed the zero-inflated and hurdle models and highlighted their differences in terms of their data generating processes. We also conducted simulation studies to evaluate the performances of both types of models. The final choice of regression model should be made after a careful assessment of goodness of fit and should be tailored to a particular data in question.

scholarly journals Sex-Specific Associations between Blood Pressure and Risk of Atrial Fibrillation Subtypes in the Tromsø Study

2021 ◽  
Vol 10 (7) ◽  
pp. 1514
Author(s):  
Hilde Espnes ◽  
Jocasta Ball ◽  
Maja-Lisa Løchen ◽  
Tom Wilsgaard ◽  
Inger Njølstad ◽  
...  
Keyword(s):  
Atrial Fibrillation ◽  
Blood Pressure ◽  
Proportional Hazards ◽  
Cox Proportional Hazards ◽  
Pressure Management ◽  
Reference Models ◽  
Proportional Hazards Regression ◽  
Hazard Ratios ◽  
Increased Risk

The aim of this study was to explore sex-specific associations between systolic blood pressure (SBP), hypertension, and the risk of incident atrial fibrillation (AF) subtypes, including paroxysmal, persistent, and permanent AF, in a general population. A total of 13,137 women and 11,667 men who participated in the fourth survey of the Tromsø Study (1994–1995) were followed up for incident AF until the end of 2016. Cox proportional hazards regression analysis was conducted using fractional polynomials for SBP to provide sex- and AF-subtype-specific hazard ratios (HRs) for SBP. An SBP of 120 mmHg was used as the reference. Models were adjusted for other cardiovascular risk factors. Over a mean follow-up of 17.6 ± 6.6 years, incident AF occurred in 914 (7.0%) women (501 with paroxysmal/persistent AF and 413 with permanent AF) and 1104 (9.5%) men (606 with paroxysmal/persistent AF and 498 with permanent AF). In women, an SBP of 180 mmHg was associated with an HR of 2.10 (95% confidence interval [CI] 1.60–2.76) for paroxysmal/persistent AF and an HR of 1.80 (95% CI 1.33–2.44) for permanent AF. In men, an SBP of 180 mmHg was associated with an HR of 1.90 (95% CI 1.46–2.46) for paroxysmal/persistent AF, while there was no association with the risk of permanent AF. In conclusion, increasing SBP was associated with an increased risk of both paroxysmal/persistent AF and permanent AF in women, but only paroxysmal/persistent AF in men. Our findings highlight the importance of sex-specific risk stratification and optimizing blood pressure management for the prevention of AF subtypes in clinical practice.

scholarly journals Risk factors for tooth loss with a mean follow-up period of 13.9 years in supportive periodontal therapy patients

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tomotaka Kato ◽  
Natsuki Fujiwara ◽  
Tomohisa Ogawa ◽  
Yukihiro Numabe
Keyword(s):  
Risk Factors ◽  
Tooth Loss ◽  
Periodontal Therapy ◽  
Dental Hygienists ◽  
Multiple Classification Analysis ◽  
Hazard Ratios ◽  
Dental Office ◽  
Multiple Classification ◽  
Supportive Periodontal Therapy

Abstract Background Clinical evidence indicates that there are various risk factors of tooth loss. However, the degree of this risk among other risk factors remains unclear. In this retrospective cohort study, the authors evaluated the hazard ratios of several risk factors for tooth loss. Methods Included patients had all been treated for dental disorders, were in the supportive phase of periodontal therapy by dental hygienists, and visited a Japanese dental office continually during a 10-year period. Periodontal parameters, tooth condition, and general status of all teeth (excluding third molars) at the initial visit and at least 10 years later were evaluated by using multiple classification analysis. Results The authors evaluated a total of 7584 teeth in 297 patients (average age: 45.3, mean follow-up time: 13.9 years) Non-vital pulp was the most significant predictor of tooth loss according to Cox hazards regression analysis (hazard ratio: 3.31). The 10-year survival rate was approximately 90% for teeth with non-vital pulp and 99% for teeth with vital pulp. Fracture was the most common reason for tooth loss. Conclusions Non-vital pulp had the most significant association with tooth loss among the parameters. Therefore, it is very important to minimize dental pulp extirpation.

The Efficacy of Etoposide-Based Therapy in Adult Secondary Hemophagocytic Lymphohistiocytosis

2021 ◽  
pp. 1-9
Author(s):  
Leonard Naymagon ◽  
Douglas Tremblay ◽  
John Mascarenhas
Keyword(s):  
Hemophagocytic Lymphohistiocytosis ◽  
Proportional Hazards ◽  
Multivariable Analysis ◽  
Cox Proportional Hazards ◽  
Rank Test ◽  
Kaplan Meier ◽  
Hazard Ratios ◽  
Significant Difference ◽  
The Impact

Data supporting the use of etoposide-based therapy in hemophagocytic lymphohistiocytosis (HLH) arise largely from pediatric studies. There is a lack of comparable data among adult patients with secondary HLH. We conducted a retrospective study to assess the impact of etoposide-based therapy on outcomes in adult secondary HLH. The primary outcome was overall survival. The log-rank test was used to compare Kaplan-Meier distributions of time-to-event outcomes. Multivariable Cox proportional hazards modeling was used to estimate adjusted hazard ratios (HRs) with 95% confidence intervals (CIs). Ninety adults with secondary HLH seen between January 1, 2009, and January 6, 2020, were included. Forty-two patients (47%) received etoposide-based therapy, while 48 (53%) received treatment only for their inciting proinflammatory condition. Thirty-three patients in the etoposide group (72%) and 32 in the no-etoposide group (67%) died during follow-up. Median survival in the etoposide and no-etoposide groups was 1.04 and 1.39 months, respectively. There was no significant difference in survival between the etoposide and no-etoposide groups (log-rank <i>p</i> = 0.4146). On multivariable analysis, there was no association between treatment with etoposide and survival (HR for death with etoposide = 1.067, 95% CI: 0.633–1.799, <i>p</i> = 0.8084). Use of etoposide-based therapy was not associated with improvement in outcomes in this large cohort of adult secondary HLH patients.

scholarly journals Dietary intake of tocopherols and risk of incident disabling dementia

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shoko Aoki ◽  
Kazumasa Yamagishi ◽  
Koutatsu Maruyama ◽  
Rie Kishida ◽  
Ai Ikeda ◽  
...  
Keyword(s):  
Dietary Intake ◽  
Independent Effect ◽  
Spearman Correlation ◽  
Total Tocopherol ◽  
Community Based ◽  
Acid Intake ◽  
Hazard Ratios ◽  
Linoleic Acid Intake ◽  
History Of

AbstractTocopherols, strong antioxidants, may be useful in preventing dementia, but the epidemiological evidence is insufficient. We performed a community-based follow-up study of Japanese, the Circulatory Risk in Community Study, involving 3739 people aged 40–64 years at baseline (1985–1999). Incident disabling dementia was followed up from 1999 through 2020. For subtype analysis, we classified disabling dementia into that with and that without a history of stroke. Dietary intake of tocopherols (total, α, β, γ, and δ) were estimated using 24-h recall surveys. During a median follow-up of 19.7 years, 670 cases of disabling dementia developed. Total tocopherol intake was inversely associated with risk of disabling dementia with multivariable hazard ratios (95% confidence intervals) of 0.79 (0.63–1.00) for the highest versus lowest quartiles of total tocopherol intake (P for trend = 0.05). However, the association was strengthened when further adjusted for α-linolenic acid intake (Spearman correlation with total tocopherol intake = 0.93), with multivariable hazard ratios of 0.50 (0.34–0.74) (P for trend = 0.001) but was weakened and nonsignificant when further adjusted for linoleic acid intake (Spearman correlation with total tocopherol intake = 0.92), with multivariable hazard ratios of 0.69 (0.47–1.01) (P for trend = 0.05). Similar but nonsignificant inverse associations were observed for α-, γ-, and δ-tocopherols but not for β-tocopherol. These results were similar regardless of the presence of a history of stroke. Dietary tocopherol intake was inversely associated with risk of disabling dementia, but its independent effect was uncertain owing to a high intercorrelation of α-linolenic linoleic acids with total tocopherol intake. Even with such confounding, a diet high in tocopherols may help prevent the onset of dementia.

Consumption of flavonoid-rich fruits, flavonoids from fruits, and stroke risk: a prospective cohort study

2021 ◽  
pp. 1-26
Author(s):  
Qi Gao ◽  
Jia-Yi Dong ◽  
Renzhe Cui ◽  
Isao Muraki ◽  
Kazumasa Yamagishi ◽  
...  
Keyword(s):  
Lower Risk ◽  
Stroke Risk ◽  
Proportional Hazards ◽  
Cox Proportional Hazards ◽  
Dietary Factors ◽  
Citrus Fruits ◽  
Proportional Hazards Regression ◽  
Hazard Ratios ◽  
Index Study

Abstract We sought to examine the prospective associations of specific fruit consumption, in particular flavonoid-rich fruit (FRF) consumption, with the risk of stroke and subtypes of stroke in a Japanese population. A study followed a total of 39,843 men and 47,334 women aged 44-76 years, and free of cardiovascular disease, diabetes, and cancer at baseline since 1995 and 1998 to the end of 2009 and 2012, respectively. Data on total and specific FRF consumption for each participant were obtained using a self-administrated food frequency questionnaire. The hazard ratios (HRs) of stroke in relation to total and specific FRF consumption were estimated through Cox proportional hazards regression models. During a median follow-up of 13.1 years, 4092 incident stroke cases (2557 cerebral infarctions and 1516 hemorrhagic strokes) were documented. After adjustment for age, body mass index, study area, lifestyles, dietary factors, and other risk factors, it was found that total FRF consumption was associated with a significantly lower risk of stroke in women (HR= 0.70; 95% CI, 0.58-0.84), while the association in men was not significant (HR= 0.93; 95% CI, 0.79-1.09). As for specific FRFs, consumptions of citrus fruits, strawberries, and grapes were found associated with a lower stroke risk in women. Higher consumptions of FRFs, in particular citrus fruits, strawberries, and grapes, were associated with a lower risk of developing stroke in Japanese women.

Sign in / Sign up

Export Citation Format

Share Document