Predicting Later Study Withdrawal in Participants Active in a Longitudinal Birth Cohort Study for 1 Year: The TEDDY Study

Factors assessed in the first year of a longitudinal study predict subsequent study visit compliance: the TEDDY study

BACKGROUND

Compliance with a study protocol is central to meeting its research goals. In longitudinal research studies, data loss due to missed visits limit statistical power and introduce bias. The Environmental Determinants of Diabetes in the Young (TEDDY) study is a longitudinal multinational (US, Finland, Germany, and Sweden) investigation of children at risk for type 1 diabetes (T1D) that seeks to identify the environmental triggers of islet autoimmunity and T1D. The purpose of the current study was to identify sociodemographic variables and maternal characteristics assessed in the first year of TEDDY that were associated with study visit compliance in the subsequent 3 years.

METHODS

Sociodemographic variables, maternal life-style behaviors, post-partum depression, maternal reactions to the child's T1D risk, and study-related variables were collected at child-age 6 months and 15 months. Multiple linear regression was used to examine the association of these variables to study visit compliance in the subsequent 3 years.

RESULTS

Study visit compliance was highest in Sweden (p > 0.001), in children who were their mother's first child (p > 0.001), and whose mothers were older (p > 0.001) and more satisfied with the TEDDY study (p > 0.001). Father participation was also associated with better study visit compliance (p > 0.001). In contrast, children whose mothers smoked (p > 0.001), suffered from post-partum depression (p = 0.034), and were more anxious about their child's T1D risk (p = 0.002), completed fewer visits. Father's study satisfaction was also associated with study visit compliance (p = 0.029); however, it was not significant in models that included maternal study satisfaction.

CONCLUSIONS

Sociodemographic variables, maternal characteristics-including study satisfaction-and fathers' participation in the first year of a longitudinal study were associated with subsequent study visit compliance in a sample of children genetically at-risk for T1D followed for 4 years. This information can inform future strategies designed to improve study visit compliance in longitudinal pediatric studies.

TRIAL REGISTRATION

NCT00279318, 06/09/2004.

SAI-CH-6: Development of a Short Form of the State Anxiety Inventory for Children At-Risk for Type 1 Diabetes

OBJECTIVE

To develop a reliable and valid short form of the State Anxiety Subscale of the State-Trait Anxiety Inventory for Children (STAI-CH) in the Environmental Determinants of Diabetes in the Young (TEDDY) study.

METHODS

A Development Sample of 842 10-year-old TEDDY children completed the STAI-CH State Subscale about their type 1 diabetes (T1D) risk. The best 6 items (three anxiety-present and three anxiety-absent) for use in a short form (SAI-CH-6) were identified via item-total correlations. SAI-CH-6 reliability was examined in a Validation Sample (n = 257) of children who completed the full 20-item STAI-CH State Subscale and then again in an Application Sample (n = 2,710) who completed only the SAI-CH-6. Expected associations between the children's SAI-CH-6 scores and country of residence, sex, T1D family history, accuracy of T1D risk perception, worry about getting T1D, and their parents' anxiety scores were examined.

RESULTS

The SAI-CH-6 was reliable (α = 0.81-0.87) and highly correlated with the full 20-item STAI-CH State Subscale (Development Sample: r = 0.94; Validation Sample: r = 0.92). SAI-CH-6 scores detected significant differences in state anxiety symptoms associated with T1D risk by country, T1D family history, accuracy of T1D risk perception, and worry about getting T1D and were correlated with the child's parent's anxiety.

CONCLUSION

The SAI-CH-6 appears useful for assessing children's state anxiety symptoms when burden and time limitations prohibit the use of the STAI-CH. The utility of the SAI-CH-6 in older children with and without chronic conditions needs to be assessed.

Is staff consistency important to parents' satisfaction in a longitudinal study of children at risk for type 1 diabetes: the TEDDY study

BACKGROUND

Participants' study satisfaction is important for both compliance with study protocols and retention, but research on parent study satisfaction is rare. This study sought to identify factors associated with parent study satisfaction in The Environmental Determinants of Diabetes in the Young (TEDDY) study, a longitudinal, multinational (US, Finland, Germany, Sweden) study of children at risk for type 1 diabetes. The role of staff consistency to parent study satisfaction was a particular focus.

METHODS

Parent study satisfaction was measured by questionnaire at child-age 15 months (5579 mothers, 4942 fathers) and child-age four years (4010 mothers, 3411 fathers). Multiple linear regression analyses were used to identify sociodemographic factors, parental characteristics, and study variables associated with parent study satisfaction at both time points.

RESULTS

Parent study satisfaction was highest in Sweden and the US, compared to Finland. Parents who had an accurate perception of their child's type 1 diabetes risk and those who believed they can do something to prevent type 1 diabetes were more satisfied. More educated parents and those with higher depression scores had lower study satisfaction scores. After adjusting for these factors, greater study staff change frequency was associated with lower study satisfaction in European parents (mothers at child-age 15 months: - 0.30,95% Cl - 0.36, - 0.24, p < 0.001; mothers at child-age four years: -0.41, 95% Cl - 0.53, - 0.29, p < 0.001; fathers at child-age 15 months: -0.28, 95% Cl - 0.34, - 0.21, p < 0.001; fathers at child-age four years: -0.35, 95% Cl - 0.48, - 0.21, p < 0.001). Staff consistency was not associated with parent study satisfaction in the US. However, the number of staff changes was markedly higher in the US compared to Europe.

CONCLUSIONS

Sociodemographic factors, parental characteristics, and study-related variables were all related to parent study satisfaction. Those that are potentially modifiable are of particular interest as possible targets of future efforts to improve parent study satisfaction. Three such factors were identified: parent accuracy about the child's type 1 diabetes risk, parent beliefs that something can be done to reduce the child's risk, and study staff consistency. However, staff consistency was important only for European parents.

TRIAL REGISTRATION

NCT00279318 .

Nested case-control data analysis using weighted conditional logistic regression in The Environmental Determinants of Diabetes in the Young (TEDDY) study: A novel approach

BACKGROUND

A nested case-control (NCC) design within a prospective cohort study can realize substantial benefits for biomarker studies. In this context, it is natural to consider the sample availability in the selection of controls to minimize data loss when implementing the design. However, this violates the randomness required for selection, and it leads to biased analyses. An inverse probability weighting may improve the analysis, but the current approach using weighted Cox regression fails to maintain the benefits of NCC design.

METHODS

This paper introduces weighted conditional logistic regression. We illustrate our proposed analysis using data recently investigated in The Environmental Determinants of Diabetes in the Young (TEDDY). Considering the potential data loss, the TEDDY NCC design was moderately selective in its selection of controls. A data-driven simulation study was performed to present the bias correction when a nonrandom control selection was ignored in the analysis.

RESULTS

The TEDDY data analysis showed that the standard analysis using conditional logistic regression estimated the parameter: -0.015 (-0.023, -0.007). The biased estimate using Cox regression was -0.011 (95% confidence interval: -0.019, -0.003). Weighted Cox regression estimated -0.013 (-0.026, 0.0004). The proposed weighted conditional logistic regression estimated -0.020 (-0.033, -0.007), showing a stronger negative effect size than the one using conditional logistic regression. The simulation study also showed that the standard estimate of β ignoring the nonrandom control selection tends to be greater than the true β (ie, positive relative biases).

CONCLUSION

Weighted conditional logistic regression can enhance the analysis by offering flexibility in the selection of controls, while maintaining the matching.

Why do participants drop-out: findings from a prospective pediatric cohort for fever surveillance established at Vellore, southern India

BACKGROUND

Cohort studies are pivotal in understanding the natural history, and to thereby determine the incidence of a disease. The conduct of large-scale community-based cohort studies is challenging with reference to money, manpower and time. Further, attrition inherent to cohort studies can affect the power, and thereby the study's validity. Our objective was to estimate the percentage of participant withdrawal and to subsequently understand reasons for the same in the Vellore Typhoid Surveillance (VTS) cohort.

METHODS

VTS study, a prospective community-based pediatric cohort, was established in a semi-urban settlement of Vellore to estimate the incidence rate of typhoid fever. An active weekly surveillance identified children with fever, and blood cultures were performed for fevers of ≥3 days. Reasons for participant drop-out in the cohort were documented. Nine focus group discussions (FGD), each with 5 to 7 parents/primary caregivers of former as well current participants were conducted separately, to understand reasons for consent withdrawal as well as the good aspects of the study that the current participants perceived. A descriptive, as well as an interpretative account of the themes that emerged from the FGDs were done.

RESULTS

Of the 5639 children in the VTS cohort, 404 (7.2%) withdrew consent during the 12-month surveillance. Of these, 50% dropped out due to migration from study area; 18.1% as their parents were unhappy with the blood draws for blood culture; and 14.4% did not clearly put forth the reason for consent withdrawal. Being from an orthodox background, high socio-economic status and joint family were associated with a decision to drop-out. Frequent and voluminous blood draws, male field research assistants (FRA) making weekly home-visits, the perception that inquiring about fever made their child fall sick, and that the study clinic did not initiate antibiotics immediately, were the important themes that emerged from the FGDs conducted among drop-outs.

CONCLUSION

Our study showed that specific beliefs and behaviours within the community influenced the drop-out rate of the VTS cohort. Background characteristics and perceptions that exist, along with attrition data from previous cohort studies in the specific community are important to be considered while implementing large-scale cohort studies.

Who Is Enrolling? The Path to Monitoring in Type 1 Diabetes TrialNet's Pathway to Prevention

OBJECTIVE

To better understand potential facilitators of individual engagement in type 1 diabetes natural history and prevention studies through analysis of enrollment data in the TrialNet Pathway to Prevention (PTP) study.

RESEARCH DESIGN AND METHODS

We used multivariable logistic regression models to examine continued engagement of eligible participants at two time points: 1) the return visit after screening to confirm an initial autoantibody-positive (Ab⁺) test result and 2) the initial oral glucose tolerance test (OGTT) for enrollment into the monitoring protocol.

RESULTS

Of 5,387 subjects who screened positive for a single autoantibody (Ab), 4,204 (78%) returned for confirmatory Ab testing. Younger age was associated with increased odds of returning for Ab confirmation (age <12 years vs. >18 years: odds ratio [OR] 2.12, P < 0.0001). Racial and ethnic minorities were less likely to return for confirmation, particularly nonwhite non-Hispanic (OR 0.50, P < 0.0001) and Hispanic (OR 0.69, P = 0.0001) relative to non-Hispanic white subjects. Of 8,234 subjects, 5,442 (66%) were identified as eligible to be enrolled in PTP OGTT monitoring. Here, younger age and identification as multiple Ab⁺ were associated with increased odds of returning for OGTT monitoring (age <12 years vs. >18 years: OR 1.43, P < 0.0001; multiple Ab⁺: OR 1.36, P < 0.0001). Parents were less likely to enroll into monitoring than other relatives (OR 0.78, P = 0.004). Site-specific factors, including site volume and U.S. site versus international site, were also associated with differences in rates of return for Ab⁺ confirmation and enrollment into monitoring.

CONCLUSIONS

These data confirm clear differences between successfully enrolled populations and those lost to follow-up, which can serve to identify strategies to increase ongoing participation.

The association between stressful life events and respiratory infections during the first 4 years of life: The Environmental Determinants of Diabetes in the Young study

The aim of this study was to conduct a prospective analysis of the association between negative life events (NLEs) and respiratory infections in children genetically at risk for islet autoimmunity (IA) and type 1 diabetes (T1D). Long- and short-term temporal associations between NLEs and rate of respiratory infection episodes (RIEs) in 5,618 children in The Environmental Determinants of Diabetes in the Young study for at least 1 up to 4 years were analysed. All models were adjusted for demographic, day care, season of infection, and psychosocial factors associated with the rate of child RIEs between study visits. The rate of child RIEs was 26% higher in Europe (Sweden, Finland, Germany) than in the United States (rate ratio [RR] = 1.26, p < 0.001). However, the percentage of child NLEs (odds ratio [OR] = 1.18, p < 0.001) and mother NLEs (OR = 1.83, p < 0.001) was higher in the United States compared with Europe. In both continents (Europe, RR = 1.12, p < 0.001; United States, RR = 1.07, p = 0.006), high child cumulative NLEs (>1 NLE per year since study inception) was significantly associated with an increased rate of child RIEs. This large-scale prospective study confirms observations that stress may increase the susceptibility for infections in paediatric populations and suggests at least one mechanism by which stress could increase risk for IA and T1D in genetically at risk children.

Retention strategies in longitudinal cohort studies: a systematic review and meta-analysis

BACKGROUND

Participant retention strategies that minimise attrition in longitudinal cohort studies have evolved considerably in recent years. This study aimed to assess, via systematic review and meta-analysis, the effectiveness of both traditional strategies and contemporary innovations for retention adopted by longitudinal cohort studies in the past decade.

METHODS

Health research databases were searched for retention strategies used within longitudinal cohort studies published in the 10-years prior, with 143 eligible longitudinal cohort studies identified (141 articles; sample size range: 30 to 61,895). Details on retention strategies and rates, research designs, and participant demographics were extracted. Meta-analyses of retained proportions were performed to examine the association between cohort retention rate and individual and thematically grouped retention strategies.

RESULTS

Results identified 95 retention strategies, broadly classed as either: barrier-reduction, community-building, follow-up/reminder, or tracing strategies. Forty-four of these strategies had not been identified in previous reviews. Meta-regressions indicated that studies using barrier-reduction strategies retained 10% more of their sample (95%CI [0.13 to 1.08]; p = .01); however, studies using follow-up/reminder strategies lost an additional 10% of their sample (95%CI [- 1.19 to - 0.21]; p = .02). The overall number of strategies employed was not associated with retention.

CONCLUSIONS

Employing a larger number of retention strategies may not be associated with improved retention in longitudinal cohort studies, contrary to earlier narrative reviews. Results suggest that strategies that aim to reduce participant burden (e.g., flexibility in data collection methods) might be most effective in maximising cohort retention.

The Environmental Determinants of Diabetes in the Young (TEDDY) Study: 2018 Update

PURPOSE OF REVIEW

The environmental triggers of islet autoimmunity leading to type 1 diabetes (T1D) need to be elucidated to inform primary prevention. The Environmental Determinants of Diabetes in the Young (TEDDY) Study follows from birth 8676 children with T1D risk HLA-DR-DQ genotypes in the USA, Finland, Germany, and Sweden. Most study participants (89%) have no first-degree relative with T1D. The primary outcomes include the appearance of one or more persistent islet autoantibodies (islet autoimmunity, IA) and clinical T1D.

RECENT FINDINGS

As of February 28, 2018, 769 children had developed IA and 310 have progressed to T1D. Secondary outcomes include celiac disease and autoimmune thyroid disease. While the follow-up continues, TEDDY has already evaluated a number of candidate environmental triggers, including infections, probiotics, micronutrient, and microbiome. TEDDY results suggest that there are multiple pathways leading to the destruction of pancreatic beta-cells. Ongoing measurements of further specific exposures, gene variants, and gene-environment interactions and detailed "omics" studies will provide novel information on the pathogenesis of T1D.

Vitamin D and probiotics supplement use in young children with genetic risk for type 1 diabetes

BACKGROUND/OBJECTIVES

Vitamin D and probiotics are nutrients of interest in the context of type 1 diabetes (T1D). We assessed the prevalence of and factors associated with vitamin D and probiotic supplementations among young children with genetic risk of T1D.

SUBJECTS/METHODS

Use of supplements during the first 2 years of life was collected prospectively from 8674 children in The Environmental Determinants of Diabetes in the Young (TEDDY) study.

RESULTS

Single and/or multivitamin/mineral (MVM) supplements were reported by 81% of the children. The majority of participants in Finland, Germany and Sweden (97-99%) and 50% in the United States received vitamin D supplements that were mostly MVMs. Probiotics use varied from 6% in the United States to 60% in Finland and was primarily from probiotics-only preparations. More than 80% of the vitamin D and probiotics supplementation was initiated during infancy, and more than half of the uses lasted longer than a year. Being the first child, longer duration of breastfeeding, born in a later year, older maternal age and higher maternal education level were associated with both vitamin D and probiotics use. Shorter gestational age and mother not smoking during pregnancy were associated with a higher likelihood of probiotics supplementation only.

CONCLUSIONS

Vitamin D and probiotics supplementations are popular in children 0-2 years old and are associated with common factors. Data documented here will allow evaluation of the relationship between early childhood dietary intake and the development of islet autoimmunity and progression to T1D.

Respiratory infections are temporally associated with initiation of type 1 diabetes autoimmunity: the TEDDY study

AIMS/HYPOTHESIS

Respiratory infections and onset of islet autoimmunity are reported to correlate positively in two small prospective studies. The Environmental Determinants of Diabetes in the Young (TEDDY) study is the largest prospective international cohort study on the environmental determinants of type 1 diabetes that regularly monitors both clinical infections and islet autoantibodies. The aim was to confirm the influence of reported respiratory infections and to further characterise the temporal relationship with autoantibody seroconversion.

METHODS

During the years 2004-2009, 8676 newborn babies with HLA genotypes conferring an increased risk of type 1 diabetes were enrolled at 3 months of age to participate in a 15 year follow-up. In the present study, the association between parent-reported respiratory infections and islet autoantibodies at 3 month intervals up to 4 years of age was evaluated in 7869 children. Time-dependent proportional hazard models were used to assess how the timing of respiratory infections related to persistent confirmed islet autoimmunity, defined as autoantibody positivity against insulin, GAD and/or insulinoma antigen-2, concordant at two reference laboratories on two or more consecutive visits.

RESULTS

In total, 87,327 parent-reported respiratory infectious episodes were recorded while the children were under study surveillance for islet autoimmunity, and 454 children seroconverted. The number of respiratory infections occurring in a 9 month period was associated with the subsequent risk of autoimmunity (p < 0.001). For each 1/year rate increase in infections, the hazard of islet autoimmunity increased by 5.6% (95% CI 2.5%, 8.8%). The risk association was linked primarily to infections occurring in the winter (HR 1.42 [95% CI 1.16, 1.74]; p < 0.001). The types of respiratory infection independently associated with autoimmunity were common cold, influenza-like illness, sinusitis, and laryngitis/tracheitis, with HRs (95% CI) of 1.38 (1.11, 1.71), 2.37 (1.35, 4.15), 2.63 (1.22, 5.67) and 1.76 (1.04, 2.98), respectively.

CONCLUSIONS/INTERPRETATION

Recent respiratory infections in young children correlate with an increased risk of islet autoimmunity in the TEDDY study. Further studies to identify the potential causative viruses with pathogen-specific assays should focus especially on the 9 month time window leading to autoantibody seroconversion.

The feasibility of salivary sample collection in an international pediatric cohort: The the TEDDY study

Saliva offers a relatively noninvasive method for measuring analytes such as cortisol, holding particular promise for use in pediatric populations on a large scale if a rigorous collection protocol is feasible in diverse settings. The Environmental Determinants of Diabetes in the Young study protocol, conducted in centers in the United States, Sweden, Finland, and Germany, used salivary collection to assess cortisol level as a physiologic marker of stress. Saliva was collected using Sorbettes from subjects at 3.5, 4.5, and 5.5 years of age. Parents collected a morning sample, and staff collected pre- and post-blood draw samples. Feasibility was assessed based on protocol completion, adherence with instructions, factors affecting adherence, and sufficiency of saliva sample for cortisol determination. Collection of saliva samples in a diverse pediatric population is feasible. Establishing non-invasive and acceptable methods for collecting physiological parameters of stress will allow better exploration of determinants of health in this important population.