Studies with low response proportions may be less biased than studies with high response proportions

Influence of School Type and Class Level on Mean Caries Experience in 12-Year-Olds in Serial Cross-Sectional National Oral Health Survey in Germany-Proposal to Adjust for Selection Bias

The objective of this study is to analyse the effects of attended school type and class level on the reported caries experience (DMFT) obtained in the serial cross-sectional National Oral Health Study in Children in Germany (NOHSC) for the WHO reference group of 12-year-olds.

METHODS

Caries data from the 2016 NOHSC were adjusted for each federal state on the basis of two additional large-scale datasets for school type and class level.

RESULTS

Twelve-year-olds in all grades in Saxony-Anhalt (n = 96,842) exhibited significantly higher DMFT values than 12-year-olds in 6th grade (n = 76,456; +0.10 DMFT; ~14.2%, p < 0.001). Adjustments for school type had effects on DMFT on the level of federal states but almost balanced out on the national level (-0.01 DMFT; ~2%). Due to putatively similar structures of the federal states, the national mean DMFT for 12-year-olds in the latest NOHSC (2016; n = 55,002) was adjusted from 0.44 to 0.50 DMFT, correcting for selection bias.

CONCLUSION

Selection bias in this NOHSC leads to an underestimation of caries levels by about 15%. Due to very low caries experience in children in Germany, these precise adjustments (+0.06 DMFT) have only a minor effect on interpretations of the national epidemiologic situation. Consequently, other national caries studies worldwide using the robust marker of DMFT should also adjust for systematic selection bias related to socio-economic background rather than increasing efforts in examination strategy.

Demographic differences in willingness to share electronic health records in the All of Us Research Program

OBJECTIVE

Participant willingness to share electronic health record (EHR) information is central to success of the National Institutes of Health All of Us Research Program (AoURP). We describe the demographic characteristics of participants who decline access to their EHR data.

MATERIALS AND METHODS

We included participants enrolling in AoURP between June 6, 2017 and December 31, 2019 through the Trans-American Consortium for the Health Care Systems Research Network (TACH). TACH is a consortium of health care systems spanning 6 states, and an AoURP research partner.

RESULTS

We analyzed data for 25 852 participants (89.3% of those enrolled). Mean age = 52.0 years (SD 16.8), with 66.5% White, 18.7% Black/African American, 7.7% Hispanic, 32.5% female, and 76% with >a high school diploma. Overall, 2.3% of participants declined to share access to their EHR data (range across TACH sites = 1.3% to 3.5%). Younger age, female sex, and education >high school were significantly associated with decline to share EHR data, odds ratio (95% confidence interval) = 1.26 (1.19-1.33), 1.74 (1.42-2.14), and 2.44 (1.86-3.21), respectively. Results were similar when several sensitivity analyses were performed.

DISCUSSION

AoURP seeks a dataset reflecting our nation's diversity in all aspects of participation. Those under-represented in biomedical research may be reluctant to share access to their EHR data.

CONCLUSION

In our data, race and ethnicity were not independently related to participant decision to decline access to their EHR information. Results suggest that the value of the AoURP dataset is unlikely to be constrained by the size or the racial/ethnic composition of this subgroup.

The Swedish RAND-36: psychometric characteristics and reference data from the Mid-Swed Health Survey

BACKGROUND

This study aims to evaluate data quality, scaling properties, and reliability of the Swedish RAND-36 in a general population sample and to present reference data for the Swedish population.

METHODS

Testing of data quality, scaling assumptions and reliability followed methods recommended for the International Quality of Life Assessment Project, previously used for psychometric testing of SF-36 and RAND-36. Data were collected via regular mail for a random stratified sample of the general population in a Swedish county. Weighted means for RAND-36 scores were used and differences by sex, age, education, and occupational groups were tested.

RESULTS

The response rate was 42%, and the sample comprised 3432 persons (45% men, 55% women) with a median age of 56.9 years. The internal consistency reliability was satisfactory, with Cronbach's alphas > 0.80 for all eight scales. The percentage of missing items was low, ranging between 1.3% and 3.2%. No floor effects (≥15%) were noted, while ceiling effects were observed for physical functioning, role-functioning/physical, pain, role-functioning/emotional, and social functioning. Item-scale correlations were satisfactory (r ≥ 0.40). Correlations among the physical health scales were strong (range 0.58-0.68) as were the correlations among the mental health scales (range 0.58-0.73). Men reported significantly better health-related quality of life (HRQoL) on all scales, although the gender differences were small. Comparisons among age groups showed approximately equal scores among those 20-29, 30-39, and 40-49 years, while significant decreases in physical health were observed in the older age groups. Substantially worse physical health scores were observed in the oldest age group (80+). Significant differences among age groups were noted also for the mental health scales; however, better energy/fatigue and emotional well-being scores were seen in the older age groups, except for the oldest (80+). Those with university education reported significantly better scores on all scales compared to those with mandatory education.

CONCLUSIONS

The study suggests that the Swedish version of RAND-36 is an acceptable and reliable instrument for measuring HRQoL in the general population. The study provides reference data that can be used for norm-based comparisons.

The Danish National Youth Study 2019: study design and participant characteristics

AIM

To present the study design, study population and questionnaire content of the Danish National Youth Study 2019, and to describe the differences between participants and non-participants regarding demographic and socioeconomic characteristics.

METHOD

The Danish National Youth Study 2019 is a nationwide web-survey among high school students in Denmark. Data was collected from January to April 2019 through a self-administered questionnaire in the classroom. The questionnaire included 120 questions on, for example, physical and mental health, health behaviour and well-being. Data collection took place at 50 general high schools, 32 preparatory high schools, 15 commercial high school and 19 technical high schools.

RESULTS

A total of 29,086 students participated (20,287 general high school students, 2,113 preparatory higher school students, 4027 commercial high school students and 2659 technical high school students) corresponding to 66% of the students in the 88 participating schools (31% of invited schools). Among students, 55% were female and the mean age was 17.8 years. Participants were more likely to be female, to be younger, to be of Danish origin, and have family disposable income in the highest quartile compared to non-participants.

CONCLUSIONS

The Danish National Youth Study 2019 contributes to knowledge on high school students' health, health behaviour and well-being that can support health planning and prioritizing, through identification of specific risk groups at both local and national level. The study also offers great opportunities for future research as it provides possibility of linkage to various Danish national registers.

Desire to lose weight and need of weight loss support in the adult population-Results from a cross-sectional study in Sweden

OBJECTIVE

Evidence-based methods to lose weight are important in tackling increasing obesity trends in adult populations. More knowledge about persons who want to lose weight and do not/do need weight loss support is necessary to design effective preventive practices. Thus, the aim of the study was to investigate the prevalence of desire to lose weight in the general population and the prevalence of health problems and health-related factors in persons with overweight or obesity who want to lose weight and believe that they do not/do need weight loss support.

METHODS

The study included 14 126 persons aged 30 to 69 years who responded to a questionnaire sent to a random sample. Persons with overweight or obesity (BMI ≥ 25 kg/m2) were divided into three groups: those who do not want to lose weight (n = 1236), those who want to lose weight but do not believe they need support (n = 5484), and those who want to lose weight and believe they need weight loss support (n = 1462).

RESULTS

In total, 69% of the women and 59% of the men reported that they wanted to lose weight. The prevalence of hypertension, musculoskeletal pain, poor self-rated health, anxiety/worry, and depression was highest among persons with overweight or obesity who wanted to lose weight and believed they need weight loss support. They were also more physically inactive and reported less social support.

CONCLUSIONS

To want to lose weight is very common among adults. People with overweight or obesity who want to lose weight and believe they need weight loss support have higher frequency of various health problems, including mental health problems, and less social support.

What German dentists choose for their teeth: A Web-based survey of molar restorations and their longevity

STATEMENT OF PROBLEM

Which restorative material is best suited for treating the posterior molar region is unclear. As dentists presumably choose the most appropriate restoration, German dentists were asked how their own molars were treated.

PURPOSE

The purpose of this survey study was to examine molar restorations and their durability in German dentists.

MATERIAL AND METHODS

In the official journal of the Federal Dental Association, German dentists were asked to participate in an online survey that gathered demographic data and information on the type and durability of their molar restorations. To reduce selection bias, the data were weighted for region, sex, and age of the dentist.

RESULTS

The data set consisted of 1719 molars from 288 dentists. Restorations included gold inlays (25%), composite resin (24.3%), amalgam (11.8%), ceramic inlays (5.4%), glass ionomer cement or compomer (0.8%), gold crowns (21.8%), ceramic crowns (6.6%), and metal-ceramic crowns (4.3%). Notable differences were identified based on the sex, age, and region of the dentist. Women selected increased esthetic options, as did young dentists. Restorations made of gold, amalgam, and base metal had the highest longevity, at more than 20 years CONCLUSIONS: Among German dentists, restorations with metallic materials dominated in molars, with gold accounting for the largest share. In recent years, the proportion of tooth-colored restorations has increased, and in particular, young dentists use composite resin and ceramics.

Gender-specific hearing loss in German adults aged 18 to 84 years compared to US-American and current European studies

INTRODUCTION

From an epidemiological point of view, the increase of pure-tone hearing thresholds as one aspect of biological ageing is moderated by societal factors. Since health policies refer to empirical findings, it is reasonable to replicate population-based hearing surveys and to compare estimates for different birth cohorts from the same regions or, conversely, for the same birth cohorts from different regions.

METHODS

We pooled data from two independent cross-sectional German studies conducted between 2008 and 2012 and including 3105 adults. The increase of thresholds, the prevalence and risk of hearing impairment (HI) by age and gender were compared to results reported for European and US-American studies that were carried out at about the same time. Since these studies differed with regard to the age limits, the statistical approaches and, importantly, their definitions of HI, data adjustments were performed to enable the comparison.

RESULTS

Overall, 15.5% of the participants in the German studies showed a pure-tone average at 0.5, 1, 2, and 4 kHz in the better ear (PTA) greater than 25 dB HL and 8.6% had a PTA of at least 35 dB HL. Based on one-to-one comparisons, the German estimates demonstrated a good agreement to a large Dutch study and with some reservations to a Swedish study, but considerable differences to US-American results. Comprehensive comparisons of the within-study gender differences showed that age-related HI was less and the gender gap was markedly smaller in Europe compared to the US due to the lower HI in males found in the European studies.

CONCLUSION

Discrepancies in measurement procedures, conditions, and equipment that complicate the comparison of absolute HI estimates across studies play no or only a marginal role when comparing relative estimates. Hence, the gender gap differences reviewed in this analysis possibly stem from societal conditions that distinguish societies commonly labeled modern industrialized western countries.

Factors influencing attrition in 35 Alzheimer's Disease Centers across the USA: a longitudinal examination of the National Alzheimer's Coordinating Center's Uniform Data Set

OBJECTIVE

A lack of understanding of the causes of attrition in longitudinal studies of older adults may lead to higher attrition rates and bias longitudinal study results. In longitudinal epidemiological studies of Alzheimer's disease and related dementias, high rates of attrition may cause a systematic underestimation of dementia prevalence and skew the characterization of the disease. This can compromise the generalizability of the study results and any inferences based on the surviving sample may grossly misrepresent the importance of the risk factors for dementia. The National Institute on Aging outlined a National Strategy for Recruitment and Participation in Alzheimer's Disease Clinical Research to address this problem, providing evidence of the magnitude of this problem.

METHOD

To explore predictors of attrition, this study examined the National Alzheimer's Coordinating Center (NACC) Uniform Data Set, a repository of observations of older adults spanning 11 years, using survival analysis. Four samples were examined: the full sample (n = 30,433), the alive subsample excluding those who died (n = 24,231), the MRI sample [participants with complete MRI data (n = 1104)], and the alive MRI subsample [participants with MRI data excluding those who died (n = 947)].

RESULTS

Worsening cognitive impairment, neuropsychiatric symptoms, and difficulty with functional activities predicted attrition, as did lower hippocampal volume in the MRI subsample. Questionable co-participant reliability and an informant other than a spouse also increased risk of attrition.

DISCUSSION

Special considerations exist in recruiting and retaining older adults in longitudinal studies, and results of baseline psychological, functional, and cognitive functioning should be used to identify targeted retention strategies.

Study invitations with envelopes made from recycled paper do not increase likelihood of active responses or study participation in the German National Cohort

OBJECTIVE

We conducted a trial embedded within the German National Cohort comparing the responses to study invitations sent in recycled envelopes of grey color vs. envelopes of white color. We analyzed paradata for reactions to the invitation letters by potential subjects, the duration between mailing date of the invitation and active responses, and study participation.

RESULTS

Grey envelopes only slightly increased the chance of active responses (OR 1.16, 95% CI 0.83, 1.62) to the invitation letter. Potential study subjects with German nationality (OR 3.75, 95% CI 2.07, 7.66) and age groups above 50 years (50-59: OR 1.78, 95% CI 1.19, 2.69; 60-69: OR 2.25, 95% CI 1.48, 3.43) were more likely to actively respond to the invitation letter. The duration between mailing date of the invitation and active response was not associated with envelope color, sex, nationality, or age. Our trial replicates previous observations that the color of the envelope of a study invitation does not influence the likelihood of an active response or study participation.

40-Year Longitudinal Caries Development in German Adolescents in the Light of New Caries Measures

This study assessed the 40-year longitudinal caries development in German adolescents in the light of the sixth National Oral Health Survey in Children (NOHSC, 2016) employing initial DMFT (IDMFT), Significant Caries Index (SiC) and Specific Affected Caries Index (SaC). On the basis of the current NOHSC (randomized cluster selection using school list or regional community school surveys, 55,956 12-year-old sixth-graders examined by 482 calibrated community/study dentists) DMFT, SiC, a novel IDMFT including initial lesions (IT) and the recently introduced SaC were calculated and also recalculated for national and international surveys from the last 4 decades. In 2016, 78.8% of children were caries-free (DMFT = 0), 65.5% including IT lesions. The mean DMFT was 0.44 (single components: DT = 0.14, MT = 0.02, FT = 0.29, IT = 0.52) showing a clear association with the school type as marker for the socio-economic status. The mean number of affected teeth in children with DMFT >0 was 2.07 (SaC) in comparison to almost 9 teeth in the 1970s. The current care index on the tooth level was 66.3%, leaving only 7.7% of children with restorative treatment needs. Longitudinally, a continuous caries decline of more than 80%, including the risk groups (SiC/SaC), to an internationally extremely low level was observed. In conclusion, the National Oral Health Surveys reveal a continuous caries decline to a very low caries level in 12-year-old 6th-graders in Germany even if IT lesions are included (IDMFT). In spite of proportional reductions in the risk groups (SiC/SaC), the polarized caries distribution according to socio-economic parameters reveals the need for targeted preventive programmes.

Caries Trends in the Primary Dentition of 6- to 7-Year-old Schoolchildren in Germany from 1994 to 2016: Results from the German National Oral Health Surveys in Children

Long-term nationally representative caries data in the primary dentition are rare, but nonetheless central to assess needs in caries prevention and treatment. This study evaluated the prevalence and trends of caries levels in the primary dentition of 6- to 7-year-olds in Germany as a whole and its federal states individually. In 2016, employing a randomized cluster selection, 6- to 7-year-old first graders were included in the National German Oral Health Survey performed regularly since 1994/95. Children were examined by 482 calibrated dentists in all 17 German regions using the WHO criteria for the decayed, missing, and filled teeth (dmft) including the assessment of initial carious lesions (it). In total, 151,555 6- to 7-year-olds were examined. Caries prevalence in the primary dentition dropped from 65% in 1994 to 44% in 2016, while the mean caries experience dropped from 2.89 to 1.73 dmft (dt = 0.74, mt = 0.19, ft = 0.80). When initial lesions were included, the mean caries experience increased to idmft = 2.12 (it = 0.38). In 2016, 49.7% of the examined 6- to 7-year-olds were caries-free including initial lesions. The Care Index at the tooth level was 57.5%, and the Significant Caries Index was 4.84 dmft. Depending on the German region, the mean dmft varied considerably, ranging from 1.37 to 2.31. In conclusion, despite the overall caries decline in 6- to 7-year-olds in Germany, only minor caries reductions were observed over the last decade, with a still existing high proportion of untreated dental decay. This calls for more effective preventive and restorative efforts with focus on the primary dentition in Germany.

[Ethical consideration of studies involving human subjects outside the regulatory framework: not mandatory, but of high relevance]

According to the Declaration of Helsinki, ethics committees are obliged to evaluate any type of medical research involving human subjects in order to ensure an objective view on ethical considerations. This does not only mean considering whether the risks to study participants are ethically justifiable or not, but also checking whether the scientific quality of a study is sufficient. However, the role of ethics committees differs depending on whether the study to be considered is, for example, an approval study according to the German Medicines Act (AMG) or whether the study is outside the regulatory framework. For these so-called unregulated studies it is not always mandatory to obtain approval from an ethics committee or an institutional review board.In this paper, we first explain the term "unregulated studies" in detail and elaborate for which types of unregulated studies an application for ethical approval is required before we deal with the application for ethical approval as such and in particular with the study protocol as one of its major components. Registry studies, postmarketing surveillance studies, analyses of secondary data, surveys, intervention, and prognostic studies serve as examples to illustrate the broad range of unregulated studies.Finally, we discuss crucial aspects of the role of ethics committees with respect to the consideration of unregulated studies. In our conclusion, we point out the necessity of having ethics committees at each university in Germany that are also responsible for unregulated studies. In addition, the German legislature should define a stricter regulation such that unregulated studies also have to adhere to the vote of the ethics committee.

Irritable bowel syndrome, mental health, and quality of life: Data from a population-based survey in Germany (SHIP-Trend-0)

BACKGROUND

Irritable bowel syndrome (IBS) is associated with reduced quality of life and high healthcare costs. This study aimed to assess the prevalence and risk factors for IBS in a general adult population.

METHODS

The Study of Health in Pomerania (SHIP) is a population-based cohort study in northeastern Germany. SHIP-Trend-0 participants enrolled from 2008 to 2012 were grouped according to Rome III criteria (main criteria: abdominal discomfort or crampy or bloating pain for at least six months plus 2/3 additional criteria). Factors associated with IBS were assessed using survey-weighted backward stepwise logistic regression.

KEY RESULTS

The final data set included 4194 records. IBS prevalence was 3.5% (3.0%-4.2%). Unemployment (OR: 2.02, 1.26-3.21), headaches (OR: 2.37, 1.59-3.52), mental quality of life (OR: 0.95 per unit increase, 0.93-0.97), and interactions between gender and physical quality of life (P = 0.004) and gender and alexithymia (P = 0.002) predicted IBS probability. The model resulted in a good discrimination (area under the curve = 75.4%) and model fit (F = 0.72, P = 0.69). History of depression (OR: 2.77, 1.94-3.95), back pain (OR: 2.38, 1.69-3.35), early trauma (OR: 1.03, 1.02-1.04), and duration of inpatient treatment within the last twelve months (OR: 1.02, 1.01-1.04) lost their significance in multivariable analysis.

CONCLUSIONS & INFERENCES

IBS prevalence was relatively low compared to other studies. Factors predicting IBS were of biological, psychological, and social nature. The association between IBS and pain in different areas of the body indicates a potential underlying complex somatic symptom disorder.

Study design and characteristics of the Luxembourg European Health Examination Survey (EHES-LUX)

Background

The European Health Examination Survey in Luxembourg (EHES-LUX) is a population based survey performed from 2013 to 2015 with the aim to establish baseline information on the general health status of the Luxembourg population aged 25 to 64 years. The paper introduces the study design, recruitment method and representativeness of the sample, and summarizes the sociodemographic characteristics of participants and the prevalence of major health outcomes.

Methods

EHES-LUX is based on a random sample representative of the population of Luxembourg based on gender, age and district of residence. The sample size of the study was determined to provide accurate prevalence estimates for major chronic conditions. During two visits, data were collected from participants through a questionnaire (personal data, health status and health care), medical examinations (anthropometric measures, electrocardiogram and spirometry) and biological analysis (blood, urine and hair). Means and frequencies were used to describe the general characteristics of the population and a one-way ANOVA to test the representativeness of the sample and the comparability of participants and non-participants.

Results

A total of 1529 individuals participated in this study (participation rate of 24.1%). Differences between participants and non-participants based on gender, age and district of residence were corrected by sampling weights. The mean age (±SD) of participants was 44.9 (±10.1) years, of which 52.8% were women. Based on clinical measurements, nearly 20% of participants were obese and more than one in three participants were overweight. From measurements (respectively from self-report), 22.0% (respectively 12.2%) were hypertensive, 49.3% (respectively 22.5%) had hypercholesterolemia, 3.5% (respectively 3.7%) had diabetes and 7.6% (respectively 6.0%) had depressive symptoms.

Conclusions

This nationwide epidemiological study on the general health status of Luxembourg residents provides updated prevalence estimates on a range of major health conditions. This information can be used by health authorities to evaluate policies and public health initiatives. At European level, prevalence data obtained by this study following the EHES-Reference Committee (EHES-RC) recommendations, will be comparable between European countries participating in this program.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-6087-0) contains supplementary material, which is available to authorized users.

Patient-rated importance of key information on screening colonoscopy in Germany: a survey of statutory health insurance members

BACKGROUND

Primary colonoscopic screening is considered to be of great benefit but also has the potential to cause severe harm. Thus, eligible subjects should be supported in making an informed choice whether to participate.

OBJECTIVES

To identify information on screening colonoscopy that colonoscopy-naïve subjects rate as particularly important for decision making.

DESIGN

Survey of German statutory health insurance members using a written questionnaire in November 2015.

STUDY POPULATION

Colonoscopy-naïve individuals aged 50 to 65 years.

MAIN OUTCOME MEASURES

Importance of key information about screening colonoscopy, including potential risks and benefits, baseline risk of colorectal cancer/polyps and practical aspects of the procedure, as well as associations between participants' characteristics and their judgement of information as to being 'very important'.

RESULTS

Of 1871 respondents (overall response rate: 31%), a subgroup of 370 colonoscopy-naïve subjects was eligible for inclusion (average age: 55 years, 47% male). Information on the risks was rated as very important by most respondents, unimportant by 6%. Information on the benefits was considered unimportant by 26%. Regression analysis showed that less educated persons regarded most items to be more often relevant than highly educated subjects. A greater proportion of women than men rated details regarding pain and practical aspects as very important. Subjects with a low educational level living alone were identified as the group with the least interest in information on risks.

CONCLUSION

Cultivating awareness around the central meaning of the (quantitative) benefits of screening in informed decision making should be focused on more in future information materials. The high requirement of less educated people to become more informed provides a strong motivation for further efforts to develop evidence-based information that adequately informs this group. Tailoring information according to gender-specific needs may be warranted in light of the observed differences in information preferences between women and men.

Racial Differences in Data Quality and Completeness: Spinal Cord Injury Model Systems' Experiences

Background: Among people with spinal cord injury (SCI), minorities experience a disproportionately higher burden of diseases. Knowledge of data quality by race/ethnicity will help better design racial health disparity research and understand potential errors/biases. Objective: To investigate racial/ethnic differences in response completeness in a longitudinal SCI database. Methods: This study included 7,507 participants (5,483 non-Hispanic whites, 1,414 non-Hispanic blacks, and 610 Hispanics) enrolled in the National SCI Database who returned for follow-up between 2001 and 2006 and were aged ≥18 years at follow-up. Missing data were defined as any missing, unknown, or refusal response to interview items. Results: The overall missing rate was 29.7%, 9.5%, 9.7%, 10.7%, 12.0%, and 9.8% for the Craig Handicap Assessment and Reporting Technique-Short Form (CHART) economic self-sufficiency subscale, CAGE questionnaire, drug use, Diener's Satisfaction with Life Scale, Patient Health Questionnaire, and pain severity, respectively. The missing rate for the CHART measure was significantly higher among non-Hispanic blacks and Hispanics than among non-Hispanic whites, after controlling for demographics, injury factors, mode of data collection, and study sites. The missing data in the other outcome measures examined were also significantly higher among non-Hispanic blacks than among non-Hispanic whites but were not significantly different between Hispanics and non-Hispanic whites. Conclusion: Our study highlights the importance of research methodology designed to improve non-response or response incompleteness, particularly in non-Hispanic blacks, as we move to reduce racial/ethnic disparities and strive to explain how and why disparities occur in the SCI population.

Factors associated with attrition in a longitudinal online study: results from the HaBIDS panel

Background

Knowing about predictors of attrition in a panel is important to initiate early measures against loss of participants. We investigated attrition in both early and late phase of an online panel with special focus on preferences regarding mode of participation.

Methods

We used data from the HaBIDS panel that was designed to investigate knowledge, attitudes, and practice regarding infections in the German general population. HaBIDS was divided into two phases: an initial phase when some participants could choose their preferred mode of participation (paper-and-pencil or online) and an extended phase when participants were asked to become members of an online panel that was not limited regarding its duration (i.e. participants initially preferring paper questionnaires switched to online participation). Using competing risks regression, we investigated two types of attrition (formal withdrawal and discontinuation without withdrawal) among online participants, separately for both phases. As potential predictors of attrition, we considered sociodemographic characteristics, physical and mental health as well as auxiliary information describing the survey process, and, in the extended phase, initial mode preference.

Results

In the initial phase, higher age and less frequent Internet usage predicted withdrawal, while younger age, higher stress levels, delay in returning the consent form, and need for receiving reminder emails predicted discontinuation. In the extended phase, only need for receiving reminder emails predicted discontinuation. Numbers of withdrawal in the extended phase were too small for analysis. Initial mode preference did not predict attrition in the extended phase. Besides age, there was no evidence of differential attrition by sociodemographic factors in any phase.

Conclusions

Predictors of attrition were similar in both phases of the panel, but they differed by type of attrition (withdrawal vs. discontinuation). Sociodemographic characteristics only played a minor role for both types of attrition. Need for receiving a reminder was the strongest predictor of discontinuation in any phase, but no predictor of withdrawal. We found predictors of attrition, which can be identified already in the early phase of a panel so that countermeasures (e.g. special incentives) can be taken.

Electronic supplementary material

The online version of this article (10.1186/s12874-017-0408-3) contains supplementary material, which is available to authorized users.

Self-Perception of Medical Students' Knowledge and Interest in Disaster Medicine: Nine Years After the Approval of the Curriculum in German Universities

BACKGROUND

Following the recommendations of the World Association for Disaster and Emergency Medicine (WADEM; Madison, Wisconsin USA) to develop standards for training the undergraduates in disaster-relevant fields (2004), a German curriculum was approved in 2006. This paper aims to describe the level of training and interest of medical students nine years later. Problem The aim of this study was to assess the self-perception of medical students' knowledge and interest in disaster medicine nine years after the implementation of a standardized disaster medicine curriculum in German medical schools.

METHODS

This prospective, cross-sectional, observational study was conducted with medical students in Germany using a web-based, purpose-designed questionnaire consisting of 27 mandatory and 11 optional questions.

RESULTS

Nine hundred ninety-two students from 36 of 37 medical schools in Germany participated. More than one-half of medical students were aware of the field of disaster medicine. One hundred twenty-one students undertook training internally within their university and 307 undertook training externally at other institutions. Only a small content of the curriculum was taught. A difference in self-perception of knowledge between trained and untrained participants was found, despite the level of training being low in both groups. Participants were generally highly motivated to learn disaster medicine in a variety of institutions.

CONCLUSION

German students are still largely not well educated regarding disaster medicine, despite their high motivation. The curriculum of 2006 was not implemented as originally planned and the number of trained students still remains low as the self-perception of knowledge. Currently, there is no clear and standardized training concept in place. A renewal in the agreement of implementation of the curriculum at medical schools should be targeted in order to follow the recommendation of WADEM. Wunderlich R Ragazzoni L Ingrassia PL Della Corte F Grundgeiger J Bickelmayer JW Domres B . Self-perception of medical students' knowledge and interest in disaster medicine: nine years after the approval of the curriculum in German universities. Prehosp Disaster Med. 2017;32(4):374-381.

Comparison of response patterns in different survey designs: a longitudinal panel with mixed-mode and online-only design

Background

Increasing availability of the Internet allows using only online data collection for more epidemiological studies. We compare response patterns in a population-based health survey using two survey designs: mixed-mode (choice between paper-and-pencil and online questionnaires) and online-only design (without choice).

Methods

We used data from a longitudinal panel, the Hygiene and Behaviour Infectious Diseases Study (HaBIDS), conducted in 2014/2015 in four regions in Lower Saxony, Germany. Individuals were recruited using address-based probability sampling. In two regions, individuals could choose between paper-and-pencil and online questionnaires. In the other two regions, individuals were offered online-only participation. We compared sociodemographic characteristics of respondents who filled in all panel questionnaires between the mixed-mode group (n = 1110) and the online-only group (n = 482). Using 134 items, we performed multinomial logistic regression to compare responses between survey designs in terms of type (missing, “do not know” or valid response) and ordinal regression to compare responses in terms of content. We applied the false discovery rates (FDR) to control for multiple testing and investigated effects of adjusting for sociodemographic characteristic. For validation of the differential response patterns between mixed-mode and online-only, we compared the response patterns between paper and online mode among the respondents in the mixed-mode group in one region (n = 786).

Results

Respondents in the online-only group were older than those in the mixed-mode group, but both groups did not differ regarding sex or education. Type of response did not differ between the online-only and the mixed-mode group. Survey design was associated with different content of response in 18 of the 134 investigated items; which decreased to 11 after adjusting for sociodemographic variables. In the validation within the mixed-mode, only two of those were among the 11 significantly different items. The probability of observing by chance the same two or more significant differences in this setting was 22%.

Conclusions

We found similar response patterns in both survey designs with only few items being answered differently, likely attributable to chance. Our study supports the equivalence of the compared survey designs and suggests that, in the studied setting, using online-only design does not cause strong distortion of the results.

Electronic supplementary material

The online version of this article (doi:10.1186/s12982-017-0058-2) contains supplementary material, which is available to authorized users.

Obtaining a genetic diagnosis in a child with disability: impact on parental quality of life

Recent progress in genetic testing has facilitated obtaining an etiologic diagnosis in children with developmental delay/intellectual disability (DD/ID) or multiple congenital anomalies (MCA) or both. Little is known about the benefits of diagnostic elucidation for affected families. We studied the impact of a genetic diagnosis on parental quality of life (QoL) using a validated semiquantitative questionnaire in families with a disabled child investigated by array-based comparative genomic hybridization (aCGH). We received completed questionnaires from 95 mothers and 76 fathers of 99 families. We used multivariate analysis for adjustment of potential confounders. Taken all 99 families together, maternal QoL score (percentile rank scale 51.05) was significantly lower than fathers' QoL (61.83, p = 0.01). Maternal QoL score was 20.17 [95% CI (5.49; 34.82)] percentile rank scales higher in mothers of children with diagnostic (n = 34) aCGH as opposed to mothers of children with inconclusive (n = 65) aCGH (Hedges' g = 0.71). Comparison of these QoL scores with retrospectively recalled QoL before aCGH revealed an increase of maternal QoL after diagnostic clarification. Our results indicate a benefit for maternal QoL if a genetic test, here aCGH, succeeds to clarify the etiologic diagnosis in a disabled child.

Prävalenz von Schwerhörigkeit im Nordwesten Deutschlands

Hintergrund

Der mittlere Luftleitungshörverlust bei 0,5, 1, 2 und 4 kHz („pure tone average“, PTA-4) im besseren Ohr ist das international anerkannte Kriterium der Weltgesundheitsorganisation (WHO) zur Beschreibung des Hörvermögens. Zurzeit gibt es keine epidemiologischen Daten zum Hörverlust in der deutschen Bevölkerung, in der dieses Kriterium verwendet wird.

Methoden

Eine populationstypische Stichprobe erwachsener Personen aus Oldenburg und Emden wurde zu einer eingeladen. Analysiert wird der Zusammenhang von Hörverlusten mit Alter, Geschlecht, Lärm, Berufsbereich und schulischer Bildung. Die alters- und geschlechtsspezifische Prävalenz nach WHO wird mit internationalen Studienergebnissen verglichen.

Ergebnisse

Die Prävalenz von Schwerhörigkeit nach der WHO-Klassifikation lag bei den Studienteilnehmern (n = 1866) bei etwa 16 %. Bei Männern, die häufiger in lärmbelasteten Berufsbereichen tätig waren, wurde eine höhere Prävalenz als bei Frauen gleichen Alters beobachtet. Der Unterschied zwischen den Geschlechtern ist jedoch geringer als in internationalen Vergleichsstudien. Bei Berücksichtigung beruflicher Lärmexposition gleichen sich beide Geschlechter im PTA-4, signifikante Unterschiede zwischen verschiedenen Berufsbereichen aber bleiben erhalten.

Schlussfolgerung

Im internationalen Vergleich liegt die altersabhängige Prävalenz in HÖRSTAT niedrig. Aus den Studienergebnissen der vergangenen 25 Jahre ist eine Tendenz zu abnehmender Prävalenz von Schwerhörigkeit im mittleren bis oberen Altersbereich zu beobachten.

Mental health impact of the 2010 Haiti earthquake on the Miami Haitian population: A random-sample survey

This study examined the mental health consequences of the January 2010 Haiti earthquake on Haitians living in Miami-Dade County, Florida, 2-3 years following the event. A random-sample household survey was conducted from October 2011 through December 2012 in Miami-Dade County, Florida. Haitian participants (N = 421) were assessed for their earthquake exposure and its impact on family, friends, and household finances; and for symptoms of posttraumatic stress disorder (PTSD), anxiety, and major depression; using standardized screening measures and thresholds. Exposure was considered as "direct" if the interviewee was in Haiti during the earthquake. Exposure was classified as "indirect" if the interviewee was not in Haiti during the earthquake but (1) family members or close friends were victims of the earthquake, and/or (2) family members were hosted in the respondent's household, and/or (3) assets or jobs were lost because of the earthquake. Interviewees who did not qualify for either direct or indirect exposure were designated as "lower" exposure. Eight percent of respondents qualified for direct exposure, and 63% qualified for indirect exposure. Among those with direct exposure, 19% exceeded threshold for PTSD, 36% for anxiety, and 45% for depression. Corresponding percentages were 9%, 22% and 24% for respondents with indirect exposure, and 6%, 14%, and 10% for those with lower exposure. A majority of Miami Haitians were directly or indirectly exposed to the earthquake. Mental health distress among them remains considerable two to three years post-earthquake.

Random sample community-based health surveys: does the effort to reach participants matter?

OBJECTIVES

Conducting health surveys with community-based random samples are essential to capture an otherwise unreachable population, but these surveys can be biased if the effort to reach participants is insufficient. This study determines the desirable amount of effort to minimise such bias.

DESIGN

A household-based health survey with random sampling and face-to-face interviews. Up to 11 visits, organised by canvassing rounds, were made to obtain an interview.

SETTING

Single-family homes in an underserved and understudied population in North Miami-Dade County, Florida, USA.

PARTICIPANTS

Of a probabilistic sample of 2200 household addresses, 30 corresponded to empty lots, 74 were abandoned houses, 625 households declined to participate and 265 could not be reached and interviewed within 11 attempts. Analyses were performed on the 1206 remaining households.

PRIMARY OUTCOME

Each household was asked if any of their members had been told by a doctor that they had high blood pressure, heart disease including heart attack, cancer, diabetes, anxiety/ depression, obesity or asthma. Responses to these questions were analysed by the number of visit attempts needed to obtain the interview.

RESULTS

Return per visit fell below 10% after four attempts, below 5% after six attempts and below 2% after eight attempts. As the effort increased, household size decreased, while household income and the percentage of interviewees active and employed increased; proportion of the seven health conditions decreased, four of which did so significantly: heart disease 20.4-9.2%, high blood pressure 63.5-58.1%, anxiety/depression 24.4-9.2% and obesity 21.8-12.6%. Beyond the fifth attempt, however, cumulative percentages varied by less than 1% and precision varied by less than 0.1%.

CONCLUSIONS

In spite of the early and steep drop, sustaining at least five attempts to reach participants is necessary to reduce selection bias.

Cohort studies with low baseline response may not be generalisable to populations with different exposure distributions

Several advocates of mega-cohorts in epidemiology recently stated that high baseline response needs not be a driving scientific factor. We illustrate how cohort studies with low baseline response can become less generalisable than cohort studies with reasonable high baseline response. Assuming exposure prevalences of 32%, and 39% for former, and current smoking in the general population, we postulate that 10% in each group have a specific genotype G that makes them susceptible for the effect of smoking on the outcome (synergism between genotype and smoking). The existence and the mechanism of this synergism is unknown to the investigator. The parameter of interest is the average effect of smoking on the outcome expressed as relative risk (RR). We consider three different scenarios. In scenario 1, the RR for former and present smokers is 50 and 100 for subjects with G, translating into RR of 5.9 and 10.9 at population level. In scenario 2, the according figures are 10 and 20 for subjects with G and 1.9 and 2.9 at the population level, while in scenario 3, the according numbers are 2 and 5, and 1.1 and 1.4, respectively. We assume a differential baseline response by genotype G with overall baseline responses of 10% (low) and 50% (high). In all scenarios, we observe generalisability for a high baseline response. In contrast, for low baseline response the RRs for former and current smokers lack generalisability with loss of dose response relationship leading to 2.58 and 2.09 in scenario 1, to 1.29 and 1.21 in scenario 2, and in scenario 3 with RRs very close to unity (1.03 and 1.04 respectively). RR estimates may lack generalisability and dose response relationships even may be inverted if baseline response is low. Thus, even mega-cohorts should strive for a reasonable high baseline response.

Shifting curves? Trends in thinness and obesity among Australian youth, 1985 to 2010

OBJECTIVE

To describe 25-year trends in the prevalence of ≤Grade 2 thinness and obesity among Australian children by sex, age and socioeconomic (SES) background.

METHODS

Cross-sectional surveys of New South Wales school-aged children aged 6.0-16.9 years conducted in 1985-1997-2004-2010 (n = 19 434). Height/weight were measured, and thinness and obesity were defined by international standards. SES was derived from children's residential postcode using the Australian Bureau of Statistics' Index of Relative Socioeconomic Disadvantage, most proximal to the survey year.

RESULTS

Since 1985, the prevalence of thinness has not varied by survey year. Age was not associated with thinness; however, thinness was lower among middle SES boys, compared with high SES (OR: 0.45, 95%CI: 0.21, 0.97). The prevalence of obesity trebled between 1985 and 1997 (1.7% vs. 5.1% P = 0.000); however, since 1997, obesity prevalence has not significantly changed. Since 1997, obesity was higher among younger compared with older girls (OR: 2.11, 95%CI: 1.48, 3.00) and SES was inversely associated with obesity in boys (OR: 2.05, 95%CI: 1.44, 2.92) and girls (OR: 1.86, 95%CI: 1.27, 2.74).

CONCLUSIONS

The apparent plateau in child obesity is a welcome finding; however, the SES gradients are of concern. If the obesity stabilization is associated with the impact of multiple lifestyle behavioural interventions, the findings suggest obesity programmes have done 'no harm', but potentially the dose/delivery of interventions has not been sufficient or appropriate to reduce child obesity levels.

A selective follow-up study on a public health survey

BACKGROUND

The non-response rates in surveys are increasing which is problematic as it means that a progressively smaller proportion of the population represents the majority, and it is uncertain how health survey results are affected. This follow-up was performed on the non-responders to the postal questionnaire in the public health survey Life and Health, conducted in Örebro County Council, Sweden, where large differences in response rates had been found between different socio-demographic groups and geographical areas. The main objective was to analyse non-response bias regarding self-rated health.

METHODS

This follow-up study was conducted as a census to all non-responders in the area that had the lowest response rate and, in one other geographical area used as a control. It was carried out by telephone interviews, 49.3% (580 individuals) answered the follow-up. The outcome variable was self-rated health, a main variable in public health surveys. Differences in response patterns between responders and initial non-responders were approximated by prevalences with confidence intervals and adjusted odds ratios.

RESULTS

Poor health was more common in the initial non-response group than among the responders, even with consideration given to sex, age, country of birth and education. However, good health was equally common among responders and initial non-responders.

CONCLUSIONS

Public health surveys can be biased due to certain groups being under-represented or not represented at all. For this reason, in repeated public health surveys, we recommend selective follow-ups of such groups at regular intervals.

The Danish National Cohort Study (DANCOS)

Introduction: The Danish National Cohort Study (DANCOS) is a nationally representative public health survey based on linkage of information in the repeated Danish Health Interview surveys, 1986—2005, to the national Danish registers on health and welfare. It facilitates studies of self-reported health behaviour and utilisation of healthcare services by subgroups and analysis of non-response bias. Research topics: DANCOS data are utilised in a variety of analyses presented here by a few examples that emphasise the impact of modifiable risk factors on public health, description of non-response bias, and the epidemiology of chronic pain and of osteoarthritis. Examples of DANCOS-based results are shown for each of the four topics. Smoking results in 24% of all deaths and, compared to other risk factors for public health, smoking accounts for the highest number of years of life lost. For non-response the mortality is higher among non-respondents than among respondents, but no significant bias on healthcare estimates can be seen. On average individuals with chronic pain had 12.8 contacts per year to the primary healthcare sector compared with 7.3 for individuals without. For osteoarthritis it is estimated that in 2020 there will be 22,600 incident cases. Conclusion: DANCOS is a public health survey linked with registers with many research possibilities. With this article we hope to stimulate further interest in the survey.

Golf-related lower back injuries: an epidemiological survey

OBJECTIVE

This study describes the playing characteristics of golfers who had an injury to their lower back in the course of play or practice in the previous year (12 months).

METHODS

A retrospective survey was mailed to members of randomly selected golf clubs across Australia. Statistical methods used included 2-sample t test to compare means of 2 independent populations and the chi(2) test to examine the association between categorical variables/factors in the study.

RESULTS

Of 1634 Australian amateur golfers surveyed, 17.6% of golfers sustained at least 1 injury in the previous year. The lower back accounted for 25% of all golf-related injuries in the previous year, making the lower back the most common site of injury. The golfer with a golf-related lower back injury was likely to have a previous history of lower back injury, while the injury had a progressive onset compared with an acute single onset. The follow-through phase of the golf swing was reported to be associated with the greatest likelihood of injury compared with other phases of the swing. Most of the injured golfers received treatment of their injury with a general practitioner (69%), a physiotherapist (49%), or a chiropractor (40%).

CONCLUSION

Practitioners treating golfers with a history of lower back injury should evaluate the golf swing follow-through to identify potential causes of aggravation to the lower back. Targeted measures such as spinal manipulative therapy, soft tissue and back exercise, and conditioning programs to assist the strength and mobility of the golfer could then be implemented.

Comparison of early-, late-, and non-participants in a school-based asthma management program for urban high school students

Background

To assess bias and generalizability of results in randomized controlled trials (RCT), investigators compare participants to non-participants or early- to late-participants. Comparisons can also inform the recruitment approach, especially when working with challenging populations, such as urban adolescents. In this paper, we describe characteristics by participant status of urban teens eligible to participate in a RCT of a school-based, web-based asthma management program.

Methods

The denominator for this analysis was all students found to be eligible to participate in the RCT. Data were analyzed for participants and non-participants of the RCT, as well as for students that enrolled during the initially scheduled recruitment period (early-participants) and persons that delayed enrollment until the following fall when recruitment was re-opened to increase sample size (late-participants). Full Time Equivalents (FTEs) of staff associated with recruitment were estimated.

Results

Of 1668 teens eligible for the RCT, 386 enrolled early, and 36 enrolled late, leaving 1246 non-participants. Participants were younger (p < 0.01), more likely to be diagnosed, use asthma medication, and have moderate-to-severe disease than non-participants, odds ratios (95% Confidence Intervals) = 2.1(1.7-2.8), 1.7(1.3-2.1), 1.4(1.0-1.8), respectively. ORs were elevated for the association of late-participation with Medicaid enrollment, 1.9(0.7-5.1) and extrinsic motivation to enroll, 1.7(0.6-5.0). Late-participation was inversely related to study compliance for teens and caregivers, ORs ranging from 0.1 to 0.3 (all p-values < 0.01). Early- and late-participants required 0.45 FTEs/100 and 3.3 FTEs/100, respectively.

Conclusions

Recruitment messages attracted youth with moderate-to-severe asthma, but extending enrollment was costly, resulting in potentially less motivated, and certainly less compliant, participants. Investigators must balance internal versus external validity in the decision to extend recruitment. Gains in sample size and external validity may be offset by the cost of additional staff time and the threat to internal validity caused by lower participant follow-up.

Trial Registration

ClinicalTrials.gov: NCT00201058

Effect of reminders on mitigating participation bias in a case-control study

Background

Researchers commonly employ strategies to increase participation in health studies. These include use of incentives and intensive reminders. There is, however, little evidence regarding the quantitative effect that such strategies have on study results. We present an analysis of data from a case-control study of Campylobacter enteritis in England to assess the usefulness of a two-reminder strategy for control recruitment.

Methods

We compared sociodemographic characteristics of participants and non-participants, and calculated odds ratio estimates for a wide range of risk factors by mailing wave.

Results

Non-participants were more often male, younger and from more deprived areas. Among participants, early responders were more likely to be female, older and live in less deprived areas, but despite these differences, we found little evidence of a systematic bias in the results when using data from early reponders only.

Conclusions

We conclude that the main benefit of using reminders in our study was the gain in statistical power from a larger sample size.

A case-control study: occupational cooking and the risk of uveal melanoma

Background

A European-wide population based case-control study (European rare cancer study) undertaken in nine European countries examined risk factors for uveal melanoma. They found a positive association between cooks and the risk of uveal melanoma. In our study we examine whether cooks or people who worked in cook related jobs have an increased uveal melanoma risk.

Methods

We conducted a case-control study during 2002 and 2005. Overall, 1653 eligible subjects (age range: 20-74 years, living in Germany) participated. Interviews were conducted with 459 incident uveal melanoma cases, 827 population controls, 180 ophthalmologist controls and 187 sibling controls. Data on occupational exposure were obtained from a self-administered postal questionnaire and a computer-assisted telephone interview. We used conditional logistic regression to estimate odds ratios adjusting for the matching factors.

Results

Overall, we did not observe an increased risk of uveal melanoma among people who worked as cooks or who worked in cook related jobs. When we restricted the source population of our study to the population of the Federal State of Northrhine-Westphalia, we observed an increased risk among subjects who were categorized as cooks in the cases-control analysis.

Conclusion

Our results are in conflict with former results of the European rare cancer study. Considering the rarity of the disease laboratory in vitro studies of human uveal melanoma cell lines should be done to analyze potential exposure risk factors like radiation from microwaves, strong light from incandescent ovens, or infrared radiation.

The effect of health, socio-economic position, and mode of data collection on non-response in health interview surveys

Aims: To investigate the relationship between potential explanatory factors (socio-economic factors and health) and non-response in two general population health interview surveys (face-to-face and telephone), and to compare the effects of the two interview modes on non-response patterns. Methods: Data derives from The Danish Health Interview Survey 2000 (face-to-face interview) and The Funen County Health Survey 2000/2001 (telephone interview). Data on all invited individuals were obtained from administrative registers and linked to survey data at individual level. Multiple logistic regression analyses were used to examine associations between potential explanatory factors and non-response. Results: The overall response rate was higher in the face-to-face interview survey (74.5%) than in the telephone survey (69.2%). Refusal was the most common reason for non-response and the same factors were generally associated with non-response in both modes of interview. The non-response rate was high among persons with low socio-economic position. No significant associations between health and non-response were found. Conclusions: Health status does not play a systematic role for non-response rates in health interview surveys, but the non-response rate is higher in lower socio-economic groups. Analyses of non-response should be performed to understand the implications of survey findings.

Comparison of participants and non-participants to the ORISCAV-LUX population-based study on cardiovascular risk factors in Luxembourg

Background

Poor response is a major concern in public health surveys. In a population-based ORISCAV-LUX study carried out in Grand-Duchy of Luxembourg to assess the cardiovascular risk factors, the non-response rate was not negligible. The aims of the present work were: 1) to investigate the representativeness of study sample to the general population, and 2) to compare the known demographic and cardiovascular health-related profiles of participants and non-participants.

Methods

For sample representativeness, the participants were compared to the source population according to stratification criteria (age, sex and district of residence). Based on complementary information from the "medical administrative database", further analysis was carried out to assess whether the health status affected the response rate. Several demographic and morbidity indicators were used in the univariate comparison between participants and non-participants.

Results

Among the 4452 potentially eligible subjects contacted for the study, there were finally 1432 (32.2%) participants. Compared to the source population, no differences were found for gender and district distribution. By contrast, the youngest age group was under-represented while adults and elderly were over-represented in the sample, for both genders. Globally, the investigated clinical profile of the non-participants was similar to that of participants. Hospital admission and cardiovascular health-related medical measures were comparable in both groups even after controlling for age. The participation rate was lower in Portuguese residents as compared to Luxembourgish (OR = 0.58, 95% CI: 0.48-0.69). It was also significantly associated with the professional status (P < 0.0001). Subjects from the working class were less receptive to the study than those from other professional categories.

Conclusion

The 32.2% participation rate obtained in the ORISCAV-LUX survey represents the realistic achievable rate for this type of multiple-stage, nationwide, population-based surveys. It corresponds to the expected rate upon which the sample size was calculated. Given the absence of discriminating health profiles between participants and non-participants, it can be concluded that the response rate does not invalidate the results and allows generalizing the findings for the population.

Predictors of nonresponse in a questionnaire-based outcome study of vocational rehabilitation patients

OBJECTIVE

To identify predictors of nonresponse to a self-report study of patients with orthopedic trauma hospitalized for vocational rehabilitation between November 15, 2003, and December 31, 2005. The role of biopsychosocial complexity, assessed using the INTERMED, was of particular interest.

DESIGN

Cohort study. Questionnaires with quality of life, sociodemographic, and job-related questions were given to patients at hospitalization and 1 year after discharge. Sociodemographic data, biopsychosocial complexity, and presence of comorbidity were available at hospitalization (baseline) for all eligible patients. Logistic regression models were used to test a number of baseline variables as potential predictors of nonresponse to the questionnaires at each of the 2 time points.

SETTING

Rehabilitation clinic.

PARTICIPANTS

Patients (N=990) hospitalized for vocational rehabilitation over a period of 2 years.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURE

Nonresponse to the questionnaires was the binary dependent variable.

RESULTS

Patients with high biopsychosocial complexity, foreign native language, or low educational level were less likely to respond at both time points. Younger patients were less likely to respond at 1 year. Those living in a stable partnership were less likely than singles to respond at hospitalization. Sex, psychiatric, and somatic comorbidity and alcoholism were never associated with nonresponse.

CONCLUSIONS

We stress the importance of assessing biopsychosocial complexity to predict nonresponse. Furthermore, the factors we found to be predictive of nonresponse are also known to influence treatment outcome and vocational rehabilitation. Therefore, it is important to increase the response rate of the groups of concern in order to reduce selection bias in epidemiologic investigations.

The study design and characteristics of the Danish national health interview surveys

AIMS

The Danish National Institute of Public Health, University of Southern Denmark has carried out national representative health interview surveys among adult Danes in 1987, 1994, 2000 and 2005. The aim of this study is to describe the characteristics of the design, including the response rates of the four surveys.

METHODS

The samples in 1987 and 1994 are based on simple random sampling. The samples in 2000 and 2005 are based on stratified random sampling. In addition, all invited to the survey in 1994 were re-invited in both 2000 and 2005. Data were collected via face-to-face interview at the respondent's home. Following the interview in 1994, 2000 and 2005, all respondents were asked to complete a self-administered questionnaire.

RESULTS

The response rate for the face-to-face interview fell from 79.9% in 1987 to 66.7% in 2005 and the response rate for the self-administered questionnaire from 68.1% in 1994 to 51.5% in 2005. The decrease is particularly marked among the young. The mean interview length has increased from 33.3 minutes in 1987 to 50.2 minutes in 2005.

CONCLUSIONS

The declining response rate in the surveys is a major concern and can pose problems in generalizing data from the surveys to the Danish population. However, these surveys are essential, as the information collected cannot be gathered by means of official statistical registers. Hence, efforts to increase the response rate will be important in the forthcoming surveys.

Psychological distress, depression and generalised anxiety in Turkish and Moroccan immigrants in Belgium: a general population study

BACKGROUND

This study assesses the prevalence of and risk and protective factors for common mental health complaints in a general population sample of Turkish and Moroccan immigrants living in Belgium. Focus is on between- and within-group variation.

METHODS

The study is based on pooled data from the Belgian Health Interview Surveys 2001 and 2004 and focuses on the Turkish and Moroccan immigrant population aged 18-65 (N = 147 Turks, N = 359 Moroccans). Mental health status is assessed with the General Health Questionnaire-12 and the Symptom Checklist 90-R subscales for depression and generalised anxiety. Risk and protective factors considered are gender, age, household type, labor market position, educational level, household income, homeownership, being foreign- or native born and social support.

RESULTS

Between-group variance was not significant. Within-group analysis showed significant effects of gender and social support. Although not significant, the results suggested positive associations between social adversity and mood status. In addition, there was a tendency for higher risks for psychological distress, depression and generalised anxiety in foreign-born as compared to Belgian-born Turkish and Moroccan immigrants.

The German case-control scene investigation study on SIDS: epidemiological approach and main results

The present study, which was part of the German SIDS Study (GeSID), enrolled sudden infant death syndrome (SIDS) cases and population controls and obtained objective scene data via specifically trained observers shortly after discovery of each dead infant. Infants who had died suddenly and unexpectedly at ages between 8 and 365 days were enrolled in five regions of Germany between November 1998 and October 2001. Shortly after discovery of each dead infant, a specially trained doctor of legal medicine visited the bereaved family at home. Data were obtained by measurements and observations. Dead infants underwent a standardised autopsy, additional information being obtained by standardised parent interviews. Investigation of the sleep environment and wake-up scene in matched controls followed the same protocol. A total of 52 SIDS cases and 154 controls were enrolled, 58% were boys, and median age of cases vs. controls was 126 vs. 129 days. Risk factors in the sleeping environment were pillow use (adjusted OR 4.3; 95%CI 1.6-11.6), heavy duvets (OR 4.4; 1.5-13.3), soft underlay (OR 3.0; 1.1-8.7), face covered by bedding (OR 15.8; 2.5-102.1) and entire body covered by bedding (OR 35.5; 5.5-228.3). Using a standardised protocol, including objective measurements of the sleep environment and a case-control design, this study was able to confirm many risk factors for SIDS.

Associations between dietary factors and pancreatitis in dogs

OBJECTIVE

To estimate associations between dietary factors and pancreatitis in dogs. Design-Retrospective case-control study.

ANIMALS

198 dogs with a clinical diagnosis of pancreatitis and 187 control dogs with a diagnosis of renal failure without clinical evidence of pancreatitis.

PROCEDURES

Information on signalment, weight, body condition, dietary intake, medical history, diagnostic tests performed, concurrent diseases, treatments, duration of hospitalization, and discharge status was extracted from medical records. Information on dietary intake, signalment, weight, and medical, surgical, and environmental history was collected through a telephone questionnaire. Logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals.

RESULTS

On the basis of information extracted from the medical record, ingesting unusual food items (OR, 4.3) increased the odds of pancreatitis. On the basis of information gathered through the telephone questionnaire, ingesting unusual food items (OR, 6.1), ingesting table scraps the week before diagnosis (OR, 2.2) or throughout life (OR, 2.2), and getting into the trash (OR, 13.2) increased the odds of pancreatitis. Multivariable modeling indicated that reporting exposure to > or = 1 dietary factor during the telephone questionnaire (OR, 2.6), being overweight (OR, 1.3) or neutered (OR, 3.6), previous surgery other than neutering (OR, 21.1), and the interaction between neuter status and previous surgery other than neutering (OR, 0.1) were associated with the odds of pancreatitis.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that dietary factors, being neutered, and previous surgery other than neutering increased the odds of pancreatitis in dogs.

Extended recruitment efforts minimize attrition but not necessarily bias

OBJECTIVES

There has been a debate about the effect of extended recruitment efforts on attrition and bias. The aims of the present study are (1) to investigate the effectiveness of extensive multimode recruitment procedures; (2) to study their effect on attrition and bias; and (3) to determine the potential predictors of attrition.

STUDY DESIGN AND SETTING

We used data from the longitudinal population-based study of health in Pomerania.

RESULTS

Using multimode recruitment methods, we reached a follow-up response proportion of 83.6%. In-person contacts at home turned out to be an effective recruitment tool. Sociodemographic and health characteristics of late respondents and converted nonrespondents were most distinct from early respondents but not necessarily indicative of nonrespondents. Analyzing attrition bias, extended recruitment efforts produced an effect only for sociodemographic characteristics but not for health-related indicators. The strongest predictors for attrition from the regression model were late recruitment at baseline, unemployment, low educational level, female sex, and smoking habit.

CONCLUSION

Extended recruitment efforts appeared justified in terms of response maximization. However, enhanced response proportions may not necessarily minimize bias. In our analysis, aiming for a high-response proportion in terms of health-related indicators had no effect, because late respondents did not differ from early respondents.

Veterinary student and veterinarian attitudes toward veterinary public health and epidemiology

OBJECTIVE

To identify predictors of veterinary students and veterinarians having an interest in veterinary public health and epidemiology (PH&E).

DESIGN

Cross-sectional study.

SAMPLE POPULATION

Veterinary students enrolled in the College of Veterinary Medicine and Biomedical Sciences at Texas A&M University and veterinarians with membership in a Texas veterinary professional organization.

PROCEDURES

2 questionnaires were designed and administered to investigate hypothesized predictors of PH&E interests among veterinary students and veterinarians. Descriptive statistics were calculated for all variables from both questionnaires. Prevalence ratios, 95% confidence intervals, and chi(2) tests were used to evaluate bivariate associations between variables and an interest in PH&E. Multivariable logistic regression was used to adjust for the effects of multiple variables on the outcome.

RESULTS

70% (215/305) of students believed that a course in PH&E was necessary, and 46% (140/304) believed that more courses in PH&E would improve the veterinary curriculum. Ninety-nine percent (299/303) of veterinarians believed that a course in PH&E was necessary in the curriculum. Ninety-two percent (272/297) of veterinarians agreed that knowledge related to PH&E was important to perform the functions of their job. History of raising animals and membership in 4-H or Future Farmers of America were significant predictors of veterinary students having an interest in PH&E. Being male and growing up in a rural environment were not significant predictors.

CONCLUSIONS AND CLINICAL RELEVANCE

Most veterinary students and veterinarians agreed that knowledge of PH&E is important. Variables identified as associated with an interest in PH&E may be useful for designing mitigation strategies to increase the number of veterinarians entering public health careers.

Does response bias influence population studies of thyroid disorders?

BACKGROUND

Monitoring of iodine fortification programs is required for early recognition of oversupply or ineffective supply with iodine. We investigated the potential role of selection bias for studies performed to monitor the iodine supply and prevalence of thyroid disorders.

METHODS

We used the baseline population of 3949 subjects recruited for the Study of Health in Pomerania as a hypothesized source population and associated the information on response behavior from the 5-year follow-up examinations with baseline sociodemographic and thyroid-related characteristics. Due to nonresponse, 649 subjects were lost. The 3300 follow-up respondents were divided into early and late respondents according to their recruitment level.

RESULTS

We found no significant bias in the prevalence estimates of thyroid-related variables in the comparison between all respondents, and the source population after response maximization techniques had been applied. Prevalence estimates of thyroid-related characteristics (prior thyroid disorders, goiter, thyroid nodules, low serum thyrotropin, as well as increased and positive antithyroperoxidase [TPO] levels), however, were biased if we would have only investigated subjects who agreed to participate in our study after first invitation. When analyses were adjusted for sociodemographic variables, differences between early and late respondents were only statistically significant for positive anti-TPO levels.

CONCLUSIONS

We conclude that selection bias likely influences prevalence data for some studies of thyroid epidemiology. This could be diminished by making invitation procedures more rigorous.