A population comparison of participants and nonparticipants in a health survey

Prädiktoren der Teilnahmebereitschaft von Jugendlichen in Langzeitstudien: Ergebnisse der Ohrkan Kohortenstudie zur Freizeitlärmexposition

Hintergrund und Ziel In Kohortenstudien kann der Verlust von Teilnehmern während der Nachbeobachtungsphasen zu Verzerrungen führen, wenn sich Teilnehmer und Nichtteilnehmer unterscheiden. Viele Studien haben den Einfluss soziodemografischer und gesundheitlicher Faktoren auf die Teilnahmebereitschaft untersucht, es liegen jedoch nur relativ wenige Studien für schulbasierte Kohorten vor. Ziel dieser Arbeit ist die Bestimmung von Prädiktoren der Teilnahmebereitschaft im Rahmen der Ohrkan Kohortenstudie, die die Exposition von Jugendlichen gegenüber Freizeitlärm und mögliche Effekte auf das Hörvermögen im Zeitverlauf untersucht.

Methoden Die Daten dieser Studie basieren auf den Angaben der Ohrkankohorte (n=2148), die 2009–2011 (O-I) unter den Neuntklässlern weiterführender Schulen in Regensburg rekrutiert und 2012–14 (O-II) und 2015–16 (O-III) nachbefragt wurde.

Ergebnisse Die Teilnahmewahrscheinlichkeit in O-II und O-III war höher für Personen ohne Migrationshintergrund, die zu Studienbeginn das Gymnasium besuchten und deren Eltern ein höheres Bildungsniveau hatten oder zusammenlebten. Auch nahmen Personen, die in den letzten 2,5 Jahren ihren Wohnort nicht gewechselt hatten, 3-mal so häufig teil wie Befragte mit Wohnortwechsel.

Schlussfolgerung Die Kenntnis von Merkmalen der Studienteilnehmer, die die Teilnahmebereitschaft vorhersagen, ermöglicht durch gezielte Ansprache den Verlust von Studienteilnehmern zu reduzieren bzw. die statistische Korrektur von fehlenden Daten.

Challenges and benefits of integrating diverse sampling strategies in the observation of cardiovascular risk factors (ORISCAV-LUX 2) study

Background

It is challenging to manage data collection as planned and creation of opportunities to adapt during the course of enrolment may be needed. This paper aims to summarize the different sampling strategies adopted in the second wave of Observation of Cardiovascular Risk Factors (ORISCAV-LUX, 2016–17), with a focus on population coverage and sample representativeness.

Methods

Data from the first nationwide cross-sectional, population-based ORISCAV-LUX survey, 2007–08 and from the newly complementary sample recruited via different pathways, nine years later were analysed. First, we compare the socio-demographic characteristics and health profiles between baseline participants and non-participants to the second wave. Then, we describe the distribution of subjects across different strategy-specific samples and performed a comparison of the overall ORISCAV-LUX2 sample to the national population according to stratification criteria.

Results

For the baseline sample (1209 subjects), the participants (660) were younger than the non-participants (549), with a significant difference in average ages (44 vs 45.8 years; P = 0.019). There was a significant difference in terms of education level (P < 0.0001), 218 (33%) participants having university qualification vs. 95 (18%) non-participants. The participants seemed having better health perception (p < 0.0001); 455 (70.3%) self-reported good or very good health perception compared to 312 (58.2%) non-participants. The prevalence of obesity (P < 0.0001), hypertension (P < 0.0001), diabetes (P = 0.007), and mean values of related biomarkers were significantly higher among the non-participants. The overall sample (1558 participants) was mainly composed of randomly selected subjects, including 660 from the baseline sample and 455 from other health examination survey sample and 269 from civil registry sample (constituting in total 88.8%), against only 174 volunteers (11.2%), with significantly different characteristics and health status. The ORISCAV-LUX2 sample was representative of national population for geographical district, but not for sex and age; the younger (25–34 years) and older (65–79 years) being underrepresented, whereas middle-aged adults being over-represented, with significant sex-specific difference (p < 0.0001).

Conclusion

This study represents a careful first-stage analysis of the ORISCAV-LUX2 sample, based on available information on participants and non-participants. The ORISCAV-LUX datasets represents a relevant tool for epidemiological research and a basis for health monitoring and evidence-based prevention of cardiometabolic risk in Luxembourg.

Electronic supplementary material

The online version of this article (10.1186/s12874-019-0669-0) contains supplementary material, which is available to authorized users.

Evaluation of a digital health resource providing physiotherapy information for postnatal women in a tertiary public hospital in Australia

BACKGROUND

Pregnancy and childbirth have a profound and lasting effect on the female body. Reduced length of postnatal hospital stay has impacted the ability of physiotherapy staff to provide early intervention and education on postnatal recovery and rehabilitation. A novel method of providing physiotherapy education to postnatal women was implemented in an attempt to meet consumer needs in the changing hospital environment. A digital health resource was developed and evaluated to determine consumer satisfaction and access.

METHODS

Postnatal women admitted to the postnatal ward were invited to participate in a survey of the digital health resource during a 17-day recruitment period. A participant information sheet was provided to the patient and a signed consent form collected from those willing to participate. Online surveys were emailed to women at approximately 2 weeks postnatal and a thematic analysis of the responses was completed.

RESULTS

A total of 88 women were recruited to the study during a 17-day recruitment period with a 30% response rate (n=27) to an online survey sent at approximately 2 weeks postpartum. Of the 27 respondents, 33% had watched the digital health resource and were able to provide feedback on resource content, format and length, as well as enablers and barriers to access and viewing habits. Survey responses indicated the resource was viewed only after discharge from hospital and most commonly on a mobile device. Most women engaged with the resource to learn more about their own recovery, and all women found the advice on pelvic floor exercise useful. Lack of time was the most commonly reported barrier to viewing the digital health resource.

CONCLUSIONS

This quality assurance project demonstrated the existing digital health resource provides useful information to women following discharge from the postnatal ward but strategies to improve awareness of the resource should be investigated further.

Health checkup behavior and individual health beliefs in older adults

AIM

Despite Japan being a developed nation, half of its older population does not attend regular health checkups. The aim of the present study was to examine the individual health beliefs and personal recommendations that strongly influence health checkup attendance among community-dwelling older adults.

METHODS

In 2013, questionnaires were sent to 5401 community-dwelling older adults who were not receiving long-term institutionalized care. The response rate was 94.3%. We analyzed response data from 4984 older adults using multiple imputation to manage missing data. Participation in health checkups was defined as having undergone at least one checkup in the past 3 years, and non-participation as having attended no checkups in this period.

RESULTS

The participants' mean age was 75.8 years, and 57.9% were women. The adjusted odds ratio of health checkup participation ranged from 1.35 (95% confidence interval [CI] 1.13-1.61) to 1.62 (95% CI 1.34-1.95) for positive individual health beliefs about health checkups, and was 2.21 (95% CI: 1.51-3.24) and 1.28 (95% CI: 1.17-2.08) for recommendations to participate from family and neighbors, respectively. All odds ratios were adjusted for age, sex, driving by oneself to daily shopping or clinic, paid work, method of response, internal medical therapy, polypharmacy, serious disease, periodic blood test, frailty and neighborly relationships.

CONCLUSIONS

The present findings suggest that both individual and community approaches might be effective in promoting participation in health checkups among community-dwelling older adults. Geriatr Gerontol Int 2018; 18: 338-351.

Active and passive exposure to tobacco smoke in relation to insulin sensitivity and pancreatic β-cell function in Japanese subjects

AIM

Several studies have suggested that cigarette-smoking affects insulin sensitivity in Western populations. The present study evaluated glucose tolerance, pancreatic β-cell function and insulin sensitivity in relation to active and passive smoking among the Japanese.

METHODS

A total of 411 men and 586 women were recruited into a community-based cross-sectional study in Gifu, Japan. Diabetes, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) were screened for by a 75g oral glucose tolerance test. HOMA and insulinogenic (ΔI0-30/ΔG0-30) indexes were used to estimate insulin secretion and sensitivity. To assess the possible association of self-reported smoking status and parameters of glucose metabolism, logistic regression was applied after adjusting for potential confounders.

RESULTS

Currently smoking women were more likely to have diabetes, IGT or IFG compared with never-smoking women (OR: 2.26, 95% CI: 1.05-4.84). Heavy-smoking men (≥25 cigarettes/day) were likely to be in the lowest tertile group of ΔI0-30/ΔG0-30 compared with never-smoking men (OR: 2.64, 95% CI: 1.05-6.68, Ptrend=0.04). The number of cigarettes/day was borderline significantly associated with diabetes in men. Also with borderline significance, never-smoking women with smoking husbands were more likely to have diabetes, IGT or IFG (OR: 1.62, 95% CI: 1.00-2.62) and significantly more likely to have lower HOMA-β (OR: 2.17, 95% CI: 1.36-3.48) than those without smoking husbands.

CONCLUSION

The greater the number of cigarettes smoked per day appears to be associated with diabetes among men whereas, among women, both active and passive smoking appear to be associated with diabetic states, including IGT and IFG. An association between smoking status and insulin secretion is also suggested, whereas no significant association was observed with HOMA-IR in this Japanese subjects, suggesting that the influence of smoking on glucose metabolism may differ among races.

Heritability of objectively assessed daily physical activity and sedentary behavior

BACKGROUND

Twin and family studies that estimated the heritability of daily physical activity have been limited by poor measurement quality and a small sample size.

OBJECTIVE

We examined the heritability of daily physical activity and sedentary behavior assessed objectively by using combined heart rate and movement sensing in a large twin study.

DESIGN

Physical activity traits were assessed in daily life for a mean (± SD) 6.7 ± 1.1 d in 1654 twins from 420 monozygotic and 352 dizygotic same-sex twin pairs aged 56.3 ± 10.4 y with body mass index (in kg/m(2)) of 26.1 ± 4.8. We estimated the average daily movement, physical activity energy expenditure, and time spent in moderate-to-vigorous intensity physical activity and sedentary behavior from heart rate and acceleration data. We used structural equation modeling to examine the contribution of additive genetic, shared environmental, and unique environmental factors to between-individual variation in traits.

RESULTS

Additive genetic factors (ie, heritability) explained 47% of the variance in physical activity energy expenditure (95% CI: 23%, 53%) and time spent in moderate-to-vigorous intensity physical activity (95% CI: 29%, 54%), 35% of the variance in acceleration of the trunk (95% CI: 0%, 44%), and 31% of the variance in the time spent in sedentary behavior (95% CI: 9%, 51%). The remaining variance was predominantly explained by unique environmental factors and random error, whereas shared environmental factors played only a marginal role for all traits with a range of 0-15%.

CONCLUSIONS

The between-individual variation in daily physical activity and sedentary behavior is mainly a result of environmental influences. Nevertheless, genetic factors explain up to one-half of the variance, suggesting that innate biological processes may be driving some of our daily physical activity.

Programmatic influences on outcomes of an evidence-based fall prevention program for older adults: a translational assessment

Investigating the implementation and dissemination of evidence-based health-promotion programs to reach large numbers of diverse older adults is needed. The purpose of this study is to examine relationships between class size and session attendance and assess differences in intervention outcomes based on these community-based fall prevention program characteristics. Pre-post data were analyzed from 2,056 falls prevention program participants. PROC MIXED for repeated measures and ordinary least squares regressions were employed. Approximately 32% of participants enrolled in recommended class sizes (eight to 12 participants) and 76.4% of enrolled seniors attended more than five of eight sessions. Enrolling in smaller class sizes was associated with higher class attendance (X (2) = 43.43, p < 0.001). Recommended class sizes and those with 13-20 participants reported significant improvements in falls efficacy and physical activity. Perfect attendance was associated with improvements in falls efficacy (t = 2.52, p < 0.05) and activity limitation (t = -2.66, p < 0.01). Findings can inform fall prevention program developers and lay leader deliverers about ideal class sizes relative to maximum intervention benefits and cost efficiency.

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.

Factors influencing participation rate in a baseline survey of a genetic cohort in Japan

BACKGROUND

Although many studies have examined factors that influence the response to postal questionnaires, few have addressed baseline recruitment for cohort studies involving genetic analyses. The aim of this study was to describe the method used for a baseline survey, the Japan Multi-institutional Collaborative Cohort Study (J-MICC Study), in Saga Prefecture, and to examine the factors that might influence the recruitment of participants in such studies.

METHODS

The Saga J-MICC Study is an ongoing population-based prospective cohort study of the genetic and environmental interactions associated with lifestyle-related disease. From 2005 through 2007, a total of 61 447 residents between the ages of 40 and 69 were invited by mail to participate in this study. The survey date and time were arranged by telephone.

RESULTS

Among that population, 31 002 (50.5%) responded and 12 078 (19.7%) agreed to participate. A completed questionnaire and blood pressure and anthropometric data were collected from all participants; blood, DNA specimens, and accelerometer measures were obtained from the great majority of them. Female sex and older age were associated with a higher participation rate. In addition, the convenience of the survey location and the sending of a reminder significantly improved the participation rate (odds ratio, 1.3).

CONCLUSIONS

Our findings suggest that making the survey location as convenient as possible and sending a reminder can both substantially improve participation rate in population-based studies.

How many mailouts? Could attempts to increase the response rate in the Iraq war cohort study be counterproductive?

Background

Low response and reporting errors are major concerns for survey epidemiologists. However, while nonresponse is commonly investigated, the effects of misclassification are often ignored, possibly because they are hard to quantify. We investigate both sources of bias in a recent study of the effects of deployment to the 2003 Iraq war on the health of UK military personnel, and attempt to determine whether improving response rates by multiple mailouts was associated with increased misclassification error and hence increased bias in the results.

Methods

Data for 17,162 UK military personnel were used to determine factors related to response and inverse probability weights were used to assess nonresponse bias. The percentages of inconsistent and missing answers to health questions from the 10,234 responders were used as measures of misclassification in a simulation of the 'true' relative risks that would have been observed if misclassification had not been present. Simulated and observed relative risks of multiple physical symptoms and post-traumatic stress disorder (PTSD) were compared across response waves (number of contact attempts).

Results

Age, rank, gender, ethnic group, enlistment type (regular/reservist) and contact address (military or civilian), but not fitness, were significantly related to response. Weighting for nonresponse had little effect on the relative risks. Of the respondents, 88% had responded by wave 2. Missing answers (total 3%) increased significantly (p < 0.001) between waves 1 and 4 from 2.4% to 7.3%, and the percentage with discrepant answers (total 14%) increased from 12.8% to 16.3% (p = 0.007). However, the adjusted relative risks decreased only slightly from 1.24 to 1.22 for multiple physical symptoms and from 1.12 to 1.09 for PTSD, and showed a similar pattern to those simulated.

Conclusion

Bias due to nonresponse appears to be small in this study, and increasing the response rates had little effect on the results. Although misclassification is difficult to assess, the results suggest that bias due to reporting errors could be greater than bias caused by nonresponse. Resources might be better spent on improving and validating the data, rather than on increasing the response rate.

Beta-blocker use and risk of fractures in men and women from the general population: the MONICA/KORA Augsburg cohort study

Use of beta-blockers is associated with a reduced risk of fractures in middle-aged and older subjects from the general population.

INTRODUCTION

The present prospective population-based study investigated the association between use of beta-blockers and incidence of any fracture.

METHODS

The study was based on 1,793 persons 55 to 74 years of age who participated in one of the three MONICA Augsburg surveys between 1984 and 1995. Subjects were without any fracture at baseline. Incident fractures were assessed using a health questionnaire. Hazard ratios (HRs) were estimated from Cox proportional hazard models.

RESULTS

During a mean follow-up of 10.7 years, there occurred 263 incident fractures. beta-blocker users were older, were significantly more likely to be obese, to drink no alcohol, to have hypertension or diabetes, to use thiazides and statins, and to be physically inactive. The use of beta-blockers was associated with a lower risk of any fracture (HR 0.57; 95% CI = 0.36-0.90) after adjustment for age, sex and survey. Further adjustment for body mass index and education years only slightly attenuated the relationship (HR 0.60; 95% CI = 0.38-0.95) and additional adjustment for a variety of further risk factors did not attenuate the association (HR 0.60; 95% CI = 0.37-0.96).

CONCLUSION

Use of beta-blockers was associated with a reduced risk of fractures in middle-aged and older subjects from the general population.

Non-participation and mortality in different socioeconomic groups: the FINRISK population surveys in 1972-92

BACKGROUND

Declining response rates pose a serious threat to the validity of estimates derived from epidemiological studies. If respondents and non-respondents differ systematically from each other, there can be a bias in the results of the study. A population-based cohort study was conducted to investigate disparities in socioeconomic structure between respondents and non-respondents and the contribution of these disparities to socioeconomic differences in total and cardiovascular mortality.

DESIGN

Data comprised 32,354 male and female participants and 4890 non-participants aged 35-74 years who belonged to the sample in one of the five FINRISK surveys in 1972, 1977, 1982, 1987 or 1992 in Finland. They were followed up for 9 years and 6 months.

RESULTS

It was found that the lower socioeconomic groups were over-represented among non-respondents both in men and women. When comparing the relative risk of death using the highest socioeconomic group of the participants as the reference group, it was found that although the socioeconomic gradient was similar for participants and non-participants-that is, lower groups had a higher risk of death-the risk was at a higher level among non-respondents.

CONCLUSIONS

Basing analysis on participants does not distort the relative risk of death associated with socioeconomic position. However, it does underestimate the absolute risk.

Participants Who Left a Multiple-Wave Cohort Study Had Similar Baseline Characteristics to Participants Who Returned

PURPOSE

Research on determinants of an individual's pattern of response, considered as a profile across time, for cohort studies with multiple waves is limited. In this prospective population-based pregnancy cohort, we investigated baseline characteristics of participants after partitioning them according to their history of response to different interview waves.

METHODS

Data are from the Mater-University of Queensland Study of Pregnancy 1981 to 1983 cohort, Brisbane, Australia. Complete baseline information was collected for 7223 of 7535 eligible individuals (95.9%). Follow-up occurred at 6 months, 5 years, and 14 years. Response rates were 93.0%, 72.5%, and 71.8%. Participants were allowed to leave and reenter the study. Participants were categorized as always, intermittent, or never responders. Intermittent responders were categorized further as leavers (responded at least once before leaving the study) or returners (left the study before reentering).

RESULTS

Participants who always responded were older, more educated, married, Caucasian, and nonsmokers and had higher incomes. Intermittent responders shared similar baseline characteristics. Relative risk for being an intermittent responder was located between risks for always or never responding.

CONCLUSIONS

Participants who left and reentered the study had baseline characteristics similar to participants who responded at least once and then left the study.

Nonresponse error in injury-risk surveys

BACKGROUND

Nonresponse is a potentially serious source of error in epidemiologic surveys concerned with injury control and risk. This study presents the findings of a records-matching approach to investigating the degree to which survey nonresponse may bias indicators of violence-related and unintentional injuries in a random-digit-dialed (RDD) telephone survey.

METHODS

Data from a statewide RDD survey of 4155 individuals aged 16 years and older conducted in Illinois in 2003 were merged with ZIP code-level data from the 2000 Census. Using hierarchical linear models, ZIP code-level indicators were used to predict survey response propensity at the individual level. Additional models used the same ZIP code measures to predict a set of injury-risk indicators.

RESULTS

Several ZIP code measures were found to be predictive of both response propensity and the likelihood of reporting partner violence. For example, people residing in high-income areas were less likely to participate in the survey and less likely to report forced sex by partner, processes that suggest an over-estimation of this form of violence. In contrast, estimates of partner isolation may be under-estimated, as those residing in geographic areas with smaller-sized housing were less likely to participate in the survey but more likely to report partner isolation. No ZIP code-level correlates of survey response propensity, however, were found also to be associated with driving-under-the-influence (DUI) indicators.

CONCLUSIONS

There is evidence of a linkage between survey response propensity and one variety of injury prevention measure (partner violence) but not another (DUI). The approach described in this paper provides an effective and inexpensive tool for evaluating nonresponse error in surveys of injury prevention and other health-related conditions.

Non-response in a survey of cardiovascular risk factors in the Dutch population: determinants and resulting biases

BACKGROUND

The aim of the research was to study the determinants of participation in a health examination survey (HES) which was carried out in a population that previously participated in a health interview survey (HIS) of Statistics Netherlands, and to estimate the effect of non-participation on both the prevalence of the main HES outcomes (risk factors for cardiovascular disease) and on relationships between variables.

METHODS

Logistic regression was used to study the determinants of participation in the HES (n=3699) by those who had previously participated in the HIS (n=12,786). Linear models were used to predict the main outcomes in non-participants of the HES. Item non-response was handled by multiple imputation.

RESULTS

HES participants had a higher socio-economic status and comprised more 'worried well', while the rural population were less likely to participate in the HES. Most predicted values of outcomes in HES non-participants differed from those in HES participants, but much of this was due to differences in the age and gender composition of both groups. Taking age and gender differences into account, most predicted values of outcomes in the entire HIS population were within the 95% confidence intervals of the HES values, with the exception of body height in men and high-density lipoprotein cholesterol, fasting glucose and body weight in women. These differences are most likely to be due to the higher socio-economic status of HES participants. Relationships between HIS variables did not change significantly when using HES participants alone compared with all HIS participants.

CONCLUSIONS

Despite a high rate of non-participation, some bias, mostly small, was seen in the prevalence rates of the main outcome variables. Bias in the relationships between variables was negligible.

Telephone Recruitment of a Random Stratified Youth Sample for a Physical Activity Study

It is important that studies on youth health behavior obtain sufficiently large representative samples so that power is adequate and results are generalizable. Few researchers, however, have documented procedures and methods for recruitment of a random stratified youth sample for studies on health-related behavior, specifically physical activity. This study describes the recruitment methods used to attain a stratified sample of 360 target youth (male and female from 10-, 12-, and 14-year old cohorts), and a parent of each child, representing families in 58 different neighborhoods. A peer of each target youth was also invited to participate. Recruitment was conducted primarily by telephone, using computer-assisted telephone interviewing (CATI) software. Approximately 38% of calls resulted in person contact, of which about 98% of families did not qualify. Of those qualified, about 68% agreed to participate. The telephone recruitment was supplemented by door-to-door recruitment in selected neighborhoods. The average cost of telephone recruitment was approximately $99 per family. Advantages and limitations of the recruitment method are discussed.

Public Health Surveillance of Low-Frequency Populations

Public health agencies often require data that address the needs of special populations, such as minority groups. Sources of surveillance data often contain insufficient numbers of subjects to fully inform health agencies. In this review, we address the problems of and potential approaches for situations with insufficient surveillance data. We use the examples of race and ethnic minority groups throughout our discussion. However, many of the broad issues are applicable to other special groups with low frequency or who are especially hard to reach. Our recommendations are based, in part, on a symposium held in Missouri with the collaboration of state health agency, community, and academic research participants. We review problems in using existing data and collecting new data, especially from nonprobability samples. We also describe fieldwork issues for reaching and collecting information from special populations. Decisions among methods and solutions may require seeking additional resources for surveillance.

Occupational mobility and risk factors in working men: selection, causality or both? Results from the GAZEL study

OBJECTIVE

To explore the relation between risk factors (RF) and occupational mobility in working men.

SETTING

20 000 volunteers working at the French National Electricity and Gas Company (GAZEL cohort).

PARTICIPANTS

Men aged 43 to 53 years in 1992.

DESIGN

Three designs were used for analysis. (1) The association between occupational mobility experienced before 1992 and RF reported at that date was analysed among 10 383 men. (2) The predictive role of RF on occupational mobility over 1992-1999 was studied in a subsample of 4715 men. (3) Reciprocally, occupational mobility in 1985-1992 was analysed in relation to RF changes over 1993-1999.

MAIN OUTCOME MEASURES

Self reported smoking status, excessive alcohol consumption, arterial hypertension, and overweight. Occupational mobility defined by any upward transition between senior executives and professionals/middle executives/employees, and workers.

RESULTS

(1) Cross sectionally, non-mobile men as their entry into the company had a higher risk of being smokers, excessive alcohol drinkers, and overweight in 1992 than mobile men. (2) Longitudinally, smokers and excessive alcohol drinkers in 1992 had a higher risk of non-mobility than, respectively, non-smokers and non-excessive alcohol drinkers. (3) Non-mobile men in 1985-1992 had a higher risk of becoming smokers, excessive alcohol drinkers, and hypertensive in 1993-1999 than upwardly mobile men.

CONCLUSION

These results suggest a complex relation between RF and occupational mobility. A high level of RF, particularly health behaviours, might account for a selection process reducing upward occupational mobility. In turn, a lack of upward occupational mobility might be associated with an increased incidence of RF.

Sampling procedure, participation rates and representativeness in the Swedish part of the European Youth Heart Study (EYHS)

OBJECTIVE

The European Youth Heart Study (EYHS) is a cross-sectional, school-based population study on risk factors for future cardiovascular disease in children, with an overall participation rate in Sweden of about 50%. To study the representativeness of the participants in the Swedish part of EYHS, a comprehensive non-participant follow-up study was carried out.

DESIGN

A structured multilevel analysis model was developed, addressing each level in the sampling procedure. The income, educational and occupational categories of the geographical regions of the study (level I), school catchment areas (level II) and parents (level III) were compared with official data. Participating and non-participating pupils (level IV) were compared through a questionnaire.

SETTING

Thirty-seven state schools in two regions of Central Sweden (Orebro and southern Stockholm) were visited during the school year 1998/1999.

SUBJECTS

Boys and girls aged 9 and 15 years were randomly sampled through a multiphase sampling procedure.

RESULTS

Data for socio-economic status for levels I and II corresponded well to national and regional official data. At level III, non-manually working parents were slightly over-represented among parents of participating children. At level IV, non-participating subjects corresponded in most respects to participants with a few exceptions--mainly more interest in physical exercise among participants.

CONCLUSIONS

Based on the knowledge from the non-participant study, we do not foresee problems regarding interpretation of the outcomes in the EYHS, despite the low participation rate.

High prevalence of undiagnosed diabetes mellitus in Southern Germany: target populations for efficient screening. The KORA survey 2000

AIMS/HYPOTHESIS

To estimate the prevalence of undiagnosed diabetes mellitus, impaired glucose tolerance (IGT) and impaired fasting glucose (IFG), and their relations with cardiovascular risk factors in the general population aged 55 to 74 years in Southern Germany.

METHODS

Oral glucose tolerance tests were carried out in a random sample of 1353 subjects aged 55 to 74 years participating in the KORA (Cooperative Health Research in the Region of Augsburg) Survey 2000. Prevalences of glucose tolerance categories (1999 WHO criteria) were adjusted for sample probabilities. The numbers needed to screen (NNTS) to identify one person with undiagnosed diabetes were estimated from age-adjusted logistic regression models.

RESULTS

Sample design-based prevalences of known and unknown diabetes, IGT, and IFG were 9.0%, 9.7%, 16.8%, 9.8% in men, and 7.9%, 6.9%, 16.0%, 4.5% in women, respectively. In both sexes, participants with undiagnosed diabetes had higher BMI, waist circumference, systolic blood pressure, triglycerides, uric acid, and lower HDL-cholesterol than normoglycaemic subjects. A combination of abdominal adiposity, hypertension, and parental diabetes in men resulted in a NNTS of 2.9 (95%CI: 2.0-4.6). In women, the combination of increased triglycerides, hypertension and parental diabetes history yielded a NNTS of 3.2 (95%CI: 2.2-5.1).

CONCLUSION/INTERPRETATION

About 40% of the population aged 55 to 74 years in the Augsburg region have disturbed glucose tolerance or diabetes. Half of the total cases with diabetes are undiagnosed. Cardiovascular risk factors worsen among glucose tolerance categories, indicating the need for screening and prevention. Screening for undiagnosed diabetes could be most efficient in individuals with abdominal adiposity (men), hypertriglyceridaemia (women), hypertension, and parental diabetes history.

Health and demographic characteristics of respondents in an Australian national sexuality survey: comparison with population norms

STUDY OBJECTIVE

To assess the representativeness of survey participants by systematically comparing volunteers in a national health and sexuality survey with the Australian population in terms of self reported health status (including the SF-36) and a wide range of demographic characteristics.

DESIGN

A cross sectional sample of Australian residents were compared with demographic data from the 1996 Australian census and health data from the 1995 National Health Survey.

SETTING

The Australian population.

PARTICIPANTS

A stratified random sample of adults aged 18-59 years drawn from the Australian electoral roll, a compulsory register of voters. Interviews were completed with 1784 people, representing 40% of those initially selected (58% of those for whom a valid telephone number could be located).

MAIN RESULTS

Participants were of similar age and sex to the national population. Consistent with prior research, respondents had higher socioeconomic status, more education, were more likely to be employed, and less likely to be immigrants. The prevalence estimates, means, and variances of self reported mental and physical health measures (for example, SF-36 subscales, women's health indicators, current smoking status) were similar to population norms.

CONCLUSIONS

These findings considerably strengthen inferences about the representativeness of data on health status from volunteer samples used in health and sexuality surveys.

Predictors of participation and attrition in a health promotion study involving psychiatric outpatients

Participant selection biases can reduce the generalizability of research findings and lead to misestimates of intervention effectiveness. The authors examined factors associated with study participation and attrition among psychiatric outpatients recruited for the initial phase of a health promotion trial. Medical records were reviewed to obtain HIV-risk and substance abuse data, as well as psychiatric and demographic characteristics of potential participants. Of 895 eligible outpatients, 67% (n = 601) consented to participate, among whom 69% (n = 415) completed all baseline appointments. Compared with nonconsenters, consenters were more likely to be at risk for drug problems and to receive care from clinics serving more impaired patients. Study completion was associated with older age, a psychiatric diagnosis other than adjustment disorder, and a recent sexually transmitted disease diagnosis. These findings suggest that patients who could most benefit from risk reduction interventions are more likely to participate.

Predictors of participation and attrition in a health promotion study involving psychiatric outpatients

Participant selection biases can reduce the generalizability of research findings and lead to misestimates of intervention effectiveness. The authors examined factors associated with study participation and attrition among psychiatric outpatients recruited for the initial phase of a health promotion trial. Medical records were reviewed to obtain HIV-risk and substance abuse data, as well as psychiatric and demographic characteristics of potential participants. Of 895 eligible outpatients, 67% (n = 601) consented to participate, among whom 69% (n = 415) completed all baseline appointments. Compared with nonconsenters, consenters were more likely to be at risk for drug problems and to receive care from clinics serving more impaired patients. Study completion was associated with older age, a psychiatric diagnosis other than adjustment disorder, and a recent sexually transmitted disease diagnosis. These findings suggest that patients who could most benefit from risk reduction interventions are more likely to participate.

Subgroups of refusers in a disability prevention trial in older adults: baseline and follow-up analysis

OBJECTIVES

This study explored differences between refusers and participants in a longitudinal study with extensive baseline and follow-up information.

METHODS

Results of a trial comparing 791 participants and 401 community-residing older adults who refused to participate in a study concerning preventive home visits were examined. Information was collected from interviews, insurance records, and government files.

RESULTS

Despite similarities in terms of age, sex, and self-perceived health at baseline, 3-year follow-up data indicated that refusers had a 1.58-fold higher risk of entering a nursing home than participants. There were additional differences between refusers and participants when refusers were categorized in 4 subgroups based on self-reported reason for refusal (too ill, too healthy, no interest, and other reasons).

CONCLUSIONS

Future studies should include follow-up data to allow comparisons between refusers and participants and should address the presence of multiple subgroups of refusers.

Comparison of cause-specific mortality between respondents and nonrespondents in a population-based prospective study: ten-year follow-up of JPHC Study Cohort I. Japan Public Health Center

To evaluate the magnitude and duration of the "healthy volunteer effect" (HVE) in a middle-aged general population in Japan, we followed 54,396 subjects (26,998 men, 27,398 women) of the JPHC Study Cohort I from 1990 through 1999, and compared cause-specific mortality between respondents (79%) and nonrespondents to a baseline questionnaire survey. Age and area-adjusted RRs of mortality were higher among nonrespondents for all causes (2.02, 95% CI = 1.83-2.24), all cancers (1.43, 1.20-1.71), all circulatory system diseases (2.26, 1.86-2.74), and cerebrovascular disease (2.73, 2.04-3.66) in men, and 1.63 (1.39-1.92), 1.22 (0.94-1.58), 1.53 (1.07-2.20), and 1.65 (1.02-2.65), respectively, in women. These effects were not observed for ischemic heart disease. RR elevation for cancer was observed only in the first 2 years of follow-up (4.14, 2.74-6.26 versus 1.14, 0.93-1.40 after 2 years), while that for cerebrovascular disease was relatively stable for the entire period. In conclusion, HVE differed according to the causes and length of follow-up.

Selection bias in Teratology Information Service pregnancy outcome studies

BACKGROUND

Pregnancy outcome studies conducted through Teratology Information Services (TIS) rely on volunteer subjects. If these subjects tend to have different risk profiles than the population from which they are drawn, the results of TIS studies may have limited generalizability.

METHODS

We selected all subjects who enrolled in the California Teratogen Information Service (CTIS) pregnancy outcome study for prenatal exposure to carbamazepine or valproic acid between 1990 and 1997 and who received prenatal care through Kaiser Permanente of Southern California (n = 13). We compared these subjects to Kaiser patients identified through the Maternal Serum Alpha Fetoprotein Program with exposure to carbamazepine or valproic acid but who had not enrolled in the CTIS project. The controls were matched by Kaiser location and pregnancy year using a 2:1 ratio (n = 26). Medical records were reviewed and the prevalence of 14 pregnancy risk factors was compared between the two groups.

RESULTS

There were no significant differences between the groups on any one risk factor; however, a notably higher proportion of women who did not enroll in the CTIS study used tobacco or had a positive family history of congenital anomalies.

CONCLUSIONS

Although the sample was small, and results may not apply to other exposures in different health care environments, these data provide some evidence that women who enroll in TIS pregnancy outcome studies do not have a substantially different pregnancy risk profile than women who do not. Efforts to address possible selection bias should be incorporated in future TIS study design.