Selection of elderly controls using random digit dialing.

The experience of identifying and soliciting elderly male controls, using a nonclustered random digit dialing procedure in a case-control study, is presented. For elderly controls (ages 65-84) 3.5 times more residential telephone numbers were required than for controls encompassing a much broader age range (ages 40-84). This is a function of the proportion of elderly in the population and their lower response to telephone identification. Elderly controls, age 70 and older, also had lower participation rates.     

Reliability of random digit dialing calls to enumerate an adult female population

Challenges to random digit dialing have been documented, but the reliability of random digit dialing outcomes from telephone number calling, household identification, and enumeration has never been addressed, despite its potential to bias population representativeness by affecting completeness of coverage. The authors explored interobserver reliability of calls to numbers generated by random digit dialing for a 1990-1996 population-based case-control study in San Francisco, California, area women, using data from a quality control effort in which 122 of 4,890 random digit dialing numbers were assigned to a second interviewer for recontacting within 4 months. The 34 numbers discrepant between the first and second calls did not differ from the 88 unchanged outcomes, and reliability was good (kappa = 0.65, 95% confidence interval: 0.55, 0.75). Eligibility (an adult woman in the household) was confirmed for nine of 11 eligible households. However, six of 29 households originally ineligible because of gender were eligible on recontact, and eligible residences rose from 24% to 39% between the two calls, although the two groups of eligible women did not differ in age or race. This underenumeration of women by random digit dialing confirms prior observations, although interviewer differences or changes in respondents or household composition between the first and second calls may have contributed. Recontact of gender-ineligible households may improve completeness of random digit dialing coverage for female populations.     

Feasibility of including cellular telephone numbers in random digit dialing for epidemiologic case-control studies

The usefulness of landline random digit dialing (RDD) in epidemiologic studies is threatened by the rapid increase in households with only cellular telephone service. This study assessed the feasibility of including cellular telephone numbers in RDD and differences between young adults with landline telephones and those with only cellular telephones. Between 2008 and 2009, a total of 9,023 cellular telephone numbers were called and 43.8% were successfully screened; 248 men and 249 women who resided in 3 Washington State counties, were 20-44 years of age, and used only cellular telephones were interviewed. They were compared with 332 men and 526 women with landline telephones interviewed as controls for 2 case-control studies conducted in parallel with cellular telephone interviewing. Cellular-only users were more likely to be college educated and less likely to have fathered/birthed a child than were their landline counterparts. Male cellular-only users were less likely to be obese and more likely to exercise, to be Hispanic, and to have lower incomes, while female cellular-only users were more likely to be single than landline respondents. Including cellular telephone numbers in RDD is feasible and should be incorporated into epidemiologic studies that rely on this method to ascertain subjects, although low screening rates could hamper the representativeness of such a sample.     

Evaluation of random digit dialing as a method of control selection in case-control studies.

Control groups selected by random digit dialing are frequently used in case-control studies. Concern about the potential for bias in these control groups has been expressed, primarily because of low response rates. This study compares the characteristics of a hypothetical control group consisting of 341 men and women aged 40-74 years, selected by random digit dialing and participating in an interview in 1990, with the characteristics of 15,563 men and women aged 40-74 years who participated in a privately conducted census in the same upstate New York county in 1989. For most measures, no differences were seen between the random digit dialing sample and the census population. However, the hypothetical control group was more likely to have had their cholesterol checked in the past 2 years and was somewhat more likely to have had other screening tests as well. In addition, the hypothetical control group was somewhat better educated. The results suggest that, at least in this setting, control groups selected by random digit dialing are representative of the general population in most respects; however, caution should be used when studying the relation between screening tests and disease occurrence by means of case-control studies using controls selected by random digit dialing.     

Sampling elderly in the community: a comparison of commercial telemarketing lists and random digit dialing techniques for assessing health behaviors and health status.

A study of health behaviors in four communities in the western United States in 1988 provided the opportunity to compare two methods of sampling elderly respondents for a telephone interview. The Polk telemarketing lists were used to identify 1,407 respondents aged 65 years and older in four communities, where 253 respondents in the same age group were also identified by the method of random digit dialing. Individuals identified from the Polk lists received a letter prior to the initial telephone contact. The overall response rate was 49.3% for random digit dialing and 57.3% for the Polk lists. On the average, the identification of one elderly respondent using the Polk lists required about 20-25% as much interviewer time per subject identified as was required by the random digit dialing method. The elderly identified by the Polk lists were significantly older than those identified by random digit dialing, and the proportions of the Polk sample who were married, white, or had an income of greater than $10,000 were slightly higher than those of the random digit dialing sample. Among 40 variables measuring various health behaviors, indicators of health status, and participation in health-related programs and classes, only three differed significantly between the two samples. The authors conclude that sampling from commercial telemarketing lists was an efficient method of identifying elderly respondents and that in these four communities, the estimates of health behaviors and health status were comparable with those obtained by random digit dialing techniques.     

Alternative strategies for selecting population controls: comparison of random digit dialing and targeted telephone calls

PURPOSE: This project was carried out to identify a valid framework for selecting controls to be used in a population-based case-control study of breast cancer, and to compare participation rates and characteristics between women contacted using a standard random digit dialing (RDD) strategy and those who were sent a letter of presentation prior to telephone contact (targeted telephone calls, TTC). METHODS: Twelve hundred women, ages 20-74, were sampled from the Department of Motor Vehicles (DMV) and Health Care Financing Administration (HCFA) records. Women for whom telephone numbers were obtained (N = 771) were randomly assigned to RDD or TTC. The respondents participated in a brief telephone interview. Odd ratios (OR) and their 95% confidence intervals (CI) were used to estimate differences in characteristics of the respondents between the two contact strategies. RESULTS: Telephone numbers were obtained for 79% of women aged > or = 55 years and for only 38% of women aged < 55 years. Interviews were obtained for 48% of women for whom we obtained telephone numbers, and for 77% of women for whom eligibility was confirmed via telephone contact. Participation of target women appeared to be higher for the TTC than the RDD group (42% vs. 35%, p = 0.054). Among respondents who were > or = 55 years old, those in the TTC group were 80% more likely (OR = 1.8, 95% CI: 0.9-3.4) to report a serious medical condition than women in the RDD group, 60% less likely (OR = 0.4, 95% CI: 0.2-1.0) to report having used oral contraceptives, and 80% less likely (OR = 0.2, 95% CI: 0.1-0.5) to report having had breast surgery. CONCLUSIONS: Characteristics of respondents differed according to method of contact. These differences, along with the sampling frame used, should be considered when interpreting findings of case-control studies.     

Secular trends in response rates for controls selected by random digit dialing in childhood cancer studies: a report from the Children's Oncology Group

Since the mid-1990s, epidemiologists have anecdotally reported difficulty in recruiting controls using random digit dialing (RDD), but few empirical data have been published. From 1982 to 2003, epidemiologists from the Children's Oncology Group conducted 17 case-control studies using RDD controls. Data for calculating RDD and field response rates were available from eight and 13 of these studies, respectively. Over the period of analysis, the contact rate declined 2.5% per year (95% confidence interval (CI): -3.4, -1.6; p = 0.001), from above 90% in the 1980s to 63-69% in the most recent studies. The response rate (the product of the contact and cooperation rates) showed a decline parallel to that of the contact rate (-2.4% per year, 95% CI: -3.2, -1.6; p < 0.001), from above 80% in the 1980s to 50-67% after the mid-1990s. Field response rates appeared to have declined modestly. The overall response rate (the product of the RDD response and field response rates) paralleled that of the RDD response rate and decreased 2.4% per year (95% CI: -2.7, -2.0; p < 0.001). The current low response rates for RDD indicate a substantial potential for selection bias and a need to seek alternative sources of controls.     

Recruitment of healthy participants for studies on risks for alcoholism: effectiveness of random digit dialling

AIMS: To compare the effectiveness of two strategies for recruiting healthy research volunteers. METHODS: Demographic characteristics and recruitment costs of participants who completed a laboratory study examining risk factors for alcoholism recruited through random digit dialling (N = 11) and community advertisements (N = 102) were compared. RESULTS: Advertisement yielded a more representative sample [76% Caucasian, less well educated (M = 15.2 years, SEM = 0.2; P < 0.05), more equally divided by family history of alcoholism (43% FH- and 57% FH+), and lower in SES (M = 42.8, SEM = 1.3; P < 0.05)] and was more cost effective (72 dollars vs 2272 dollars per participant) than random digit dialling. CONCLUSIONS: Findings are relevant to alcohol researchers trying to determine the recruitment strategy that will yield the most representative sample at the lowest cost.     

Smoking behavior among participants in the nurses' health study.

We analyzed smoking behavior of 91,651 married female nurses, aged 30-55 years in 1976. The prevalence of smoking was similar among all birth cohorts. The largest percentage increase in starting to smoke occurred between ages 15 and 25 years; by age 25, 50 per cent had started smoking. The cessation rate was lowest in earlier birth cohorts and among nurses starting to smoke at earlier ages. The cessation rate increased substantially between 1963-73 compared with the period 1948-58.     

Random digit dialing for control selection. A review and a caution on its use in studies of childhood cancer

Random digit dialing is an effective method for creating a probability sample of households for telephone interviews. Epidemiologists have successfully used the technique to select controls for population-based case-control studies. However, a modified version of random digit dialing used in some institution-based studies of childhood cancer etiology involves a selection process which is biased against children from families with closely spaced births. The author discusses alternative approaches to reducing this bias in control group selection.     

Referrals of participants in an urban WIC program to health and welfare services.

The Special Supplemental Food Program for Women, Infants, and Children (WIC) provides supplemental food, nutrition education, and referrals to available health and welfare services. Recipients are income-eligible pregnant and postpartum women, their infants, and their children who are younger than 5 years of age. Although studies have documented the nutritional benefits of the program, the extent to which WIC nutritionists help eligible women to obtain available health and welfare services, and the degree to which this referral activity promotes health, is largely unknown. The researchers examined the referral activity at one urban WIC clinic, but did not evaluate the outcomes. Of 1,850 persons seen, there were 762 referrals by WIC nutritionists for 597 persons at the Lawrence, MA, clinic during a 2-month period. Of the 597 persons, 494 (83 percent) were WIC participants and 103 (17 percent) were nonparticipants. The rate of referrals for WIC participants was 27 percent. Multiple referrals were common, with 127 people receiving more than one referral. WIC nutritionists at this site offered a variety of referrals to their clients. The majority of referrals (61.7 percent) were for supplemented food. Nonnutrition-related referrals were to medical and dental services (20.5 percent), developmental and educational services (12.5 percent), and social services (5.4 percent). Nonnutrition-related referrals for women included referrals for family planning, substance abuse, job training, teenaged parenting, and high school equivalency programs. Infants and children were referred for dental care, growth failure, the Head Start Program, kindergarten enrollment, early intervention, and protective services.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of enhanced calling efforts on response rates,estimates of health behavior,and costs in a telephone health survey using random-digit dialing.

Public health researchers frequently rely on random-digit dialing (RDD) telephone surveys in monitoring trends in health behavior and evaluating health promotion interventions. RDD response rates have declined during the past decade, and cost-effective methods to increase response rates are needed. The authors evaluated two levels of enhanced calling efforts in an RDD survey of cancer-related health behavior in the State of Washington. The first level of enhanced calling effort was 1 month after 11 original calling attempts to a household, when the authors attempted up to 11 recalls. The second level was 6 months after the first answered call, when the authors recalled those persons who could not be interviewed. Enhanced calling efforts increased the overall survey response rate by 11 percent. Nine percentage points of the increase were attributable to call backs. There were demographic differences among the participants reached at different levels of calling effort, but no consistent associations of level of calling effort with health behavior related to alcohol use, smoking, diet, or health screening. Marginal costs for interviews completed with enhanced calling efforts were about 50 percent higher than costs for interviews reached in the first 11 calls. The authors concluded that enhanced calling efforts may be justified, because they increase confidence in the generalizability of survey results. However, the authors found very little change in survey results by including interviews from persons who were difficult to reach and to interview.     

Imported care: recruiting foreign nurses to U.S. health care facilities

As U.S. health care facilities struggle to fill current registered nurse staffing vacancies, a more critical nurse undersupply is predicted over the next twenty years. In response, many institutions are doubling their efforts to attract and retain nurses. To that end, foreign nurses are increasingly being sought, creating a lucrative business for new recruiting agencies both at home and abroad. This paper examines past and current foreign nurse use as a response to nurse shortages and its implications for domestic and global nurse workforce policies.     

Skew‐elliptical spatial random effect modeling for areal data with application to mapping health utilization rates

Mixed models incorporating spatially correlated random effects are often used for the analysis of areal data. In this setting, spatial smoothing is introduced at the second stage of a hierarchical framework, and this smoothing is often based on a latent Gaussian Markov random field. The Markov random field provides a computationally convenient framework for modeling spatial dependence; however, the Gaussian assumption underlying commonly used models can be overly restrictive in some applications. This can be a problem in the presence of outliers or discontinuities in the underlying spatial surface, and in such settings, models based on non‐Gaussian spatial random effects are useful. Motivated by a study examining geographic variation in the treatment of acute coronary syndrome, we develop a robust model for smoothing small‐area health service utilization rates. The model incorporates non‐Gaussian spatial random effects, and we develop a formulation for skew‐elliptical areal spatial models. We generalize the Gaussian conditional autoregressive model to the non‐Gaussian case, allowing for asymmetric skew‐elliptical marginal distributions having flexible tail behavior. The resulting new models are flexible, computationally manageable, and can be implemented in the standard Bayesian software WinBUGS. We demonstrate performance of the proposed methods and comparisons with other commonly used Gaussian and non‐Gaussian spatial prior formulations through simulation and analysis in our motivating application, mapping rates of revascularization for patients diagnosed with acute coronary syndrome in Quebec, Canada. Copyright © 2012 John Wiley & Sons, Ltd.     

Functional health measure for adjusting health maintenance organization capitation rates.

Because of increasing interest in at-risk enrollment of Medicare beneficiaries by health maintenance organizations, a number of modifications to the adjusted average per capita cost (AAPCC) formula employed by the Health Care Financing Administration have been proposed recently. Researchers have found that new models, which include measures of prior years' utilization and costs, predict Medicare payments significantly better than does the purely demographic formula currently used. In this article, we show that inclusion of instrumental activities of daily living (IADL), a measure of beneficiaries' functional health status, can further improve AAPCC models that already incorporate measures of previous-period utilization and costs. Various models for predicting Medicare payments were examined and compared using survey data and Medicare claims for a random sample of 1,934 beneficiaries. For these models, explained variation in subsequent Medicare payments (as indicated by R2 values) increased considerably when the IADL variable was included. Although actuarial concerns are associated with inclusion of the IADL score in the AAPCC, use of this measure is likely to offset other, possibly more serious, actuarial problems associated with including measures of previous utilization and costs.     

Effectiveness of monetary incentives for recruiting adolescents to an intervention trial to reduce smoking

BACKGROUND: The study objective is to evaluate the effect of monetary incentives on response rates of adolescents to a smoking-related survey as the first step toward participation in an intervention trial. METHODS: A sample of 4,200 adolescent members of a managed care organization were randomized to one of four incentive groups: a $2 cash group, a $15 cash group, a $200 prize drawing group, or a no-incentive group. We compared group-specific response rates and willingness to be contacted about future study activities, as well as costs. RESULTS: Incentives increased survey response rates (55% response without incentive vs. a 69% response with incentive), with response of 74% in the $15 cash group, 69% in the token group, and 63% with a prize incentive. Incentives did not adversely affect willingness of adolescents to be contacted about a smoking intervention, (65% willing with incentives vs. 60% without, P = 0.03). In terms of cost per additional survey completed, token and prize groups were marginally more expensive than the no-incentive group ($0.40 and $1.42, respectively) while the large cash incentive was substantially more costly ($11.37). CONCLUSIONS: Monetary incentives improve response rates to a mailed survey, without adverse impact on willingness to further participate in intervention activities. However, a variety of issues must be considered when using incentives for recruitment to intervention studies.     

Comparison of two procedures for tracing participants in an epidemiologic cohort study

The effectiveness and accuracy of using a commercial firm for tracing survey participants were compared with the results of an established, University of Minnesota tracing protocol. Studying a cohort of 622 survey participants ages 25-74 who were living in a single Midwestern community, we were unable to locate 142 (23%) at their original address after four years. We traced them according to the Minnesota protocol, using information obtained from contact persons (friends or relatives) and other sources. Overall, current address information was found for 96% of the participants lost to follow-up, and 113 (81%) of 139 addresses were supplied through the contact person. An independent attempt to obtain similar information using only credit bureau tracing through Associated Credit Services provided addresses for 123 of the participants. Associated Credit Services provided correct, current addresses for 39 (29%) of the 136 surviving participants (six fatal cases were excluded) and supplied correct, current addresses for a majority (58%) of the study participants found by protocol to be living in the study area and eligible for a follow-up clinic examination. We support the use of commercial services as secondary sources of address information in tracing participants after the initial use of contact persons to optimize participant contact. We recommend the use of commercial services as primary sources when contact persons are unavailable.     

Recruiting participants for interventions to prevent the onset of depressive disorders: Possibile ways to increase participation rates

Background  

Although indicated prevention of depression is available for about 80% of the Dutch population at little or no cost, only a small proportion of those with subthreshold depression make use of these services.