Effect of incentives and mailing features on online health program enrollment.

BACKGROUND: With the growing use of Internet-based interventions, strategies are needed to encourage broader participation. This study examined the effects of combinations of monetary incentives and mailing characteristics on enrollment, retention, and cost effectiveness for an online health program. METHODS: In 2004, a recruitment letter was mailed to randomly selected Midwestern integrated health system members aged 21-65 and stratified by gender and race/ethnicity; recipients were randomly pre-assigned to one of 24 combinations of incentives and various mailing characteristics. Enrollment and 3-month retention rates were measured by completion of online surveys. Analysis, completed in 2005, compared enrollment and retention factors using t tests and chi-square tests. Multivariate logistic regression modeling assessed the probability of enrollment and retention. RESULTS: Of 12,289 subjects, 531 (4.3%) enrolled online, ranging from 1% to 11% by incentive combination. Highest enrollment occurred with unconditional incentives, and responses varied by gender. Retention rates ranged from 0% to 100%, with highest retention linked to higher-value incentives. The combination of a $2 bill prepaid incentive and the promise of $20 for retention (10% enrollment and 71% retention) was optimal, considering per-subject recruitment costs ($32 enrollment, $70 retention) and equivalent enrollment by gender and race/ethnicity. CONCLUSIONS: Cash incentives improved enrollment in an online health program. Men and women responded differently to mailing characteristics and incentives. Including a small prepaid monetary incentive ($2 or $5) and revealing the higher promised-retention incentive was cost effective and boosted enrollment.     

The effects of cash and lottery incentives on mailed surveys to physicians: a randomized trial

Low response rates, especially among physicians, are a common problem in mailed survey research. We conducted a randomized trial to examine the effects of cash and lottery incentives on response rates. A total of 4,850 subjects were randomized to one of three interventions accompanying a mailed survey-no incentive (n = 1,700), cash payment [three levels of Hong Kong dollars (HKD) $10, $20, and $40; N = 50 in each subgroup], or entry into a lottery (three levels of HKD$1,000, $2,000, and $4,000; N = 1,000 in each subgroup) on receipt of the completed questionnaire. The response rates were higher among those offered incentives than those without (19.8% vs. 16.8%, P =.012). Cash was the more effective incentive compared to lottery (27.3% vs. 19.4%, P =.017). Response also increased substantially between the first and second mailings (14.2% vs. 18.8%, P >.001). In addition, those with specialist qualifications were more willing to participate in mailed surveys. We found no significant differences in response outcomes among the various incentive arms. Cash reward at the $20 level was the most cost-effective intervention, in terms of cost per responder. Further systematic examination of the effects of different incentive strategies in epidemiologic studies should be encouraged.     

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.     

Effect of survey instrument on participation in a follow-up study: a randomization study of a mailed questionnaire versus a computer-assisted telephone interview

ABSTRACT: BACKGROUND: Many epidemiological and public health surveys report increasing difficulty obtaining high participation rates. We conducted a pilot follow-up study to determine whether a mailed or telephone survey would better facilitate data collection in a subset of respondents to an earlier telephone survey conducted as part of the National Birth Defects Prevention Study. METHODS: We randomly assigned 392 eligible mothers to receive a self-administered, mailed questionnaire (MQ) or a computer-assisted telephone interview (CATI) using similar recruitment protocols. If mothers gave permission to contact the fathers, fathers were recruited to complete the same instrument (MQ or CATI) as mothers. RESULTS: Mothers contacted for the MQ, within all demographic strata examined, were more likely to participate than those contacted for the CATI (86.6% vs. 70.6%). The median response time for mothers completing the MQ was 17 days, compared to 29 days for mothers completing the CATI. Mothers completing the MQ also required fewer reminder calls or letters to finish participation versus those assigned to the CATI (median 3 versus 6), though they were less likely to give permission to contact the father (75.0% vs. 85.8%). Fathers contacted for the MQ, however, had higher participation compared to fathers contacted for the CATI (85.2% vs. 54.5%). Fathers recruited to the MQ also had a shorter response time (median 17 days) and required fewer reminder calls and letters (median 3 reminders) than those completing the CATI (medians 28 days and 6 reminders). CONCLUSIONS: We concluded that offering a MQ substantially improved participation rates and reduced recruitment effort compared to a CATI in this study. While a CATI has the advantage of being able to clarify answers to complex questions or eligibility requirements, our experience suggests that a MQ might be a good survey option for some studies.     

The cost-effectiveness of cash versus lottery incentives for a web-based, stated-preference community survey

We present the results of a randomized experiment to test the effectiveness and cost-effectiveness of response incentives for a stated-preference survey of a general community population. The survey was administered using a mixed-mode approach, in which community members were invited to participate using a traditional mailed letter using contact information for a representative sample of the community; but individuals completed the survey via the web, which exploited the advantages of electronic capture. Individuals were randomized to four incentive groups: (a) no incentive, (b) prepaid cash incentive ($2), (c) a low lottery (10 prizes of $25) and (d) a high lottery (2 prizes of $250). Letters of invitation were mailed to 3,000 individuals. In total, 405 individuals (14.4%) contacted the website and 277 (9.8%) provided complete responses. The prepaid cash incentive generated the highest contact and response rates (23.3 and 17.3%, respectively), and no incentive generated the lowest (9.1 and 5.7%, respectively). The high lottery, however, was the most cost-effective incentive for obtaining completed surveys: compared with no incentive, the incremental cost-effectiveness ratio (ICER) per completed survey for high lottery was $13.89; for prepaid cash, the ICER was $18.29. This finding suggests that the preferred response incentive for community-based, stated-preference surveys is a lottery with a small number of large prizes.     

Effects of incentives and prenotification on response rates and costs in a national web survey of physicians

Little is known about what strategies are cost-effective in increasing participation among physicians in surveys that are conducted exclusively via the web. To assess the effects of incentives and prenotification on response rates and costs, general internists (N = 3,550) were randomly selected from the American Medical Association (AMA) Masterfile and assigned to experimental groups that varied in the amount of a promised incentive (none, entry into a $200 lottery, $50, or $100) and prenotification (none, prenotification letter only, or prenotification letter containing a $2 preincentive). Results indicated that the response rates were highest in the groups promised $100 and $50, respectively. While the postal prenotification letter increased response rates, the inclusion of a small token $2 preincentive had no effect on participation. Further, unlike mail surveys of physicians, the $2 preincentive was not cost-effective. Among physicians, larger promised incentives of $50 or $100 are more effective than a nominal preincentive in increasing participation in a web-only survey. Consistent with prior research, there was little evidence of nonresponse bias among the experimental groups.     

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.     

Black art posters, an incentive to increase study enrollment among Blacks in a large cohort study

OBJECTIVE: Black art posters were offered to replace or augment the established $10 incentive for questionnaire completion in a longitudinal cohort study. METHOD: Eighty-one churches located in the US southern region were divided between two intervention groups, with a control group of 24 churches from the same region. Primary outcome measures were study enrollment rates and questionnaire return rates between December 2003 and July 2004 as a proportion of church goal. RESULTS: 9.3% of participants returning questionnaires selected a poster in preference to $10. Half of participants offered both monetary and art incentives indicated a poster selection. Crude questionnaire return rates were 57.4% for the pooled intervention churches and 38.2% for the control churches. Enrollment rates among those offered both incentives were significantly higher (p<0.01) than when monetary incentives alone were offered after adjustment for church size, promotional dates, and average income of church members. Survey return rates were also higher in the churches offered both incentives (p=0.04). CONCLUSION: These data suggest that the black art posters improved study enrollment and survey return rates. The relatively low rate of poster selection suggests that the art primarily influenced participation indirectly, by creating a more culturally inclusive image of the study.     

Impact of Participant Incentives and Direct and Snowball Sampling on Survey Response Rate in an Ethnically Diverse Community: Results from a Pilot Study of Physical Activity and the Built Environment

Community-wide efforts to encourage healthy behaviours must respond to the needs of existing neighbourhoods, especially those where low physical activity (PA) is associated with social, economic, and cultural challenges. This study reports on the effect of direct and snowball sampling strategies and financial incentive levels on the response rates of a built environment and PA survey in a predominately urban, low-SES new-immigrant community. Women residing in the Jane-Finch neighbourhood of Toronto, Ontario were selected to participate by quasi-random sampling, yielding a response rate of 41.5%. The survey completion rate per contact attempt increased 2-fold when incentives were increased from $10 to $20 and a further threefold following the increase from $20 to $30. Snowball sampled respondents were older, less likely to have full-time employment, and had lower educational attainment than directly sampled participants. With appropriate incentives, face-to-face contact, and snowball sampling, survey-based research is feasible within a low-SES, high minority population.     

Lottery-based versus fixed incentives to increase clinicians' response to surveys

Objective. To compare the effects of lottery‐based and fixed incentives on clinicians' response to surveys. Data Sources. Three randomized trials with fixed payments and actuarially equivalent lotteries. Study Design. Trial 1 compared a low‐probability/high‐payout lottery, a high‐probability/low‐payout lottery, and no incentive. Trial 2 compared a moderate‐probability/moderate‐payout lottery with an unconditional fixed payment (payment sent with questionnaire). Trial 3 compared a moderate‐probability/moderate‐payout lottery with a conditional fixed payment (payment promised following response). Principal Findings. Neither the low‐probability nor high‐probability lotteries improved response compared with no incentive. Unconditional fixed payments produced significantly greater response than actuarially equivalent lotteries, but conditional fixed payments did not. Conclusions. Lottery‐based incentives do not improve clinicians' response rates compared with no incentives, and they are inferior to unconditional fixed payments.     

Recruitment to mammography screening: a randomised trial and meta-analysis of invitation letters and telephone calls

OBJECTIVES: To determine the effectiveness of three recruitment strategies to encourage women to attend for an initial mammography screen, and to compare results with similar service studies. Interventions were: (1) an invitation letter; (2) two invitation letters; and (3) an invitation letter plus a follow-up telephone call. METHODS: All women aged 50-54 years in two BreastScreen New South Wales (BSNSW) Screening and Assessment Service catchment areas (n=3,144) were recruited from the Australian Electoral Roll and randomised to the four groups. Response rates for each intervention were compared relative to standard practice (one invitation letter) at 12-weeks follow-up. Marginal cost-effectiveness for each condition was calculated. Other similar randomised trials were also meta-analysed. RESULTS: The screening rate for two letters was 8.5% (OR=1.61, 95% CI 1.08-2.40) and 7.8% (OR=1.46, 95% CI 0.97-2.18) for one letter plus a telephone call, compared with 5.5% for standard practice (one letter) (OR=1.00). The response rate in the one letter plus a phone call group was 13.3% (OR=2.65, 95% CI 1.76-4.00) for women where a phone number was located. CONCLUSION: Initial screening rates after a 12-week follow-up were significantly higher in the women receiving a second invitation letter, compared with standard practice (one letter). Marginal cost-effectiveness favoured the two-letter approach. IMPLICATIONS: A follow-up invitation letter is more cost-effective than one invitation letter plus a follow-up telephone call in the BSNSW program. However, an invitation letter plus follow-up phone call is more cost-effective in recruiting women to BSNSW only if a phone number is located.     

Prepayment was superior to postpayment cash incentives in a randomized postal survey among physicians

OBJECTIVE: Improving response rates, particularly among physicians, is important to minimize nonresponder bias and increase the effective sample size in epidemiologic research. We conducted a randomized trial to examine the impact of prepayment vs. postpayment incentives on response rates. STUDY DESIGN AND SETTING: Self-completion postal questionnaires were mailed to 949 physicians who were respondents to an earlier survey and representative of the general physician population in Hong Kong. These physicians were randomly allocated to receive a HK dollar 20 cash prepayment incentive that accompanied the survey (n=474) or a postpayment reward of the same amount on receipt of the completed questionnaire (n=475). RESULTS: The final prepayment response rate was 82.9%, compared with 72.5% in the postpayment arm (P < .001). Of the eight alternative incentive and follow-up strategies evaluated, three lie on the efficiency frontier (i.e., not dominated), including postpayment with three mailings at HK dollar 42.7, prepayment with three mailings at HK dollar 66.5 and prepayment with three mailings and telephone follow-up at HK dollar 112.1 per responder recruited (US dollar 1=HK dollar 7.8). CONCLUSION: The findings demonstrate that prepayment cash incentives are superior to postpayment of the equivalent amount in improving response rates among a representative sample of Hong Kong physicians. Further research should concentrate on confirming the generalizability of these findings in other health care occupation groups and settings.     

The effect on response rates of offering a small incentive with a mailed questionnaire.

To determine whether response rates to a mailed questionnaire sent to population control subjects could be increased through offer of a small incentive, half of the control subjects (n = 477) in a case-control study of renal cell carcinoma were randomly selected to receive a contact letter offering a lottery ticket if a completed questionnaire was returned; the remaining subjects (n = 477) received the same letter but with no mention of a lottery ticket. Overall response rates did not differ between the two groups (72.6% versus 74.4%), although a higher percentage of those offered a lottery ticket responded without follow-up (24.4% versus 18.5%). Binomial regression modeling of the effect of the lottery ticket offer, sex, age, and percent of urban dwellers on response indicated a significant effect only for percent of urban dwellers, the rate of response increasing with a decreasing percentage of urban dwellers. The effect of sex was of borderline significance (P = 0.05), with females having the higher rate of response.     

Racial and ethnic disparity in participation in DNA collection at the Atlanta site of the National Birth Defects Prevention Study

Genetic risk factors are a critical component of many epidemiologic studies; however, concerns about genetic research might affect participants' willingness to enroll. The authors assessed factors associated with completion of mailed buccal-cell collection kits following telephone interviews at the Atlanta, Georgia, study site of the National Birth Defects Prevention Study. Pregnant women who were interviewed after June 30, 1999, and had an estimated delivery date of December 31, 2002, or earlier were included (n = 1,606). For this time period, overall interview participation was 71.9%. Among those interviewed, 47.6% completed the buccal-cell collection kit (61.1% of non-Hispanic Whites, 34.9% of non-Hispanic Blacks, and 39.1% of Hispanics). Non-Hispanic White race/ethnicity, an English-language (vs. Spanish) interview, receipt of a redesigned mailing packet and an additional $20 incentive, and consumption of folic acid were associated with higher buccal-cell kit participation. Among non-Hispanic White mothers, higher education, intending to become pregnant, and having a child with a birth defect were associated with increased participation. Among non-Hispanic Black mothers, receipt of the redesigned packet and $20 incentive was associated with increased participation. Among Hispanic mothers, an English-language interview, higher education, and receipt of the redesigned packet and $20 incentive were associated with increased participation. At this study site, minority groups were less likely to participate in DNA collection. Factors associated with participation varied by race/ethnicity.     

Computer-assisted telephone interviewing (CATI): using the telephone for obtaining information on reproductive health

The objective of this study was to evaluate the feasibility of using computer assisted telephone interviewing (CATI) as a method for obtaining information on reproductive health in Brazil. A total of 998 eligible women for the study were selected to answer a questionnaire through computer- assisted telephone interviewing undertaken by trained interviewers. The outcomes of each telephone contact attempt were described. Differences between groups were assessed using the χ(2) test. Phone contact was made in 60.3% of the attempts and 57.5% of the interviews were completed. The success rate improved with the decrease in time from hospitalization to interview and with the higher numbers of telephones available. A total of 2,170 calls were made, comprising of one to sixteen attempts per woman. The majority of situations where extra calls were necessary were due to the number being busy or to the fact that the woman was not available at the time of the call. CATI can prove be a valuable procedure for obtaining information on reproductive health among Brazilian women, particularly for relatively recent events and when more than one alternative telephone number is available.     

Adolescent preventive health visits: a comparison of two invitation protocols

BACKGROUND: Adolescent health care in family practice at times creates conflicting responsibilities for parents and their teenagers. In the context of a new adolescent preventive health program in a family practice setting, we compared attendance rates using two invitation protocols, the protocols differing in their emphasis on adolescent autonomy vs parental responsibility. METHODS: One hundred six teenagers in the seventh and tenth grades were invited for preventive health visits with the family nurse and physician using two protocols. Protocol 1 involved obtaining parental consent before approaching the adolescent. With protocol 2, an invitation letter and parental consent form were mailed to the teenager, while a letter of explanation was sent concurrently to the parents. In each case, the letter of invitation was followed up by a telephone call for those who did not respond. The spontaneous response rate (a positive response after receiving the letter), agreement to attend rate (a positive response after receiving the letter or being telephoned), and the attendance rate were determined according to grade, sex, and protocol. RESULTS: The spontaneous response rate was 21%, the agreement to attend rate was 75%, and the attendance rate was 44%. Attendance rates were higher for the girls compared with the boys (54% vs 35%, P = .08) and for the seventh graders compared with the tenth graders (53% vs 31%, P = .03). The spontaneous response rate was lower among the tenth graders using protocol 2 (8% vs 37.5% with protocol 1, P = .04), while the agreement to attend rate and attendance rate did not differ for the two protocols. CONCLUSIONS: Nearly one half of this population of adolescents attended preventive health visits at the family nurse's and physician's initiative. A follow-up telephone call after the initial written invitation resulted in increased participation, while approaching the teenager or parent initially did not make a difference in attendance. This pilot study shows the potential for initiating an adolescent health program in the family practice setting.     

Incentives vs outreach workers for latent tuberculosis treatment in drug users

BACKGROUND: Drug users are at increased risk for latent tuberculosis infection (LTBI) and also at increased risk for noncompletion of medication regimens for treatment of LTBI or tuberculosis disease. Directly observed therapy (DOT) provided by outreach workers, the use of incentives, or both have been suggested as a means to increase adherence. OBJECTIVE: To compare the independent and combined effects of monetary incentives and outreach worker provision of DOT for LTBI treatment in a sample of active drug users. METHODS: The research design was a randomized controlled trial in a community outreach program setting. Participants consisted of a volunteer sample of 163 active injection drug and crack cocaine users placed on twice weekly DOT. Condition 1 of the interventions consisted of provision of DOT by an outreach worker at a location chosen by the participant (active outreach) and a $5 per visit incentive. Condition 2 was comprised of active outreach with no monetary incentive, and Condition 3, provision of DOT at the study community site and a $5 per visit incentive. The main outcome measures were percentage of medication taken as prescribed and completion of medication regimen. RESULTS: The percentage of prescribed medication taken was higher for those who received incentives, either with (71%) or without (68%) active outreach, compared to those who received active outreach alone (13%). Only 4% of participants assigned to Condition 2 completed treatment, compared to 53% of Condition 1 participants, and 60% of Condition 3 participants. CONCLUSIONS: Monetary incentives were clearly superior to active outreach. Active outreach in combination with monetary incentives did not increase adherence over incentives alone.     

The impact of including incentives and competition in a workplace smoking cessation program on quit rates.

PURPOSE: To determine the effectiveness of a multicomponent smoking cessation program supplemented by incentives and team competition. DESIGN: A quasi-experimental design was employed to compare the effectiveness of three different smoking cessation programs, each assigned to separate worksite. SETTING: The study was conducted from 1990 to 1991 at three aerospace industry worksites in California. SUBJECTS: All employees who were current, regular tobacco users were eligible to participate in the program offered at their site. INTERVENTION: The multicomponent program included a self-help package, telephone counseling, and other elements. The incentive-competition program included the multicomponent program plus cash incentives and team competition for the first 5 months of the program. The traditional program offered a standard smoking cessation program. MEASURES: Self-reported questionnaires and carbon monoxide tests of tobacco use or abstinence were used over a 12-month period. RESULTS: The incentive-competition program had an abstinence rate of 41% at 6 months (n = 68), which was significantly better than the multicomponent program (23%, n = 81) or the traditional program (8%, n = 36). At 12 months, the quit rates for the incentive and multicomponent-programs were statistically indistinguishable (37% vs. 30%), but remained higher than the traditional program (11%). Chi-square tests, t-tests, and logistic regression were used to compare smoking abstinence across the three programs. CONCLUSIONS: Offering a multicomponent program with telephone counseling may be just as effective for long-term smoking cessation as such a program plus incentives and competition, and more effective than a traditional program.     

Helping women quit smoking: results of a community intervention program

OBJECTIVES: This intervention was implemented to reduce the prevalence of cigarette smoking among women. METHODS: We used community organization approaches to create coalitions and task forces to develop and implement a multicomponent intervention in 2 counties in Vermont and New Hampshire, with a special focus on providing support to help women quit smoking. Evaluation was by pre-intervention and post-intervention random-digit-dialed telephone surveys in the intervention counties and the 2 matched comparison counties. RESULTS: In the intervention counties, compared with the comparison counties, the odds of a woman being a smoker after 4 years of program activities were 0.88 (95% confidence interval = 0.78, 1.00) (P = .02, 1-tailed); women smokers' perceptions of community norms about women smoking were significantly more negative (P = .002, 1-tailed); and the quit rate in the past 5 years was significantly greater (25.4% vs 21.4%; P = .02, 1-tailed). Quit rates were significantly higher in the intervention counties among younger women (aged 18 to 44 years); among women with household annual incomes of $25,000 or less; and among heavier smokers (those who smoked 25 or more cigarettes daily). CONCLUSIONS: In these rural counties, community participation in planning and implementing interventions was accompanied by favorable changes in women's smoking behavior.