Brief Report
“Bird in the hand” cash was more effective than prize draws in increasing physician questionnaire response

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Abstract

Objective

To investigate the effects of two monetary incentives on response rates to postal questionnaires from primary care physicians (PCPs).

Study Design and Setting

The PCPs were randomized into three arms (n = 550 per arm), namely (1) €5 sent with the questionnaire (cash); (2) entry into a draw on return of completed questionnaire (prize); or (3) no incentive. Effects of incentives on response rates and item nonresponse were examined, as was cost-effectiveness.

Results

Response rates were significantly higher in the cash (66.1%; 95% confidence interval [CI]: 61.9, 70.4%) and prize arms (44.8%; 95% CI: 40.1, 49.3%) compared with the no-incentive arm (39.9%; 95% CI: 35.4, 44.3%). Adjusted relative risk of response was 1.17 (95% CI: 1.02, 1.35) and 1.68 (95% CI: 1.48, 1.91) in the prize and cash arms, respectively, compared with the no-incentive group. Costs per completed questionnaire were €9.85, €11.15, and €6.31 for the cash, prize, and no-incentive arms, respectively. Compared with the no-incentive arm, costs per additional questionnaire returned in the cash and prize arms were €14.72 and €37.20, respectively.

Conclusion

Both a modest cash incentive and entry into a prize draw were effective in increasing response rates. The cash incentive was most effective and the most cost-effective. Where it is important to maximize response, a modest cash incentive may be cost-effective.

Introduction

What is new?

Key findings

  1. Two modest monetary incentives, €5 cash sent with the questionnaire and entry into a draw on questionnaire completion, produced significantly higher response rates over the no-incentive arm; the cash incentive was the most effective and the most cost-effective—costing less per completed questionnaire received.

What this adds to what was known?
  1. Monetary incentives are known to increase the response rates of surveys to physicians. However, optimum use of monetary incentives remains unresolved. We directly compared two modest monetary incentives—an immediate cash incentive and possible financial gain through entry into a draw, and demonstrated that both significantly increased response rates from primary care physicians, with cash being the most effective and cost-effective option.

What is the implication and what should change now?
  1. Where maximum response is required, a cash incentive should be considered.

Surveys of primary care physicians (PCPs) are used in many areas of health services and policy research. However, response rates to PCP surveys can be low [1] owing to lack of time, perceived importance of studies, concerns about confidentiality, biased questions, and increasing volume and length of surveys [2], [3]. This may introduce bias and affect generalizability of the results. Dilman's Tailored Design Method (TDM) advises on questionnaire format and implementation [4] and recommends token financial incentives [5]. A range of incentives, both monetary (eg, cash or lottery tickets) and nonmonetary (eg, pens or pencils) incentives have been shown to be effective in increasing response rates to postal questionnaires in health settings (reviews and references therein Refs. [6], [7], [8], [9], [10]). However, little is known about the most effective interventions among PCP surveys, and optimum monetary incentives within this group remain unknown [7], [8]. Furthermore, many of these studies involved a mix of health care professionals and were conducted in the United States with some exceptions in China, Australia, and Britain and may not be generalizable to other health care systems [6], [7], [8], [9], [10].

We conducted a randomized controlled trial to compare the effect on response to a PCP postal survey, and the cost, of the three scenarios, namely (1) a modest direct cash incentive, (2) a small monetary incentive through inclusion in a prize draw on receipt of completed questionnaires, and (3) no incentive.

Section snippets

Design

This trial was conducted within the context of a postal questionnaire of PCPs' practice and costs in relation to prostate-specific antigen (PSA) testing in Ireland, distributed during July–August 2012. This was a 20-item survey over two pages, seeking information on PCP demographics, training, practice size and mix (percentage of adults, males, and public and private patients), PSA testing policy, practice, and guidelines used to inform practice. Information was sought on costs (including

Results

The overall response rate was 50% (716/1,421). The PCPs who graduated post-1970, practiced outside the country's capital, and were male were significantly more likely to respond, but response was not affected by the percentage of patients on PCP patient lists with medical cards (data not shown). Likelihood of receiving a completed questionnaire was significantly higher in the cash compared with the no-incentive arm in unadjusted (relative risk [RR]: 1.66; 95% confidence interval [CI]: 1.46,

Discussion

Both a cash incentive as modest as €5 and entry into a draw with a similar expected value (ie, €6), significantly increased response rate to a PCP survey, with no loss in item completeness. The cash incentive was most effective. Although total costs were higher, the cash incentive was also the most cost-effective with the cost per completed questionnaire being 12% lower in the cash than the prize arm.

Various reasons for the success of monetary incentives have been proposed. Immediate incentives

Acknowledgment

The authors thank Joanne Clooney for help with survey administration and data entry.

References (14)

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Funding: The study was funded by the Health Research Board (grant number HRA_HSR/2010/17).

Potential financial conflicts of interest: None.

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