J O U RN A L OF GE RI A T RI C O NC O L O G Y 5 ( 2 01 4 ) 1 2 7 – 13 2
Available online at www.sciencedirect.com
ScienceDirect Short communication
Effects of a gift certificate incentive and specialized delivery on prostate cancer survivors' response rate to a mailed survey: A randomized-controlled trial☆ Jennifer Bakana,⁎, Bing Chena,1 , Cheryl Medeiros-Nancarrowa , Jim C. Hub,2 , Philip W. Kantoff c , Christopher J. Recklitisa a
Perini Family Survivors' Center, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA Division of Urology, Brigham and Women's Hospital, 45 Francis Street, Boston, Boston, MA 02115, USA c Division of Solid Tumor Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA b
AR TIC LE I N FO
ABS TR ACT
Article history:
Objectives: Most men diagnosed with prostate cancer become long-term survivors, but are at
Received 31 July 2013
risk for medical late-effects that can affect their long-term health. Mailed surveys are well
Received in revised form
suited to study late-effects in this population, but low response rates can compromise survey
10 September 2013
validity. This study investigated whether an unconditional $5.00 gift certificate incentive or
Accepted 25 November 2013
Priority Mail delivery increased prostate cancer survivors' response to mailed surveys.
Available online 17 December 2013
Materials and Methods: 976 participants (mean age = 66.8 years), 2–8 years post-diagnosis, were randomized to one of four groups: Incentive; Priority Mail; Incentive & Priority Mail; or Control.
Keywords:
After an introductory letter, initial study packets were mailed based on randomization; 46 days
Mailed surveys
later, a second study packet was mailed to all non-responders by First-Class Mail.
Response rates
Results: The first mailing yielded a significant variation in response rates across groups
Cancer survivorship
(χ2 = 9.34; p = 0.025). Priority Mail (64.7%; p = 0.008) and Incentive & Priority Mail (63.6%; p =
Prostate cancer
0.016) groups had significantly higher response rates than Controls (52.9%). After the second
Mailing methods
mailing, the overall response rate increased significantly from 59.6% to 71.4% (p < 0.001); however, response rates no longer differed across groups (range, 69.3% [Incentive group] to 73.9% [Priority Mail group]). Conclusions: Long-term prostate cancer survivors' response rates to mailed surveys increased with the use of Priority Mail and a repeat survey mailing, but the unconditional gift certificate incentive was not supported in this population. By identifying and applying specialized survey methods, studies targeting survivors of prostate cancer and other geriatric cancers may improve response rates, thus limiting a source of potential bias. © 2013 Elsevier Ltd. All rights reserved.
☆ Financial support: Research support was provided by a grant from the American Foundation for Suicide Prevention (PRG-1-10-156; Recklitis). ⁎ Corresponding author. Tel.: + 1 617 632 3883; fax: +1 617 632 2473. E-mail address: [email protected] (J. Bakan). 1 Present address: Women's Health Unit, 801 Massachusetts Avenue, Crosstown Building, 1st Floor, Boston, MA 02118, USA. 2 Present address: Department of Urology, David Geffen School of Medicine at the University of California Los Angeles, 924 Westwood Boulevard, Los Angeles, CA 90095, USA. 1879-4068/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jgo.2013.11.005
128
1.
J O U RN A L OF GE RI A TR I C O NC O LOG Y 5 ( 20 1 4 ) 1 2 7 –1 3 2
Introduction
Prostate cancer is the most common cancer diagnosed among men in the United States, with nearly two-thirds of new diagnoses made in men aged 65 or older [1]. Due to improved detection and treatment, the majority of men diagnosed with prostate cancer today will become long-term survivors, joining the more than 2.5 million prostate cancer survivors living in the US [1]. Despite improvements in care, prostate cancer survivors are at risk for a variety of post-treatment complications [2], and there is growing interest in studying the emergence of these late-effects and their impact on long-term health. Mailed surveys are potentially valuable tools for studying prostate cancer survivors' outcomes, as surveys can reach a representative sample quickly and economically [3]. However, low response rates may lead to selection bias and compromised survey validity [3]. This vulnerability of mailed survey methodology has spurred a large body of research, demonstrating that a variety of survey techniques, including unconditional monetary incentives, pre-notification, follow-up reminders, stamped return envelopes, and specialized delivery methods, can increase response rates, at least in some populations [3–5]. Despite considerable evidence supporting methods to increase survey response, extant research has often focused on non-cancer populations and samples of younger individuals, making it unclear whether findings in these populations can be generalized to prostate cancer survivors or other geriatric cancer survivors. In addition, the few studies that have systematically investigated methods to increase response rates to mailed surveys in patients with cancer and survivors have produced inconsistent results [6,7], with some investigators speculating that results in older survivors may differ from those found in younger cancer survivors [6]. The present study aimed to address the knowledge gap in mailed survey methodology in prostate cancer survivors by determining the effectiveness of a token unconditional incentive (gift certificate) and specialized delivery (Priority Mail) in a cohort of long-term prostate cancer survivors. Unconditional incentives were selected because they have been shown to enhance response rates in a variety of populations [3], but the few studies that have investigated incentives in cancer survivors have produced contradictory results [6,8]. Specialized delivery was selected because its utility in patient populations, including cancer survivors, has been understudied, despite some supporting evidence in physician populations [9].
2.
Materials and Methods
2.1.
Study Population
This study was part of a cross-sectional study of health outcomes in prostate cancer survivors, who were 2 to 8 years post a prostate cancer diagnosis. Potential participants (n = 1500) were randomly selected from an existing cohort of English-speaking patients seen at a single cancer center in Boston, Massachusetts. This initial sample was screened for eligibility (living with a current US address) using the Social Security Death Index and National Change of Address
databases; current addresses were verified using publicly available online databases. After verification, 1000 survivors were randomly selected as the target sample for this study. Survey responders (n = 697) had an average age of 67.0 years (SD = 8.0) (Table 1). Responders were similar to non-responders (n = 279) in terms of current age, age at prostate cancer diagnosis, and time since diagnosis (all p > 0.05) (Table 1). Most responders were Caucasian, non-Hispanic (94.8%); although this was also true of non-responders (85.1%), non-Caucasians had significantly lower response rates than Caucasian, nonHispanics (47.4% vs. 74.2%; χ2 = 25.05; p < 0.001).
2.2.
Study Procedures
Participants were randomly assigned to one of four groups: (1) Incentive; (2) Priority Mail; (3) Incentive & Priority Mail; or (4) Control (no incentive and no Priority Mail). The incentive was a $5.00 gift certificate to a nationally available fast-food restaurant, stapled to the study packet. Priority Mail was delivered by the United States Postal Service (USPS), in a specially marked 12.5 × 9.5 in. Priority Mail envelope, at a cost of $5.60 per envelope. All other mailings were delivered by USPS First-Class Mail in a 10 × 13 in. envelope, at a cost of approximately $1.30 per envelope. Mailings to all groups were addressed to the intended participant using a typed label, and included a personalized cover letter, the 10-page survey, a resource sheet, and a postagepaid, pre-addressed return envelope. The survey itself assessed the participant's demographic and medical characteristics, cancer treatment history, health, and quality of life. Prior to the initial survey mailing, all groups received an introductory letter delivered by First-Class Mail. Letters were personalized by name, and omitted information regarding the incentive or delivery method used in later mailings. The letter described the study and provided a toll-free number to decline participation. Sixty days after the introductory letters, participants received the initial study packet based on randomized groups. Forty-six days after this initial mailing, a second study packet, which included a personalized reminder letter and a copy of the survey, was mailed to non-responders by First-Class Mail. Accrual was closed after 100 days from the initial survey mailing. Surveys returned within 48 days of the first survey mailing were considered responders to the first mailing, while surveys returned between 49 and 100 days after the first survey mailing were considered responders to the second mailing. All procedures were approved by the cancer center's Institutional Review Board. Eight survivors declined study participation after the introductory letter, but prior to the first mailing, and were excluded from analyses. Nine surveys were returned as undeliverable, and 7 were returned with notification of patient death, yielding an evaluable sample of 976 (Incentive, n = 244; Priority Mail, n = 241; Incentive & Priority Mail, n = 247; and Control, n = 244) (Fig. 1).
2.3.
Statistical Analysis
Independent sample t-tests and chi-squared tests were computed to assess for differences between responders and non-responders on demographic variables. Study-wide response rates and rates for the four randomized groups were calculated for the first and second mailings, and these were
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J O U RN A L OF GE RI A T RI C O NC O L O G Y 5 ( 2 01 4 ) 1 2 7 – 13 2
Table 1 – Demographic and medical characteristics of responders and non-responders (N = 976). Responders (n = 697) Characteristic Demographic characteristics Current age (years) Age at diagnosis (years) Years since diagnosis Race/ethnicity African American, non-Hispanic Caucasian, non-Hispanic Hispanic Asian or Pacific Islander Native American or Alaskan Native Other/mixed Education Less than high school High school graduate Training after high school/some college College graduate Postgraduate level training Marital status Married/living as married Never married Widowed Divorced/separated/not living as married Annual household income ≤$29,999 $30,000–$49,999 $50,000–$74,999 $75,000–$99,999 ≥$100,000 Employment status d Working full-time Working part-time Retired Disabled, unable to work Unemployed Other Medical characteristics Prostate cancer treatment d Prostate surgery Hormonal therapy Orchiectomy Radiation therapy Chemotherapy Metastases diagnosis No Yes Prostate cancer recurrence/relapse No Yes Rising/variable PSA Other cancer treatment No Yes
n (%)
M (SD)
Non-responders (n = 279)
n missing
n (%)
67.0 (8.0) 61.6 (8.0) 4.9 (1.7)
M (SD)
n missing
5
11 30 (11.2) 228 (85.1) 4 (1.5) 2 (0.7) 0 (0) 4 (1.5) c
1 23 56 143 199 275
(3.3) (8.0) (20.5) (28.6) (39.5)
602 24 24 46
(86.5) (3.4) (3.4) (6.6)
40 59 133 121 319
(6.0) (8.8) (19.8) (18.0) (47.5)
1
25
273 (39.2) 94 (13.5) 326 (46.8) 19 (2.7) 24 (3.4) 11 (1.6)
393 (57.0) 267 (38.6) 6 (0.9) 338 (48.8) 59 (8.5)
a
−1.74 −1.59 −0.58
66.0 (8.7) 60.7 (8.7) 4.9 (1.7)
18 (2.6) 656 (94.8) 4 (0.6) 2 (0.3) 6 (0.9) 6 (0.9)
t or χ2
7 6 6 4 6 26
603 (89.9) 68 (10.1) 21 597 (88.3) 68 (10.1) 11 (1.6) 11 509 (74.2) 177 (25.8)
M = mean; SD = standard deviation; χ2 = chi-squared test; PSA = prostate-specific antigen. *p < 0.001. a t-test calculated for continuous variables; chi-squared test calculated for categorical variables. b Chi-squared test calculated for Caucasian, non-Hispanic versus non-Caucasian only. c Includes other race/ethnicity only; mixed race/ethnicity unknown from prostate cancer cohort dataset (Oh et al., 2006). d Percentage not equal to 100%; categories are not mutually exclusive.
25.05*
b
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J O U RN A L OF GE RI A TR I C O NC O LOG Y 5 ( 20 1 4 ) 1 2 7 –1 3 2
Fig. 1 – Randomization of study sample and response rates.
rates differed significantly across randomized groups (χ2 = 9.34; p = 0.025). Compared to Controls, response rates were significantly higher for the Priority Mail (52.9% vs. 64.7%; Z = 2.65; p = 0.008) and Incentive & Priority Mail (52.9% vs. 63.6%; Z = 2.40; p = 0.016) groups; no differences were detected between the Control and Incentive groups (52.9% vs. 57.4%; Z = 1.00; p = 0.32). The logistic regression of survey return as a function of the incentive and delivery conditions was significant (χ2 = 9.33; p = 0.025), indicating that those who received a survey by Priority Mail were more likely to return it than those who did not (OR = 1.64; p = 0.008; 95% CI: 1.14–2.36).
compared using chi-squared tests and Z-tests. Logistic regression was also used to examine the impact of the incentive and delivery conditions on response rate. These two variables and an incentive × Priority Mail interaction term were entered simultaneously into the logistic model.
3.
Results
The initial mailing to 976 eligible prostate cancer survivors yielded an overall response rate of 59.6% (n = 582). Response
Table 2 – Logistic regression models of the effect of delivery and incentive conditions on proportion of surveys returned (N = 976). Proportion of surveys returned Condition
Main effect Interaction
Main effect Interaction
FIRST MAILING Model Incentive Priority Mail Incentive × Priority Mail SECOND MAILING Model Incentive Priority Mail Incentive × Priority Mail
B
SE
OR (95% CI)
0.18 0.49** −0.23
0.18 0.19 0.26
1.20 (0.84–1.72) 1.64 (1.14–2.36) 0.79 (0.47–1.33)
−0.08 0.15 −0.03
0.20 0.20 0.28
0.93 (0.63–1.36) 1.16 (0.78–1.73) 0.97 (0.56–1.69)
χ2 9.33*
1.30
CI = confidence interval; SE = standard error; OR = odds ratio; χ2 = chi-squared test. *p < 0.05; **p < 0.01.
J O U RN A L OF GE RI A T RI C O NC O L O G Y 5 ( 2 01 4 ) 1 2 7 – 13 2
Effects for the incentive condition and the incentive ×Priority Mail interaction were not significant (all p > 0.05) (Table 2). After the second survey mailing, 115 additional survivors responded, significantly increasing the overall response rate to 71.4% (Z = 5.48; p < 0.001) (Fig. 1). Within randomized groups, response rates increased significantly from the first to second mailing in the Incentive (57.4% vs. 69.3%; Z = 2.72; p = 0.006), Priority Mail (64.7% vs. 73.9%; Z = 2.17; p = 0.03), and Control (52.9% vs. 70.9%; Z = 4.20; p < 0.001) groups, but not in the Incentive & Priority Mail group (63.6% vs. 71.7%; Z = 1.92; p = 0.055). At the end of the accrual period, there were no significant differences in response rates across groups (χ2 = 1.30; p =0.73). The logistic regression of total response rate as a function of incentive and delivery conditions was not significant (χ2 = 1.30; p = 0.73) (Table 2).
4.
Discussion
Results indicate that specialized delivery methods can increase response rates in long-term prostate cancer survivors, but these effects may differ from those seen in some other populations. Specifically, prostate cancer survivors were most likely to return the first survey when it was delivered by Priority Mail. The positive effect of Priority Mail in prostate cancer survivors studied here is similar to the effect of specialized delivery (e.g., Federal Express and recorded delivery) found in surveys of health care providers [3,9]. Studies in a variety of populations support the use of unconditional incentives to increase survey response rates [3,8], but this approach was not supported here. Contrary to expectations, the gift certificate incentive had no effect on prostate cancer survivors' likelihood of responding. Of note, this negative finding for the unconditional gift card incentive is consistent with at least one study in patients with prostate cancer [7] and a second in prostate cancer survivors [6], which found unconditional incentives had no effect on response to mailed surveys. This lack of effect of incentives on response rate in prostate cancer groups may be related to the older age of prostate cancer survivors compared to other groups [6]. Consistent with reports among several patient groups [5], the reminder letter and second survey used in the present study also significantly increased the likelihood of response. In fact, after the second mailing, the increase in returned surveys was so large that differences between the randomized mailing groups were no longer significant. This study has several limitations. Most notably, only one type of incentive was studied. Different types of incentives (e.g., cash, gift cards, sweepstakes, etc.) could appeal differently to different groups, and the effect of incentives on response rate in prostate cancer survivors may depend on types of incentives offered. Additionally, because this study utilized several methods shown to increase response rates in other populations (e.g., pre-notification letter [3,4], postage-paid pre-addressed return envelope [3], personalization at each mailing [3], and a second survey mailing with a duplicate survey [3]), results presented here may not be generalizable to studies lacking these features. As noted, prostate cancer survivors in this study were English-speaking, predominately Caucasian, of a relatively high socioeconomic status, and recruited from a single cancer
131
center; thus, results may not be generalizable to other sociodemographic groups. Results of this study have practical implications for future surveys in the growing population of prostate cancer survivors. Though Priority Mail has not been widely investigated in cancer populations, our finding that it effectively increased response rate should encourage more widespread use of specialized mailing in future surveys to prostate cancer survivors and, potentially, other patient groups. Priority Mail does have additional costs to be considered, especially because, with additional time, a second regular mailing can be just as effective, as seen here. A second regular mailing also had associated costs, including postage, survey reproduction, return envelopes, and staff time. A second mailing without specialized delivery may be a viable option whenever time to receipt of a completed survey is not a priority, whereas Priority Mail may be desirable when rapid survey response is valued or survey printing costs are high. Ultimately, researchers must determine the appropriate tradeoff between time and costs for each study. With this being the second study to show no effect of an incentive on survey return among prostate cancer populations [6,7], and with similar results seen in other patient populations [5], there is little evidence to support its use in prostate cancer survivors. Future research may seek to investigate other forms of incentives (e.g., cash, sweepstakes, etc.), but non-monetary incentives of limited financial value should not be considered effective for increasing response rates in prostate cancer survivors. Finally, the results reported here serve as a reminder that response to survey methods can vary significantly across populations. Unconditional incentives, though widely used and supported in studies of younger and less medicallyinvolved populations [3,8], were not found to be effective in increasing response rates in prostate cancer survivors. Future studies should investigate the generalizability of our findings to other groups of geriatric patients with cancer, including women and men with other cancer types. As the population of older cancer survivors continues to grow [10], surveys that can quantify the health needs, treatment late-effects, and quality of life of geriatric cancer survivors will grow in importance. The literature on survey methods provides several promising techniques to increase survey responses, but specifically validating them in geriatric cancer survivors is critical in determining their effectiveness in this growing population.
Disclosure and Conflict of Interest Statement The authors indicate no conflict of interest to disclose.
Author Contributions Study concept: J.C. Hu, P.W. Kantoff, C.J. Recklitis Study design: C.J. Recklitis Data acquisition: B. Chen, C. Medeiros-Nancarrow Quality control of data and algorithms: C. Medeiros-Nancarrow Data analysis and interpretation: J. Bakan, B. Chen, C.J. Recklitis Statistical analysis: J. Bakan, B. Chen Manuscript preparation and editing: J. Bakan, C.J. Recklitis
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J O U RN A L OF GE RI A TR I C O NC O LOG Y 5 ( 20 1 4 ) 1 2 7 –1 3 2
Manuscript review: J. Bakan, B. Chen, C. Medeiros-Nancarrow, J.C. Hu, P.W. Kantoff, C.J. Recklitis All authors approved the final version of the manuscript.
6.
REFERENCES 7. 1. American Cancer Society. What are the key statistics about prostate cancer? c2012 [updated 2013 Mar 15; cited 2013 Jul 15] Available fromhttp://www.cancer.org/cancer/prostatecancer/ detailedguide/prostate-cancer-key-statistics. 2. Potosky AL, Davis WW, Hoffman RM, Stanford JL, Stephenson RA, Penson DF, et al. Five-year outcomes after prostatectomy or radiotherapy for prostate cancer: the prostate cancer outcomes study. J Natl Cancer Inst 2004;96:1358–1367. http://dx.doi.org/10.1093/jnci/djh259. 3. Edwards P, Roberts I, Clarke M, DiGuiseppi C, Pratap S, Wentz R, et al. Increasing response rates to postal questionnaires: systematic review. BMJ 2002;324:1183. http://dx.doi.org/10. 1136/bmj.324.7347.1183. 4. Harrison RA, Cock D. Increasing response to a postal survey of sedentary patients — a randomised controlled trial [ISRCTN45665423]. BMC Health Serv Res 2004;4:31. http://dx.doi.org/ 10.1186/1472-6963-4-31. 5. Nakash RA, Hutton JL, Jorstad-Stein EC, Gates S, Lamb SE. Maximising response to postal questionnaires—a
8.
9.
10.
systematic review of randomised trials in health research. BMC Med Res Methodol 2006;6:5. http://dx.doi.org/10. 1186/1471-2288-6-5. Evans BR, Peterson BL, Demark-Wahnefried W. No difference in response rate to a mailed survey among prostate cancer survivors using conditional versus unconditional incentives. Cancer Epidemiol Biomarkers Prev 2004;13:277–278. Kelly BJ, Fraze TK, Hornik RC. Response rates to a mailed survey of a representative sample of cancer patients randomly drawn from the Pennsylvania Cancer Registry: a randomized trial of incentive and length effects. BMC Med Res Methodol 2010;10:65. http: //dx.doi.org/10.1186/1471-2288-10-65. Rosoff PM, Werner C, Clipp EC, Guill AB, Bonner M, Demark-Wahnefried W. Response rates to a mailed survey targeting childhood cancer survivors: a comparison of conditional versus unconditional incentives. Cancer Epidemiol Biomarkers Prev 2005;14:1330–1332. http://dx.doi.org/10. 1158/1055-9965.EPI-04-0716. Kasprzyk D, Montano DE, St Lawrence JS, Phillips WR. The effects of variations in mode of delivery and monetary incentive on physicians' responses to a mailed survey assessing STD practice patterns. Eval Health Prof 2001;24: 3–17. Gundrum JD, Go RS. Cancer in the oldest old in the United States: current statistics and projections. J Geriatr Oncol 2012;3: 299–306. http://dx.doi.org/10.1016/j.jgo.2012.08.003.
Available online at www.sciencedirect.com
ScienceDirect Short communication
Effects of a gift certificate incentive and specialized delivery on prostate cancer survivors' response rate to a mailed survey: A randomized-controlled trial☆ Jennifer Bakana,⁎, Bing Chena,1 , Cheryl Medeiros-Nancarrowa , Jim C. Hub,2 , Philip W. Kantoff c , Christopher J. Recklitisa a
Perini Family Survivors' Center, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA Division of Urology, Brigham and Women's Hospital, 45 Francis Street, Boston, Boston, MA 02115, USA c Division of Solid Tumor Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA b
AR TIC LE I N FO
ABS TR ACT
Article history:
Objectives: Most men diagnosed with prostate cancer become long-term survivors, but are at
Received 31 July 2013
risk for medical late-effects that can affect their long-term health. Mailed surveys are well
Received in revised form
suited to study late-effects in this population, but low response rates can compromise survey
10 September 2013
validity. This study investigated whether an unconditional $5.00 gift certificate incentive or
Accepted 25 November 2013
Priority Mail delivery increased prostate cancer survivors' response to mailed surveys.
Available online 17 December 2013
Materials and Methods: 976 participants (mean age = 66.8 years), 2–8 years post-diagnosis, were randomized to one of four groups: Incentive; Priority Mail; Incentive & Priority Mail; or Control.
Keywords:
After an introductory letter, initial study packets were mailed based on randomization; 46 days
Mailed surveys
later, a second study packet was mailed to all non-responders by First-Class Mail.
Response rates
Results: The first mailing yielded a significant variation in response rates across groups
Cancer survivorship
(χ2 = 9.34; p = 0.025). Priority Mail (64.7%; p = 0.008) and Incentive & Priority Mail (63.6%; p =
Prostate cancer
0.016) groups had significantly higher response rates than Controls (52.9%). After the second
Mailing methods
mailing, the overall response rate increased significantly from 59.6% to 71.4% (p < 0.001); however, response rates no longer differed across groups (range, 69.3% [Incentive group] to 73.9% [Priority Mail group]). Conclusions: Long-term prostate cancer survivors' response rates to mailed surveys increased with the use of Priority Mail and a repeat survey mailing, but the unconditional gift certificate incentive was not supported in this population. By identifying and applying specialized survey methods, studies targeting survivors of prostate cancer and other geriatric cancers may improve response rates, thus limiting a source of potential bias. © 2013 Elsevier Ltd. All rights reserved.
☆ Financial support: Research support was provided by a grant from the American Foundation for Suicide Prevention (PRG-1-10-156; Recklitis). ⁎ Corresponding author. Tel.: + 1 617 632 3883; fax: +1 617 632 2473. E-mail address: [email protected] (J. Bakan). 1 Present address: Women's Health Unit, 801 Massachusetts Avenue, Crosstown Building, 1st Floor, Boston, MA 02118, USA. 2 Present address: Department of Urology, David Geffen School of Medicine at the University of California Los Angeles, 924 Westwood Boulevard, Los Angeles, CA 90095, USA. 1879-4068/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jgo.2013.11.005
128
1.
J O U RN A L OF GE RI A TR I C O NC O LOG Y 5 ( 20 1 4 ) 1 2 7 –1 3 2
Introduction
Prostate cancer is the most common cancer diagnosed among men in the United States, with nearly two-thirds of new diagnoses made in men aged 65 or older [1]. Due to improved detection and treatment, the majority of men diagnosed with prostate cancer today will become long-term survivors, joining the more than 2.5 million prostate cancer survivors living in the US [1]. Despite improvements in care, prostate cancer survivors are at risk for a variety of post-treatment complications [2], and there is growing interest in studying the emergence of these late-effects and their impact on long-term health. Mailed surveys are potentially valuable tools for studying prostate cancer survivors' outcomes, as surveys can reach a representative sample quickly and economically [3]. However, low response rates may lead to selection bias and compromised survey validity [3]. This vulnerability of mailed survey methodology has spurred a large body of research, demonstrating that a variety of survey techniques, including unconditional monetary incentives, pre-notification, follow-up reminders, stamped return envelopes, and specialized delivery methods, can increase response rates, at least in some populations [3–5]. Despite considerable evidence supporting methods to increase survey response, extant research has often focused on non-cancer populations and samples of younger individuals, making it unclear whether findings in these populations can be generalized to prostate cancer survivors or other geriatric cancer survivors. In addition, the few studies that have systematically investigated methods to increase response rates to mailed surveys in patients with cancer and survivors have produced inconsistent results [6,7], with some investigators speculating that results in older survivors may differ from those found in younger cancer survivors [6]. The present study aimed to address the knowledge gap in mailed survey methodology in prostate cancer survivors by determining the effectiveness of a token unconditional incentive (gift certificate) and specialized delivery (Priority Mail) in a cohort of long-term prostate cancer survivors. Unconditional incentives were selected because they have been shown to enhance response rates in a variety of populations [3], but the few studies that have investigated incentives in cancer survivors have produced contradictory results [6,8]. Specialized delivery was selected because its utility in patient populations, including cancer survivors, has been understudied, despite some supporting evidence in physician populations [9].
2.
Materials and Methods
2.1.
Study Population
This study was part of a cross-sectional study of health outcomes in prostate cancer survivors, who were 2 to 8 years post a prostate cancer diagnosis. Potential participants (n = 1500) were randomly selected from an existing cohort of English-speaking patients seen at a single cancer center in Boston, Massachusetts. This initial sample was screened for eligibility (living with a current US address) using the Social Security Death Index and National Change of Address
databases; current addresses were verified using publicly available online databases. After verification, 1000 survivors were randomly selected as the target sample for this study. Survey responders (n = 697) had an average age of 67.0 years (SD = 8.0) (Table 1). Responders were similar to non-responders (n = 279) in terms of current age, age at prostate cancer diagnosis, and time since diagnosis (all p > 0.05) (Table 1). Most responders were Caucasian, non-Hispanic (94.8%); although this was also true of non-responders (85.1%), non-Caucasians had significantly lower response rates than Caucasian, nonHispanics (47.4% vs. 74.2%; χ2 = 25.05; p < 0.001).
2.2.
Study Procedures
Participants were randomly assigned to one of four groups: (1) Incentive; (2) Priority Mail; (3) Incentive & Priority Mail; or (4) Control (no incentive and no Priority Mail). The incentive was a $5.00 gift certificate to a nationally available fast-food restaurant, stapled to the study packet. Priority Mail was delivered by the United States Postal Service (USPS), in a specially marked 12.5 × 9.5 in. Priority Mail envelope, at a cost of $5.60 per envelope. All other mailings were delivered by USPS First-Class Mail in a 10 × 13 in. envelope, at a cost of approximately $1.30 per envelope. Mailings to all groups were addressed to the intended participant using a typed label, and included a personalized cover letter, the 10-page survey, a resource sheet, and a postagepaid, pre-addressed return envelope. The survey itself assessed the participant's demographic and medical characteristics, cancer treatment history, health, and quality of life. Prior to the initial survey mailing, all groups received an introductory letter delivered by First-Class Mail. Letters were personalized by name, and omitted information regarding the incentive or delivery method used in later mailings. The letter described the study and provided a toll-free number to decline participation. Sixty days after the introductory letters, participants received the initial study packet based on randomized groups. Forty-six days after this initial mailing, a second study packet, which included a personalized reminder letter and a copy of the survey, was mailed to non-responders by First-Class Mail. Accrual was closed after 100 days from the initial survey mailing. Surveys returned within 48 days of the first survey mailing were considered responders to the first mailing, while surveys returned between 49 and 100 days after the first survey mailing were considered responders to the second mailing. All procedures were approved by the cancer center's Institutional Review Board. Eight survivors declined study participation after the introductory letter, but prior to the first mailing, and were excluded from analyses. Nine surveys were returned as undeliverable, and 7 were returned with notification of patient death, yielding an evaluable sample of 976 (Incentive, n = 244; Priority Mail, n = 241; Incentive & Priority Mail, n = 247; and Control, n = 244) (Fig. 1).
2.3.
Statistical Analysis
Independent sample t-tests and chi-squared tests were computed to assess for differences between responders and non-responders on demographic variables. Study-wide response rates and rates for the four randomized groups were calculated for the first and second mailings, and these were
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Table 1 – Demographic and medical characteristics of responders and non-responders (N = 976). Responders (n = 697) Characteristic Demographic characteristics Current age (years) Age at diagnosis (years) Years since diagnosis Race/ethnicity African American, non-Hispanic Caucasian, non-Hispanic Hispanic Asian or Pacific Islander Native American or Alaskan Native Other/mixed Education Less than high school High school graduate Training after high school/some college College graduate Postgraduate level training Marital status Married/living as married Never married Widowed Divorced/separated/not living as married Annual household income ≤$29,999 $30,000–$49,999 $50,000–$74,999 $75,000–$99,999 ≥$100,000 Employment status d Working full-time Working part-time Retired Disabled, unable to work Unemployed Other Medical characteristics Prostate cancer treatment d Prostate surgery Hormonal therapy Orchiectomy Radiation therapy Chemotherapy Metastases diagnosis No Yes Prostate cancer recurrence/relapse No Yes Rising/variable PSA Other cancer treatment No Yes
n (%)
M (SD)
Non-responders (n = 279)
n missing
n (%)
67.0 (8.0) 61.6 (8.0) 4.9 (1.7)
M (SD)
n missing
5
11 30 (11.2) 228 (85.1) 4 (1.5) 2 (0.7) 0 (0) 4 (1.5) c
1 23 56 143 199 275
(3.3) (8.0) (20.5) (28.6) (39.5)
602 24 24 46
(86.5) (3.4) (3.4) (6.6)
40 59 133 121 319
(6.0) (8.8) (19.8) (18.0) (47.5)
1
25
273 (39.2) 94 (13.5) 326 (46.8) 19 (2.7) 24 (3.4) 11 (1.6)
393 (57.0) 267 (38.6) 6 (0.9) 338 (48.8) 59 (8.5)
a
−1.74 −1.59 −0.58
66.0 (8.7) 60.7 (8.7) 4.9 (1.7)
18 (2.6) 656 (94.8) 4 (0.6) 2 (0.3) 6 (0.9) 6 (0.9)
t or χ2
7 6 6 4 6 26
603 (89.9) 68 (10.1) 21 597 (88.3) 68 (10.1) 11 (1.6) 11 509 (74.2) 177 (25.8)
M = mean; SD = standard deviation; χ2 = chi-squared test; PSA = prostate-specific antigen. *p < 0.001. a t-test calculated for continuous variables; chi-squared test calculated for categorical variables. b Chi-squared test calculated for Caucasian, non-Hispanic versus non-Caucasian only. c Includes other race/ethnicity only; mixed race/ethnicity unknown from prostate cancer cohort dataset (Oh et al., 2006). d Percentage not equal to 100%; categories are not mutually exclusive.
25.05*
b
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Fig. 1 – Randomization of study sample and response rates.
rates differed significantly across randomized groups (χ2 = 9.34; p = 0.025). Compared to Controls, response rates were significantly higher for the Priority Mail (52.9% vs. 64.7%; Z = 2.65; p = 0.008) and Incentive & Priority Mail (52.9% vs. 63.6%; Z = 2.40; p = 0.016) groups; no differences were detected between the Control and Incentive groups (52.9% vs. 57.4%; Z = 1.00; p = 0.32). The logistic regression of survey return as a function of the incentive and delivery conditions was significant (χ2 = 9.33; p = 0.025), indicating that those who received a survey by Priority Mail were more likely to return it than those who did not (OR = 1.64; p = 0.008; 95% CI: 1.14–2.36).
compared using chi-squared tests and Z-tests. Logistic regression was also used to examine the impact of the incentive and delivery conditions on response rate. These two variables and an incentive × Priority Mail interaction term were entered simultaneously into the logistic model.
3.
Results
The initial mailing to 976 eligible prostate cancer survivors yielded an overall response rate of 59.6% (n = 582). Response
Table 2 – Logistic regression models of the effect of delivery and incentive conditions on proportion of surveys returned (N = 976). Proportion of surveys returned Condition
Main effect Interaction
Main effect Interaction
FIRST MAILING Model Incentive Priority Mail Incentive × Priority Mail SECOND MAILING Model Incentive Priority Mail Incentive × Priority Mail
B
SE
OR (95% CI)
0.18 0.49** −0.23
0.18 0.19 0.26
1.20 (0.84–1.72) 1.64 (1.14–2.36) 0.79 (0.47–1.33)
−0.08 0.15 −0.03
0.20 0.20 0.28
0.93 (0.63–1.36) 1.16 (0.78–1.73) 0.97 (0.56–1.69)
χ2 9.33*
1.30
CI = confidence interval; SE = standard error; OR = odds ratio; χ2 = chi-squared test. *p < 0.05; **p < 0.01.
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Effects for the incentive condition and the incentive ×Priority Mail interaction were not significant (all p > 0.05) (Table 2). After the second survey mailing, 115 additional survivors responded, significantly increasing the overall response rate to 71.4% (Z = 5.48; p < 0.001) (Fig. 1). Within randomized groups, response rates increased significantly from the first to second mailing in the Incentive (57.4% vs. 69.3%; Z = 2.72; p = 0.006), Priority Mail (64.7% vs. 73.9%; Z = 2.17; p = 0.03), and Control (52.9% vs. 70.9%; Z = 4.20; p < 0.001) groups, but not in the Incentive & Priority Mail group (63.6% vs. 71.7%; Z = 1.92; p = 0.055). At the end of the accrual period, there were no significant differences in response rates across groups (χ2 = 1.30; p =0.73). The logistic regression of total response rate as a function of incentive and delivery conditions was not significant (χ2 = 1.30; p = 0.73) (Table 2).
4.
Discussion
Results indicate that specialized delivery methods can increase response rates in long-term prostate cancer survivors, but these effects may differ from those seen in some other populations. Specifically, prostate cancer survivors were most likely to return the first survey when it was delivered by Priority Mail. The positive effect of Priority Mail in prostate cancer survivors studied here is similar to the effect of specialized delivery (e.g., Federal Express and recorded delivery) found in surveys of health care providers [3,9]. Studies in a variety of populations support the use of unconditional incentives to increase survey response rates [3,8], but this approach was not supported here. Contrary to expectations, the gift certificate incentive had no effect on prostate cancer survivors' likelihood of responding. Of note, this negative finding for the unconditional gift card incentive is consistent with at least one study in patients with prostate cancer [7] and a second in prostate cancer survivors [6], which found unconditional incentives had no effect on response to mailed surveys. This lack of effect of incentives on response rate in prostate cancer groups may be related to the older age of prostate cancer survivors compared to other groups [6]. Consistent with reports among several patient groups [5], the reminder letter and second survey used in the present study also significantly increased the likelihood of response. In fact, after the second mailing, the increase in returned surveys was so large that differences between the randomized mailing groups were no longer significant. This study has several limitations. Most notably, only one type of incentive was studied. Different types of incentives (e.g., cash, gift cards, sweepstakes, etc.) could appeal differently to different groups, and the effect of incentives on response rate in prostate cancer survivors may depend on types of incentives offered. Additionally, because this study utilized several methods shown to increase response rates in other populations (e.g., pre-notification letter [3,4], postage-paid pre-addressed return envelope [3], personalization at each mailing [3], and a second survey mailing with a duplicate survey [3]), results presented here may not be generalizable to studies lacking these features. As noted, prostate cancer survivors in this study were English-speaking, predominately Caucasian, of a relatively high socioeconomic status, and recruited from a single cancer
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center; thus, results may not be generalizable to other sociodemographic groups. Results of this study have practical implications for future surveys in the growing population of prostate cancer survivors. Though Priority Mail has not been widely investigated in cancer populations, our finding that it effectively increased response rate should encourage more widespread use of specialized mailing in future surveys to prostate cancer survivors and, potentially, other patient groups. Priority Mail does have additional costs to be considered, especially because, with additional time, a second regular mailing can be just as effective, as seen here. A second regular mailing also had associated costs, including postage, survey reproduction, return envelopes, and staff time. A second mailing without specialized delivery may be a viable option whenever time to receipt of a completed survey is not a priority, whereas Priority Mail may be desirable when rapid survey response is valued or survey printing costs are high. Ultimately, researchers must determine the appropriate tradeoff between time and costs for each study. With this being the second study to show no effect of an incentive on survey return among prostate cancer populations [6,7], and with similar results seen in other patient populations [5], there is little evidence to support its use in prostate cancer survivors. Future research may seek to investigate other forms of incentives (e.g., cash, sweepstakes, etc.), but non-monetary incentives of limited financial value should not be considered effective for increasing response rates in prostate cancer survivors. Finally, the results reported here serve as a reminder that response to survey methods can vary significantly across populations. Unconditional incentives, though widely used and supported in studies of younger and less medicallyinvolved populations [3,8], were not found to be effective in increasing response rates in prostate cancer survivors. Future studies should investigate the generalizability of our findings to other groups of geriatric patients with cancer, including women and men with other cancer types. As the population of older cancer survivors continues to grow [10], surveys that can quantify the health needs, treatment late-effects, and quality of life of geriatric cancer survivors will grow in importance. The literature on survey methods provides several promising techniques to increase survey responses, but specifically validating them in geriatric cancer survivors is critical in determining their effectiveness in this growing population.
Disclosure and Conflict of Interest Statement The authors indicate no conflict of interest to disclose.
Author Contributions Study concept: J.C. Hu, P.W. Kantoff, C.J. Recklitis Study design: C.J. Recklitis Data acquisition: B. Chen, C. Medeiros-Nancarrow Quality control of data and algorithms: C. Medeiros-Nancarrow Data analysis and interpretation: J. Bakan, B. Chen, C.J. Recklitis Statistical analysis: J. Bakan, B. Chen Manuscript preparation and editing: J. Bakan, C.J. Recklitis
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Manuscript review: J. Bakan, B. Chen, C. Medeiros-Nancarrow, J.C. Hu, P.W. Kantoff, C.J. Recklitis All authors approved the final version of the manuscript.
6.
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