Increasing response to a postal survey of sedentary patients - a randomised controlled trial [ISRCTN45665423]

Background

A systematic review identified a range of methods, which can influence response rates. However, analysis specific to a healthcare setting, and in particular, involving people expected to be poor responders, was missing, We examined the effect of pre-warning letters on response rates to a postal survey of sedentary patients whom we expected a low rate of response.

Methods

Participants were randomised to receive a pre-warning letter or no pre-warning letter, seven days before sending the main questionnaire. The main questionnaire included a covering letter and pre-paid return envelope. After seven days, non-responders were sent a reminder letter and seven days later, another reminder letter with a further copy of the questionnaire and return envelope.

Results

627 adults, with a mean age of 48 years (SD 13, range 18 to 78) of whom 69.2% (434/627) were women, were randomised. 49.0% (307/627) of patients were allocated to receive a pre-warning letter and 51.0% (320/627) no pre-warning letter, seven days in advance of posting the main questionnaire. The final response rate to the main questionnaire was 30.0% (92/307) amongst those sent a pre-warning letter and 20.9% (67/320) not sent a pre-warning letter, with an adjusted odds ratio of 1.60 (95% CI 1.1, 2.30).

Conclusions

The relatively low cost method of sending a pre-warning letter had a modest impact on increasing response rates to a postal questionnaire sent to a group of patients for whom a low response rate was anticipated. Investigators should consider incorporating this simple intervention when conducting postal surveys, to reduce the potential for nonresponse bias and to increase the study power. Methods other than postal surveys may be needed however when a low response rate to postal surveys is likely.     

Postal surveys of physicians gave superior response rates over telephone interviews in a randomized trial

BACKGROUND AND OBJECTIVES: To compare general practitioner (GP) response to a telephone interview with response to a postal survey with three reminders in a randomized controlled trial. METHODS: GPs were randomly assigned to either a telephone interview or a postal survey. GPs in the telephone group were mailed a letter of invitation and asked to undertake a telephone interview. GPs in the postal group were mailed a letter of invitation and questionnaire. Non-responders were sent up to three reminders, the final by registered post. Response rates were calculated for each group. RESULTS: 416 GPs were randomized to the telephone interview and 451 to the postal survey. Eighty-six in the telephone group and 30 in the postal were ineligible. One hundred thirty-four GPs completed the telephone interview with a response rate of 40.6% (95% confidence interval [CI]: 35.3%, 46.1%). Two hundred fifty-two GPs completed the postal survey with a response rate of 59.9% (95%CI: 55.0%, 64.6%). The difference in response was 19.3% (95%CI: 12.2%, 26.3%). CONCLUSIONS: These results show that postal surveys with three reminders can have superior response rates compared with a telephone interview.     

Increasing response rates of gynaecologists to a survey: a randomised trial of telephone prompts

Abstract: This study used a randomised controlled trial to evaluate the effectiveness of telephone prompts to increase the response rate of gynaecologists to a survey. A nine-page questionnaire about management of women with abnormal Pap smears was mailed to Fellows of the Royal Australian College of Obstetricians and Gynaecologists. A random sample was contacted in advance by telephone, and nonrespondents received a telephone reminder 14 days after the initial mail-out. The control group was mailed questionnaires and a reminder letter conventionally. On Day 25, nonresponders in both groups were mailed a second questionnaire. Of the intervention group, 84 per cent responded to the survey compared to 69 per cent of the control group (P = 0.005). A telephone call in anticipation of a mailed questionnaire is highly recommended.     

Postal survey on airborne occupational exposure and respiratory disorders in Norway: causes and consequences of non-response.

STUDY OBJECTIVE--The aim was to examine causes for non-response in a community survey, and how non-response influences prevalence estimates of some exposure and disease variables, and associations between the variables. DESIGN--This was a cross sectional questionnaire study with two reminder letters. The questionnaire asked for information on smoking habits, occupational airborne exposure and respiratory disorders. SETTING--A random sample of 4992 subjects from the general population aged 15-70 years of Hordaland County, Norway. MAIN RESULTS--The overall response rate was 90%, with a 63% response to the initial letter. The response rates to the first and second reminder letters were 56% and 36% respectively. In 20% of the non-respondents an uncompleted questionnaire was returned with cause for non-response; in two thirds of these the cause for non-response was that the subject was not resident at the mailing address. A home visit to a random sample of 50 urban non-respondents provided further information on 29 subjects. A wrong address at the Central Population Registry and the subject's feeling of lack of personal benefit from a postal survey were the major reasons for non-response. Smokers were late respondents and subjects with respiratory disorders tended to be early respondents. CONCLUSION--The main reasons for non-response were a wrong mailing address and a feeling of lack of personal benefit from responding. Using only the initial letter would have changed the estimated prevalence of smokers from 39% to 35%. Otherwise, the estimated prevalence of the exposure and disease variables as well as the associations between them were only slightly changed after including the respondents to the first and second reminder letters.     

Primer postcard improves postal survey response rates

OBJECTIVE: This study measures the effect of an intervention to improve mailed survey response rates. METHOD: A randomised controlled trial of a 'primer' postcard was performed as part of a large survey in Victoria in 1997. Prior to the survey mailout, half the sample of 800 general practitioners supplied by the Health Insurance Commission was sent, at random, a primer card to request prompt return of the survey. RESULTS: The intervention resulted in a more rapid return of the survey and improved overall response rates from 60% to 66%. The increased cost per returned survey (40 cents) was largely offset by fewer non-responders requiring follow-up. CONCLUSIONS: A primer postcard is a time and cost-efficient method to increase response rates in general practitioner surveys. IMPLICATIONS: Public health researchers should consider implementing this intervention to improve response rates to postal surveys. Reports of other response maximising strategies should report the cost per returned survey to allow better comparison.     

A very low response rate in an on-line survey of medical practitioners

OBJECTIVE: To report on the response rate achieved in a survey of medical practitioners and discuss the reasons for it. METHOD: An on-line (internet-based) survey of all 609 registered pharmacotherapy prescribers in Victoria and Queensland; invitations to participate were sent by mail in late April 2007, and one reminder letter in late May 2007. RESULTS: Six hundred and nine invitation letters were mailed, nine were returned to sender, and 52 questionnaires completed, making the overall response rate 52/600 = 8.7%. The response rate in Queensland was 13.2% (16/121), and in Victoria 7.5% (36/479). CONCLUSIONS: Despite utilising sound techniques, our response rate was much lower than those achieved in recent Australian paper-based surveys of medical practitioners. It is possible that the issue being addressed (injecting-related injuries and diseases) was not of high priority for many invitees, leading to reduced response. IMPLICATIONS: On-line surveys are not yet an effective method of collecting data from Australian medical practitioners; researchers should continue to use paper questionnaires for maximum response.     

Participation in a mail survey: role of repeated mailings and characteristics of nonrespondents among recent mothers

This study analysed the characteristics of respondent and nonrespondent mothers at each stage of a survey procedure, from a initial questionnaire to a reminder letter and two repeated mailings. Of 938 mothers of liveborn children who, while maternity inpatients, received a questionnaire and information about a mail survey to follow 2 months later, 828 completed and returned the initial questionnaire, 708 agreed to participate in the mail survey and were sent the mail questionnaire, and 612 finally completed and returned the questionnaire at 2 months. There were differences between respondents and non-respondents for socio-demographic factors at each stage of the process. The final response rate to the mail questionnaire was higher among mothers who were younger, were breast feeding, and had more education, an occupation and fewer children. The characteristics of late respondents were intermediate between those of early to middle respondents and nonrespondents for age, educational level, breast feeding and occupation. Maternal and infant health varied only slightly according to response status. Repeated mailings increased response and diminished selection. A mail questionnaire after contact in a maternity ward is a cost-effective means of gathering data about a large sample of recent mothers and their children.     

Impact of a postcard versus a questionnaire as a first reminder in a postal lifestyle survey.

STUDY OBJECTIVE--The study aimed to consider the impact of two different types of reminder on response rates and costs in a postal survey. DESIGN--The study was a cross sectional survey. A self-completion lifestyle questionnaire was used. Those who did not respond after the initial mailing were randomly allocated to receive either a postcard or questionnaire as a first reminder. All outstanding non-responders received a questionnaire as a second reminder. SUBJECTS--A representative sample of 698 adults aged 16-70 was used, drawn from a family health services authority register. MAIN RESULTS--Postcard reminders were as effective as questionnaire reminders in increasing response whether one or two reminders are sent. The costs per response were calculated. Two questionnaires as reminders were found to be 1.7 times more expensive than a postcard plus questionnaire. Including the initial mailing, the cost per response using all questionnaires was 1.3 times the cost when a postcard was used for the first reminder. CONCLUSIONS--To increase the response to a postal survey effectively and economically, two reminders should be sent--first a postcard and then a questionnaire.     

Do incentives, reminders or reduced burden improve healthcare professional response rates in postal questionnaires? two randomised controlled trials

ABSTRACT: BACKGROUND: Healthcare professional response rates to postal questionnaires are declining and this may threaten the validity and generalisability of their findings. Methods to improve response rates do incur costs (resources) and increase the cost of research projects. The aim of these randomised controlled trials (RCTs) was to assess whether 1) incentives, 2) type of reminder and/or 3) reduced response burden improve response rates; and to assess the cost implications of such additional effective interventions. METHODS: Two RCTs were conducted. In RCT A general dental practitioners (dentists) in Scotland were randomised to receive either an incentive; an abridged questionnaire or a full length questionnaire. In RCT B non-responders to a postal questionnaire sent to general medical practitioners (GPs) in the UK were firstly randomised to receive a second full length questionnaire as a reminder or a postcard reminder. Continued non-responders from RCT B were then randomised within their first randomisation to receive a third full length or an abridged questionnaire reminder. The cost-effectiveness of interventions that effectively increased response rates was assessed as a secondary outcome. RESULTS: There was no evidence that an incentive (52% versus 43%, Risk Difference (RD) -8.8 (95%CI [MINUS SIGN]22.5, 4.8); or abridged questionnaire (46% versus 43%, RD [MINUS SIGN]2.9 (95%CI [MINUS SIGN]16.5, 10.7); statistically significantly improved dentist response rates compared to a full length questionnaire in RCT A. In RCT B there was no evidence that a full questionnaire reminder statistically significantly improved response rates compared to a postcard reminder (10.4% versus 7.3%, RD 3 (95%CI [MINUS SIGN]0.1, 6.8). At a second reminder stage, GPs sent the abridged questionnaire responded more often (14.8% versus 7.2%, RD [MINUS SIGN]7.7 (95%CI [MINUS SIGN]12.8, -2.6). GPs who received a postcard reminder followed by an abridged questionnaire were most likely to respond (19.8% versus 6.3%, RD 8.1%, and 9.1% for full/postcard/full, three full or full/full/abridged questionnaire respectively). An abridged questionnaire containing fewer questions following a postcard reminder was the only cost-effective strategy for increasing the response rate ([POUND SIGN]15.99 per response). CONCLUSIONS: When expecting or facing a low response rate to postal questionnaires, researchers should carefully identify the most efficient way to boost their response rate. In these studies, an abridged questionnaire containing fewer questions following a postcard reminder was the only cost-effective strategy. An increase in response rates may be explained by a combination of the number and type of contacts. Increasing the sampling frame may be more cost-effective than interventions to prompt non-responders. However, this may not strengthen the validity and generalisability of the survey findings and affect the representativeness of the sample.     

Evaluation of the New South Wales Cancer Council Pap Test Reminder Service

Abstract: This study aimed to assess the effect of reminder letters on Pap test rates for women enrolled on the New South Wales Cancer Council Pap Test Reminder Service and to identify predictors of response to the letter. Ten weeks after they had received their reminder letter a questionnaire was sent to 3086 women. It was completed by 1525 (49 percent) women, of whom 1393 (91 percent) said they had received their reminder letter. Of these 1393, 48 per cent (95 per cent confidence interval 46 per cent to 51 per cent) reported having had a Pap test within 10 weeks of the reminder letter arriving. The proportion of women having a Pap test in response to the reminder letter did not differ by age, region of residence or language spoken at home. Women were less likely to have had a Pap test if they did not know how they were enrolled, were of low socioeconomic status or had some tertiary education. Women on the reminder service have 15-month rescreening rates at least 9 per cent higher than other women in New South Wales; for women aged 50 to 69 in nonmetropolitan areas the increase is estimated at 19 per cent. Reminder services may be a cost-effective way to increase Pap test rescreening rates. Reminder services need accurate records and to follow up changes in address and date of next test.     

Contribution of follow-up of nonresponders to prevalence and risk estimates: a Norwegian respiratory health survey

Achieving a high response rate is often expensive and time consuming. Does an extensive survey effort change prevalence estimates and exposure-disease relations? In 1998-1999, the authors conducted a population-based respiratory health survey in two Norwegian counties (Oslo, n = 20,000; Hordaland, n = 5,000) of a random sample of the adult population aged 15-70 years. A postal questionnaire was mailed, with as many as two reminder letters. A 25% random sample of postal nonresponders was contacted by ordinary or cellular telephone. Cumulative response rates after the first mailing, first reminder, second reminder, and telephone follow-up were 42.7%, 60.7%, 68.3%, and 79.9%, respectively. Compared with initial postal responders, responders at later stages were younger, and more were male. Late responders had a lower educational level, were more often smokers, and were occupationally exposed to dusts or gases more frequently. After the authors adjusted for these factors, late responders were found to have less asthma, attacks of breathlessness, and hay fever. Hardly any changes in prevalences and odds ratios were noted when initial responders were compared with all responders. The additional contribution of sending reminder letters and conducting a telephone follow-up to prevalence estimates and the exposure-disease relation was small. A single letter would have produced nearly the same prevalence estimates and risk factor associations.     

Improving referral compliance after public cholesterol screening.

BACKGROUND. Noncompliance with referral to a physician for retesting and diagnosis is a concern in public cholesterol screening. METHODS. Participants (n = 2109) were referred by a health professional or lay communicator and randomly assigned to a coupon offer, referral reminder letter, or control group. A questionnaire was completed at screening, and a telephone interview was conducted 5 months later. RESULTS. Physician visit rates showed no professional or lay differences. For "no history" subjects, the behavioral interventions were effective compared with controls (coupon = 60.7% and reminder = 57.7% vs control = 46.1%). With professional counseling, only the coupon was effective; for lay counseling, both coupon and reminder yielded higher visit rates. Adjusted for sociodemographics, heart disease risk factors, and health perceptions, the intervention effects remained (professional-coupon offer: odds ratio [OR] = 1.94, 95% confidence interval [CI] = 1.21, 3.09; professional-reminder letter: OR = 1.04, 95% CI = 0.67, 1.63; lay-coupon offer: OR = 2.52, 95% CI = 1.52, 4.18; and lay-reminder letter: OR = 3.10, 95% CI = 1.83, 5.22). CONCLUSIONS. For unaware participants, lay counselors and referral follow-up efforts tailored to specific cholesterol risk groups are indicated.     

Cost-effectiveness comparison of five interventions to increase mammography screening

BACKGROUND: Mammography is the primary method used for breast cancer screening. However, compliance with recommended screening practices is still below acceptable levels. This study examined the cost-effectiveness of five combinations of physician recommendation and telephone or in-person individualized counseling strategies for increasing compliance with mammography. METHODS: There were 808 participants who were randomly assigned to one of six groups. A logistic regression model with compliance as the dependent variable and group as the independent variable was used to test for significant differences and a ratio of cost to improvement in mammogram compliance evaluated the cost-effectiveness. RESULTS: Three of the interventions (in-person, telephone plus letter, and in-person plus letter) had significantly better compliance rates compared with the control, physician letter, or telephone alone. However, when considering costs, only one emerged as the superior strategy. The cost-effectiveness ratios for the five interventions show that telephone-plus-letter is the most cost-effective strategy, achieving a 35.6% mammography compliance at a marginal cost of $0.78 per 1% increase in women screened. CONCLUSIONS: A tailored phone prompt and physician reminder is an effective and economical intervention to increase mammography. Future research should confirm this finding and address its applicability to practice.     

A comparison of mail, telephone, and home interview strategies for household health surveys.

The method of data collection in household health surveys can be a major determinant of cost and data quality. A survey strategy can comprise mail, telephone, or home interview methods, individually or in combination to follow up non-respondents. The purpose of this study in Montreal was to compare cost and data quality of various strategies. Strategies which began with mail or telephone contact, followed by the two other methods, provided response rates as high as a home interview strategy (all between 80 and 90 per cent), for one-half the cost of home interviews when used as the sole method. The telephone response rate was higher than the mail response rate. Comparing different follow-up approaches to strategies beginning with mail or telephone, it proved less costly, and equally effective, to use home interviewing as a last resort for persistent non-respondents. Validity of response (comparing individual responses with records of a government health insurance data bank) and willingness to answer sensitive questions were greatest in mail strategy.     

Increasing Colorectal Cancer Screening in an Overdue Population: Participation and Cost Impacts of Adding Telephone Calls to a FIT Mailing Program

Many people who live in rural areas face distance barriers to colonoscopy. Our previous study demonstrated the utility of mailing fecal immunochemical tests (FIT) to average risk patients overdue for colorectal cancer (CRC screening). The aims of this study were to determine if introductory and reminder telephone calls would increase the proportion of returned FITs as well as to compare costs. Average risk patients overdue for CRC screening received a high intensity intervention (HII), which included an introductory telephone call to see if they were interested in taking a FIT prior to mailing the test out and reminder phone calls if the FIT was not returned. This HII group was compared to our previous low intensity intervention (LII) where a FIT was mailed to a similar group of veterans with no telephone contact. While a higher proportion of eligible respondents returned FITs in the LII (92 vs. 45 %), there was a much higher proportion of FITs returned out of those mailed in the HII (85 vs. 14 %). The fewer wasted FITs in the HII led to it having lower cost per FIT returned ($27.43 vs. $44.86). Given that either intervention is a feasible approach for patients overdue for CRC screening, health care providers should consider offering FITs using a home-based mailing program along with other evidence-based CRC screening options to average risk patients. Factors such as location, patient population, FIT cost and reimbursement, and personnel costs need to be considered when deciding the most effective way to implement FIT screening.     

An advance letter did not increase the response rates in a telephone survey: a randomized trial

ObjectiveTo test the impact of an advance letter on response and cooperation rates in a nationwide telephone survey, given previous inconsistent results.Study Design and SettingWithin the context of a larger telephone survey, 1,000 Australian households were randomly selected to take part in this trial. Half were randomly allocated to receive an advance letter, whereas the remainder did not receive any advance communication. Response and cooperation rates were compared between the two groups.ResultsA total of 244 interviews were completed, 134 of which were with households that had been sent an advance letter. Intention-to-treat analysis revealed no significant difference in response between those who had received a letter and those who had not (26.8% vs. 22.0%, respectively). In addition, there was no significant difference between the groups in terms of either cooperation (78.4% vs. 79.7%) or response rate (56.3% vs. 57.9%), and no clear differences emerged in terms of the demographic characteristics of the two groups.ConclusionAn advance letter was not seen to be effective in increasing response or cooperation rates in a nationwide telephone survey. Researchers should consider alternative methods of increasing participation in telephone surveys.     

Carer satisfaction with end-of-life care in Powys, Wales: a cross-sectional survey

A cross-sectional postal survey of bereaved carers was conducted in order to examine levels of satisfaction with services provided for people in their last year of life in the rural county of Powys, Wales, UK. A self-complete questionnaire, using a modified version of the Views of Informal Carers - Evaluation of Services instrument was sent to all bereaved carers of all those people dying of cancer in Powys between 1 April 1999 and 30 June 2001. Eight hundred and five (out of a possible of 815 people) were contacted and 407 agreed to receive the questionnaire. Out of these 407 individuals, 301 (74% of those who agreed to receive a questionnaire and 37% of the 815 contacted) returned a completed questionnaire. A single reminder letter was sent to non-responders. It was found that the majority of those who received help from district nurses or practice nurses (90%) said that they were excellent or good. However, nearly 40% of respondents reported needing more nursing help. More help was also needed from social care services. For 103 out of the 301 respondents, it was known that the deceased person wanted to die at home; only 44 did so. Only one-fifth of respondents had the opportunity to talk to someone from health and social services after their bereavement; a large majority (four-fifths) found this helpful. One-tenth of respondents reported untreated pain at home; however, there was evidence for an increasing proportion of those treated having received good pain relief. Although there are high levels of satisfaction with care and services received by Powys residents, deficits exist in relation to: symptom control, nursing help, assistance from social services with transport and bathing, communication, and bereavement support.     

Response patterns to a postal survey using a cervical screening register as the sampling frame

This study compared different types of respondent to a postal survey. A random sample of women aged 20-64 years (n = 4057) was selected from a population-based cervical screening register to examine their information experience during the screening programme. The initial response rate was 57%, and this increased to 81% after one reminder. Respondents were older (P < 0.0001) than non-respondents, but both groups were comparable with regard to attendance history for cervical screening (respondents 89.3%; non-respondents 89.1%) and normal smear test results (respondents 84.0%; non-respondents 81.4%). Early and late respondents were similar in age. Compared with late respondents, early respondents were more likely to live in highly affluent (P < 0.0001) and rural areas (P = 0.026). They were also more likely to be non-attenders (P < 0.0001), but they were less likely to have had inadequate smear results (P = 0.030) than late respondents. These results suggest that consideration should be given to factors other than sociodemographic differences when examining response patterns to postal surveys.     

Lifestyle surveys--the complete answer?

STUDY OBJECTIVES: These were as follows: to study incompleteness of data, herein called item non-response, generated by a self completion questionnaire; to identify the characteristics of item non-responders and the types of questions liable to high item non-response rates; and to discuss possible reasons for item non-response. DESIGN: Item non-response patterns in 12,307 responders (62%) to a representative postal survey based on a stratified sample drawn from family health services authorities' (FHSA) registers were investigated. MAIN OUTCOME MEASURES: Data were analysed for item non-response in three groups depending on when the questionnaire was returned (wave analysis). The overall completion rate of the questionnaire was examined and the natural logarithm of the proportion of completed questions was used as an outcome variable in multiple regression analysis. Item nonresponse to key questions and questions of different types was examined. RESULTS: Wave analysis: the overall completion rate of the questionnaire was 86% in questionnaires returned before the first reminder and 83%-84% in those sent back after subsequent reminders. Overall pattern of item non-response; respondents failed to complete a mean of 15% and a median of 10% of the questionnaire. All questions in the questionnaire had some item non-response, ranging from 1% to 85%. Completion rates were associated with gender, age, indicators of lower socioeconomic status, and general health status. Individual questions: particular types of questions were liable to have higher item non-response, for example, linked binary questions. CONCLUSIONS: Item non-response in population postal surveys is likely to present problems in the interpretation of data by introducing bias additional to that of total non-response. Item non-response does not increase greatly with later returns, suggesting that the quality of data across responses generated by two reminders is similar. There are obstacles to reducing item non-response, such as respondent error or socioeconomic and health characteristics of the general population, that cannot be totally overcome. However, the evidence that individuals tend to complete only options within questions that apply to them and their positive behaviour is useful information for those designing questionnaires and interpreting survey data.     

Patient views on reminder letters for influenza vaccinations in an older primary care patient population: a mixed methods study

OBJECTIVES: To explore the perspectives of older adults on the acceptability of reminder letters for influenza vaccinations. METHODS: We randomly selected 23 family physicians from each Family Health and Primary Care network participating in a demonstration project designed to increase the delivery of preventive services in Ontario. From the roster of each physician, we surveyed 35 randomly selected patients over 65 years of age who recently received a reminder letter regarding influenza vaccinations from their physician. The questionnaires sought patient perspectives on the acceptability and usefulness of the letter. We also conducted follow-up telephone interviews with a subgroup of respondents to explore some of the survey findings in greater depth. RESULTS: 85.3% (663/767) of patients completed the questionnaire. Sixty-five percent of respondents recalled receiving the reminder (n=431), and of those, 77.3% found it helpful. Of the respondents who recalled the letter and received a flu shot (n=348), 11.2% indicated they might not have done so without the letter. The majority of respondents reported that they would like to continue receiving reminder letters for influenza vaccinations (63.0%) and other preventive services (77.1%) from their family physician. The interview participants endorsed the use of reminder letters for improving vaccination coverage in older adults, but did not feel that the strategy was required for them personally. CONCLUSIONS: The general attitude of older adults towards reminder letters was favourable, and the reminders appear to have contributed to a modest increase in influenza vaccination rates.