Abstract
BackgroundA follow-up study on a cohort of stroke patients through a postal survey questionnaire 3 and 12 months after discharge from hospital was performed. The response rate at 3-months follow-up was lower than desired, and pre-contact by phone as a measure for increasing the response rate at 12 months was studied.MethodsThe study design was a randomized controlled trial on a cohort of 3 months follow-up-non-responders where the intervention group was pre-contacted with an aim to obtain an informal ’consent to receive’ the questionnaire before the 12-months survey was mailed, and the control group was not.The primary outcome was 45 days response rate; secondary outcome was 365 days response rate. The main analysis followed the intention to treat principle. A secondary, per-protocol analysis (i.e. subjects who were not reached by phone were reassigned to the control group) is included. Also included is a rudimentary cost-utility analysis, where we estimated the cost per additional response.ResultsOf the 235 subjects, 116 were randomized to the intervention group and 119 to the control group. 10 were excluded due to death (7 in the IG and 3 in the CG), 6 due to dementia (3 in the IG and 3 in the CG), and 2 (1 in the IG and 1 in the CG) for other reasons. The primary outcome was a response rate of 42.9 % in the intervention group, and 26.8 % in the control group, giving p =0.014, with estimated OR of 2.04 (95 % CI [1.16,3.64]). The secondary outcome had p =0.009 with OR 2.10 (95 % CI [1.20,3.70]). The as-per-protocol analyses gave stronger results with p =0.001 and p =0.003, respectively. The cost-utility analysis gave a time cost of 1 working hour per additional response.ConclusionsThe results are in line with previous research, and show that pre-contact has a positive effect on response rate also for a population of elderly with reduced health. Given the importance of high response rate in surveys, a cost of 1 working hour per additional response is likely to be worth while.Trial registrationRegistration with ISRCTN initiated on 05/21/2013 and finalised on 06/30/2014 with http://www.isrctn.com/ISRCTN31304930. Following the prospective submission in May 2013, there were no subsequent changes to the protocol. The recruitment started on 01/06/13, after initiation of public registration.
Highlights
MethodsThe study design was a randomized controlled trial on a cohort of 3 months follow-up-non-responders where the intervention group was pre-contacted with an aim to obtain an informal ’consent to receive’ the questionnaire before the 12-months survey was mailed, and the control group was not
A follow-up study on a cohort of stroke patients through a postal survey questionnaire 3 and 12 months after discharge from hospital was performed
It was discovered through the ongoing data collection that 6 patients (3 in each arm) suffered from known dementia, and these were excluded from the randomized controlled trial (RCT). 10 patients (7 in the intervention group (IG) and 3 in the control group (CG)) died before 12 months had passed from discharge from the Stroke Unit (SU); these were excluded
Summary
RCT The RCT was prospectively registered with Current Controlled Trials [5] on May 25th 2013 with International Standard RCT Number ISRCTN31304930. The main analysis of the effect of the pre-contact intervention on response rates is performed according to the principle of intention to treat for both the primary and the outcomes This means that the response rates calculated for the IG include those who could not be reached by telephone and patients who refused to have a questionnaire sent to them when contacted. The variable living with a spouse was included because the main protocol for mailing questionnaires involved printing the name of the spouse in addition to the name of the patient wherever a registered spouse existed on the same address This practise originated in a hope that it would be more likely that the questionnaires were opened and returned when two individuals were named on the envelope. Under the original NORSPOT project, ethical approval for sending out the questionnaires was approved without the necessity of obtaining prior consent
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