Date of this Version
12-15-2014
Document Type
Article
Abstract
Objectives Conducting health surveys with community-based random samples are essential to capture an otherwise unreachable population, but these surveys can be biased if the effort to reach participants is insufficient. This study determines the desirable amount of effort to minimise such bias.
Design A household-based health survey with random sampling and face-to-face interviews. Up to 11 visits, organised by canvassing rounds, were made to obtain an interview.
Setting Single-family homes in an underserved and understudied population in North Miami-Dade County, Florida, USA.
Participants Of a probabilistic sample of 2200 household addresses, 30 corresponded to empty lots, 74 were abandoned houses, 625 households declined to participate and 265 could not be reached and interviewed within 11 attempts. Analyses were performed on the 1206 remaining households.
Primary outcome Each household was asked if any of their members had been told by a doctor that they had high blood pressure, heart disease including heart attack, cancer, diabetes, anxiety/ depression, obesity or asthma. Responses to these questions were analysed by the number of visit attempts needed to obtain the interview.
Results Return per visit fell below 10% after four attempts, below 5% after six attempts and below 2% after eight attempts. As the effort increased, household size decreased, while household income and the percentage of interviewees active and employed increased; proportion of the seven health conditions decreased, four of which did so significantly: heart disease 20.4–9.2%, high blood pressure 63.5–58.1%, anxiety/depression 24.4–9.2% and obesity 21.8–12.6%. Beyond the fifth attempt, however, cumulative percentages varied by less than 1% and precision varied by less than 0.1%.
Conclusions In spite of the early and steep drop, sustaining at least five attempts to reach participants is necessary to reduce selection bias.
Identifier
FIDC000599
Recommended Citation
Messiah A, Castro G, Rodríguez de la Vega P, et al Random sample community-based health surveys: does the effort to reach participants matter? BMJ Open 2014;4:e005791. doi: 10.1136/bmjopen-2014-005791
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License
Rights Statement
In Copyright - Non-Commmercial Use Permitted. URI: http://rightsstatements.org/vocab/InC-NC/1.0/
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. In addition, no permission is required from the rights-holder(s) for non-commercial uses. For other uses you need to obtain permission from the rights-holder(s).
Comments
Originally published in BMJOpen.