Article Text
Abstract
Objectives In addition to researcher-designed sampling biases, population-representative surveys for biomarker measurement of STIs often have substantial missingness due to non-contact, non-consent and other study-implementation issues. STI prevalence estimates may be biased if this missingness is related to STI risk. We investigated how accounting for sampling, interview non-response and non-provision of biological samples affects prevalence estimates in the third National Survey of Sexual Attitudes and Lifestyles (Natsal-3).
Methods Natsal-3 was a multistage, clustered and stratified probability sample of 16–74 year-olds conducted between 2010 and 2012. Individuals were sampled from all private residential addresses in Britain; respondents aged 16–44 were further sampled to provide a urine specimen based on characteristics including self-reported sexual behaviours. We generated prevalence estimates and confidence intervals for six STIs in five stages: first without accounting for sampling or non-response, then applying inverse-probability weights cumulatively accounting for interview sampling, interview non-response, urine sampling and urine non-response.
Results Interview non-completion occurred for 42.3% of interview-sampled individuals; urine non-completion occurred for 43.5% of urine-sampled individuals. Interview-sampled individuals, interview respondents, those selected for urine samples and those providing urine samples were each in turn slightly more at-risk for most STIs, leading to lower prevalence estimates after incorporating each set of weights. Researcher-controlled sampling had more impact than respondent-controlled response.
Conclusions Accounting for both sampling structures and willingness to interview or provide urine specimens can affect national STI prevalence estimates. Using both types of weights, as was done in Natsal-3, is important in reporting on population-based biomarker surveys.
- bacterial infection
- epidemiology (general)
- statistics
- HPV
- HIV
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Footnotes
Handling editor Deborah Williamson
Twitter @harlingg, @soazigclifton, @fienige
Contributors GH, SC, CHM and PS conceptualised and designed the study. GH conducted the analyses, summarised the results in tables and graphs, and wrote the first draft of the paper. All authors contributed to data interpretation and final revisions to the text. All authors read and approved the final manuscript.
Funding Natsal-3 was funded by grants from the Medical Research Council (G0701757) and the Wellcome Trust (084840), with contributions from the Economic and Social Research Council and Department of Health. GH is supported by a fellowship from the Wellcome Trust and the Royal Society (210479/Z/18/Z).
Disclaimer The authors' work was independent of the funders, who had no role in the design, collection, analysis or interpretation of the data or the decision to submit for publication.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval Natsal-3 obtained ethical approval from Oxfordshire Research Ethics Committee A (Ref: 10/H0604/27).
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.