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Using expert opinion to quantify unmeasured confounding bias parameters

  • Quantitative Research
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Canadian Journal of Public Health Aims and scope Submit manuscript

Abstract

OBJECTIVE: To develop and apply a method to quantify bias parameters in the case example of the association between alcohol use and HIV-serodiscordant condomless anal sex with potential confounding by sensation seeking among men who have sex with men (MSM), using expert opinion as an external data source.

METHODS: Through an online survey, we sought the input of 41 epidemiologist and behavioural scientists to quantify six parameters in the population of MSM: the proportion of high sensation seeking among heavy-drinking MSM, the proportion of sensation seeking among low-level drinking MSM, and the risk ratio (RR) of the association between sensation seeking and condomless anal sex, for HIV-positive and HIV-negative MSM.

RESULTS: Eleven experts responded. For HIV-positive heavy drinkers, the proportion of high sensation seeking was 53.6% (beta distribution [α = 5.50, β = 4.78]), and 41.1% (beta distribution [α = 3.10, β = 4.46]) in HIV-negative heavy drinkers. In HIV-positive low-level alcohol drinkers, high sensation seeking was 26.9% (beta distribution [α = 1.81, β = 4.92]), similar to high sensation seeking among HIV-negative low-level alcohol drinkers (25.3%) (beta distribution [α = 2.00, β = 5.89]). The lnRR for the association between sensation seeking and condomless anal sex was ln(2.4) (normal distribution [μ = 0.889, α = 0.438]) in HIV-positive and ln(1.5) (normal distribution [μ = 0.625, σ = 0.391]) in HIV-negative MSM.

CONCLUSION: Expert opinion can be a simple and efficient method for deriving bias parameters to quantify and adjust for hypothesized confounding. In this test case, expert opinion confirmed sensation seeking as a confounder for the effect of alcohol on condomless anal sex and provided the parameters necessary for probabilistic bias analysis.

Résumé

OBJECTIF: En utilisant l’opinion d’experts comme source de données externe, élaborer et appliquer une méthode pour chiffrer les paramètres de biais dans le cas de l’association entre la consommation d’alcool et le sexe anal sans condom entre partenaires sérodifférents pour le VIH, avec un facteur de confusion possible, la recherche de sensations, chez les hommes ayant des relations sexuelles avec des hommes (HARSAH).

MÉTHODE: Au moyen d’un sondage en ligne, nous avons sollicité l’opinion de 41 épidémiologistes et spécialistes du comportement pour chiffrer six paramètres dans la population des HARSAH: la proportion de chercheurs de sensations fortes chez les HARSAH grands buveurs d’alcool, la proportion de chercheurs de sensations chez les HARSAH petits buveurs d’alcool, et le risque relatif (RR) de l’association entre la recherche de sensations et le sexe anal sans condom chez les HARSAH séropositifs et séronégatifs.

RÉSULTATS: Onze spécialistes ont répondu. Chez les grands buveurs séropositifs, la proportion de chercheurs de sensations fortes était de 53,6 % (distribution bêta [α =5,50, β =4,78]); elle était de 41,1 % (distribution bêta [α =3,10, β= 4,46]) chez les grands buveurs séronégatifs. Chez les petits buveurs séropositifs, les chercheurs de sensations fortes représentaient 26,9 % (distribution bêta [α =1,81, β =4,92]), ce qui est comparable aux chercheurs de sensations fortes chez les petits buveurs séronégatifs (25,3 %) (distribution bêta [α= 2,00, β =5,89]). Le logarithme du risque relatif (lnRR) de l’association entre la recherche de sensations et le sexe anal sans condom était ln(2,4) (distribution normale [μ = 0,889, σ = 0,438]) chez les HARSAH séropositifs et ln(1,5) (distribution normale [μ =0,625, σ =0,391]) chez les HARSAH séronégatifs.

CONCLUSION: L’opinion d’experts peut être une méthode simple et efficace pour dériver des paramètres de biais afin de chiffrer les facteurs de confusion hypothétiques et d’apporter les ajustements nécessaires. Dans ce cas type, l’opinion d’experts a confirmé que la recherche de sensations est un facteur de confusion de l’effet de l’alcool sur le sexe anal sans condom, et cette opinion a fourni les paramètres nécessaires à une analyse du biais probabiliste.

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Authors and Affiliations

  1. Global Health Sciences, University of California, San Francisco, CA, USA

    Soodabeh Navadeh MD, MPH & Ali Mirzazadeh MD, MPH, PhD

  2. Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, PO Box: 14155-6446, Tehran, Iran

    Soodabeh Navadeh MD, MPH &  Mohammad Ali Mansournia MD, MPH, PhD

  3. Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, USA

    Ali Mirzazadeh MD, MPH, PhD & Willi McFarland MD, PhD

  4. San Francisco Department of Public Health, San Francisco, CA, USA

    Willi McFarland MD, PhD

  5. Department of Medicine, Center for AIDS Prevention Studies, University of California, San Francisco, CA, USA

    Sarah Woolf-King PhD, MPH

Authors
  1. Soodabeh Navadeh MD, MPH
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  2. Ali Mirzazadeh MD, MPH, PhD
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  3. Willi McFarland MD, PhD
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  4. Sarah Woolf-King PhD, MPH
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  5. Mohammad Ali Mansournia MD, MPH, PhD
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Corresponding author

Correspondence to Mohammad Ali Mansournia MD, MPH, PhD.

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Conflict of Interest: None to declare.

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Navadeh, S., Mirzazadeh, A., McFarland, W. et al. Using expert opinion to quantify unmeasured confounding bias parameters. Can J Public Health 107, e43–e48 (2016). https://doi.org/10.17269/cjph.107.5240

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  • DOI: https://doi.org/10.17269/cjph.107.5240

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