Abstract
Despite variation in Canadian privacy laws between provinces and territories, increasing legislative protection of personal privacy has imposed restrictions on health research across the country. The effects of these restrictions on patient recruitment include increased study costs, durations, and decreased participation rates. Low participation rates can jeopardize the validity of research findings and the accuracy of measures of association by introducing non-response, or participation bias. We constructed simulations to assess potential effects of non-response bias on the accuracy of measures of association in a hypothetical case-control study. Small biases that alter the probability of selecting an exposed case can lead to dramatic inflation or attrition of the odds ratio (OR) in case-control studies. ORs are more unstable and subject to error when the true probability of selecting an exposed case is greater, such that strong positive associations are subject to error even at low levels of bias. Well-powered, population-based epidemiological research is a cornerstone of public health. Therefore, when weighing the benefits of protecting personal privacy, the benefits of valid and robust health research must also be considered. Options might include special legislative treatment of health research, or the use of an “opt-out” (vs. the current “opt-in”) construct for consent in confidential research.
Key words: Privacy, legislation, public health, epidemiology
Résumé
Les lois sur la protection des renseignements personnels diffèrent d’une province et d’un territoire à l’autre au Canada, mais dans l’ensemble, la protection juridique accrue accordée à la protection de la vie privée impose des restrictions à la recherche en santé dans tout le pays. Comme ces restrictions ont un effet sur le recrutement des patients, elles font augmenter le coût et la durée des études, et diminuer les taux de participation. Or, de faibles taux de participation peuvent compromettre la validité des résultats de recherche et l’exactitude des mesures du degré d’association en introduisant des biais de non-réponse ou de participation. Nous avons construit des simulations pour analyser les effets possibles du biais de non-réponse sur l’exactitude des mesures d’association pour une étude cas-témoin hypothétique. On sait que de faibles biais, s’ils modifient la probabilité de sélectionner un cas exposé, peuvent entraîner une inflation ou une attrition considérable du rapport de cotes (RC) dans une étude cas-témoins. Les RC sont plus instables, et comportent un risque d’erreur plus grand, lorsque la probabilité réelle de sélectionner un cas exposé est plus grande, ce qui fait que des associations fortement positives peuvent être erronées même si les biais sont faibles. La recherche épidémiologique fondée sur la population et dotée d’un bon degré de puissance est la pierre angulaire de la santé publique. Par conséquent, lorsqu’on soupèse les avantages de la protection de la vie privée, il faut tenir compte de l’avantage de pouvoir mener des études de recherche en santé valides et robustes. On pourrait par exemple appliquer un traitement juridique particulier à la recherche en santé ou faire appel à la « participation facultative » (par opposition à la « participation sur demande » en vigueur actuellement) pour obtenir le consentement des patients aux travaux de recherche confidentiels.
Mots clés: protection des renseignements personnels, lois, santé publique, épidémiologie
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