When to Adjust for Potentially Confounding Variables

Abstract

impossible. We replicated this analysis among publicly funded insulin users of all ages, and the results were generally consistent, with 0.6% of users exceeding these limits prior to the policy coming into place. Therefore, the sample size issue described by Dr Witteman is simply driven by the fact that use of test strips in quantities outside of this policy was exceptionally rare among insulin-treated patients before its implementation. Moreover, the policy allows people to access additional strips in any clinically appropriate circumstance (eg, during pregnancy) using a simple pharmacy override code. 2,3 We suggest that other jurisdictions considering such a policy review the policy documents cited in our article, 1 which outline these details. Moreover, we support expanded communication of these policy details to help ensure that the small subset of patients requiring additional strips obtain them easily.Second, we have acknowledged that we are able to examine the policy's impact on only a limited set of outcome measures, and that other outcomes such as quality of life are important and may have been influenced by the policy. Although some evidence suggests that routine testing of blood glucose may increase anxiety among individuals not receiving insulin, 4 these data may not be applicable to patients taking insulin, particularly those with type 1 diabetes. We specifically address this issue in the Discussion section of our article, 5 and would strongly support future qualitative analyses to investigate this further.Finally, regarding disclosure of conflicts of interest, our overarching research program is supported by an externally peer-reviewed grant obtained from the Ontario Ministry of Health and Long-Term Care (MOHLTC) and by the Institute for Clinical Evaluative Sciences, which receives partial funding from the MOHLTC. We explicitly acknowledge our affiliations and funding sources in the article. No funding was specifically targeted toward the completion of this particular study. The decision to undertake the study was ours, and the funder had no role in the design, conduct, or reporting of the work.