Title: Prevalence of Inappropriateness of Parenteral Vitamin B<sub>12</sub> Administration in Ontario, Canada
Abstract: Results | A total of 60 consecutive patients (32 men [67%]; mean [SD] age, 62.1 [13.1] years) were enrolled in the study, and after exclusion of those who withdrew consent (n = 4), did not attend DOT (n = 4), or missed subsequent ABPM (n = 4), 48 participants completed this study for the primary outcome and 46 for the secondary outcome.Baseline characteristics are reported in Table 1.After DOT, daytime systolic BP remained 135 mm Hg or greater in 34 of 48 patients (71%) who experienced a mean (SD) decrease in systolic BP of 3 (10) mm Hg.In contrast, in 14 participants (29%), treatment-resistant hypertension resolved and systolic BP decreased by 26 (20) mm Hg (Table 2).This proportion was similar at 1 month in 14 of 46 patients (30%) who no longer had treatment-resistant hypertension.Discussion | The results suggest that nonadherence to BPlowering drug regimens is high among referred patients with apparent treatment-resistant hypertension, even among those who said they were adherent on questioning before DOT, had pristine pharmacy filling records, and had accurate pill counts.Moreover, this apparent nonadherence occurred despite more than 50% of these patients already having had an adverse vascular event related to uncontrolled hypertension.However, we cannot exclude the possibility that the process of being in the study or receiving treatment from a nurse in a clinic was associated with lower BP for some patients.Of interest, most of those with markedly improved BP after DOT had a sustained improvement in BP control seen at 1 month.Limitations of the study include that the patients were highly selected and likely do not represent most patients with hypertension in the community.The use of DOT as described here was strictly dichotomous (adherence vs nonadherence) and thus does not allow for precise assessment of the degree of nonadherence (eg, partial vs complete), as may be the case with therapeutic drug monitoring. 5,6 Overall, the findings suggest that rigorous methods of adherence assessment and intervention such as DOT should be considered for patients with apparent treatmentresistant hypertension.