High non-adherence rates to secondary prevention by chemical adherence testing in patients with TIA

Introduction: Transient ischaemic attack (TIA) clinics are important for secondary prevention of fatal or disabling stroke. Non-adherence to prescribed medications is an important reason for treatment failure but difficult to diagnose. This study ascertained the utility of a novel biochemical tool in the objective biochemical diagnosis of non-adherence. Methods: One-hundred consecutive urine samples collected from patients attending the TIA clinic, at a tertiary centre, were analysed for presence or absence of prescribed cardiovascular medications using liquid chromatography-mass spectrometry (LC-MS/MS). Patients were classified as adherent or non-adherent, respectively. Demographic and clinical characteristics were compared between the two cohorts. Univariate regression analyses were performed for individual variables and model fitting was undertaken for significant variables. Results: The mean duration of follow-up from the index event was 31 days [standard deviation (SD): 18.9]. The overall rate of non-adherence for at least one medication was 24%. In univariate analysis, the number of comorbidities [3.4 (SD: 1.9) vs. 2.5 (1.9), P = 0.032] and total number of all prescribed medications [6.0 (3.3) vs 4.4 (2.1), P = 0.032] were higher in the non-adherent group. On multivariate analysis, the total number of medications prescribed correlated with increased non-adherence (odds ratio: 1.27, 95% Confidence Intervals: 1.1-1.5, P = 0.01). Conclusions: LC-MS/MS is a clinically useful tool for the diagnosis of non-adherence. Nearly a quarter of TIA patients were non-adherent to their cardiovascular medications Addressing non-adherence early may reduce the risk of future disabling cardiovascular events.