Impact of Clinical Practice Guidelines on Blood Glucose Test Strip Prescription Rates in Manitoba and Saskatchewan (Canada): An Interrupted Time-Series Analysis

Objectives: Our aim in this study was to assess the impact of the Diabetes Canada Dissemination & Implementation strategy on population-level prescription rates of blood glucose test strips. Methods: We extracted all diabetes-related drugs and test strip claims in Manitoba and Saskatchewan between January 1, 2000 and September 30, 2015 from the Canadian Institute for Health Information's National Prescription Drug Utilization Information System. The primary outcome was the proportion of the cohort in each quarter who had been dispensed strips in accordance with the Diabetes Canada 2013 guidelines. We conducted an interrupted time-series analysis examining prescribing trends overall and by drug groups. Results: The overall average sample size per quarter was 57,576 (standard deviation [SD]= 12,320) and 49,533 (SD=10,206) individuals; the average age was 62.1 (SD=0.3) and 63.8 (SD=0.3) years, and the average proportion of total beneficiaries in the sample was 12.7% (SD=1.9%) and 12.6% (SD=1.7%) for Manitoba and Saskatchewan, respectively. On average preintervention, 27.9% (SD=0.68%, Manitoba) and 31.9% (SD=0.73%, Saskatchewan) of the sampled patients used strips according to the guidelines. On average postintervention, 26.5% (SD=0.29%, Manitoba) and 30.6% (SD=0.53%, Saskatchewan) of the patients used strips according to the guidelines. None of the interrupted time-series models reached statistical significance (p values ranging from 0.44 to 0.98 for Manitoba and 0.13 to 0.81 for Saskatchewan, depending on drug group). Conclusions: The guideline and its Dissemination & Implementation strategy did not change strip prescribing. Potential reasons include complexity of the recommendations, lack of penetrance to primary care physicians and/or disagreement with recommendations. (C) 2020 Canadian Diabetes Association.