Detecting Patients with Non-Valvular Atrial Fibrillation and Atrial Flutter in the Canadian Primary Care Sentinel Surveillance Network: First Steps

Abstract Background A recent feasibility assessment of quality indicators for non-valvular atrial fibrillation/atrial flutter (NVAF/AFL) identified the Canadian Primary Care Sentinel Surveillance Network (CPCSSN), a national outpatient electronic medical record (EMR) system, as a data source for measurement. As a first step, we adapted and validated an existing EMR case definition. Methods A diagnosis of NVAF/AFL was defined using ICD-9 codes (427.3) in either the physician billing, encounter diagnosis, or health condition fields. We identified all presumed cases in a single clinical site with the algorithm and selected a random sample of those who were presumed NVAF/AFL negative with the same algorithm. A chart audit diagnosis of ‘definite’ NVAF/AFL was confirmed by electrocardiogram and non-valvular diagnosis confirmed after echocardiogram, attending physician or specialist letter review. To demonstrate face validity, clinical characteristics were compared for patients with and without NVAF/AFL. Results The case definition identified a possible 184 patients with and 184 without NVAF/AFL. The case validation resulted in a sensitivity of 100% (95% CI, 100-100), specificity of 84.3% (95% CI, 78.8-89.9), positive and negative predictive value of 74.7% (95% CI, 66.4-83.2) and 100% (95% CI 100-100) respectively. NVAF/AFL patients were older (63 vs 42 years), had a higher proportion of cardiovascular comorbidities and relevant medications. Conclusions We think it is possible, that with further validation work, NVAF/AFL can be accurately identified using this large pan-Canadian EMR system and used as a future tool to measure quality of care in the outpatient setting.