Ascertainment of outpatient visits by patients with diabetes: The National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS)

AimsTo estimate and evaluate the sensitivity and specificity of providers' diagnosis codes and medication lists to identify outpatient visits by patients with diabetes.MethodsWe used data from the 2006 to 2010 National Ambulatory Medical Care Survey and National Hospital Ambulatory Medical Care Survey. We assessed the sensitivity and specificity of providers' diagnoses and medication lists to identify patients with diabetes, using the checkbox for diabetes as the gold standard. We then examined differences in sensitivity by patients' characteristics using multivariate logistic regression models.ResultsThe checkbox identified 12,647 outpatient visits by adults with diabetes among the 70,352 visits used for this analysis. The sensitivity and specificity of providers' diagnoses or listed diabetes medications were 72.3% (95% CI: 70.8% to 73.8%) and 99.2% (99.1% to 99.4%), respectively. Diabetic patients ≥ 75 years of age, women, non-Hispanics, and those with private insurance or Medicare were more likely to be missed by providers' diagnoses and medication lists. Diabetic patients who had more diagnosis codes and medications recorded, had glucose or hemoglobin A1c measured, or made office- rather than hospital-outpatient visits were less likely to be missed.ConclusionsProviders' diagnosis codes and medication lists fail to identify approximately one quarter of outpatient visits by patients with diabetes.