Objectives: Herpes zoster (HZ) is a common infection in Canada that can result in serious and long-term complications. People with diabetes may be at an increased risk for HZ. The objectives of this study were to develop and validate a case definition of HZ diagnosis based on electronic medical records; determine a prevalence estimate for HZ in adult patients in the Canadian Primary Care Sentinel Surveillance Network (CPCSSN) and assess the association between HZ and diabetes.
Methods: This was a retrospective cross-sectional study. Patients 18 years of age or older who had made at least 1 visit to their primary health-care providers within the past 2 years in the CPCSSN were included. These data came from a 2015 extract of CPCSSN data, and a subsample of 289 patients was used to validate our case definition. Prevalences were estimated for the overall population and for people with diabetes, chronic obstructive pulmonary disease, cancer or HIV. Risk ratios were modelled for these conditions.
Results: The sensitivity, specificity, positive predictive value and negative predictive values for HZ were 100%, 73.8%, 83.9% and 100%, respectively. The 1-year prevalence of HZ in the CPCSSN data was 0.32%. The prevalence of HZ was higher in females (0.35%) than in males (0.28%). People with diabetes have an increased risk for HZ infection (RR 2.64, 95% CI 2.34, 2.99).
Conclusions: People with diabetes have an increased risk for the diagnosis of HZ infection in the primary care setting in Canada. Women over the age of 65 years with diabetes and/or other chronic conditions are at greatest risk for developing HZ.
Keywords: chronic disease; diabetes; diabète; dossiers médicaux électroniques; electronic medical records; epidemiology; herpes zoster; herpès zoster; infectious disease; maladie chronique; maladie infectieuse; épidémiologie.
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