Geospatial Discrepancy of Chronic Hepatitis B and Hepatitis D Testing in Alberta: A Population-Based Spatial Analysis

Abstract

Chronic hepatitis B (CHB) and hepatitis D virus (HDV) coinfection are major causes of cirrhosis and hepatocellular carcinoma. The geographic distribution of CHB and alignment of anti-HDV testing with CHB burden remain poorly defined. We aimed to examine if anti-HDV testing and seropositivity align with areas of highest CHB burden. Adults with CHB (2014–2022) were identified using a validated serologic algorithm in the provincial laboratory database capturing HBV/HDV serology. Cases were geolocated to Aggregate Dissemination Areas (ADAs), linked to Alberta Health Services zones and rural–urban continuum levels. Age- and sex-standardized CHB prevalence was calculated per ADA using the 2016 Canadian Census. Descriptive mapping, global spatial autocorrelation and local hotspot analysis were used to assess spatial clustering. Among 8317 persons with CHB, the provincial age- and sex-standardized prevalence was 1.70 per 1000 population (95% CI, 1.66–1.74). Prevalence ranged from 2.15 per 1000 in metropolitan areas to 0.40 per 1000 in remote regions and was higher in Calgary than Edmonton (2.53 vs. 1.73 per 1000). Overall, 17.5% of CHB patients were tested for anti-HDV, and 4.1% of those tested were anti-HDV positive. CHB prevalence hotspots were concentrated in metropolitan ADAs, whereas hotspots of anti-HDV testing and positivity showed only partial overlap with these high-burden areas. CHB burden in Alberta is geographically clustered, particularly within specific neighbourhoods of metropolitan cities, whereas anti-HDV testing remains infrequent and only partially aligned with high-burden areas. Reflex or systematic anti-HDV testing, paired with geographically informed outreach, may improve case detection.