Implementation of quantitative HBsAg testing in clinical microbiology laboratories in Spain: Results from a national GEHEP-SEIMC survey

Abstract

Introduction

Quantitative hepatitis B surface antigen (qHBsAg) is increasingly recognized as a key biomarker for chronic hepatitis B (CHB) management. This study aimed to assess the adoption, practices, and barriers to qHBsAg testing in Spanish clinical microbiology laboratories.

Methods

A cross-sectional survey was distributed through the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC) Viral Hepatitis Study Group (GEHEP). Clinical microbiology laboratory professionals across Spain were invited to complete an anonymous online questionnaire. The survey collected information on qHBsAg implementation, technical practices, barriers, and patient-related data. Descriptive statistics were applied.

Results

Of 118 laboratories invited, 91 responded (77.1%); only 37.4% performed qHBsAg. Among non-performing centers, 86% did not refer samples, mainly due to perceived low clinical demand (57.1%), plus lack of equipment/resources. Implementation correlated with hospital size (p = 0.041): 0% (<200 beds), 23.3% (200–500), 44.9% (500–1000), 62.5% (≥1000). Among performing labs, 57.6% quantified after a positive qualitative test, 27.3% on request, and 15.2% as initial screening. Proactive reporting was 69.7%, and 81.8% diluted samples above limits. In the last year, 40.7% of results were <100 IU/mL and 27.1% >3000 IU/mL; over five years (≈14,500 tests), 29.5% >3000 IU/mL and 27.3% <100 IU/mL, supporting the clinical relevance of these thresholds.

Conclusions

qHBsAg testing is not uniformly implemented across Spanish clinical microbiology laboratories and workflows and reporting practices are heterogeneous. Given the descriptive design and potential selection bias, these results should be interpreted as a baseline assessment to inform harmonization efforts and future evaluations linking testing availability to clinical decision-making.