Validity of the rapid strip assay test for detecting HBsAg in patients admitted to hospital in Uganda

Abstract

Commercially available rapid strip assays (RSAs) for hepatitis B surface antigen (HBsAg) are used for most routine clinical testing in sub-Saharan Africa. This study evaluated the validity of RSA and a more sophisticated enzyme immunoassay (EIA) with confirmation by nucleic acid testing (NAT) in hospitalized patients in Uganda. Sera from 380 consecutive patients collected and tested for HBsAg and anti-HIV in Kampala, Uganda by RSA were sent frozen to Dallas for EIA including HBsAg, total anti-hepatitis B core, hepatitis B e antigen, and anti-HIV. NAT was performed on all HBsAg-positives and on a random sample of 102 patients that were HBsAg-negative by both assays. Overall, 31 (8%) were HBsAg positive by RSA while 50 (13%) were HBsAg-positive by EIA; 26 were concordant between the two assays. Of 55 HBsAg-positive patients, nearly all showed detectable serum hepatitis B virus (HBV) DNA by bDNA (46) or PCR (4) assay. The 26 patients who were HBsAg positive by both EIA and RSA had significantly higher median serum HBV DNA levels than the 24 patients who were HBsAg positive by EIA alone. An additional 12/102 (12%) HBsAg negative patients had very low serum HBV DNA levels by NAT. Several differences in expected results of serologic testing were observed in this large series of African patients. RSA HBsAg testing is less sensitive than EIA; even EIA failed to detect all HBV DNA positive sera. A more complex testing protocol than RSA alone will be needed in Africa to improve patient care.

Decompensated cirrhosis-related admissions in a large urban hospital in Uganda: prevalence, clinical and laboratory features and implications for planning patient management

“…However, unlike in Uganda where chronic HBV is the second commonest cause of cirrhosis, chronic HCV ranks second in the United States and Europe. The proportion of HBV related cirrhosis may even be higher than apparent in this study because the rapid strip test used to diagnose HBV infection in this study has been shown to have low sensitivity of only 43.5% 15 . On the other hand, HCV was not a major risk factor for cirrhosis (3.5%) and this reflected the low prevalence of HCV in the general population.…”

Hepatitis B serological markers and plasma DNA concentrations

“…Previous studies are either based on small sample sizes or do not distinguish HIV-uninfected and HBV/HIV-coinfected individuals. A previous study of mostly HIV-negative, HBsAg-seropositive inpatients in Kampala found 27% HBeAg seropositive [22]. An earlier study of inpatients in the same hospital found six (28.1%) of 23 HIV-positive and three (17.6%) of 17 HIV-negative patients to be HBeAg seropositive [18].…”

“…This serological pattern may represent a false-positive, resolved and cleared infection, or chronic infection with a low rate of viral replication (occult HBV infection). In a previous small study in Uganda, 15% (seven of 48) HIV-positive patients with negative HBsAg had detectable HBV DNA [22]. The clinical implications of occult HBV infection are unclear, but it is generally accepted that individuals with detectable plasma HBV DNA may be at risk of HBV reactivation and inflammatory liver flares [43].…”

Epidemiology, Diagnosis, and Treatment of HIV-Associated Non-Hodgkin Lymphoma in Resource-Limited Settings

“…Hepatitis B virus (HBV) is another infection that has been shown to reactivate more commonly when corticosteroids are included in chemotherapy regimens for lymphoma [46] and is well known to reactivate during rituximab therapy if viral prophylaxis is not administered in previously exposed patients [47]. There is a 13% rate of detectable serum hepatitis B DNA in patients admitted to Mulago Hospital in Uganda, [48] which could enable further clarification of the magnitude of risk associated with HBV reactivation compared with the treatment benefit of corticosteroids. These results could improve clinical decision-making concerning the ideal chemotherapy regimen to use in the setting of concurrent HIV and HBV infection.…”