Sickle Cell Study Finds Low Rate of Transfusion-Transmitted Infection Screening

Vignesh Chidambaram, MD

Sickle cell disease guidelines published in 2014 by the National Heart, Lung and Blood Institute (NHLBI) recommend annual screening for transfusion-transmitted infections among patients who are chronically transfused. However, implementing such protocols may be resource intensive.

A recent single-center, retrospective cohort study showed that adherence to these guidelines was low, especially for HBV.

The team, led by Vignesh Chidambaram, MD, of Johns Hopkins Bloomberg School of Public Health, assessed their own center’s adherence to the NHLBI guidelines as well as rates of HBV immunity in this particular population.

The Study

As such, they evaluated patients (n = 85) who had initiated chronic transfusion therapy at least 12 months prior to study inclusion. Any patients who received on-demand transfusions were excluded from the study.

Chidambaram and colleagues performed a systematic chart review, collecting clinical data and information on transfusions. Further, they looked at screening intervals as well as the results of all HIV, HCV, and HBV tests.

“We considered subjects screened for HIV, HCV, or HBV if a test result for the corresponding TTI was available during the study period,” they indicated.

Immunity to HBV was then assessed. The team relied on patient vaccination records to classify individual immunization status as actively infected, immune after infection, nonimmune, or unknown.

They used descriptive statistics for the patient’s annual HIV, HCV, and HBV tests, HBV vaccination rates, as well as immune status. Linear regression was used to determine the association between chronic transfusion duration, adherence to scheduled transfusions, and transfusion-transmitted screening.

The Results

None of the patients received annual screening for HIV and HCV over the 5-year study period. However, 80% were screened at least once for HIV, and 71% were screened at least once for HCV.

No patient was identified with HIV infection, and 1 patient without previous HCV testing tested positive for the virus — although, the mode of transmission was uncertain.

As for HBV testing, 62% were tested for HBsAg, 38% were tested for anti-HBc, and 36% for anti-HBs.

They further found that the proportion of patients screened for any of the 3 viruses decreased over time.

“Linear regression analysis showed an inverse association between the transfusion duration and receiving annual HIV and HCV testing,” the investigators wrote. They reported that each additional year of transfusion decreased the probability of testing for HIV by 15% (P = .005) and HCV by 14% (P = .001). However, this was not the case for HBsAg (P = .28).

And finally, there was no reported association between adherence to transfusion and testing rates for HIV, HCV, and HbsAg.

HBV Testing

Of the 58 patients tested for HBV, 30 (35.3%) had immunity acquired from vaccination, 5 (6%) had previous infection, and 23 (27%) had no immunity.

As for the patients with HBV vaccination documentation (n = 17), 12 (70.6%) received anti-HBs testing. As such, half were anti-HBs positive.

Furthermore, 23 patients were anti-HBs negative, 2 were subsequently vaccinated, and 1 of the newly vaccine showed seroconversion.

Concluding Thoughts

“Adherence to the NHLBI Screening guidelines for transfusion-transmitted infection in adults with SCD on chronic transfusion was low as was the diagnosis of new transfusion-transmitted infections,” Chidambaram’s team wrote.

“This evidence forms the basis for our ongoing effort to determine best practice for transfusion-transmitted infection screening and highlights the need for further information about HBV vaccine immunogenicity, and the cost-effectiveness of the NHLBI guidelines.”

They indicated that their study raises questions as to whether annual screening for these patients is necessary. Therefore, further studies to investigate the true risk of transfusion-transmitted infections among this patient population and define clinical resources needed for adherence are warranted.

The study, “Low rates of transfusion-transmitted infection screening in chronically transfused adults with sickle cell disease,” was published online in Transfusion.