Abstract
Intro: Guidelines advise screening patients for latent TB infection (LTBI) prior to initiation of biologic therapy. We examined the impact of interferon gamma release assay (IGRA) availability on rates of adequate screening and treatment for LTBI prior to biologic therapy in a low TB incidence setting.
Method: We analysed clinic letters, laboratory and pharmacy data to assess LTBI screening for patients starting biologics at a UK district general hospital between 2009-14. We used logistic regression to identify predictors of LTBI treatment.
Results: 450 patients initiated biologics 2009-14: 116 before, and 334 after, IGRA availability (Jan 2010). 100/334 (30%) were IGRA tested. Adequate screening, defined as any immunological test and clinical review, increased with IGRA availability but remained low (105/334 vs 14/116; p<0.001). The proportion treated for LTBI did not change after IGRA availability (27/334 vs 10/116; p=0.847). Only 10/27 treated after IGRA availability had a positive IGRA (11 negative, 6 equivocal/not done). Reasons for treating the other 17: 9 from endemic country, 5 TB contact, 1 both, 2 other. A negative IGRA was paradoxically associated with being treated (Odds Ratio (OR) 5.5 vs equivocal/no IGRA; p<0.001), as was being from an endemic country (OR 22.3; p<0.001). There was 1 case of TB reactivation, despite appropriate LTBI treatment.
Conclusion: LTBI screening in patients starting biologics improved after IGRA availability, but 69% were inadequately screened. Historically a negative IGRA has not influenced the decision to treat, but improved data on the negative predictive value of IGRAs may reduce treatment rates. In our limited sample, this did not adversely affect outcomes.
- Copyright ©ERS 2015
