Use of an IGRA test for prescribing latent TB infection therapy in 374 immigrants applying to night shelters in Milan, Italy

The IFN-gamma tests for latent TB (IGRA) can aim preventive therapy (PT) to selected groups, reducing costs and resources. Homeless subjects (HS) have high risk for TB and for defaulting treatment. We evaluated the impact of Quantiferon TB Gold IT (QFT) in HS immigrants applying for night-shelter in Milan who, according to local TB guidelines based on TST ≥10 mm, normal Chest Xray and age ≤ 35 yrs, were candidate for PT. From Nov 2009 to Dec 2010, 1420 HS were referred to our Centre: 374 (37 F, 337 M, mean age 30 yrs) were eligible to PT and were offered IGRA testing with QFT. Twelve M refused; of the remaining: 187 were QFT+ (51.6%, M166, F 21), and 175 were QFT- (M159, F 16,), mean TST respectively 19.6 and 13.9 mm (P<0.0001). QFT results by nationality QFT+ QFT– QFT+ QFT– East Europe 20 30 Africa 145 111 Rumania 15 8 Somalia 41 20 Kosovo 1 7 Erithrea 25 18 Bulgaria 1 5 Ethiopia 7 0 Others 3 10 Kenia 6 1 Latin America 0 4 Morocco 15 5 Asia 22 30 Nigeria 9 6 Afghanistan 20 15 Egypt 6 19 Iran 0 5 Tunisia 2 6 Pakistan 0 4 Others 34 36 Others 2 6 Highest % of QFT+ were in Moroccans (75%), East-africans (67%), Rumanians (65%) Nigerians (60%) and Afghans 57% while lowest level were in other East-europeans (14%), other North-africans (24%) or West-africans (37%). Compared to other studies, our population shows a very high% of QFT+(>50%), especially in some nationalities and in Pts with TST>15 mm, partly decreasing the economic advantage of its use to reduce PTs. Better information on QFT role could be obtained extending this program to HS with TST ≤9 mm or age≥36 yrs but QFT technicalities and health-care budget cuts do not allow this wider on-field application.