The incidence of tuberculosis (TB) amongst HIV-positive patients in France doubled between 1997 and 2008, investigators report in the January 28th edition of AIDS. During this period there was a particularly large increase in TB incidence among HIV-positive migrants, especially those from sub-Saharan Africa.
A low CD4 cell count and a high viral load were risk factors for TB, and a large number of patients were diagnosed with HIV and TB at the same time. Treatment with anti-HIV drugs was associated with a lower risk of TB. The researchers believe that such findings warrant “the co-prescription of TB-preventative therapy and combination antiretroviral therapy for severely immunodepressed high-risk patients such as migrants and socially excluded patients”.
The introduction of effective HIV treatment led to a massive and sustained fall in the number of AIDS-defining illnesses diagnosed in HIV-positive patients in richer countries such as France.
Worldwide, TB is the leading cause of serious illness and death among patients with HIV. Even in industrialised countries including France and the UK, TB is one of the most common AIDS-defining illnesses.
Many of the cases of TB diagnosed amongst patients with HIV in France and similar countries are among migrants from countries with a high TB prevalence.
French investigators wished to gain a better understanding of the incidence and risk factors for TB among patients with HIV in the period since effective combination antiretroviral therapy became available.
They therefore designed a prospective study involving 72,580 HIV-positive adults who received care between January 1997 and December 2008.
The proportion of patients who were migrants increased from 9% in 1997 to 29% in 2008. By this time 21% of all patients were from sub-Saharan Africa.
A total of 2625 patients were diagnosed with TB. A little over a third (36%) of these had their TB and HIV diagnosed at the same time.
The patients contributed over 427,000 person-years of follow-up. TB incidence was 0.40 per 100 person years amongst non-migrants and 1.03 per 100 person years amongst migrants.
During the period of analysis, overall TB incidence increased from 0.69 per 100 person years in 1997 to 1.39 per 100 person years in 2008.
Incidence of TB amongst migrants was approximately twice that seen in non-migrants. However, in both groups of patients TB incidence increased significantly – by 85% amongst non-migrants and by 151% in migrants.
The only group of non-migrant patients in whom TB incidence did not increase significantly (p < 0. 0001) was gay men.
When the investigators looked at the risk factors for TB, they found migrants from sub-Saharan Africa had twice the risk of TB compared to HIV-positive individuals born in France (adjusted risk ratio, 2.16; 95% CI, 1.88-2.48). Furthermore, the risk of TB was 83% higher amongst migrants from other regions compared to French-born patients with HIV.
Late diagnosis of HIV was associated with an increased risk of TB for both migrants and non-migrants. The risk of TB was highest during the first six months of HIV care, and among patients with lower CD4 cell counts and higher viral loads (p < 0.0001 for all risk factors).
Patients who had been taking combination HIV treatment for at least six months had a 50% lower risk of TB compared to those not taking antiretroviral therapy (p < 0.0001).
Area of residence was also associated with TB risk, and was highest for those living in Paris or the French West Indies. Both these regions have large migrant populations.
“The incidence rates of TB among HIV-infected patients in this study was 40 times higher than those reported among the general population in France and 20 times higher than those reported in the Paris area…confirming that HIV itself is a risk factor for TB”, comment the investigators.
In a third of patients, HIV was diagnosed at the same time as TB. “TB continues to reveal HIV in industrialised countries”, write the investigators. Late diagnosis of HIV is a matter of concern in many western European countries, and it is recommended that all patients diagnosed with TB should be offered an HIV test.
All groups other than gay men had an increasing incidence of TB. The investigators suggest that this demonstrates TB’s association with social deprivation. Gay men generally have a higher socio-economic status than other groups affected by HIV.
Although the risk of TB fell the longer a patient received HIV treatment, the investigators note that, overall, TB incidence increased. They therefore conclude, “selected patients, such as migrants from highly endemic regions and patients with delayed access to care…might, therefore, benefit from co-prescription of TB-preventative therapy and combination antiretroviral therapy”.
Abgrall S et al. HIV-associated tuberculosis and immigration in a high-income country: incidence trends and risk factors in recent years. AIDS 24 (online edition), 2010.