Bolette Soborg

Prednisolone treatment affects the performance of the QuantiFERON gold in-tube test and the tuberculin skin test in patients with autoimmune disorders screened for latent tuberculosis infection†‡

Background: During screening for latent tuberculosis infection (LTBI), before anti‐tumor‐necrosis‐factor‐&agr; treatment, most patients are already receiving immunosuppressive therapy. The objective was to evaluate the performance of the QuantiFERON Gold In‐Tube (QFT‐IT) and the Tuberculin Skin Test (TST). Methods: A prospective multicenter study included 248 patients with ulcerative colitis (39), Crohns disease (54), rheumatoid arthritis (111), and spondylo‐arthropathy (44). Results: QFT‐IT was positive in 7/248 (3%), negative in 229 (92%), and indeterminate in 12 (5%). TST was positive in 54/238 (23%) patients. Chest x‐ray was suspect for tuberculosis in 5/236 (2%), and 35/167 (21%) had ≥1 risk‐factors for infection with Mycobacterium tuberculosis. The main finding was a pronounced negative effect on QFT‐IT and TST performance associated with prednisolone treatment. During prednisolone treatment interferon gamma (IFN‐&ggr;) response to mitogen stimulation was impaired (median IFN‐&ggr; response 4.9 IU/mL; interquartile range [IQR] 0.8 to ≥10.0) compared to patients 1) not receiving corticosteroids (median ≥10.0; IQR 5.0 to ≥10.0; P = 0.0015) or 2) receiving long‐acting corticosteroids (median >10.0; IQR 9.7 to >10.0; P = 0.0058). Prednisolone treatment was strongly associated with negative TST, adjusted odds ratio (AOR) 0.22 (0.1–0.8; P = 0.018), and with an increased risk of indeterminate QFT‐IT results AOR 16.1 (4.1–63.2; P < 0.001), whereas no negative effect was found for long‐acting corticosteroids. Doses of ≥10 mg prednisolone were associated with a 27% risk of indeterminate results. Single use of azathioprine, methotrexate, or 5‐aminosalicylate (5‐ASA) did not affect the test results. Conclusions: Oral prednisolone severely suppressed QFT‐IT and TST performance, whereas the long‐acting corticosteroids methotrexate, azathioprine, and 5‐ASA did not have a similar detrimental effect. Patients should be screened for LTBI with QFT‐IT or TST prior to initiation of prednisolone therapy and negative QFT‐IT or TST results interpreted with caution in patients treated with any corticosteroid until further data are available. (Inflamm Bowel Dis 2011;)

Both high and low serum vitamin D concentrations are associated with tuberculosis: a case–control study in Greenland

Vitamin D deficiency has been associated with increased risk of tuberculosis (TB). Changes from a traditional to a Westernised diet among Greenlanders have resulted in reduced serum vitamin D, leading to considerations of whether preventive vitamin D supplementation should be introduced. The association between vitamin D status and TB was examined to assess the feasibility of vitamin D supplementation in Greenland. This was examined in a case-control study involving seventy-two matched pairs of TB patients (cases) and controls aged 8-74 years. Cases were diagnosed with TB during 2004-6 based on clinical findings in combination with either (1) positive Mycobacterium tuberculosis culture, (2) characteristic X-ray abnormalities together with a positive tuberculin skin test or a positive interferon-γ release assay or (3) characteristic histology. Controls were individually matched on age ( ± 5 years), sex and district. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured and OR of TB were the outcome. Compared with individuals with 25(OH)D concentrations between 75 and 140 nmol/l, individuals with concentrations < 75 nmol/l (OR 6.5; 95% CI 1.8, 23.5) or > 140 nmol/l (OR 6.5; 95% CI 1.9, 22.2) had higher risks of active TB (P = 0.003; adjustment for alcohol and ethnicity). Supplementing individuals with low vitamin D to normalise serum 25(OH)D concentrations was estimated to result in a 29% reduction in the number of TB cases. The study indicated that vitamin D supplementation may be beneficial to individuals with insufficient vitamin D concentrations but may increase the risk of TB among individuals with normal or high concentrations.

Comparison of Screening Procedures for Mycobacterium tuberculosis Infection Among Patients with Inflammatory Diseases

Objective. To test if Mycobacterium tuberculosis screening results differ among patients with inflammatory disease depending on whether the QuantiFeron TB-Gold test (QFT) or tuberculin skin test (TST) is used; and to evaluate if a possible difference is influenced by the presence of risk factors or immunosuppression. Methods. The interferon-γ response to in vitro stimulation of M. tuberculosis-specific antigens was measured with QFT and results were compared with TST. Associations to bacillus Calmette-Guerin (BCG) vaccination, risk factors, and immunosuppression were analyzed for both tests. Results. QFT and TST results were available for 294/302 and 241/302 patients, respectively; 234 had results from both tests. Twenty-one (7%) tested positive with QFT and 45 (19%) with TST. A positive QFT was associated with risk factors for M. tuberculosis infection: i.e., birth or upbringing in a TB-endemic area [risk ratio (RR) = 7.8, 95% CI 1.5–18.2, p < 0.001], previous TB treatment (RR 4.7, 95% CI 1.6–13.5, p = 0.005), and any latent TB infection risk factor (RR 4.7, 95% CI 2.1–11.0, p = 0.0002). Treatment with corticosteroids increased the risk for an inconclusive QFT result (RR 4.2, 95% CI 1.6–10.7, p = 0.04) and decreased the risk for a positive TST result (RR 0.4, 95% CI 0.1–1.0, p = 0.04). Agreement between the tests was low (kappa 0.2, 95% CI 0.02–0.3, p = 0.002). Conclusion. The study documented a high degree of discordant positive QFT and TST results. A positive QFT was more closely associated with risk factors for M. tuberculosis infection than the TST. The use of corticosteroids affected test outcome by increasing the risk for an inconclusive QFT result and decreasing the risk for a positive TST result.

Detecting a low prevalence of latent tuberculosis among health care workers in Denmark detected by M. tuberculosis specific IFN-γ whole-blood test

The study was designed to estimate prevalence of tuberculosis infection among health care workers, using the tuberculin skin test (TST) and the new M. tuberculosis specific diagnostic whole-blood test and to identify possible risk factors. Employees at 2 departments of infectious diseases in Copenhagen were invited to enter the study. All attendants completed a questionnaire, had a TST and blood drawn for detection of interferon-γ produced after stimulation with M. tuberculosis specific antigens ESAT-6 and CFP-10 (QuantiFERON-TB-Gold®, Cellestis). 47 of 139 (34%) participants had a positive TST whereas only 2 of 139 (1%) had a positive QuantiFERON TB-Gold test (QFT-TB). 42 of 106 (40%) BCG vaccinated had positive TST (≥12 mm) compared with 2 of 27 (7%) unvaccinated persons. Among 47 persons with positive TST, 42 (89%) were BCG- vaccinated. The 2 QFT-TB positive participants as well as the remaining 45 TST positive participants showed no sign of active tuberculous disease and were allocated to 6-month clinical follow-up, without medical therapy. Today, 1.5 y later, all remain healthy. The high rate of positive TST among health care workers was most probably due to BCG vaccination and not to infection with M. tuberculosis. The overall transmission rate determined by QFT-TB was found to be very low. The QFT-TB may be useful in distinguishing persons with latent TB infection from persons with positive TST due to BCG vaccination and its use may reduce anxiety.

The effectiveness of BCG vaccination in preventing Mycobacterium tuberculosis infection and disease in Greenland

Background The BCG vaccines ability to prevent Mycobacterium tuberculosis infection (MTI) remains highly debated. In Greenland, BCG vaccination was introduced in 1955, but was temporarily discontinued (1991–1996) due to nationwide policy changes. The study aimed to use the transient stop in BCG vaccination to evaluate the effect of vaccination on MTI prevalence and TB incidence. Methods MTI study: A cross-sectional study (2012), comprising East Greenlanders born during 1982–2006, evaluated the effect of BCG vaccination on MTI prevalence; a positive interferon γ release assay defined an MTI case. Associations were estimated using logistic regression. TB study: a cohort study covering the same birth cohorts with follow-up until 2012 evaluated the vaccines effect on TB incidence. A personal identifier allowed for follow-up in the TB notification system. Associations were estimated using Cox regression. Results MTI study: Included 953 participants; 81% were BCG-vaccinated; 29% had MTI, 23% among vaccinated and 57% among non-vaccinated. BCG vaccination reduced the odds of MTI, OR 0.52 (95% CI 0.32 to 0.85), p=0.01. Vaccine effectiveness against MTI was 20%. TB study: Included 1697 participants followed for 21 148 person-years. 6% were notified with TB, 4% among vaccinated and 11% among non-vaccinated. BCG vaccination reduced the risk of TB, HR 0.50 (95% CI 0.26 to 0.95), p=0.03, yielding a vaccine effectiveness of 50%. Conclusions BCG vaccination was effective in reducing both MTI and TB disease among children and young adults in a TB high-endemic setting in Greenland.

Ongoing tuberculosis transmission to children in Greenland

Inuit in the Arctic are experiencing an increase in tuberculosis cases, reaching levels in Greenland comparable to high-incidence countries. This prompted us to study the level of tuberculosis transmission to Greenlandic children. Specifically, we estimated the current prevalence of Mycobacterium tuberculosis infection (MTI) and the underlying annual risk of MTI. 2,231 Greenlandic school children aged 5–17 yrs (∼25% of the Greenlandic population in the relevant age group) were tested for MTI using the tuberculin skin test and the QuantiFERON®-TB Gold in-tube test. Subjects with dual-positive results were considered infected and subjects with dual-negative results uninfected. The children with discordant test results were classified as probably having MTI and analysed separately. 8.1% of the children had dual-positive test results. The annual risk of MTI was estimated as 0.80% (95% CI 0.67–0.92%) giving a cumulative risk at the 18th birthday of 13.4%. The annual risk of MTI varied substantially by ethnicity (0.87% in Inuit children, 0.02% in non-Inuit children; p<0.001) and by location (0.13% on the west coast, 1.68% on the south coast; p<0.001). M. tuberculosis transmission occurs at a very high level in Inuit children with pronounced geographic differences emphasising the need for immediate public health interventions.

Tracing Mycobacterium tuberculosis transmission by whole genome sequencing in a high incidence setting: a retrospective population-based study in East Greenland

In East Greenland, a dramatic increase of tuberculosis (TB) incidence has been observed in recent years. Classical genotyping suggests a genetically similar Mycobacterium tuberculosis (Mtb) strain population as cause, however, precise transmission patterns are unclear. We performed whole genome sequencing (WGS) of Mtb isolates from 98% of culture-positive TB cases through 21 years (n = 182) which revealed four genomic clusters of the Euro-American lineage (mainly sub-lineage 4.8 (n = 134)). The time to the most recent common ancestor of lineage 4.8 strains was found to be 100 years. This sub-lineage further diversified in the 1970s, and massively expanded in the 1990s, a period of lowered TB awareness in Greenland. Despite the low genetic strain diversity, WGS data revealed several recent short-term transmission events in line with the increasing incidence in the region. Thus, the isolated setting and the uniformity of circulating Mtb strains indicated that the majority of East Greenlandic TB cases originated from one or few strains introduced within the last century. Thereby, the study shows the consequences of even short interruptions in TB control efforts in previously TB high incidence areas and demonstrates the potential role of WGS in detecting ongoing micro epidemics, thus guiding public health efforts in the future.

Decrease in vitamin D status in the Greenlandic adult population from 1987-2010.

Background Low vitamin D status may be pronounced in Arctic populations due to limited sun exposure and decreasing intake of traditional food. Objective To investigate serum 25(OH)D3 as a measure of vitamin D status among adult Inuit in Greenland, predictors of low serum 25(OH)D3 concentrations and the trend from 1987 to 2005–2010. Design A total of 2877 randomly selected Inuit (≥18 years) from the Inuit Health in Transition study were included. A sub-sample (n = 330) donated a blood sample in 1987 which allowed assessment of time trends in vitamin D status. Results The geometric mean serum 25(OH)D3 (25[OH]D2 concentrations were negligible and not reported) in 2005–2010 was lowest among the 18–29 year old individuals (30.7 nmol/L; 95% CI: 29.7; 31.7) and increased with age. In all age-groups it decreased from 1987 to 2005–2010 (32%–58%). Low 25(OH)D3 concentrations (<50 nmol/L) were present in 77% of the 18–29 year old and decreased with age. A characteristic seasonal variation in 25(OH)D3 concentrations was observed (range 33.2–57.1 nmol/L, p<0.001), with the highest concentrations in August to October. Age (2.0% per year increase; CI: 1.7, 2.2), female gender (7.1%; CI: 2.0; 12.5), alcohol intake (0.2% per increase in drinks/week; 0.0; 0.4), and traditional diet (10.0% per 100 g/d increase; CI: 7.9; 12.1) were associated with increased serum 25(OH)D3, whereas smoking (−11.6%; CI: −16.2; −6.9), BMI (−0.6%; CI: −1.1; −0.2) and latitude (−0.7% per degree increase; CI: −1.3; −0.2) were associated with decreased concentrations. Conclusion We identified a remarkable decrease in vitamin D status from 1987 to 2005–2010 and a presently low vitamin D status among Inuit in Greenland. A change away from a traditional diet may well explain the observed decline. The study argues for the need of increased dietary intake of vitamin D and supplementation might be considered.

Quantiferon test for tuberculosis screening in sarcoidosis patients

Abstract Background: Tumour necrosis factor-alpha (TNF-α) inhibitors have been introduced in the treatment of refractory sarcoidosis. These biologics may reactivate latent tuberculosis infection (LTBI). Despite its known limitations, the tuberculin skin test (TST) is currently used for the diagnosis of LTBI in Danish sarcoidosis patients. We report the results of a screening using the interferon-gamma release assay (IGRA) QuantiFERON TB Gold (QFN) for the diagnosis of LTBI. We aimed to assess whether the QFN is reliable for diagnosing LTBI among sarcoidosis patients and if results are influenced by disease activity or immunosuppressive treatment. Methods: A prospective study was performed from 2005 to 2007 among sarcoidosis patients who were candidates for TNF-α inhibitor treatment. Information on immunosuppressive treatment was obtained from the medical records. Disease activity was assessed by biochemistry, chest roentgenograms and pulmonary function tests. The predictive value of QFN results was evaluated by follow-up in the Danish National Tuberculosis Registry. Results: A total of 44 sarcoidosis patients (22 men) with a median age of 39 y (range 25–59 y) were enrolled; 93% had a negative QFN test result and 7% had an indeterminate result. Forty-three percent had disease activity and 57% (n = 25) received immunosuppressive treatment. There was no significant difference in QFN interferon-γ response between subjects with or without disease activity (p > 0.4) and between treated vs non-treated patients (p > 0.5). At follow-up using the Danish tuberculosis registry, there was no occurrence of tuberculosis among study participants. Conclusions: The predictive value of the QFN seems good among Danish sarcoidosis patients and the results appear to be unaffected by sarcoidosis disease activity and immunosuppressive treatment.

Risk of sensitization in healthy adults following repeated administration of rdESAT-6 skin test reagent by the Mantoux injection technique.

Limited specificity of the tuberculin skin test incited the development of the intradermal Mycobacterium tuberculosis-specific rdESAT-6 skin test. Animal studies have shown, however, that there is a possible risk of sensitization when repeated injections of rdESAT-6 are given. The aim of this phase 1 open clinical trial was to assess the sensitization risk and safety of repeated administration of rdESAT-6 reagent in 31 healthy adult volunteers. Three groups of volunteers received two fixed doses of 0.1 microg rdESAT-6 28, 56 or 112 days apart, respectively. After the second injection, the diameter of induration and/or redness at the injection site was measured and taken as a possible sensitization reaction if >5mm. In vitro interferon gamma (IFN-gamma) responses were measured as supportive evidence. Local adverse reactions at the injection site and adverse events were recorded. One out of 31 (3%) volunteers showed a positive skin reaction (sensitization) upon a second injection of rdESAT-6 after 28days and an increased IFN-gamma response to ESAT-6. For 7 (23%) of the volunteers, local adverse reactions related to the product were registered, but all reactions were mild and predictable. In conclusion, repeated injections of the rdESAT-6 skin test reagent are safe, and sensitization occurs at a low rate, especially if the time span between succeeding doses is wide.