To document experience with directly observed chemoprophylaxis (DOPT) compared to self-administered isoniazid (INH) among aboriginal persons in British Columbia.
DOPT was compared to self-administered delivery (SAD) over a 3-year period. All aboriginal persons who received INH chemoprophylaxis in British Columbia between 1992 and 1994 were evaluated. Therapy completion rates and adverse outcomes associated with SAD were compared with DOPT. Treatment allocation was by patient choice.
Of 608 people who received INH prophylaxis, 443 received SAD (mean age 31.6 years) and 165 received DOPT (mean age 23.9 years). Two hundred and seventy (60.9%) SAD compared to 124 (75.2%) in the DOPT group completed 6 months of INH (P = 0.0011). The 12-month completion rates were 162/443 (36.6%) for the SAD group and 84/165 (50.9%) for the DOPT group (P = 0.0014). Adverse reactions requiring discontinuation of medication occurred in 13.5% of the patients on SAD and 9.7% of those receiving DOPT (P = 0.202). The most common reason cited for failure to complete therapy was non-cooperation in both groups. There were three deaths in the SAD group, one of which was due to suicide by self-ingestion of INH.
These data demonstrate that in aboriginal people compliance with preventive therapy can be improved by DOPT. Non random allocation to treatment groups might have influenced our findings, and further prospective randomized trials and cost-effectiveness analyses are required.
Estimations of prevalence of latent tuberculous infection (LTBI) are confounded by factors known to influence the results of the tuberculin skin test (TST) such as age, contact history and bacille Calmette-Guerin (BCG) vaccination. Appropriate interpretation of TST results is necessary to ensure LTBI treatment for those at greatest risk.
To document the prevalence of LTBI in Aboriginal people living on a reserve in British Columbia (BC) and to determine the influence of BCG.
A population-based, retrospective descriptive analysis of all epidemiological data collected for the on-reserve Aboriginal programme in BC (1951-1996).
Of 17615 persons who received a TST during the study period, 42% had received BCG. During the study period, an average of 2517 TSTs were completed per year (SD = 1228) among persons with an average age of 26 years (SD = 16). Among all subjects, the average prevalence of LTBI was 25% (95 %CI 24-25). The presence of BCG (OR = 3.1, 95%CI 2.8-3.4) and multiple BCGs (OR = 10.2, 95%CI 7.7-13.6) were both associated with a positive TST. A positive TST was also associated with a shorter duration in years between the most recent BCG and the TST.
The average prevalence of LTBI in a sequential sample of Aboriginal people living on a reserve in BC was estimated at 25%. BCG, especially in multiple doses, increased the likelihood of a positive TST.
The clinical features of 81 cases of abdominal tuberculosis (TB) are presented. The peritoneum was involved in 41 patients, the ileocecal area in 17, the anorectal area in 16, and mesenteric glands in 8. There was one case each involving the liver and sigmoid colon. Most patients were young women. The tuberculin reaction was significant in 83% of patients tested, and 54% had evidence of TB elsewhere. Tuberculous peritonitis was more common in native North American Indians and presented as an acute abdomen, abdominal tumor, or cirrhosis. Asians developed the majority of ileocecal and mesenteric lymph node disease and were frequently diagnosed as having Crohn's disease, appendicitis, or cancer. Anorectal cases presented with fistulae or abscesses and usually had concomitant pulmonary TB. The disease was fatal in five patients (6%), four of whom were diagnosed only after death. One noncompliant patient had a relapse. All other patients were cured after receiving treatment.
Recent approval of interferon-gamma release assays that are more specific for Mycobacterium tuberculosis has given new options for the diagnosis of latent tuberculosis infection (LTBI).
To assess the cost-effectiveness of Quanti-FERON-TB Gold (QFT-G) vs. the tuberculin skin test (TST) in diagnosing LTBI in contacts of active TB cases using a decision analytic Markov model.
Three screening strategies--TST alone, QFT-G alone and sequential screening of TST then QFT-G--were evaluated. The model was further stratified according to ethnicity and bacille Calmette-Guérin (BCG) vaccination status. Data sources included published studies and empirical data. Results were reported in terms of the incremental net monetary benefit (INMB) of each strategy compared with the baseline strategy of TST-based screening in all contacts.
The most economically attractive strategy was to administer QFT-G in BCG-vaccinated contacts, and to reserve TST for all others (INMB CA$3.70/contact). The least cost-effective strategy was QFT-G for all contacts, which resulted in an INMB of CA$-11.50 per contact. Assuming a higher prevalence of recent infection, faster conversion of QFT-G, a higher rate of TB reactivation, reduction in utility or greater adherence to preventive treatment resulted in QFT-G becoming cost-effective in more subgroups.
Selected use of QFT-G appears to be cost-effective if used in a targeted fashion.
To determine the risk factors for pulmonary colonization by non-tuberculous mycobacteria (NTM).
Retrospective study of subjects colonized by NTM from 1990 to 2006. Subjects without mycobacterial disease and with at least three negative cultures served as controls.
Mycobacterium avium complex (MAC) species were the most common NTM. Risk factors of colonization included age > or = 60 years (aOR 2.3), female sex (aOR 1.2), residency in Canada for at least 10 years (aOR 3.8), Canadian-born aboriginal (aOR 1.8), and Canadian-born non-aboriginal (aOR 1.4). Predictors of MAC colonization included White race (aOR 1.6) and residency in Canada for at least 10 years, which was the strongest predictor (aOR 6.7). Aboriginal origin was associated with non-MAC colonization (aOR 1.8), and Canadian-born people from the East/South-East Asian ethnic groups were protected from MAC colonization (aOR 0.2), all aOR P
To identify patients with coexisting HIV infection and tuberculosis (TB) and recent trends in prevalence and factors associated with coinfection.
All known patients with TB and HIV infection in British Columbia, in whom TB was diagnosed between 1990 and 1994. This group was compared with those in whom TB was diagnosed between 1984 and 1990.
Patients' demographic characteristics and risk factors for HIV infection, site of TB, occurrence of drug-resistant TB, treatment and outcome.
Forty-four patients with HIV infection and TB were identified, of whom 16% were women, whereas non of those diagnosed from 1984 to 1990 were women, and 14 (32%) were aboriginal Canadians, compared with only 3 (8%) of those diagnosed from 1984 to 1990 (p
Provincial tuberculosis (TB) services, British Columbia, Canada.
To estimate the risk of drug resistance among foreign-born TB patients and to identify risk factors associated with drug resistance.
Using the provincial TB database, we examined all culture-positive foreign-born TB patients for the years 1990-2001. The risk of having a drug-resistant isolate was estimated according to country and region of origin.
Of 1940 foreign-born patients identified, 247 (12.7%, 95%CI 11.3-14.3) cases had isolates resistant to at least one of the first-line drugs, with 160 (8.3%) isolates showing monoresistance, 24 (1.2%) multidrug resistance (resistance to at least isoniazid and rifampin) and 63 (3.3%) polyresistance (resistance to two or more drugs, excluding MDR). Country-specific analysis showed that immigrants from Vietnam (adjusted OR 2.12, 95%CI 1.37-3.27) and the Philippines (adjusted OR 1.71, 95%CI 1.10-2.66) had a significantly higher risk of resistance than other immigrants. In addition, the risk was the highest for younger TB patients and patients with reactivated disease (adjusted OR 2.12, 95%CI 1.09-4.09).
The risk of drug resistance was the highest among foreign-born patients from Vietnam and the Philippines. These findings should assist clinicians in prescribing and tailoring anti-tuberculosis regimens for immigrants more appropriately.