Drug resistance study of Mycobacterium tuberculosis in Canada, February 1, 1993 to January 31, 1994.

OBJECTIVE: To estimate the prevalence of resistance of Mycobacterium tuberculosis to first-line antituberculosis drugs in Canada. METHODS: M. tuberculosis isolates from one third of all culture-positive tuberculosis (TB) cases diagnosed between February 1, 1993 to January 31, 1994 in Canada were collected prospectively. Proportion of drug-resistant isolates and the factors related to drug resistance were measured. RESULTS: Of 458 study cases, 40 (8.7%) had resistance to at least one first-line antituberculosis drug, of which 5.9% had mono-resistance, 0.7% had multidrug-resistance(MDR-TB)--i.e., resistance to at least isoniazid and rifampin--and 2.2% had other patterns. The overall prevalence of resistance among the foreign-born cases was 10.6% with the highest level among those who resided in Canada for less than four years (15.5%). CONCLUSIONS: Canada has a relatively low prevalence of antituberculosis drug resistance and a very low prevalence of MDR-TB. Some new immigrants to Canada may be at higher risk for drug resistance and their initial treatment needs to be tailored accordingly.

Cigarette smoking and peripheral arterial occlusive disease.

BACKGROUND: The importance of cigarette smoking in the etiology of peripheral arterial occlusive disease is well known, but there have been few studies that have quantified this relationship. METHODS: A case-control study design was used in which the case subjects were men with a history of claudication for at least 1 year and abnormal findings on noninvasive blood flow studies or on arteriography; control subjects were men attending the same hospital for conditions other than cancer, with no history of cancer or vascular disease and with a normal ankle-brachial index. Case and control subjects were interviewed by a trained nurse interviewer using a pilot-tested questionnaire. Current smoking status was confirmed by serum cotinine level estimation. Univariate odds ratios for smoking and other potential risk factors were calculated, and their significance was tested by comparison with the chi-squared distribution. Logistic regression analysis was used to adjust the effect of smoking for confounding variables, and the regression equation was used to estimate the proportion of disease attributable to smoking. RESULTS: Of the patients approached, 94% of the eligible case subjects and 93% of the eligible control subjects agreed to participate. Recruitment ended with 102 cases of peripheral arterial occlusive disease and 99 controls. Most of the control subjects were attending clinics for other surgical specialties. Compared with men who had never smoked the relative risk was 7 for exsmokers and 16 for current smokers (p < 0.001). The relative risk increased directly with the lifetime number of cigarettes smoked, the chi-squared test for trend being highly significant (p < 0.001). Age, lipoprotein concentration, body mass index, and history of hypertension or heart disease were also significant risk factors. CONCLUSIONS: After adjustment for confounding variables the estimate of the fraction of disease attributable to smoking was 76%.