Is quarterly cohort analysis useful for assessing treatment outcomes in a low incidence country?

In the Czech Republic, a country regarded as having a low incidence of tuberculosis (TB), short-course chemotherapy (SCC) of TB has been implemented in routine practice country-wide.To assess the outcome of SCC by quarterly cohort analysis of patients using the methodology recommended by the World Health Organization (WHO).Patients with newly detected bacteriologically confirmed pulmonary TB notified in 1998 were treated according to local recommendations (SCC) or with the WHO-recommended DOTS strategy. The type of chemotherapy and its outcome were evaluated 12 months later by quarterly cohort analysis.A total of 731 patients with bacteriologically confirmed pulmonary TB, 403 of them smear-positive, were assessed. The proportion of those treated under the DOTS strategy increased from 56.2% to 75.1%. Favourable treatment outcomes (cure or treatment completed) were achieved in 69.0% of patients in the first quarter and 74.0% in the fourth quarter. Only four treatment failures and 21 defaulters were recorded. A total of 129 patients (15-21% in different cohorts) died before or during treatment, mostly from causes not connected with TB. If this proportion were not taken into account, treatment efficacy would have attained 85%.Analysis of SCC based on quarterly cohorts proved feasible in routine conditions in a country with a low incidence of TB and ongoing TB control, and provided more information than once yearly analysis.