By the end of 2000, close to two million immigrants were residing in the Netherlands, of a total population of nearly 16 million. Among the immigrant population, 2,661 patients with pulmonary tuberculosis were identified during 1996–2000. Information about country of origin and time since immigration was missing in 3% and 13% of the study patients, respectively, and was accounted for by multiple imputation (five times) to avoid bias in the calculation of incidence rates, relative risks, and confidence intervals (1). For country of origin and time since immigration, all information presented is based on the average number of cases in the imputed datasets. Incidence rates were only calculated for the 2,005 patients in.
