Tuberculosis in Malta : comparisons between the young and elderly in a low incidence country

Background: Malta has one of the lowest reported incidence rates of tuberculosis in Western Europe, and was approaching the elimination phase. It was observed that a disproportionate number of cases were occurring among persons of advanced age. Objective: To investigate the epidemiology of tuberculosis in the elderly Malta-born population. Methods: A retrospective review of national TB surveillance data from 1995 to 2005 with estimation of 11-year means. Age stratified comparisons between the general, the younger, and the elderly Malta-born populations were made. Results: One hundred and seventeen Malta-born patients were included in the study; 99% of all notified cases. The mean stratified incidence rates of TB among the general population, those less than 65 years of age, and the elderly (65 years and over) were 2.8, 1.6, and 10.6 per 100,000 person-years respectively. When the study sample was stratified into 15-year age groups, their mean TB incidence showed an exponential increase. All major age groups showed a fall in incidence, with the elderly group featuring the steepest decline of about 5% per year. The stratified incidence ratio of males to females, and pulmonary to extra-pulmonary TB was greatest in the elderly. Relapse occurred more commonly amongst elderly males. Conclusion: Contrasting age-stratified differences in incidence, gender, site, relapse, and mortality rates were discovered between the two major age groups, with the elderly forming a sub-population with distinct TB-related characteristics. Thus, the elderly, even when living in very low TB-incidence regions, should receive particular consideration.